The effects of cold on a partially denervated muscle

The abductor digiti minimi of a patient had undergone partial denervation with some subsequent re-innervation. Cooling of the muscle caused a severe reduction in the EMG and force which accompanied either voluntary effort or tetanic nerve stimulation, but it had little effect on the response to single stimuli. The ineffectual attempts at voluntary contraction of the cooled muscle did, however, block the response to single nerve stimuli. Administration of cholinesterase inhibitors did not improve neuromuscular transmission in the cooled muscle, but usually made it worse. It is concluded that depolarisation block may contribute to the weakness of cooled denervated muscles.