Experimental decompression of spinal cord.

An artificial, slowly expanding mass which compressed the spinal cord produced histological, electrophysiological, and neurological changes. A comparison was made of the effects of laminectomy in the cat with dorsally and ventrally placed masses. Laminectomy reversed declining cord function and produced prompt recovery of somatosensory evoked potentials in cats with dorsally placed masses. In contrast, a worsening of these functions occurred following laminectomy in animals with ventrally placed masses. In all cases, evoked potential changes were consistent with neurological status and were predictive of the outcome of surgery.