John D. Waggener

Ultrastructure of three choroid plexus papillomas

This report describes the ultrastructure of three choroid plexus papillomas (CPP) from female patients, aged 2 months, 3 years, and 57 years, respectively. The infantile case manifested clinical evidence of excess CSF formation. All three were well‐differentiated neoplasms resembling normal choroid plexus (CP). Each displayed distinctive individual patterns of plasmalemmas, organelle population, and nuclei. The two childhood tumors contained prominent deposits of cytoplasmic glycogen, thus simulating the embryonic state. The vasculature of all three lesions included fenestrated capillaries indistinguishable from those of normal CP. Ventricular plasmalemmas were separated from lateral and basal plasmalemmas by tight junctions. The geometrical relationship between capillaries, tumor cells, and ventricle was characteristic of epithelia involved in fluid transport. These findings offer structural evidence that well‐differentiated CPPs are capable of participating in CSF formation.

Comparative Study of Neuroma Formation in the Rat Sciatic Nerve after CO2 Laser and Scalpel Neurectomy

Recent reports have suggested that peripheral neurectomy with the CO2 laser may be effective in preventing subsequent neuroma formation. To study this question further, we performed bilateral sciatic nerve sections in 31 rats using a steel scalpel on one nerve and a CO2 laser on the opposite side. The animals were killed 30 days after neurectomy and specimens were removed for gross observation, light microscopy, and electron microscopy. Axon composition studies were carried out in selected animals and axon diameter histograms were prepared. Well-formed neuromas were present in nerves transected by both the scalpel and the CO2 laser. The scalpel neuromas were characterized by a greater degree of interfascicular collagen deposition and perineurial cell proliferation. Laser neuromas demonstrated less perineurial compartmentalization and scar tissue formation. In addition, a foreign body reaction with multinucleated giant cells surrounding carbonaceous debris was seen that was not present in the scalpel neuromas. Analysis of axon composition studies revealed that both neuromas had a greater density of axons and a higher percentage of small diameter myelinated and unmyelinated axons as compared to control nerves. Laser neuromas had more axons per unit area than scalpel neuromas, but the percentage composition of axons was very similar in the two groups. We could find no evidence in the rat sciatic nerve model that CO2 laser neurectomy is less likely to result in neuroma formation than is conventional scalpel neurectomy.

Effect of Naloxone on Experimental Stroke in Awake Monkeys

Naloxone has recently been reported to be of benefit in the treatment of central nervous system ischemia. To study the effect of naloxone in an experimental stroke model, we subjected 40 awake monkeys to middle cerebral artery (MCA) occlusion 2 weeks after the placement of a MCA ligature by a transorbital technique. Cerebral blood flow (CBF) was monitored with stereotactically placed H2 electrodes, and the neurological course was serially recorded. Infarct size was determined 2 weeks after MCA occlusion. Twenty animals served as control and received no naloxone; 10 of these underwent permanent occlusion, and 10 underwent 4-hour MCA occlusion. In 25 treatment animals, naloxone was administered in three different intravenous dosages: (a) naloxone, 2-mg/kg bolus 20 minutes postocclusion and 2 mg/kg/hour X 4 hours, in 10 animals with permanent MCA occlusion; (b) naloxone, 10-mg/kg bolus 20 minutes postocclusion and 10 mg/kg/hour X 4 hours, in 10 animals with 4-hour MCA occlusion; and (c) naloxone, 20-mg/kg bolus, in 5 animals with various neurological deficits. MCA occlusion typically produced a moderate deficit: hemiparesis, hemianopsia, and facial paresis. In most instances, naloxone in the 2- and 10-mg/kg dose regimens produced little or no change in the neurological function. CBF decreased after MCA occlusion and was unaffected by naloxone in most cases. Infarct size was not significantly different between the control and treated groups. However, the 20-mg/kg dose consistently produced a nonfunctional, transient increase in total body motor tone in normal and hemiparetic animals. Naloxone did not significantly improve useful neurological function, CBF, or infarct size in an experimental primate stroke model.

Surgical treatment of an abscess in a rathke's cleft cyst

An abscess in a Rathkes cleft cyst was surgically treated in a 39-year-old man. The patient presented with headaches, fever, and visual deficits. Transcranial decompression of the optic chiasm was carried out first. The abscess recurred, however, and drainage of the abscess and removal of its wall via the transsphenoidal route was carried out 4 weeks later. Visual evoked responses were useful in the successful management of this lesion. The patient regained normal pituitary function and visual function after the operation.

Effect of mannitol on experimental focal ischemia in awake monkeys.

The effect of mannitol on focal cerebral ischemia in cynomolgus monkeys was studied. After the implantation of a snare ligature about the right middle cerebral artery (MCA) and of deep electrodes for measurement of cerebral blood flow, unanesthetized animals underwent 4-hour MCA occlusion. Ten monkeys were untreated, and 12 animals received mannitol (1.2 g/kg i.v.) 20 minutes after occlusion. The preocclusion and postocclusion deep hemispheric cerebral blood flows (mean CBFs) were similar in the treated and untreated groups. Occlusion produced an average decrease in flow of about 50% in both groups. In the mannitol-treated group the mean CBF of 30.0 fell to 15.8 ml/100 g/minute, and in the untreated group the mean CBF of 29.5 fell to 12.5 ml/100 g/minute. Several animals showed increased CBF after mannitol treatment, and there was an average 21% increase in CBF in the mannitol group after treatment, but this was not a statistically significant difference from the untreated group. With regard to clinical status, there was no significant difference between the mannitol group and the untreated group after MCA occlusion. In individual animals, mannitol treatment caused no significant improvement. Two weeks after occlusion, brains were evaluated for infarct size; there was no significant difference between the mannitol and the untreated groups. In this study, treatment with mannitol (1.2 g/kg) 20 minutes after MCA occlusion failed to modify significantly the mean hemispheric CBF, clinical status, or the pathological effects of 4-hour focal cerebral ischemia.

Surgical management of pineal area tumors in early childhood.

Three cases of tumors of the pineal area in young children are presented. Surgical intervention is advocated because of the greater than 50% chance of the tumors being benign in this age group and the greater risk from radiation to the developing brain.

The Pathophysiology of Bacterial Meningitis

Bacterial meningitis is the most common type of central nervous system (CNS) infection. Most recent reviews of the subject quote an incidence of five per 100,000 with the majority of cases appearing in the pediatric age group.1–4 Approximately 25,000 cases occur annually in the U.S. The mortality rate is 15 percent and the morbidity rate is at least twice this figure.5