Idiopathic normal-pressure hydrocephalus (INPH) is an adult-onset syndrome of uncertain origin that involves excessive enlargement of the cerebral ventricles. It is considered a potentially treatable neurological disorder by shunt surgery and characterized by a triad of symptoms including gait disturbance, cognitive impairment and urinary dysfunction. Although disorders of white matter are generally viewed as the principal pathological features of INPH, analysis of cortical features are important since the destruction of neural tracts could be associated with cortical structural changing. The aim of the study was to determine whether there was any relationship between gait pattern and structural features of cerebral cortex in INPH patients.
A computer-based, 5.8-m-long, pressure-sensitive carpet system (GAITRite, CIR System, Havertown, PA) was used to assess gait. Gait parameters were measured as follows: step width (distance of the same feet (cm)), toe in/out angle, coefficient of variation (CV) value of stride length (distance of the same foot (cm)), CV value of stride time. The CV value of stride time and stride length were calculated as follows: standard deviation of parameter × 100/mean of parameter. After brain MRI was obtained from 38 patients with INPH, individual images were registered in stereotaxic space and classified into white matter (WM), gray matter (GM), and cerebrospinal fluid (CSF). Hemispheric cortical surfaces were automatically extracted from each MR volume, which reconstructed the inner cortical surface by deforming a spherical mesh onto the WM/GM boundary and then expanded the deformable model to the GM/CSF boundary. Then, cortical thickness was measured by calculating the Euclidean distance between surfaces and cortical surface area was measured by calculating the voronoi diagram in each vertex. Cortical volume was measured from thickness and area. All statistical analyses were performed with Surfstat toolbox of MATLAB 2017 (https://www.math.mcgill.ca/keith/surfstat/) and IBM SPSS statistic 19.
Gait disturbances were positively correlated with postcentral gyrus, left precentral gyrus, left posterior parietal cortex, left insula, right superior frontal gyrus. These results showed that it would be related to reactive gliosis, structural changes in the cerebral cortex of INPH patients. Our results can provide the basis for differential diagnosis of INPH patients through gait analysis which would be used as a new diagnostic tool.