Functional and magnetic resonance imaging correlates of corpus callosum in normal pressure hydrocephalus before and after shunting

Background: Normal pressure hydrocephalus (NPH) is associated with corpus callosum abnormalities. Objectives: To study the clinical and neuropsychological effect of callosal thinning in 18 patients with idiopathic NPH and to investigate the postsurgical callosal changes in 14 patients. Methods: Global corpus callosum size and seven callosal subdivisions were measured. Neuropsychological assessment included an extensive battery assessing memory, psychomotor speed, visuospatial and frontal lobe functioning. Results: After surgery, patients showed improvements in memory, visuospatial and frontal lobe functions, and psychomotor speed. Two frontal corpus callosum areas, the genu and the rostral body, were the regions most related to the clinical and neuropsychological dysfunction. After surgery, total corpus callosum and four of the seven subdivisions presented a significant increase in size, which was related to poorer neuropsychological and clinical outcome. Conclusion: The postsurgical corpus callosum increase might be the result of decompression, re-expansion and increase of interstitial fluid, although it may also be caused by differences in shape due to cerebral reorganisation.