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

Objective: Investigate 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.

Methods: The 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.

Results: Chronic 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).

Conclusions: Short-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.

Significance: The 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.