Proportional Recovery From Lower Limb Motor Impairment After Stroke.
In people with preserved corticospinal tract (CST) function after stroke, upper limb impairment resolves by ≈70% within 3 months. This is known as the proportional recovery rule. Patients without CST function do not fit this rule and have worse upper limb outcomes. This study investigated resolution of motor impairment in the lower limb (LL).



Patients with stroke and LL weakness were assessed 3 days and 3 months after stroke with the LL Fugl-Meyer. CST integrity was determined in a subset of patients using transcranial magnetic stimulation to test for LL motor-evoked potentials and magnetic resonance imaging to measure CST lesion load. Linear regression analyses were conducted to predict resolution of motor impairment (ΔFugl-Meyer) including factors initial impairment, motor-evoked potential status, CST lesion load, and LL therapy dose.



Thirty-two patients completed 3-month follow-up and recovered 74% (95% confidence interval, 60%-88%) of initial LL motor impairment. Initial impairment was the only significant predictor of resolution of motor impairment. There was no identifiable cluster of patients who did not fit the proportional recovery rule. Measures of CST integrity did not predict proportional LL recovery.



LL impairment resolves by ≈70% within 3 months after stroke. The absence of a nonfitter group may be because of differences in the neuroanatomical organization of descending motor tracts to the upper limb and LL. Proportional recovery of the LL is not influenced by therapy dose providing further evidence that it reflects a fundamental biological process.
From the Department of Medicine, University of Auckland, New Zealand (M.-C.S., P.A.B., C.M.S.); Centre for Brain Research (M.-C.S., W.D.B., P.A.B., C.M.S.) and Department of Exercise Sciences (W.D.B.), University of Auckland, New Zealand.
Marie-Claire
MC
Smith
From the Department of Medicine, University of Auckland, New Zealand (M.-C.S., P.A.B., C.M.S.); Centre for Brain Research (M.-C.S., W.D.B., P.A.B., C.M.S.) and Department of Exercise Sciences (W.D.B.), University of Auckland, New Zealand.
Winston D
WD
Byblow
From the Department of Medicine, University of Auckland, New Zealand (M.-C.S., P.A.B., C.M.S.); Centre for Brain Research (M.-C.S., W.D.B., P.A.B., C.M.S.) and Department of Exercise Sciences (W.D.B.), University of Auckland, New Zealand.
P Alan
PA
Barber
From the Department of Medicine, University of Auckland, New Zealand (M.-C.S., P.A.B., C.M.S.); Centre for Brain Research (M.-C.S., W.D.B., P.A.B., C.M.S.) and Department of Exercise Sciences (W.D.B.), University of Auckland, New Zealand. c.stinear@auckland.ac.nz.
Cathy M
CM
Stinear
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D019054:Evoked Potentials, Motor / Q000502:physiology*; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D035002:Lower Extremity / Q000503:physiopathology*; D008297:Male; D008875:Middle Aged; D009069:Movement Disorders / Q000209:etiology / Q000503:physiopathology*; D011712:Pyramidal Tracts / Q000000981:diagnostic imaging* / Q000503:physiopathology*; D020127:Recovery of Function / Q000502:physiology*; D020521:Stroke / Q000150:complications / Q000503:physiopathology*; D050781:Transcranial Magnetic Stimulation / Q000379:methods*
lower extremity; motor; stroke; upper extremity