Cumulative Corticospinal Pathway Disruption after Recurrent Brainstem and Anterior Circulation Stroke Presenting as Bilateral Motor Deficit: A Case Report

Cumulative Corticospinal Pathway Disruption after Recurrent Brainstem and Anterior Circulation Stroke Presenting as Bilateral Motor Deficit: A Case Report | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Case Report Cumulative Corticospinal Pathway Disruption after Recurrent Brainstem and Anterior Circulation Stroke Presenting as Bilateral Motor Deficit: A Case Report Rinisha Das T P, Avinash Krishnan, Binoy Mathew K V, Gladies Kamalam S, and 1 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-9016645/v1 This work is licensed under a CC BY 4.0 License Status: Posted Version 1 posted You are reading this latest preprint version Abstract Background Brainstem infarctions are relatively uncommon but often result in significant neurological deficits due to the dense concentration of motor pathways within a limited anatomical space. Bilateral motor weakness following stroke is rare and usually associated with extensive supratentorial or bilateral brainstem involvement. Case Presentation: We report the case of a 56-year-old male with multiple vascular risk factors, including type 2 diabetes mellitus, hypertension, dyslipidaemia, and double-vessel coronary artery disease, who developed an unusual pattern of asymmetric bilateral lower limb weakness with bilateral foot drop following recurrent strokes. In 2018, magnetic resonance imaging revealed acute infarcts involving the bilateral anterosuperior medulla and right paramedianpontomedullary junction, presenting as left hemiparesis. In 2022, he experienced a recurrent vascular event with near-total occlusion of the right internal carotid artery confirmed on angiography. Subsequent to this event, he developed bilateral lower limb weakness, more pronounced on the left, accompanied by bilateral foot drop. Neurological examination demonstrated mild left lower limb spasticity, exaggerated reflexes, impaired coordination, and gait abnormalities with moderate fall risk, while cognition and higher mental functions were preserved. Nerve conduction studies excluded peripheral neuropathy, confirming a central origin of the deficit. Discussion The sequential involvement of the medulla at the level of pyramidal decussation and later anterior circulation compromise likely resulted in cumulative disruption of corticospinal pathways. Partial injury to decussating fibres during the initial brainstem infarct may have created bilateral motor vulnerability, which was further unmasked by reduced cortical motor drive following right internal carotid artery occlusion. Conclusion This case highlights the cumulative and dynamic nature of recurrent stroke, emphasizing the importance of detailed neuroanatomical correlation and individualized, task-oriented rehabilitation to optimize functional recovery in atypical bilateral motor presentations. Physical Medicine & Rehab Neurology Stroke Brainstem Infarct Internal Carotid Artery Neurology Rehabilitation Figures Figure 1 Introduction Stroke is a major global health threat, causing around 7 million deaths each year. It is the second leading cause of death worldwide and a leading cause of long-term disability, responsible for over 160 million disability-adjusted life years lost globally. [ 1 ] Most new strokes worldwide are ischemic, accounting for about 65% of cases. Intracerebral haemorrhage makes up nearly 29%, while subarachnoid haemorrhage accounts for about 6%. Ischemic strokes are especially more common in high-income countries. [ 2 ] In 1970, the World Health Organization defined stroke as a condition in which symptoms of brain dysfunction develop suddenly, last more than 24 hours (or result in death), and have no cause other than a problem with the blood vessels supplying the brain. [ 3 ] Brainstem infarction occurs when part of the brainstem is damaged due to reduced blood flow or bleeding. Blockage or narrowing of the posterior circulation can significantly reduce blood supply to this area. [ 4 ] The most common causes include atherosclerosis, thromboembolism, lipohyalinosis, tumours, arterial dissection, and trauma. In cases of medulla oblongata infarction, about 73% are linked to vertebral artery stenosis, 26% to arterial dissection, and the remaining cases are mainly due to cardioembolic causes. [ 5 ] The pons is the most common site of brainstem stroke, accounting for about 60% of brainstem infarctions. Brainstem infarcts make up roughly 11% of all ischemic strokes. By location, 27% involve the pons, 14% the medulla, and 7% the midbrain, while isolated pontine infarcts account for about 3% of all ischemic strokes. [ 6 ] Brainstem infarctions account for a small proportion of ischemic strokes but are associated with significant neurological morbidity due to the dense concentration of neural tracts. [ 7 ] The medulla contains corticospinal tracts before and during pyramidal decussation, and lesions in this region can produce bilateral motor weakness. [ 8 ] The pontomedullary junction contains descending motor fibres essential for voluntary movement and postural control. [ 9 ] Internal carotid artery strokes commonly involve structures in the anterior circulation, including the motor cortex and the internal capsule. Damage to these regions may result in contralateral motor weakness due to involvement of the corticospinal tract. [ 10 ] This case report describes a patient with recurrent brainstem and right internal carotid artery strokes who developed an unusual pattern of asymmetric bilateral lower limb weakness and foot drop. Clinical findings A 56-year-old, moderately built, right-hand dominant male, a known case of type 2 diabetes mellitus, systemic hypertension, dyslipidaemia, and double-vessel coronary artery disease, presented with residual neurological deficits following recurrent stroke. He was on regular medical management for his comorbid conditions. In December 2018, at the age of 49 years, he developed sudden onset weakness of the left upper and lower limbs. Magnetic resonance imaging of the brain revealed acute infarcts involving the bilateral anterosuperior medulla oblongata and the right paramedianpontomedullary junction. He was diagnosed with cerebrovascular accident presenting as left hemiparesis secondary to brainstem infarction and was managed medically, following which he was discharged in stable condition with residual weakness and underwent conventional physiotherapy. In September 2022, he experienced another neurological episode suggestive of a transient ischemic attack. Further imaging revealed severe stenosis with near-total occlusion of the right internal carotid artery, and digital subtraction angiography confirmed complete occlusion of the right internal carotid artery with established collateral circulation. Following this recurrent vascular event, the patient developed bilateral lower limb weakness associated with bilateral foot drop, initially reported as more severe on the left. At present evaluation, the patient is conscious, cooperative, and well oriented to time, place, and person, with preserved speech, cognition and higher mental functions. Cranial nerve examination reveals no active deficits. Motor examination demonstrates increased tone in the left lower limb, graded as mild spasticity (grade 1) on the modified Ashworth scale, with an extension synergy pattern. According to Brunnstromstaging, the left lower limb is categorized as stage 3, while the right lower limb is in stage 4. Manual muscle testing revealsbilateral weakness, predominantly affecting the left side, with hip flexors and knee extensors graded 4/5 on the right and 3/5 on the left; ankle dorsiflexors are graded 3/5 on the right and 2/5 on the left, consistent with a severe left-sided foot drop. The deep tendon reflexes demonstrate an exaggerated left knee jerk, a normal right knee jerk, and bilateral exaggerated ankle jerks. Sensory examination is intact for both superficial and deep sensations. Coordination testing reveals marked impairment of heel-to-shin performance on the left side, characterised by reduced smoothness, slowed execution, and poor motor control, while the right side exhibits mild incoordination; rapid alternating movements are decreased in speed and rhythm on the left.Postural assessment demonstrates trunk deviation towards the right side and left side hip hiking, extension of the left knee with asymmetrical weight bearing. Gait analysis reveals bilateral foot drop (left greater than right), left side hip hiking, reduced push-off, decreased gait speed, and dynamic balance impairment. TheBerg balance scale score is 31/56, indicating moderate fall risk; the National Institutes of Health(NIH )stroke scale score is 2/42, suggestive of minor stroke severity; and the functional independence (FIM) score is 124/126, reflecting near-complete functional independence. Investigationsreveal that neuroimaging findings support the clinical presentation. MRI of the brain (27/12/2018) reveals acute infarcts involving the bilateral anterosuperior medulla oblongata and the right paramedianpontomedullary junction, consistent with brainstem stroke. Follow–up MRI with MRA (1/09/2022) demonstrates chronic gliotic changes in the anterior medulla with significant right internal carotid artery stenosis (60%-70%) and a focal near-total occlusion segment, along with mild narrowing of the bilateral middle cerebral arteries. A Nerve conduction study (20/04/2019) shows no evidence of peripheral neuropathy, confirming the central (UMN) origin of the motor deficit. A recent cardiology evaluation (4/08/2025) reveals double-vessel coronary artery disease with preserved left ventricular function, and the patient is medically stable for monitored physiotherapy rehabilitation. The components of the individualized protocol designed for client are depicted in Table 1 Table 1 individualized protocol Sl.no Type of exercise Specification Progression Remarks 1 Stretching Gentle passive stretching of quadriceps, hamstrings, gastrocnemius and soleus; avoid breath holding. Gradually increasing hold time (no forceful stretching) 2–3 sets; 8–10 reps; hold 15–20 sec; rest 30 sec 2 Bed ROM exercises Active-assisted and active ROM exercises for hip, knee and ankle Add minimal resistance(1kg weights on both lower limbs) 1–2 sets; 10–15 reps; rest 45 sec 3 Bridging Supine bridging using body weight Increased repetitions(increased in to 10–15 reps) 2 sets; 8–10 reps; hold 3–5 sec; rest 1 min 4 Ankle strengthening Light resisted concentric-eccentric strengthening of tibialis anterior(using yellow Thera band) Increase repetition (10–15 reps), increased Thera band resistance (blue Thera band) 2–3 sets; 10 reps; rest 45 sec 5 Dynamic core stretching Trunk rotation, side bending, and forward-backward stretches to enhance trunk control, postural alignment, and gait efficiency. nil 2sets; 8–10 reps; rest 30–45 sec 6 Sit-to-supine/bed mobility Practicing transitions from sitting at the edge of the bed to supine position to promote trunk control, coordination, and safe bed mobility nil 8–10 reps; rest 1min 7 Marching in sitting Focus on hip flexion and knee lift Increased duration slowly(3 sets) 1–2 sets; 8–10 reps; rest 1min 8 Sit-to-stand Standing without support, arm crossed over the chest, to improve postural control, trunk stability, and equilibrium Increased duration slowly(3 sets) 1–2 sets; 8–10 rep; rest 1 min 9 Single-leg-stance Performed bilaterally with support, to improve postural stability, and coordination Reduction of support 1–2 sets each side; hold 15–20 sec; rest 1 min 10 Tandem standing Performed with support, to challenge balance, improve postural control, and enhance coordination Reduction of support 1sets; 10 reps; hold 20 sec; rest 1 min 11 Squatting (mini squats) Strengthening hip and knee extensors, improve balance, and reduction of extension synergy pattern. Increase repetition(10-15reps) 1–2 sets; 8–10 reps; rest 2 min 12 Marching in standing Strengthening both lower limb Increase duration to 45 sec 2 sets; 20–30 sec; rest 1 min 13 Step climbing(low step height) Step-up and step-down to strengthen the hip, knee and ankle, improve balance and coordination, and encourage weight-bearing on both limbs. Increase repetition(10–15 reps) 2 sets; 8–10 reps; rest 2 min 14 Forward and backward walking To improve gait symmetry, dynamic balance, and coordination during swing and stance phases Increase duration more than 5 min 3–5 min; rest 2 min 15 Side walking To enhance lateral stability, strengthen hip abductors, and improve weight-shifting control Increase duration (3 round) 2 rounds; rest 1 min Discussion This case presents an unusual pattern of bilateral motor weakness following strokes in both the posterior and anterior circulations. The patient initially sustained infarcts in the bilateral anterosuperior medulla and right pontomedullary junction, followed later by complete occlusion of the right internal carotid artery. Together, these sequential vascular events provide a clear neuroanatomical basis for his current deficits. The combined impact on interconnected motor pathways explains the asymmetric bilateral lower limb weakness and bilateral foot drop. Brainstem infarctions account for a relatively small proportion of ischemic strokes. Still, they are associated with significant neurological morbidity due to the compact arrangement of ascending and descending tracts within a limited anatomical space. [ 11 ] The pons and medulla contain densely packed corticospinal fibres, and lesions in these regions may produce profound motor deficits even when radiologically small. [ 7 ] In particular, the medulla houses the corticospinal tracts at and around the level of the pyramidal decussation; infarction at this level may result in bilateral motor weakness, depending on the extent and symmetry of involvement. [ 12 ] Bilateral medial medullary infarctions, although rare, have been reported to produce quadriparesis or predominant bilateral lower-limb weakness due to involvement of crossing pyramidal fibres. [ 13 ] These findings correlate with the bilateral lower limb weakness observed in our subject. In addition to the direct corticospinal tract involvement at the level of the medulla, lesions affecting the pontomedullary junction may further compromise descending motor pathways, including reticulospinal and corticoreticular fibres that contribute to postural control and gait stability. Recent neuroanatomical and diffusion tensor imaging studies have demonstrated that disruption of these pathways can significantly impair lower limb motor coordination and balance, even in the absence of extensive supratentorial damage. [ 14 ] This may partly explain the patient’s persistent gait abnormalities, postural asymmetry, and moderate fall risk despite a relatively low NIH Stroke Scale score. The development of bilateral foot drop in this case is particularly noteworthy. Foot drop after stroke is most commonly unilateral and attributed to corticospinal tract lesions affecting ankle dorsiflexor control. [ 15 ] Bilateral presentation is uncommon and generally suggests either bilateral supratentorial lesions or combined supratentorial and infratentorial pathway involvement. [ 16 ] In the present case, the initial bilateral medullary involvement likely caused partial injury to decussating pyramidal fibres, while the subsequent right internal carotid artery occlusion may have further reduced cortical motor drive to the contralateral lower limb. The cumulative effect of these sequential insults could account for the asymmetric but bilateral dorsiflexor weakness. Chronic vascular risk factors such as diabetes mellitus, hypertension, dyslipidaemia, and coronary artery disease may have progressively impaired cerebral microvasculature, contributing to small vessel disease and reduced collateral efficiency. [ 17 ] This diminished neural reserve increases susceptibility to further ischemic injury. Current evidence suggests that recurrent strokes frequently produce cumulative or synergistic deficits rather than entirely new isolated impairments, particularly when pre-existing but compensated damage exists within shared motor networks. [ 18 ] Moreover, motor recovery after an initial stroke depends on neural plasticity and adaptive cortical reorganization; disruption of these compensatory pathways by a subsequent vascular event may result in disproportionate functional decline. [ 19 ] Overall, this case illustrates the cumulative and dynamic nature of stroke-related damage. Sequential involvement of the brainstem at the level of pyramidal decussation, followed by right internal carotid artery occlusion, likely compounded the disruption of bilateral motor pathways, producing the observed asymmetric bilateral lower limb weakness and foot drop. Recognizing these atypical bilateral presentations is critical not only for accurate neuroanatomical localization and prognostic assessment but also for designing individualised, targeted neurorehabilitation strategies that maximize functional recovery. Physiotherapy should focus on improving lower limb strength, selective motor control, and gait efficiency. Task-oriented training, such as sit-to-stand practice, weight shifting, and over-ground walking, can enhance functional recovery. Ankle dorsiflexor strengthening and the use of an ankle–foot orthosis may help manage bilateral foot drop. Balance stabilization exercises are crucial for reducing fall risk, enhancing balance, and improving overall mobility. Conclusion This case highlights how stroke-related deficits may evolve in a cumulative and sometimes unexpected manner when multiple vascular territories are involved over time. The patient’s initial bilateral medullary and pontomedullary infarctions likely caused partial disruption of corticospinal fibres at the level of pyramidal decussation. The subsequent right internal carotid artery occlusion appears to have further compromised cortical motor output. Together, these sequential events produced an unusual presentation of asymmetric bilateral lower limb weakness with bilateral foot drop—an uncommon clinical pattern that reflects the interconnected nature of central motor pathways. This presentation underscores the importance of careful neuroanatomical correlation in patients with recurrent stroke. It also highlights the need for individualized, targeted rehabilitation strategies to optimize functional recovery and long-term independence. Declarations The participant provided written informed consent for participating in the study and publish the clinical findings. References Feigin VL, Brainin M, Norrving B, Martins SO, Pandian J, Lindsay P, FGrupper M, Rautalin I (2025) World stroke organization: global stroke fact sheet 2025. Int J Stroke 20(2):132–144 Feigin VL, Abate MD, Abate YH, AbdElHafeez S, Abd-Allah F, Abdelalim A, Abdelkader A, Abdelmasseh M, Abd-Elsalam S, Abdi P, Abdollahi A (2024) Global, regional, and national burden of stroke and its risk factors, 1990–2021: a systematic analysis for the Global Burden of Disease Study 2021. Lancet Neurol 23(10):973–1003 Coupland AP, Thapar A, Qureshi MI, Jenkins H, Davies AH (2017) The definition of stroke. J R Soc Med 110(1):9–12 Gowda SN, Munakomi S, De Jesus O Brainstem stroke. InStatPearls [Internet] 2024 Feb 25. StatPearls Publishing Kameda W, Kawanami T, Kurita K, Daimon M, Kayama T, Hosoya T, Kato T (2004) Lateral and medial medullary infarction: a comparative analysis of 214 patients. Stroke 35(3):694–699 Teasell R, Foley N, Doherty T, Finestone H (2002) Clinical characteristics of patients with brainstem strokes admitted to a rehabilitation unit. Arch Phys Med Rehabil 83(7):1013–1016 Kumral E, Bayülkem G, Evyapan D (2002) Clinical spectrum of pontine infarction: clinical-MRI correlations. J Neurol 249(12):1659–1670 Standring S (2016) A brief history of topographical anatomy. J Anat 229(1):32–62 Blumenfeld H (2010 May) Neuroanatomy through clinical cases. Sinauer Associates, Sunderland Bogousslavsky J (2012) Manifestations Of Stroke. Front NeurolNeurosci 30:1–3 Caplan LR (1991) Migraine and vertebrobasilar ischemia. Neurology 41(1):55 Kim JS, Kim HG, Chung CS (1995) Medial medullary syndrome: report of 18 new patients and a review of the literature. Stroke 26(9):1548–1552 Toyoda K, Imamura T, Saku Y, Oita J, Ibayashi S, Minematsu K, Yamaguchi T, Fujishima M (1996) Medial medullary infarction: analyses of eleven patients. Neurology 47(5):1141–1147 Jang SH, Seo JP, Lee SJ (2019) Diffusion tensor tractography studies of central post-stroke pain due to the spinothalamic tract injury: a mini-review. Front Neurol 10:787 Tyson SF, Rogerson L (2009) Assistive walking devices in nonambulant patients undergoing rehabilitation after stroke: the effects on functional mobility, walking impairments, and patients' opinion. Arch Phys Med Rehabil 90(3):475–479 Li S (2020) Ankle and foot spasticity patterns in chronic stroke survivors with abnormal gait. Toxins 12(10):646 Wardlaw JM, Smith C, Dichgans M (2013) Mechanisms of sporadic cerebral small vessel disease: insights from neuroimaging. Lancet Neurol 12(5):483–497 Carrera E, Tononi G (2014) Diaschisis: past, present, future. Brain 137(9):2408–2422 Di Pino G, Pellegrino G, Assenza G, Capone F, Ferreri F, Formica D, Ranieri F, Tombini M, Ziemann U, Rothwell JC, Di Lazzaro V (2014) Modulation of brain plasticity in stroke: a novel model for neurorehabilitation. Nat Reviews Neurol 10(10):597–608 Additional Declarations The authors declare no competing interests. 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Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-9016645","acceptedTermsAndConditions":true,"allowDirectSubmit":true,"archivedVersions":[],"articleType":"Case Report","associatedPublications":[],"authors":[{"id":599763375,"identity":"a4ae6b3d-4181-4f75-9196-0aaaef0858b4","order_by":0,"name":"Rinisha Das T P","email":"","orcid":"https://orcid.org/0009-0008-1481-1863","institution":"KMCT College of Allied Health Sciences, Kozhikode, India","correspondingAuthor":false,"prefix":"","firstName":"Rinisha","middleName":"Das T","lastName":"P","suffix":""},{"id":599763376,"identity":"407a1815-8410-4e87-931a-6566aba66ac8","order_by":1,"name":"Avinash Krishnan","email":"","orcid":"https://orcid.org/0009-0008-1371-034X","institution":"Composite Regional Centre for Skill Development Rehabilitation and Empowerment of Persons with Disabilities, Kozhikode, India","correspondingAuthor":false,"prefix":"","firstName":"Avinash","middleName":"","lastName":"Krishnan","suffix":""},{"id":599763377,"identity":"14afda10-3e24-490a-8321-2f0aa154489e","order_by":2,"name":"Binoy Mathew K V","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAA4ElEQVRIiWNgGAWjYBACA2YQWfFfzv54A4hrQayWM8zGDGcOgLgSRGgBEYxtzIkNNxJATCK0mLPzHnzM28aW2Djz+dUNPwokGPjbuxPwarFs5ks25jnHY9wsnVN2swfoMIkzZzfgd9hhHjNpnjIJ2TbpnLQbPEAtBhK5xGhhM2DskTyTdvMP8VraEhRnSLAfu02ULZbNPMaGc84cMDbgyWG7LWMgwUPQL+b8ZwwfvKk4IGfAfvzZzTd/bOT423vxawEBJh4wxQOOIx6CykGA8QeYYn9AlOpRMApGwSgYeQAAXIND29lpQQgAAAAASUVORK5CYII=","orcid":"https://orcid.org/0000-0002-9637-1214","institution":"Composite Regional Centre for Skill Development Rehabilitation and Empowerment of Persons with Disabilities, Kozhikode, India","correspondingAuthor":true,"prefix":"","firstName":"Binoy","middleName":"Mathew K","lastName":"V","suffix":""},{"id":599763378,"identity":"d9d85349-0fa9-4464-8e6c-79a55688309f","order_by":3,"name":"Gladies Kamalam S","email":"","orcid":"https://orcid.org/0000-0001-9384-0380","institution":"KMCT College of Allied Health Sciences, Kozhikode, India","correspondingAuthor":false,"prefix":"","firstName":"Gladies","middleName":"Kamalam","lastName":"S","suffix":""},{"id":599763379,"identity":"9475c7db-6f50-45e2-98dc-74d5cf0d452e","order_by":4,"name":"Santheep S","email":"","orcid":"https://orcid.org/0009-0005-8715-6554","institution":"KMCT College of Allied Health Sciences, Kozhikode, India","correspondingAuthor":false,"prefix":"","firstName":"Santheep","middleName":"","lastName":"S","suffix":""}],"badges":[],"createdAt":"2026-03-03 06:34:30","currentVersionCode":1,"declarations":{"humanSubjects":true,"vertebrateSubjects":false,"conflictsOfInterestStatement":false,"humanSubjectEthicalGuidelines":true,"humanSubjectConsent":true,"humanSubjectClinicalTrial":false,"humanSubjectCaseReport":true,"vertebrateSubjectEthicalGuidelines":false},"doi":"10.21203/rs.3.rs-9016645/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-9016645/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":104396912,"identity":"e97b136a-4bd9-4f5a-a4a7-5853163ccb44","added_by":"auto","created_at":"2026-03-11 11:21:40","extension":"jpeg","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":643642,"visible":true,"origin":"","legend":"\u003cp\u003estep climbing\u003c/p\u003e","description":"","filename":"floatimage1.jpeg","url":"https://assets-eu.researchsquare.com/files/rs-9016645/v1/9080d9136eed25e82450ff90.jpeg"},{"id":104396933,"identity":"7a44f680-d879-4483-9444-a57ce2bed79e","added_by":"auto","created_at":"2026-03-11 11:21:56","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":1069419,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-9016645/v1/a251f98f-ef96-48ef-ab62-ef4a133895aa.pdf"}],"financialInterests":"The authors declare no competing interests.","formattedTitle":"\u003cp\u003eCumulative Corticospinal Pathway Disruption after Recurrent Brainstem and Anterior Circulation Stroke Presenting as Bilateral Motor Deficit: A Case Report\u003c/p\u003e","fulltext":[{"header":"Introduction","content":"\u003cp\u003eStroke is a major global health threat, causing around 7\u0026nbsp;million deaths each year. It is the second leading cause of death worldwide and a leading cause of long-term disability, responsible for over 160\u0026nbsp;million disability-adjusted life years lost globally. \u003csup\u003e[\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e]\u003c/sup\u003e Most new strokes worldwide are ischemic, accounting for about 65% of cases. Intracerebral haemorrhage makes up nearly 29%, while subarachnoid haemorrhage accounts for about 6%. Ischemic strokes are especially more common in high-income countries. \u003csup\u003e[\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e]\u003c/sup\u003e In 1970, the World Health Organization defined stroke as a condition in which symptoms of brain dysfunction develop suddenly, last more than 24 hours (or result in death), and have no cause other than a problem with the blood vessels supplying the brain. \u003csup\u003e[\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e]\u003c/sup\u003e\u003c/p\u003e \u003cp\u003eBrainstem infarction occurs when part of the brainstem is damaged due to reduced blood flow or bleeding. Blockage or narrowing of the posterior circulation can significantly reduce blood supply to this area.\u003csup\u003e[\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e]\u003c/sup\u003e The most common causes include atherosclerosis, thromboembolism, lipohyalinosis, tumours, arterial dissection, and trauma. In cases of medulla oblongata infarction, about 73% are linked to vertebral artery stenosis, 26% to arterial dissection, and the remaining cases are mainly due to cardioembolic causes. \u003csup\u003e[\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e]\u003c/sup\u003eThe pons is the most common site of brainstem stroke, accounting for about 60% of brainstem infarctions. Brainstem infarcts make up roughly 11% of all ischemic strokes. By location, 27% involve the pons, 14% the medulla, and 7% the midbrain, while isolated pontine infarcts account for about 3% of all ischemic strokes. \u003csup\u003e[\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e]\u003c/sup\u003e\u003c/p\u003e \u003cp\u003eBrainstem infarctions account for a small proportion of ischemic strokes but are associated with significant neurological morbidity due to the dense concentration of neural tracts. \u003csup\u003e[\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e]\u003c/sup\u003eThe medulla contains corticospinal tracts before and during pyramidal decussation, and lesions in this region can produce bilateral motor weakness. \u003csup\u003e[\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e]\u003c/sup\u003e The pontomedullary junction contains descending motor fibres essential for voluntary movement and postural control. \u003csup\u003e[\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e]\u003c/sup\u003e Internal carotid artery strokes commonly involve structures in the anterior circulation, including the motor cortex and the internal capsule. Damage to these regions may result in contralateral motor weakness due to involvement of the corticospinal tract. \u003csup\u003e[\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e]\u003c/sup\u003eThis case report describes a patient with recurrent brainstem and right internal carotid artery strokes who developed an unusual pattern of asymmetric bilateral lower limb weakness and foot drop.\u003c/p\u003e"},{"header":"Clinical findings","content":"\u003cp\u003eA 56-year-old, moderately built, right-hand dominant male, a known case of type 2 diabetes mellitus, systemic hypertension, dyslipidaemia, and double-vessel coronary artery disease, presented with residual neurological deficits following recurrent stroke. He was on regular medical management for his comorbid conditions. In December 2018, at the age of 49 years, he developed sudden onset weakness of the left upper and lower limbs. Magnetic resonance imaging of the brain revealed acute infarcts involving the bilateral anterosuperior medulla oblongata and the right paramedianpontomedullary junction. He was diagnosed with cerebrovascular accident presenting as left hemiparesis secondary to brainstem infarction and was managed medically, following which he was discharged in stable condition with residual weakness and underwent conventional physiotherapy.\u003c/p\u003e \u003cp\u003eIn September 2022, he experienced another neurological episode suggestive of a transient ischemic attack. Further imaging revealed severe stenosis with near-total occlusion of the right internal carotid artery, and digital subtraction angiography confirmed complete occlusion of the right internal carotid artery with established collateral circulation. Following this recurrent vascular event, the patient developed bilateral lower limb weakness associated with bilateral foot drop, initially reported as more severe on the left.\u003c/p\u003e \u003cp\u003eAt present evaluation, the patient is conscious, cooperative, and well oriented to time, place, and person, with preserved speech, cognition and higher mental functions. Cranial nerve examination reveals no active deficits. Motor examination demonstrates increased tone in the left lower limb, graded as mild spasticity (grade 1) on the modified Ashworth scale, with an extension synergy pattern. According to Brunnstromstaging, the left lower limb is categorized as stage 3, while the right lower limb is in stage 4. Manual muscle testing revealsbilateral weakness, predominantly affecting the left side, with hip flexors and knee extensors graded 4/5 on the right and 3/5 on the left; ankle dorsiflexors are graded 3/5 on the right and 2/5 on the left, consistent with a severe left-sided foot drop.\u003c/p\u003e \u003cp\u003eThe deep tendon reflexes demonstrate an exaggerated left knee jerk, a normal right knee jerk, and bilateral exaggerated ankle jerks. Sensory examination is intact for both superficial and deep sensations. Coordination testing reveals marked impairment of heel-to-shin performance on the left side, characterised by reduced smoothness, slowed execution, and poor motor control, while the right side exhibits mild incoordination; rapid alternating movements are decreased in speed and rhythm on the left.Postural assessment demonstrates trunk deviation towards the right side and left side hip hiking, extension of the left knee with asymmetrical weight bearing. Gait analysis reveals bilateral foot drop (left greater than right), left side hip hiking, reduced push-off, decreased gait speed, and dynamic balance impairment. TheBerg balance scale score is 31/56, indicating moderate fall risk; the National Institutes of Health(NIH )stroke scale score is 2/42, suggestive of minor stroke severity; and the functional independence (FIM) score is 124/126, reflecting near-complete functional independence.\u003c/p\u003e \u003cp\u003eInvestigationsreveal that neuroimaging findings support the clinical presentation. MRI of the brain (27/12/2018) reveals acute infarcts involving the bilateral anterosuperior medulla oblongata and the right paramedianpontomedullary junction, consistent with brainstem stroke. Follow\u0026ndash;up MRI with MRA (1/09/2022) demonstrates chronic gliotic changes in the anterior medulla with significant right internal carotid artery stenosis (60%-70%) and a focal near-total occlusion segment, along with mild narrowing of the bilateral middle cerebral arteries. A Nerve conduction study (20/04/2019) shows no evidence of peripheral neuropathy, confirming the central (UMN) origin of the motor deficit. A recent cardiology evaluation (4/08/2025) reveals double-vessel coronary artery disease with preserved left ventricular function, and the patient is medically stable for monitored physiotherapy rehabilitation.\u003c/p\u003e \u003cp\u003eThe components of the individualized protocol designed for client are depicted in Table \u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab1\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 1\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eindividualized protocol\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"5\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eSl.no\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eType of exercise\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eSpecification\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eProgression\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003eRemarks\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eStretching\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eGentle passive stretching of quadriceps, hamstrings, gastrocnemius and soleus; avoid breath holding.\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eGradually increasing hold time (no forceful stretching)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e2\u0026ndash;3 sets; 8\u0026ndash;10 reps; hold 15\u0026ndash;20 sec; rest 30 sec\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eBed ROM exercises\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eActive-assisted and active ROM exercises for hip, knee and ankle\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eAdd minimal resistance(1kg weights on both lower limbs)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e1\u0026ndash;2 sets; 10\u0026ndash;15 reps; rest 45 sec\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eBridging\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eSupine bridging using body weight\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eIncreased repetitions(increased in to 10\u0026ndash;15 reps)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e2 sets; 8\u0026ndash;10 reps; hold 3\u0026ndash;5 sec; rest 1 min\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eAnkle strengthening\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eLight resisted concentric-eccentric strengthening of tibialis anterior(using yellow Thera band)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eIncrease repetition (10\u0026ndash;15 reps), increased Thera band resistance (blue Thera band)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e2\u0026ndash;3 sets; 10 reps; rest 45 sec\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eDynamic core stretching\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eTrunk rotation, side bending, and forward-backward stretches to enhance trunk control, postural alignment, and gait efficiency.\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003enil\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e2sets; 8\u0026ndash;10 reps; rest 30\u0026ndash;45 sec\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eSit-to-supine/bed mobility\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003ePracticing transitions from sitting at the edge of the bed to supine position to promote trunk control, coordination, and safe bed mobility\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003enil\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e8\u0026ndash;10 reps; rest 1min\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e7\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eMarching in sitting\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eFocus on hip flexion and knee lift\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eIncreased duration slowly(3 sets)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e1\u0026ndash;2 sets; 8\u0026ndash;10 reps; rest 1min\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e8\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eSit-to-stand\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eStanding without support, arm crossed over the chest, to improve postural control, trunk stability, and equilibrium\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eIncreased duration slowly(3 sets)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e1\u0026ndash;2 sets; 8\u0026ndash;10 rep; rest 1 min\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e9\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eSingle-leg-stance\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003ePerformed bilaterally with support, to improve postural stability, and coordination\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eReduction of support\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e1\u0026ndash;2 sets each side; hold 15\u0026ndash;20 sec; rest 1 min\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e10\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eTandem standing\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003ePerformed with support, to challenge balance, improve postural control, and enhance coordination\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eReduction of support\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e1sets; 10 reps; hold 20 sec; rest 1 min\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e11\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eSquatting (mini squats)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eStrengthening hip and knee extensors, improve balance, and reduction of extension synergy pattern.\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eIncrease repetition(10-15reps)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e1\u0026ndash;2 sets; 8\u0026ndash;10 reps; rest 2 min\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e12\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eMarching in standing\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eStrengthening both lower limb\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eIncrease duration to 45 sec\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e2 sets; 20\u0026ndash;30 sec; rest 1 min\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e13\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eStep climbing(low step height)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eStep-up and step-down to strengthen the hip, knee and ankle, improve balance and coordination, and encourage weight-bearing on both limbs.\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eIncrease repetition(10\u0026ndash;15 reps)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e2 sets; 8\u0026ndash;10 reps; rest 2 min\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e14\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eForward and backward walking\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eTo improve gait symmetry, dynamic balance, and coordination during swing and stance phases\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eIncrease duration more than 5 min\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e3\u0026ndash;5 min; rest 2 min\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e15\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eSide walking\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eTo enhance lateral stability, strengthen hip abductors, and improve weight-shifting control\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eIncrease duration\u003c/p\u003e \u003cp\u003e(3 round)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e2 rounds; rest 1 min\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003e \u003c/p\u003e"},{"header":"Discussion","content":"\u003cp\u003eThis case presents an unusual pattern of bilateral motor weakness following strokes in both the posterior and anterior circulations. The patient initially sustained infarcts in the bilateral anterosuperior medulla and right pontomedullary junction, followed later by complete occlusion of the right internal carotid artery. Together, these sequential vascular events provide a clear neuroanatomical basis for his current deficits. The combined impact on interconnected motor pathways explains the asymmetric bilateral lower limb weakness and bilateral foot drop.\u003c/p\u003e \u003cp\u003eBrainstem infarctions account for a relatively small proportion of ischemic strokes. Still, they are associated with significant neurological morbidity due to the compact arrangement of ascending and descending tracts within a limited anatomical space. \u003csup\u003e[\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e]\u003c/sup\u003eThe pons and medulla contain densely packed corticospinal fibres, and lesions in these regions may produce profound motor deficits even when radiologically small. \u003csup\u003e[\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e]\u003c/sup\u003eIn particular, the medulla houses the corticospinal tracts at and around the level of the pyramidal decussation; infarction at this level may result in bilateral motor weakness, depending on the extent and symmetry of involvement. \u003csup\u003e[\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e]\u003c/sup\u003e Bilateral medial medullary infarctions, although rare, have been reported to produce quadriparesis or predominant bilateral lower-limb weakness due to involvement of crossing pyramidal fibres. \u003csup\u003e[\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e]\u003c/sup\u003eThese findings correlate with the bilateral lower limb weakness observed in our subject.\u003c/p\u003e \u003cp\u003eIn addition to the direct corticospinal tract involvement at the level of the medulla, lesions affecting the pontomedullary junction may further compromise descending motor pathways, including reticulospinal and corticoreticular fibres that contribute to postural control and gait stability. Recent neuroanatomical and diffusion tensor imaging studies have demonstrated that disruption of these pathways can significantly impair lower limb motor coordination and balance, even in the absence of extensive supratentorial damage.\u003csup\u003e[\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e]\u003c/sup\u003e This may partly explain the patient\u0026rsquo;s persistent gait abnormalities, postural asymmetry, and moderate fall risk despite a relatively low NIH Stroke Scale score.\u003c/p\u003e \u003cp\u003eThe development of bilateral foot drop in this case is particularly noteworthy. Foot drop after stroke is most commonly unilateral and attributed to corticospinal tract lesions affecting ankle dorsiflexor control.\u003csup\u003e[\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e]\u003c/sup\u003e Bilateral presentation is uncommon and generally suggests either bilateral supratentorial lesions or combined supratentorial and infratentorial pathway involvement.\u003csup\u003e[\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e]\u003c/sup\u003e In the present case, the initial bilateral medullary involvement likely caused partial injury to decussating pyramidal fibres, while the subsequent right internal carotid artery occlusion may have further reduced cortical motor drive to the contralateral lower limb. The cumulative effect of these sequential insults could account for the asymmetric but bilateral dorsiflexor weakness.\u003c/p\u003e \u003cp\u003eChronic vascular risk factors such as diabetes mellitus, hypertension, dyslipidaemia, and coronary artery disease may have progressively impaired cerebral microvasculature, contributing to small vessel disease and reduced collateral efficiency.\u003csup\u003e[\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e]\u003c/sup\u003e This diminished neural reserve increases susceptibility to further ischemic injury. Current evidence suggests that recurrent strokes frequently produce cumulative or synergistic deficits rather than entirely new isolated impairments, particularly when pre-existing but compensated damage exists within shared motor networks. \u003csup\u003e[\u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e]\u003c/sup\u003e Moreover, motor recovery after an initial stroke depends on neural plasticity and adaptive cortical reorganization; disruption of these compensatory pathways by a subsequent vascular event may result in disproportionate functional decline. \u003csup\u003e[\u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e]\u003c/sup\u003e\u003c/p\u003e \u003cp\u003eOverall, this case illustrates the cumulative and dynamic nature of stroke-related damage. Sequential involvement of the brainstem at the level of pyramidal decussation, followed by right internal carotid artery occlusion, likely compounded the disruption of bilateral motor pathways, producing the observed asymmetric bilateral lower limb weakness and foot drop. Recognizing these atypical bilateral presentations is critical not only for accurate neuroanatomical localization and prognostic assessment but also for designing individualised, targeted neurorehabilitation strategies that maximize functional recovery.\u003c/p\u003e \u003cp\u003ePhysiotherapy should focus on improving lower limb strength, selective motor control, and gait efficiency. Task-oriented training, such as sit-to-stand practice, weight shifting, and over-ground walking, can enhance functional recovery. Ankle dorsiflexor strengthening and the use of an ankle\u0026ndash;foot orthosis may help manage bilateral foot drop. Balance stabilization exercises are crucial for reducing fall risk, enhancing balance, and improving overall mobility.\u003c/p\u003e"},{"header":"Conclusion","content":"\u003cp\u003eThis case highlights how stroke-related deficits may evolve in a cumulative and sometimes unexpected manner when multiple vascular territories are involved over time. The patient\u0026rsquo;s initial bilateral medullary and pontomedullary infarctions likely caused partial disruption of corticospinal fibres at the level of pyramidal decussation. The subsequent right internal carotid artery occlusion appears to have further compromised cortical motor output. Together, these sequential events produced an unusual presentation of asymmetric bilateral lower limb weakness with bilateral foot drop\u0026mdash;an uncommon clinical pattern that reflects the interconnected nature of central motor pathways. This presentation underscores the importance of careful neuroanatomical correlation in patients with recurrent stroke. It also highlights the need for individualized, targeted rehabilitation strategies to optimize functional recovery and long-term independence.\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003eThe participant provided written informed consent for participating in the study and publish the clinical findings.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\u003cli\u003e\u003cspan\u003eFeigin VL, Brainin M, Norrving B, Martins SO, Pandian J, Lindsay P, FGrupper M, Rautalin I (2025) World stroke organization: global stroke fact sheet 2025. 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StatPearls Publishing\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eKameda W, Kawanami T, Kurita K, Daimon M, Kayama T, Hosoya T, Kato T (2004) Lateral and medial medullary infarction: a comparative analysis of 214 patients. Stroke 35(3):694\u0026ndash;699\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eTeasell R, Foley N, Doherty T, Finestone H (2002) Clinical characteristics of patients with brainstem strokes admitted to a rehabilitation unit. Arch Phys Med Rehabil 83(7):1013\u0026ndash;1016\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eKumral E, Bay\u0026uuml;lkem G, Evyapan D (2002) Clinical spectrum of pontine infarction: clinical-MRI correlations. J Neurol 249(12):1659\u0026ndash;1670\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eStandring S (2016) A brief history of topographical anatomy. 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Nat Reviews Neurol 10(10):597\u0026ndash;608\u003c/span\u003e\u003c/li\u003e\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":true,"hideJournal":true,"highlight":"","institution":"Composite Regional Centre for Skill Development Rehabilitation and Empowerment of Persons with Disabilities,Kozhikode,India ","isAcceptedByJournal":false,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true},"keywords":"Stroke, Brainstem Infarct, Internal Carotid Artery, Neurology, Rehabilitation","lastPublishedDoi":"10.21203/rs.3.rs-9016645/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-9016645/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003e\u003cb\u003eBackground\u003c/b\u003e\u003c/p\u003e \u003cp\u003eBrainstem infarctions are relatively uncommon but often result in significant neurological deficits due to the dense concentration of motor pathways within a limited anatomical space. Bilateral motor weakness following stroke is rare and usually associated with extensive supratentorial or bilateral brainstem involvement.\u003c/p\u003e\u003cp\u003e\u003cb\u003eCase Presentation:\u003c/b\u003e\u003c/p\u003e \u003cp\u003eWe report the case of a 56-year-old male with multiple vascular risk factors, including type 2 diabetes mellitus, hypertension, dyslipidaemia, and double-vessel coronary artery disease, who developed an unusual pattern of asymmetric bilateral lower limb weakness with bilateral foot drop following recurrent strokes. In 2018, magnetic resonance imaging revealed acute infarcts involving the bilateral anterosuperior medulla and right paramedianpontomedullary junction, presenting as left hemiparesis. In 2022, he experienced a recurrent vascular event with near-total occlusion of the right internal carotid artery confirmed on angiography. Subsequent to this event, he developed bilateral lower limb weakness, more pronounced on the left, accompanied by bilateral foot drop. Neurological examination demonstrated mild left lower limb spasticity, exaggerated reflexes, impaired coordination, and gait abnormalities with moderate fall risk, while cognition and higher mental functions were preserved. Nerve conduction studies excluded peripheral neuropathy, confirming a central origin of the deficit.\u003c/p\u003e\u003cp\u003e\u003cb\u003eDiscussion\u003c/b\u003e\u003c/p\u003e \u003cp\u003eThe sequential involvement of the medulla at the level of pyramidal decussation and later anterior circulation compromise likely resulted in cumulative disruption of corticospinal pathways. Partial injury to decussating fibres during the initial brainstem infarct may have created bilateral motor vulnerability, which was further unmasked by reduced cortical motor drive following right internal carotid artery occlusion.\u003c/p\u003e\u003cp\u003e\u003cb\u003eConclusion\u003c/b\u003e\u003c/p\u003e \u003cp\u003eThis case highlights the cumulative and dynamic nature of recurrent stroke, emphasizing the importance of detailed neuroanatomical correlation and individualized, task-oriented rehabilitation to optimize functional recovery in atypical bilateral motor presentations.\u003c/p\u003e","manuscriptTitle":"Cumulative Corticospinal Pathway Disruption after Recurrent Brainstem and Anterior Circulation Stroke Presenting as Bilateral Motor Deficit: A Case Report","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2026-03-11 11:21:35","doi":"10.21203/rs.3.rs-9016645/v1","editorialEvents":[{"type":"communityComments","content":0}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"0c18f72d-f49d-4753-b9b0-ec8773371e73","owner":[],"postedDate":"March 11th, 2026","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"posted","subjectAreas":[{"id":63820845,"name":"Physical Medicine \u0026 Rehab"},{"id":63820846,"name":"Neurology"}],"tags":[],"updatedAt":"2026-03-11T11:21:35+00:00","versionOfRecord":[],"versionCreatedAt":"2026-03-11 11:21:35","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-9016645","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-9016645","identity":"rs-9016645","version":["v1"]},"buildId":"XKTyCvWXoU3ODBz1xrDgd","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}