Association of right precuneus compression with apathy in idiopathic normal pressure hydrocephalus: A case control study

Background: Idiopathic normal pressure hydrocephalus (iNPH) is a slowly progressive syndrome caused by the excessive accumulation of cerebrospinal fluid and is typically characterized by the triad of cognitive, gait, and urinary disturbances and ventricular dilation. In addition to this triad of symptoms, apathy is frequently observed in iNPH and worsens the cognitive impairment and gait disturbance. Although apathy is an important symptom in iNPH, its neurological basis remains unknown. Objectives: This study aimed to analyze and elucidate the brain regions associated with apathy in iNPH using statistical imaging analysis and to investigate regional cerebral blood flow and regional gray matter volume, which indicates gray matter compression, in a whole-brain study. Methods: Twenty seven patients with iNPH were assigned to two groups based on their scores on the Neuropsychiatric Inventory items related with apathy; 18 patients were assigned to the group with apathy (iNPH + APA) and 9 to the group without apathy (iNPH - APA). The magnetic resonance images and cerebral blood flow single-photon emission computed tomography data of the two groups were compared using statistical parametric mapping 12. Results: The regional gray matter volume of the right precuneus was significantly larger in the iNPH + APA group than in the iNPH − APA group, but the and regional cerebral blood flow in any region of the brain was not significantly different between the two groups. Conclusion: These results suggested that compression of the precuneus might be involved in apathy in iNPH and the importance of brain compression in iNPH symptoms. In addition, this study also shows that VBM is useful for indicating the degree of brain compression.