Cerebral Lesion Topography in Spasticity following ischemic Stroke

24-Hour Alberta Stroke Program Early CT Score Assessment in Post-Stroke Spasticity Development in Patients with a First Documented Anterior Circulation Ischemic Stroke

BACKGROUND

Neuroanatomic substrates responsible for development of post-stroke spasticity are still poorly understood. The study is focused on identification of brain regions within the territory of the middle cerebral artery associated with spasticity development.

METHODS

This is a single-center prospective cohort study of first documented anterior circulation ischemic strokes with a neurologic deficit lasting >7 days (from March 2014 to September 2016, all patients are involved in a registry). Ischemic cerebral lesions within the territory of middle cerebral artery were evaluated using the Alberta Stroke Program Early CT Score (ASPECTS) on control 24-hour computed tomography or magnetic resonance imaging. Spasticity was assessed with modified Ashworth scale.

RESULTS

Seventy-six patients (mean age 72 years, 45% females; 30% treated with IV tissue plasminogen activator, 6.5% mechanical thrombectomy) fulfilled the study inclusion criteria. Forty-nine (64%) developed early elbow or wrist flexor spasticity defined as modified Ashworth scale >1 (at day 7-10), in 44 (58%) the spasticity remained present at 6 months. There were no differences between the patients who developed spasticity and those who did not when comparing admission stroke severity (National Institutes of Health Stroke Scale 5 [interquartile range {IQR} 4-8] versus 6 [IQR 4-10]) and vascular risk factors (hypertension, diabetes mellitus, dyslipidemia, atrial fibrillation, coronary artery disease). Nor was there a difference in 24-hour ASPECTS score (9 [IQR 8-10] versus 9 [IQR 7-10]). No differences were found between the groups with and without the early upper limb flexor spasticity of particular regions (M1, M2, M3, M4, M5, M6, lentiform, insula, caudate, internal capsule) and precentral-postcentral gyrus, premotor cortex, supplementary motor area, posterior limb of internal capsule, and thalamus were compared.

CONCLUSIONS

We did not find any middle cerebral artery territory associated with post-stroke spasticity development by detailed evaluation of ASPECTS.

Lesion Characteristics of Individuals With Upper Limb Spasticity After Stroke

This study explores the relationship between lesion location and volume and upper limb spasticity after stroke. Ninety-seven stroke patients (51 with spasticity) were included in the analysis (age = 67.5 ± 13.3 years, 57 males). Lesions were traced from computed tomography and magnetic resonance images and coregistered to a symmetrical brain template. Lesion overlays from the nonspastic group were subtracted from the spastic group to determine the regions of the brain more commonly lesioned in spastic patients. Similar analysis was performed across groups of participants whose upper limb (elbow or wrist) Modified Ashworth Scale (MAS) score ranged from 1 (mild) to 4 (severe). Following subtraction analysis and Fisher's exact test, the putamen was identified as the area most frequently lesioned in individuals with spasticity. More severe spasticity was associated with a higher lesion volume. This study establishes the neuroanatomical correlates of poststroke spasticity and describes the relationship between lesion characteristics and the severity of spasticity using mixed brain imaging modalities, including computed tomography imaging, which is more readily available to clinicians. Understanding the association between lesion location and volume with the development and severity of spasticity is an important first step toward predicting the development of spasticity after stroke. Such information could inform the implementation of intervention strategies during the recovery process to minimize the extent of impairment.