Blaine S. Nashold

Trigeminal Nucleus Caudalis Dorsal Root Entry Zone: A New Surgical Approach

New radiofrequency lesion dorsal root entry zone (DREZ) electrodes for relief of facial pain were designed based on a neuroanatomic study in man of the trigeminal nucleus caudalis at the cervicomedullary junction. The human brainstems of 3 normal postmortem specimens were sectioned with measurements and relationships of the trigeminal nucleus caudalis, segmental tracts, spinocerebellar tracts and dorsal columns. Two right-angle DREZ electrodes were made by Radionics for producing DREZ lesions in the trigeminal nucleus caudalis to treat deafferentation facial pain.

Self-mutilation following brachial plexus injury sustained at birth

Self-mutilation after deafferentation injuries has been reported only rarely in adult humans. This behavior has been found to be similar to that observed in animals that have been subjected to experimental deafferentation. We present a child with a brachial plexus injury sustained at birth who began to bite her analgesic digits. Self-mutilation behavior in humans is reviewed and its relevance to current deafferentation pain animal models is examined. This behavior in humans further validates the current animal model of deafferentation pain.

Successful Treatment of Phantom Pain with Dorsal Root Entry Zone Coagulation

We studied 22 patients with amputation due to trauma, gangrene, or cancer. All developed postamputation pain, underwent a dorsal root entry zone (DREZ) procedure, and were followed from 6 months to 4 years after surgery. Overall, only 8 (36%) of these 22 patients had pain relief. However, good results were obtained in 6 (67%) of 9 patients with phantom pain alone, and in 5 (83%) of 6 patients with traumatic amputations associated with root avulsion. Poor results were obtained in patients with both phantom and stump pain, or stump pain alone. The DREZ procedure has a well-defined, but limited role in the treatment of postamputation pain.

Stereotactic Evacuation of Large Intracerebral Hematoma

Despite the declining incidence of strokes, statistics regarding intracerebral hemorrhage indicate a relatively stable incidence in this form of cerebral insult over the past 20 years. Intracerebral hemorrhage accounts for 10% of all strokes, and is fatal to 50-60% of its victims. Until the advent of computer-assisted tomography, surgical intervention offered little benefit to patients suffering primary hemorrhage within the deep gray structures of the cerebral hemispheres. Technical advances in both diagnostic and therapeutic instrumentation now permit stereotactic subtotal evacuation of deep intracerebral hematomas.

Neurosurgical Technique of the Dorsal Root Entry Zone Operation

The dorsal root entry zone operation was introduced in 1976 to relieve the pain of brachial plexus avulsion. Since then it has been applied to pain treatment in paraplegia, postherpetic pain, phantom limb pain and other types of of deafferentation pain. Over 400 operations have been done at the Duke University Medical Center with overall good results in 60% of pain patients.

The deafferentation syndrome in the rat: Effects of intraventricular apomorphine

A deafferentation syndrome, produced in rats by dorsal root ganglionectomies, is expressed as scratching of partially deafferented limb areas and/or biting of anesthetic limb areas. This self-mutilation may be objective evidence of dysesthesias, thus serving as an experimental model to study chronic dysesthesias and/or pain from deafferentation in man. This study included behavioral observations of the syndrome and the effects of intraventricular apomorphine, a dopamine agonist, on its expression. Thirty-eight female Sprague-Dawley rats underwent unilateral C5-T2 dorsal root ganglionectomies followed immediately by stereotactically guided cannulation of the right lateral ventricle in 20 of the rats. For 2 weeks continuously via an osmotic minipump, 10 rats received apomorphine (5 micrograms/h) and 10 others received L-ascorbate (the vehicle). Rats with ganglionectomies only, as well as those receiving L-ascorbate, demonstrated early onset, more severe and later onset, less severe biting groups (P less than 0.05 Mann-Whitney U). Animals receiving apomorphine exhibited low autotomy scores irrespective of time of bite onset. Among the control groups, but not the experimental animals, the earlier the onset of biting, the more severe was the autotomy. The rats receiving vehicle via the minipump had earlier bite onsets than the rats in the ganglionectomy only group. This may indicate that the presence of the minipump is a stress which can accelerate the onset of biting. Intraventricular apomorphine can affect the deafferentation syndrome in the rat; it seems to decrease the level of autotomy and disrupt the relationship of bite onset with degree of biting.

Segmental analysis of spinal cord monoamines after thoracic transection in the dog

The noradrenaline, dopamine and serotonin content from 10 segments of the dog spinal cord before and after a T7 transection were measured. The levels of amines were highest in the conus medullaris. However, when calculated per gram cord grey matter, noradrenaline was found to be concentrated in the midthoracic and sacral cord, while serotonin was concentrated in the mid-thoracic region. Levels of dopamine were very low throughout the spinal cord. Up to 3 days after a T7 transection, the levels of all 3 amines did not change in the distal cord segments. Ten days after transection the level of all 3 amines were less than twice tissue blank distally. This segmental analysis of dog spinal cord shows some potentially important differences from previous studies of cat and rat.

Dorsal Root Entry Zone Lesions for Conus medullaris Root Avulsions

We have found dorsal root entry zone (DREZ) lesions to be an effective treatment of chronic deafferentation pain in patients who have had avulsions of the dorsal rootlets from the spinal cord. Eight patients were operated in whom chronic pain of the lower extremity resulted from dorsal root avulsions from the conus medullaris. In 7 of the 8 patients, the mechanism of injury was a motor vehicle accident; all 7 sustained severe pelvic trauma. Seven of the 8 patients remained pain-free, off all narcotics, with an average follow-up of 33 months. All patients had DREZ lesions of the conus performed by radiofrequency techniques.

The deafferentation syndrome in the rat: Effects of intraventricular neurotensin and cholecystokinin

A deafferentation syndrome can be produced in rats by dorsal root ganglionectomies. This syndrome consists of scratching and/or biting of the anesthetic limb to the point of amputation. This behavior may serve as an experimental model to study certain aspects of chronic dysesthesias and/or pain caused by deafferentation in man. In this study, we made behavioral observations on the deafferentation syndrome and examined the possibility that intraventricular neurotensin and cholecystokinin alter the course of this syndrome. We found that neurotensin accelerated the scratching component without affecting the biting behavior. Cholecystokinin, however, attenuated the release of both components of the syndrome.

Clinical Review of Nucleus Caudalis DorsaI Root Entry Zone Lesions for Facial Pain

Twenty-seven patients with intractable facial pain underwent dorsal root entry zone thermocoagulation lesion of the nucleus caudalis of the spinal trigeminal nucleus. Retrospective review revealed a success rate of 85% in the immediate postoperative period declining to 52% on subsequent follow-up. The best results were in the subgroup of patients with postherpetic neuralgia, of which 67% achieved definite relief. There tended to be some correlation of satisfactory results and pain quality as well as extent of pain along trigeminal territory. The operative morbidity was low although most patients were observed to have a mild transient ipsilateral dysmetria.