Short-latency crossed spinal responses are impaired differently in sub-acute and chronic stroke patients

ObjectiveInvestigate if patients with supraspinal lesions have impaired interlimb spinal reflex pathways. The short-latency crossed spinal response will be investigated during sitting from the non-paretic to paretic and paretic to non-paretic extremities at different stimulation intensities in chronic and sub-acute stroke patients.MethodsThe ipsilateral tibial nerve of the paretic and non-paretic extremities were stimulated at motor threshold, 35% M-max and 85% M-max of the ipsilateral soleus while the contralateral soleus was contracted from 5% to 15% of the maximum voluntary contraction of the paretic soleus.ResultsChronic patients (from both extremities) had significantly less prominent inhibitory responses than healthy controls (post hoc tests: P < .01–P < .05). The responses were significantly modulated by stimulus intensity in healthy controls and chronic patients (P < .001–P < .05) but not sub-acute patients (P > .05). Some sub-acute patients had significantly more variable responses than chronic patients and healthy controls (P < .001–P ⩽ .05).ConclusionsShort-latency interlimb reflexes are impaired differently in sub-acute vs. chronic patients, are impaired from the non-paretic and paretic extremity, and abnormal when compared to healthy controls.SignificanceThe inappropriate coordination could result in an inability to quickly avoid obstacles following a mechanical disturbance to the ipsilateral extremity. It also indicates that bilateral descending projections affect the response.

► Short-latency crossed spinal interlimb reflexes are impaired differently in sub-acute and chronic stroke patients. ► The reflexes are impaired from the non-paretic to paretic and paretic to non-paretic extremities in both patient groups suggesting that projections to the paretic and non-paretic extremities modulate the response. ► The inappropriate modulation of these reflexes may result in an inability to appropriately modify the muscle activity of the opposite leg subsequently reducing the ability to quickly avoid obstacles (which may contribute to falls).