Robert B. King

Response patterns to noxious and non-noxious stimuli in rostral trigeminal relay nuclei

Postimulus time histogram analysis of second-order neuron responses in rostral trigeminal relay nuclei of cat demonstrated characteristic firing patterns after noxious (tooth pulp) and non-noxious (tooth tap) stimuli. The response to noxious stimulation was prolonged and frequently bimodal while the response to non-noxious stimulation was brief. The same neurons were fired by electrical stimuli applied directly to nucleus caudalis but with longer latencies suggesting a contributory role of nucleus caudalis to the characteristic prolonged bimodal response pattern to noxious stimuli. Interacting noxious and non-noxious stimuli using condition-test sequences demonstrated further stimulus mode-related changes in firing patterns. Electrical conditioning stimuli in nucleus caudalis reduced some responses while strychnine sulfate applied into nucleus caudalis augmented the responses evoked in rostral nuclei by both noxious and non-noxious peripheral stimuli. Nucleus caudalis appeared to contain elements which may modulate activity in rostral trigeminal nuclei by either augmenting or reducing specific firing patterns of second-order neurons in rostral relay nuclei.

Projections from the trigeminal nucleus caudalis in the squirrel monkey

Abstract The role of nucleus caudalis as a relay station in the trigeminal brain-stem nuclear complex was studied in the squirrel monkey (Saimiri sciureus). Evoked potentials incident to peripheral trigeminal stimulation were recorded from sites in the upper brain stem by means of stereotaxically placed macroelectrodes. A dorsolateral medullotomy at the level of the obex isolating nucleus caudalis from peripheral afferent input was then performed. Those potentials that persisted following the medullotomy were assumed to relay in the more rostral trigeminal relay nuclei while those that were abolished were thought to relay primarily through nucleus caudalis. Trigeminal projections dependent on a relay at nucleus caudalis were identified in the CM complex (centrum medianum and nucleus parafascicularis), nucleus paracentralis of intralaminar nuclei, posterior nuclear group of the thalamus, and ventromedial tegmental fasciculus of the midbrain. In contrast to similar findings in the cat, there was no significant projection from nucleus caudalis to nucleus ventralis posteromedialis in the primate. These findings further confirmed nucleus caudalis as a major relay station to regions of the midbrain and thalamus which have been considered as major contributive elements in the integration and perception of pain.

Certification, accreditation, and specialization in the 1990s

Subspecialization was one of the inevitable consequences of merging medicine with science in the early years of this century. The differentiation of human endeavors increases exponentially with new knowledge, technology, and services. Our current patterns of accreditation, certification, and graduate medical education are being seriously challenged by new patterns of subspecialization. How realistically and creatively we respond to this challenge will be a key element in preserving the management of these functions primarily within the purview of the profession.

Dynamic computed tomography: intracranial applications.

&NA; Rapid sequential computed tomography of the brain after the bolus injection of contrast material provides invaluable information as to the characteristic blood flow of intracranial lesions in a noninvasive manner. Plotted dynamic curves permit accurate diagnosis of particularly difficult cases of infarcts and neoplasms. Dynamic computed tomographic (CT) scanning has become a part of the CT work‐up for infarcts, which has allowed their earlier demonstration, detected as areas of hypoperfusion not clearly evident on an initial conventional CT study. Quantitative assessment of vasogenic edema and hypoperfusion are helpful in establishing the diagnosis of infarction and neoplasia. Orbital and parasellar neoplasms can be distinguished accurately from vascular lesions. Dynamic CT studies complemented conventional film screen arteriography in the evaluation of three cases of intracavernous internal carotid artery aneurysm, defining thrombus formation and wall thickness and thus influencing the therapeutic approach. In addition, this modality is useful in differentiating jugular fossa neoplasm from vascular malformation. This review elaborates on the technique involved in dynamic CT scanning and the subsequent results. (Neurosurgery 16:573‐578, 1985)

Spinal vascular tumors: dilemmas in diagnosis and management.

Three case reports of spinal vascular tumors illustrate the need for well-organized and thorough neuroradiological and neurosurgical planning to achieve an initial cure without delay and to avoid inadequate operative procedures.

Recurrent intracranial hypertension and a midbrain glioma.

At the age of 36, this patients clinical picture satisfied the criteria for the diagnosis of benign intracranial hypertension. After an essentially symptom-free interval, she developed new symptoms 17 years later that proved to be the result of a associated with glial-lined cavities in the midbrain and malignant glioma in the splenium. The possibility of a relationship between these disparate events is considered.

Hyperpolarization of trigeminal primary afferents evoked by stimulation of lumbar sympathetic trunk and peripheral nerves

Abstract The gate control theory has emphasized primary afferent hyperpolarization (PAH) as a specific determinant in the perception of a stimulus as painful. Previous studies which indicated that primary afferent depolarization (PAD) could be elicited in the trigeminal system by nonsegmental inputs suggested that this might also be the case for primary afferent hyperpolarization. Decreased excitability of trigeminal primary afferent fibers, an indirect reflection of PAH, was elicited by stimulation of the lumbar sympathetic trunk, sural, and sciatic nerves in cats. This PAH has a magnitude and time course similar to that previously demonstrated in the trigeminal system by segmental noxious inputs. We postulate that PAH is a general phenomenon related to the control of information transmission across afferent synapses rather than a phenomenon specifically related to the perception of various stimuli as painful.

The neurosciences and neurosurgery

Enhancing the time-honored bonds between the neurosciences and neurosurgery is essential. The basic neurosciences are the foundation upon which fundamental scientific training and clinical research depend. Together these form the resource essential to improving the public health. Both now face severe restraints in the support systems available to them, limited degrees of reciprocity, and uncertain human resources. It is critical that the neurosurgical and neuroscience communities renew and enhance their joint commitment and trust so that both can more effectively work together to secure resources appropriate to maintaining the cutting edge on behalf of the public health.

Management of Tic Douloureux

No one medical regimen or surgical procedure has proved ideal for treating tic douloureux. However, gratifying relief from the severe pain is possible with one or more of the therapeutic measures discussed here.