Somatosensory evoked potentials and noxious stimulation in patients with intractable, noncancer pain syndromes.

Investigations of the evoked potentials (EPs) to noxious laser stimulation have indicated consistent strong linear relationships between subjective response (R), stimulus intensity (S), and EP amplitude (A). Thirty patients with chronic intractable benign pain syndromes (CIBPS) were tested to determine whether their patterns differed from previous studies with normal volunteers. Nearly half of the CIBPS patients were found to be relatively insensitive to acute pain stimuli.

Peripheral fiber correlates to noxious thermal stimulation in humans.

Minimal conduction velocities of peripheral nerves contributing to acute thermal pain sensation in human volunteer subjects were calculated. Purely thermal stimulation was administered by a low power laser beam directed at the subjects' fingers, and subjective pain responses correlated with a peak in the event-related brain potential (ERBP). These cerebral responses were found to preclude C fiber peripheral activity from this phenomenon.

Discussion of the indications for decompressive laminectomy in epidural spinal metastases.

The authors have recently reviewed the results of their consecutive cases of decompressive thoracic or lumbar laminectomy for spinal cord compression from epidural metastatic neoplasia at the City of Hope National Medical Center over the 15-year period, 1960-1974. This limited series tends to demonstrate the effect of case selection on results, as well as contrast the type of patient with paraparesis seen at a cancer treatment center with that seen at a community or county hospital.

What is a pain center?

The authors present the concept that a multi-disciplinary interdepartmental pain center should include: 1) an initial out-patient pain clinic, 2) an inpatient pain service for diagnosis of pain problems and treatment of patients with intractable pain, including pain from cancer, 3) a psychotherapeutically-oriented chronic benign Pain Unit, 4) facilities for clinical and basic pain research, and 5) affiliations for an adequate teaching program.

The role of cutaneous mechanoreceptors in thermal sensation and pain.

The functional behavior of slowly adapting cutaneous mechanoreceptors under combined thermal-mechanical stimulation was investigated by single-unit recordings from the lumbar dorsal roots of the cat. Increased sensitivity to bimodal stimulation was observed in 24 of the 28 units studied, employing stimulus-response functional behavior as the basis for judgment. Low-threshold receptors generally did not exhibit increased spontaneous firing as accompaniment to heightened sensitivity, while such enhanced basal activity was usually observed in moderate-threshold units in addition to increased reactivity.

Neurophysiology of pain-peripheral aspects. Speculation concerning the possibility of a unitary peripheral cutaneous input system for pressure, hot, cold and tissue damage.

The gate theory of pain is criticized at three levels: (1) at the dorsal horn "gate", where pre-synaptic inhibition in the primary afferent endings may go beyond mere reduction of synaptic power at the afferent endings and induce antidromic impulses (dorsal root reflexes) that may modulate peripherally by blocking; (2) central to the "gate", where postsynaptic neuronal repetitive (epileptiform) firing is believed to be an important underlying mechanism in clinical chronic pain syndromes; and, (3) in the periphery, where there is more to input coding than a balance between the ratio of large and smaller fiber inputs. Contrary to the belief of many sensory neurophysiologists, the present authors contend that pattern theory is viable; and that specificity, while important and not to be ignored, should be considered as only a partially evolved refinement superimposed on a basic underlying spatial and temporal patterning of input that probably requires central decoding, which begins in the dorsal horn.

Needle scope attached to stereotactic frame for inspection of cisterna magna during percutaneous radiofrequency trigeminal tractotomy.

Use of a fiber optic needle scope attached to the Todd-Wells stereotactic unit has facilitated electrode placement during percutaneous trigeminal tractotomy.

Quantitative measures of the thermal reactivity of cutaneous mechanoreceptors.

Quantitative aspects of the non-specific response of cutaneous mechanoreceptors to two different modalities of stimulation were examined. Parameterization of stimulus temperature reveals the incompleteness of the commonly accepted criterion for thermal sensitivity and suggests the need for a re-examination of current concepts of specific mechanical, thermal and nociceptive sensibility.