Conus medullaris nerve root avulsions.

The association of avulsive lesions and pain has been well established in avulsions of the brachial plexus from the cervical spinal cord, but avulsive lesions of the conus medullaris have not previously been recognized or documented by direct observation. Six patients with intractable lower-extremity pain due to avulsion of nerve roots from the conus medullaris were treated by thoracolumbar laminectomy and dorsal root entry zone (DREZ) lesions. Patients with avulsion of lumbosacral roots from the conus medullaris have a characteristic clinical presentation. They are usually young men who, as a result of a motorcycle accident, have suffered multiple pelvic or long-bone fractures or traumatic amputation of part of the lower extremity. Early in their course there is pain not directly attributable to the injured part. The pain is described as intense and burning, with episodic radiation and electric shock-like sensations in the injured or phantom limb. If the leg is intact, there is usually a dermatomal pattern to the distribution of the pain and neurological deficit. A myelogram often reveals a traumatic pseudomeningocele similar to those seen in the cervical region after avulsion of the brachial plexus. Surgical exploration of the conus medullaris usually reveals the extent of nerve root avulsion, and an appropriate DREZ operation can be performed.