Extent of pyramidal tract wallerian degeneration in the brain stem on MRI and degree of motor impairment after supratentorial stroke.

The relationship between Wallerian degeneration in the brain stem and degree of motor impairment is discussed. Using MRI we studied 172 supratentorial stroke patients, whose motor impairment was graded according to Brunnstrom stage. Wallerian degeneration was represented by a T2 high-intensity area in the brain stem, and its cross-sectional extent was measured at the cerebral peduncle level. Wallerian degeneration was detected in 99 patients (57.6%). The area of T2 high intensity was significantly correlated with Brunnstrom stage. Multiple regression analysis showed that the upper extremity stage contributed most to the visualization of Wallerian degeneration. This is partly because the pyramidal tract participates in fine and precise movement. The extent of the area of Wallerian degeneration is found to be helpful in making a prognosis with respect to motor impairment in the upper extremity.