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Abstract

In this pilot study of patients with spinal cord injury (SCI), the audiospinal response (ASR), mediated by bilateral reticulospinal tracts, was assessed as a test for residual descending synaptic activity on cervical and lumbar motor pools. The Hoffman's reflex (H-reflex) from the flexor carpi radialis (FCR) and the soleus muscles was conditioned by an auditory stimulus. Facilitation of the H_max amplitude was found in eleven control subjects. In three patients with a clinically complete mid-thoracic SCI, the FCR, but not the soleus H-reflex, was facilitated. One of two patients with a motor complete, sensory incomplete mid-thoracic lesion showed facilitation of the ASR at the soleus. Two patients with incomplete cervical lesions had facilitation of both H-reflexes. Since motor pool excitability may be high below a lesion, auditory conditioning of a sub-maximal H-reflex was used to reveal facilitation when H_max was equivocally modulated by a sound burst. The ASR might serve as an adjunct to assessments for residual supraspinal influences in patients who meet clinical criteria for a complete motor spinal cord lesion.

Keywords

Rehabilitation Spinal cord injury H-reflex Motor control Electrodiagnosis.

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Use of the Audiospinal Response to Test for Completeness of Spinal Cord Injury

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