Ronald F. Young

Electrical stimulation of the brain for relief of intractable pain due to cancer

Seventeen patients with intractable pain due to progressive malignancies were treated by electrical stimulation of the brain after more conventional pain therapies applied in the University of California, Los Angeles Cancer Pain Clinic had failed. Electrodes were stereotactically implanted under local anesthesia in the periaqueductal grey (PAG) or periventricular grey (PVG) in 11 patients. In six patients electrodes were placed in both PAG–PVG targets and in the sensory thalamic nuclei. Thirteen of the 17 patients achieved virtually total pain relief and 2 others achieved partial pain relief. At the hospital discharge only 4 of 17 patients required narcotic analgesics for pain relief. Follow‐up periods ranged from 1 to 21 months and 6 patients remain alive. Fourteen patients eventually required narcotics for pain relief, usually in the terminal few weeks of their lives. Pain relief was achieved in spite of the fact that all patients were tolerant to large doses of systematically or intraspinally administered narcotics at the time of electrode placement. No complications related to brain stimulation were identified. Brain stimulation is a safe and effective method for treatment of intractable pain due to malignancy in certain patients.

Effects of chronic descending tractotomy on the response patterns of neurons in the trigeminal nuclei principalis and oralis

Abstract Unilateral, descending, trigeminal tractotomy was carried out on adult cats using aseptic technique. Unit activity, evoked by bipolar noxious stimulation of the tooth pulp and by innocuous mechanical stimulation of other receptive fields, was recorded from neurons in the trigeminal principalis and oralis nuclei, 7 to 13 weeks after tractotomy. Seventy neurons from the lesion side of the brain stem and 59 from the control side were studied. All units responded to pulpal stimuli and the great majority to mechanical stimuli. Three general response configurations were produced by each of the two forms of stimulation: brief bursts of 1 to 5 spikes, trains of 6 to 20 spikes, and multiple component discharges consisting of sequences of brief bursts. No statistically significant differences between the two populations were found for peripheral field size or location, for discharge characteristics such as latency, configuration, or mean density, or for responsiveness to the two types of stimuli. However, a statistically greater proportion of control units fired dense impulse trains (more than eight spikes) to intense pulpal stimuli. The results provide evidence that the response patterns of most somatosensory neurons in nuclei principalis and oralis are unaffected by descending trigeminal tractotomy and that stimulus modality is not coded by the response characteristics of polymodal units in these nuclei. Although some modulatory influence is exerted on polymodal neurons in the rostral nuclei by the trigeminal nucleus caudalis, it appears doubtful that this is a significant factor in determining whether a peripheral stimulus is perceived as noxious or innocuous.

Response properties of neurons in trigeminal nucleus caudalis to noxious and innocuous stimuli under chloralose anesthesia

Abstract The response properties of a population of neurons in trigeminal nucleus caudalis, responsive to electrical stimulation of the dental pulp, were quantitatively studied in cats under chloralose anesthesia. A considerable difference was noted between the firing patterns of these units, as identified by poststimulus time histogram analysis, and a group of pulpal units previously studied by others in rostral trigeminal nuclei also under chloralose anesthesia. No specific firing pattern characterized unit response to noxious as opposed to innocuous stimuli in this study. However, patterns of stimulus interaction, identified using a conditioning-testing paradigm, were identical in this study to those reported rostrally. A portion of the units identified in nucleus caudalis possess the firing characteristics required of a population of neurons which might secondarily activate more rostral cells differentially in response to noxious and innocuous stimuli. It is concluded that all the components predicted by a theory of facial sensation based on interdependence of trigeminal primary relay nuclei were shown to exist within the trigeminal brain stem complex.

Postoperative neurosurgical infections due to bacillus species.

The cases of 2 patients with postoperative ventriculitis due to Bacillus species bacteria are presented. Bacillus licheniformis was isolated from one patient following removal of an intraventricular meningioma, and Bacillus cereus from another patient following placement of a ventriculoperitoneal shunt. Both isolates were resistant to a variety of antibiotics, but both were sensitive to gentamicin and chloramphenicol. These cases emphasize several points; (a) Bacillus species, usually thought to be nonpathogenic, may produce intracranial infections; (2) species identification is important for epidemiological purposes and for the selection of appropriate chemotherapeutic agents; and (3) in cases of suspected ventriculitis, chloramphenicol or gentamicin should be considered for Grams staining revealing gram-positive bacilli. In addition, we recommend that when planning antibiotic prophylactic regimens, consideration should be given to including one of these agents to assure coverage of Bacillus species.

Acute cerebellar hemorrhage in childhood: etiology, diagnosis, and treatment.

Four cases of acute cerebellar hemorrhage in childhood are reported. Two were related to the rupture of arteriovenous malformations, one was a hemorrhage within a cerebellar tumor, and one (in a neonate) was of an undetermined etiology. Three of the cases were treated surgically, whereas the neonatal hemorrhage was managed medically. The latter case seems to be the only reported case of acute cerebellar hemorrhage in childhood that resolved spontaneously. Computed tomographpy proved to be invaluable in the diagnosis, management, and follow-up of the patients. Although surgical treatment is indicated when identifiable lesions cause the hemorrhage, nonsurgical approaches may be satisfactory when lesions are not discernible. Our cases, in addition to those reported previously, suggest a better prognosis for children than for adults with acute cerebellar hemorrhage, regardless of the etiology.

Recurrent intracerebral blastomycotic granuloma: diagnosis and treatment

We present a patient with a recurrent intracerebral blastomycotic granuloma. The computerized tomographic scan appearance of this lesion is illustrated. Of the 81 reported cases of intracranial blastomycosis, only 35 have represented solid intracerebral lesions; the other patients have had spinal lesions or meningitis. This patient represents the first reported recurrence of an intracerebral blastomycotic granuloma. The treatment utilized, surgical resection combined with intravenous and intraventricular amphotericin B, represents a unique approach to this problem. The diagnosis and currently advocated treatment of intracranial blastomycosis is reviewed, particularly in regard to the potential for recurrence of blastomycosis.