Proportional Motor Recovery After Stroke: Implications for Trial Design

Background and purpose: Recovery of upper-limb motor impairment after first-ever ischemic stroke is proportional to the degree of initial impairment in patients with a functional corticospinal tract (CST). This study aimed to investigate whether proportional recovery occurs in a more clinically relevant sample including patients with intracerebral hemorrhage and previous stroke.

Methods: Patients with upper-limb weakness were assessed 3 days and 3 months poststroke with the Fugl-Meyer scale. Transcranial magnetic stimulation was used to test CST function, and patients were dichotomized according to the presence of motor evoked potentials in the paretic wrist extensors. Linear regression modeling of Δ Fugl-Meyer score between 3 days and 3 months was performed, with predictors including initial impairment (66 - baseline Fugl-Meyer score), age, sex, stroke type, previous stroke, comorbidities, and upper-limb therapy dose.

Results: One hundred ninety-two patients were recruited, and 157 completed 3-month follow-up. Patients with a functional CST made a proportional recovery of 63% (95% confidence interval, 55%-70%) of initial motor impairment. The recovery of patients without a functional CST was not proportional to initial impairment and was reduced by greater CST damage.

Conclusions: Recovery of motor impairment in patients with intact CST is proportional to initial impairment and unaffected by previous stroke, type of stroke, or upper-limb therapy dose. Novel interventions that interact with the neurobiological mechanisms of recovery are needed. The generalizability of proportional recovery is such that patients with intracerebral hemorrhage and previous stroke may usefully be included in interventional rehabilitation trials.

Clinical trial registration: URL: http://www.anzctr.org.au. Unique identifier: ANZCTR12611000755932.