Natural history and prognostic value of corticospinal tract Wallerian degeneration in intracerebral hemorrhage

Abstract

Background: The purpose of this study was to define the incidence, imaging characteristics, natural history, and prognostic implication of corticospinal tract Wallerian degeneration (CST-WD) in spontaneous intracerebral hemorrhage (ICH) using serial MR imaging.

Methods and results: Consecutive ICH patients with supratentorial ICH prospectively underwent serial MRIs at 2, 7, 14, and 21 days. MRIs were analyzed by independent raters for the presence and topographical distribution of CST-WD on diffusion-weighted imaging (DWI). Baseline demographics, hematoma characteristics, ICH score, and admission National Institute of Health Stroke Score (NIHSS) were systematically recorded. Functional outcome at 3 months was assessed by the modified Rankin Scale (mRS) and the motor-NIHSS. Twenty-seven patients underwent 93 MRIs; 88 of these were serially obtained in the first month. In 13 patients (48%), all with deep ICH, CST-WD changes were observed after a median of 7 days (interquartile range, 7 to 8) as reduced diffusion on DWI and progressed rostrocaudally along the CST. CST-WD changes evolved into T2-hyperintense areas after a median of 11 days (interquartile range, 6 to 14) and became atrophic on MRIs obtained after 3 months. In univariate analyses, the presence of CST-WD was associated with poor functional outcome (ie, mRS 4 to 6; P=0.046) and worse motor-NIHSS (5 versus 1, P=0.001) at 3 months.

Conclusions: Wallerian degeneration along the CST is common in spontaneous supratentorial ICH, particularly in deep ICH. It can be detected 1 week after ICH on DWI and progresses rostrocaudally along the CST over time. The presence of CST-WD is associated with poor motor and functional recovery after ICH.

Keywords: diffusion‐weighted imaging; intracerebral hemorrhage; magnetic resonance imaging; natural history; prognosis; wallerian degeneration.

Figure 1.

Wallerian degeneration (WD) in the corticospinal tract. Diffusion‐weighted imaging (DWI) and corresponding apparent diffusion coefficient (ADC) maps in 3 patients with WD along the corticospinal tract. Early on, WD appears bright on DWI and dark on ADC (ie, reduced diffusion). WD along the corticospinal tract, typically observed in deep hemorrhages, is shown in the internal capsule (A), the cerebral peduncle (B), the pons (C), and the medullary pyramid (D).

Figure 2.

Spatial and temporal evolution of Wallerian degeneration in a single patient. Serial diffusion‐weighted imaging magnetic resonance images (MRIs) are shown for a single patient with a putaminal hemorrhage, obtained 2 days, 1 week, and 2 weeks after symptom onset. Corresponding fluid attenuated inversion recovery (FLAIR) sequences are shown at 3 months. A, Internal capsule. B, Cerebral peduncle. C, Pons. D, Medulla. Restricted diffusion appears along the ipsilateral corticospinal tract at 1 week in the posterior limb of the internal capsule, cerebral peduncle, and pons (arrows). At 2 weeks restricted diffusion appears in the medullary pyramid (arrow). At 3 months, areas that previously showed restricted diffusion are hyperintense on FLAIR and have undergone atrophy (arrows).

Figure 3.

Wallerian degeneration in the corpus callosum. Diffusion‐weighted imaging (DWI) and corresponding apparent diffusion coefficient (ADC) map in a patient with a large parieto‐occipital lobar intracerebral hemorrhage, showing reduced diffusion (bright on DWI and dark on ADC) in the splenium of the corpus callosum from Wallerian degeneration.