Silver nitrate therapy as an adjunct in the treatment of myelomeningocele

✓ Fifteen patients in whom immediate closure of a myelomeningocele sac was not possible were treated by continuous application of dilute solutions of silver nitrate. Local infection of the sac was prevented or irradicated in 14 of the 15 patients within 72 hours. There were no infections in subsequent shunting procedures. No adverse neurological effects were noted, although the method was usually restricted to patients with neurological deficits below the level of the myelomeningocele sac. One patient who developed persistent hyponatremia and hypochloremia after prolonged application responded well to cessation of the therapy.

Increase in regional cerebral blood flow following experimental arterial air embolism

✓ Acute intracranial hemodynamic alterations consequent to arterial air embolism were studied in the dog using the radioxenon clearance technique. In eight dogs, the mean pre-embolic (control) hemispheric flow was 28.3 ml/100 gm/min. Following the injection of varying amounts of air into the right vertebral artery, there was an augmentation in the measured cerebral blood flow in all animals. Statistical analysis revealed the flow response to be independent of the amounts of air used in these experiments. The mean post-embolic cerebral blood flow was 39.3 ml/100 gm/min, representing a statistically significant increase of 11.0 ml/100 gm/min. Although the post-embolic supernormal flow may be due to the interaction of multiple pathophysiologic factors, air-induced traumatic vasodilatation is advocated as the most important pathogenetic mechanism. Prolonged vasodilatation with loss of autoregulation results in physiological shunting of blood through the affected capillary beds. Alterations in the intracerebral vasculature due to arterial air embolism are compared with studies by other investigators who have observed the effects in extracerebral vessels.

The effects of glucosteroids on experimental cold-induced brain edema. Gross morphological alterations and vascular permeability changes

✓ Although the beneficial effects of glucosteroids on brain edema are well documented and generally accepted clinically, investigations into their effects on experimental brain edema have been somewhat contradictory. In this study brain edema was produced by local cortical freezing in animals pretreated with glucosteroids and in untreated animals. Gross estimation of edema, wet weight-dry weight determination, and mechanical planimetry of areas of extravasated dye indicated a statistically significant reduction in edema of both white and gray matter at 24, 48, and 72 hours. Gross estimation of edema indicated a persisting effect with resolution of edema at 5 days in treated animals and from 7 to 12 days in untreated animals. These studies substantiate initial investigations and indicate a primary reduction in brain edema by glucosteroids. At least one of the effects of the glucosteroids appears to be reduction of the abnormal vascular permeability causing brain edema.

Lipomas of the spinal cord and cauda equina

✓ This report presents 18 cases of lipoma of the spinal cord or cauda equina, four of which were unassociated with congenital anomalies of the spine and 14 with such anomalies. Review of the literature shows that unassociated cases are rare, with only 100 cases reported, while those associated with congenital anomalies are more common. The patients ranged in age from 2 months to 5 years. Fourteen patients had external evidence of an abnormality in the form of a mass or dimple over the vertebral column. Plain x-ray films showed evidence of an intraspinal lesion in all cases except one. The treatment was surgical in all cases, with nine good results, eight satisfactory, and one unsatisfactory. The exact pathogenesis of spinal cord lipomas is unclear, although the high incidence of associated congenital defects, age of onset, and location of the tumors suggest a developmental origin. The tumors occupy a juxtamedullary-subpial location and are composed of firm, lobulated adult fat. Early surgery consisting of generous laminectomy, incision of the pia, and subtotal removal of the tumor is felt to be the treatment of choice.

Silicone rubber: a new diffusion property useful for general anesthesia

Ether, nitrous oxide, halothane, and cyclopropane diffuse through silicone rubber. General anesthesia can be produced in dogs by passing the vapors of any of these anesthetic agents through a coil of silicone rubber tubing, each end of which is placed in an artery and vein. Potential applications include a new method for general anesthesia and a simple accurate vaporizer for halothane.