Effects of chronic flexed wrist posture on the elasticity and crosssectional area of the median nerve at the carpal tunnel among chronic stroke patients.

Abstract

To investigate the effects of chronic flexed wrist posture following spasticity on the elasticity and cross-sectionalarea (CSA) of the median nerve at the carpal tunnel among chronic stroke patients. This prospectivestudy included 24 consecutive patients (mean age, 56.5±11.56 years) with unilateral wrist spasticity following a stroke in achronic phase. The CSA of the median nerve was measured by ultrasound (US). The elasticity was measured by Virtual Touchtissue imaging quantification (VTIQ; Siemens, Erlangen, Germany). SWV and CSA of the median nerves of the affected andunaffected sides for each patient were compared. The correlations between duration of time since the stroke, SWV and CSA of the median nerve were assessed. The interobserver agreement was assessed. The CSA of the median nerve at the affected side was significantly lower than that of the unaffected side (p = 0.03). The SWV of the median nerve at the affected side was significantly higher than that on the unaffected side (p < 0.001). The interobserver agreement was excellent for both CSA and SWV measurements. There was a negatively fair correlation between CSA at the affected side and duration of time since stroke (r = -0.58, p < 0.05). The SWV of the median nerve at the affected side was not correlated with the duration of time since stroke (r ≤ 0.3, p ≥ 0.05). These results suggest that chronic flexed wrist posture may cause atrophy of the median nerve due to chronic compression after stroke and increase in the stiffness of the median nerve.