The human cortical motor map in post-stroke hemiparesis in the presence of treatment-related clinically important recovery

ObjectivesTo determine if intervention-related clinical improvement in post-stroke hemiparesis is associated with enlarged primary motor cortex representation. MethodsData were analyzed from a single site subset of the NICHE trial. Transcranial magnetic stimulation (TMS) motor mapping was performed in 23 participants (3-12 months post-stroke, 10 female, 40-88 yrs, baseline Fugl-Meyer Upper Extremity (FM-UE) range 13-58) before and after intervention. TMS motor maps were acquired for the extensor digitorum communis muscle (EDC) bilaterally, at 110% resting motor threshold (RMT). ResultsImprovement on the primary outcome measure (FM-UE) was statistically and clinically significant (mean pre= 38({+/-}15), post= 45({+/-}16); p <0.001; n=23). Significant improvement was also observed on secondary impairment and activity outcome measures (p<0.05). Ipsilesional hemisphere RMT and map volume (MV) remained unchanged (RMT pre = 42({+/-}13), post = 41({+/-}11), p=0.60; MV pre =77.98({+/-}71.37) mV*mm2, post =109.54({+/-}139.06) mV*mm2, p=0.36). The magnitude of clinical benefit was unrelated to difference in map characteristics from pre to post (Spearmans rho= 0.06, p=0.79). ConclusionsIntervention-related clinical improvement of the upper limb 3-12 months following stroke, was not associated with change in motor cortex excitability or increase in motor maps. Clinical improvements may not solely rely on consistent changes in the cortical motor representation.