Stereotactic trigeminal nucleotomy for dysesthetic facial pain.

Trigeminal nucleotomy is a relatively simple, straightforward stereotactic procedure, acting at the deafferentation site, i.e., at the nucleus caudalis. Patients were operated on in a seated position, by a posterior suboccipital approach. Out of a series of 196 patients, 143 underwent trigeminal nucleotomy for deafferentation. Clinical diagnoses were 52 cases of postherpetic pain dysesthesia, 35 of anesthesia dolorosa, 46 of dysesthetic state with superimposed tic-like sequelae of trigeminal surgery performed elsewhere and 9 of posttraumatic neuropathy. Abolition of allodynia or marked reduction in, or disappearance of deep background pain was achieved in 72.0% of the cases overall. Results are analyzed for each clinical category. There were no side effects of any kind. Follow-up ranged from 4 to 17 years. This seems to be the procedure of choice for deafferentation facial pain.

Long-term results of stimulation of the septal area for relief of neurogenic pain.

Chronic brain stimulation may be a useful method of treating chronic neurogenic pain. However, the knowledge about the basic mechanisms responsible for pain relief is still fragmentary, and the clinical results have often been inconsistent even contradictory. In an attempt to explore the possibility of stimulating other cerebral targets, stimulating electrodes have been implanted in the septal region in addition to stimulation in the sensory thalamus or the periventricular grey. In 19 patients subjected to septal stimulation, 12 experienced satisfactory relief of their spontaneous pain together with abolition of allodynia. There were no untoward side effects. The follow-up ranged from 1 to 10 years. Our result suggest that the septal area may be a suitable alternative target for chronic brain stimulation.

Multiloci stereotactic transplantation of autologous adrenal medullary tissue to the putamen and caudatum in Parkinson's disease. Technical note.

Adrenal to striatum transplants may be effective, but many technical issues are still debated. A procedure whereby a number of grafts were stereotactically placed at the putamen and caudatum is reported. It enables grafting deep nuclei, such as the putamen, the most denervated structure in Parkinson's disease, and allows a widespread spatial distribution of multiple grafts within these huge targets, conceivably enhancing the local release of neurotransmitters at the site or in the vicinity of the denervated receptors. It also enables the use of a sizeable volume of tissue, presumably a crucial but as yet unknown factor. Although preliminary, the present data seem to warrant further clinical trials.

Craniofacial postherpetic neuralgia managed by stereotactic spinal trigeminal nucleotomy.

Postherpetic craniofacial neuralgias are notoriously difficult to deal with. Nevertheless, stereotactic spinal trigeminal nucleotomy seems to be a rational approach, as both experimental and clinical data strongly suggest the relevance of nucleus caudalis for certain facial neurogenic pain phenomena. From a series of 136 consecutive nucleotomies, 80 were performed for deafferentation pain. The long-term results of 25 such cases, who underwent this procedure for postherpetic neuralgia, are reported. Their pain was referred to the Vth, to the VII, IX and Xth, and to the C2-3 dermatomes. Abolition of the allodynia, and disappearance of, or marked reduction in, the deep background pain was achieved in 76% of the cases overall. The follow-up period ranged from 1 to 13 years. There was no untoward side-effects. Technical and electrophysiological data germane to accurate target placement are discussed. Spinal trigeminal nucleotomy is then a specially suitable procedure for postherpetic craniofacial dysaesthesiae.

Stimulation of the dentate nuclei for spasticity.

It has been assumed but not been proved that cerebellar cortical stimulation activates the Purkinje cells, thereby inhibiting the deep nuclei. Furthermore, the destruction of these particular cells, consistently demonstrated in biopsy material, has not been accounted for. These has led the author to introduce chronic stimulation of the dentate nuclei for spasticity in 1978. The long-term results of stimulation in 22 such cases are reported, followed-up between 2 and 6 years. Both the clinical results and the electrophysiological changes produced by stimulation are analyzed. They seem to indicate that it is a rational approach to relieve spasticity and to improve motor function.

Chronic stimulation of the septal area for the relief of intractable pain.

Although brain stimulation techniques have changed the treatment of pain, their rationale has not yet been fully proved, and their clinical results are still frequently erratic or contradictory. In an attempt to provide alternate sites for stimulation, 10 patients were, in addition to conventional targets, chronically implanted at the septal area. Satisfactory relief of dysesthetic pain was induced by septal stimulation in 60% of the cases overall, without untoward effects. The follow-up ranged from 1 to 42 months. The available data conceivably suggest other mechanisms than the presumed exclusive activation of opiomimetic structures. They also seem to indicate that the septal area may be a suitable target for chronic stimulation.

Chronic self-stimulation of the dentate nucleus for the relief of spasticity.

It has been assumed but not yet proved that cerebellar cortical stimulation activates the Purkinje cells, with subsequent inhibition of the deep cerebellar nuclei. However, the relatively crude, widespread excitation induced by several surface electrode arrays and the parameters of stimulation currently used, may produce other effects than selective activation of only one specific cellular type which, furthermore, seems to be rarely present in these particular patients, as demonstrated by biopsy studies prior to electrode placement. The dentate nucleus was chronically implanted with a stimulating system in a patient with spasticity due to cerebral palsy. Chronic self-stimulation induced a significant improvement in motor function, with relief of spasticity and improvement in speech, posture, balance and gait. Electrophysiological studies demonstrated a decrease in the amplitude of V1 and V2 responses and in the H/M and T/M ratios, an increase in the silent period, and marked effects in the H reflex recovery curve, as well as diminished contralateral cortical somato-sensory evoked potentials. This result seems to indicate that the clinical effects of cerebellar cortical stimulation are not due to prosthetically induced inhibition of the dentate nucleus.

Chronic self-stimulation of the medial posterior inferior thalamus for the alleviation of deafferentation pain.

Since current techniques yield uncertain results on deafferentation pain, chronic brain stimulation may presumably be a valuable alternative method, without deterrent side-effects. Disappointing results with stimulation of the somato-sensory structures prompted the selection of the medial posterior inferior thalamus and adjacent brain stem for chronic stimulation in pain states of central origin. Six such cases are reported. Abolition of the hyperpathia and marked reduction in the deep background pain was achieved in 2 cases, and disappearance of the hyperpathia and moderate reduction in the deep pain was obtained in another 2, but none had complete alleviation of pain. The follow-up time ranged between 6 and 42 months. Reversal of analgesia by naloxone was not observed. Acute experimentally-induced pain was not modified by stimulation.

Spinal cord stereotactic techniques re trigeminal nucleotomy and extralemniscal myelotomy.

The application of stereotactic techniques to the spinal cord as a logical sequel to percutaneous procedures have produced significant developments by enabling the functional exploration of different cord structures. Radiofrequency lesions were placed either at the spinal trigeminal nucleus, for facial pain of central origin such as postherpetic neuralgia or anesthesia dolorosa as well as for neoplastic pain of extensive craniofacial distribution, or at the central cord region to interrupt preferentially multisynaptic nonspecific pathways mainly for midline and/or bilateral pain but also for patients with respiratory inadequacy or for certain central pain states. Technical aspects are reported, and physiological correlates relevant to surgery are analyzed. Results, indications and limitations are discussed.

Stereotactic extralemniscal myelotomy.

A procedure is reported in which radiofrequency lesions were stereotactically placed in the central cord region at the cervicomedullary junction to interrupt selectively the extralemniscal system. Physiological recognition of the target site was based upon the homuncular organization of the dorsal funiculi, which is analysed. Only subjective (segmentally unrelated) analgesia was achieved, usually without demonstrable sensory loss. Stimuli were not painful, while ability to localize it and the discrimination between sharp and blunt components were preserved. A rational approach is offered to certain central pain phenomena which resulted in abolition of hyperpathia and disappearance of, or marked reduction in, deep background pain. Both upper and lower body pain were easily dealt with. Pathways for automatic respiration or for micturition were not encroached upon. Therefore it was electively used for cases with diminished respiratory reserve and for cases with midline and/or bilateral pain.

Stereotactic hypothalamotomy for behaviour disorders.

Posterior hypothalamotomy is a relatively simple stereotactic procedure. The radiological determination of the target and its physiological corroboration by electrical stimulation are accurate. The lesions have always been made in the site of maximum sympathetic response. In this respect, the cardiovascular changes (hypertension and tachycardia), which are always elicited from a more restricted area, are of particular importance. Depth recordings, however, have been less useful. Undesirable side-effects, if present, were mild and transitory. There was no postoperative intelligence deficit, at least with the standard tests.