Brain abscess and cystic fibrosis

Brain abscess has only recently been considered a complication of cystic fibrosis. Three patients are reported here and a fourth cited from the literature. All of our patients were young adults with advanced pulmonary disease. The bacteria involved were mouth organisms and were found in the sputum culture in only one of the patients. Resistance was present to previously given antibiotics. As patients with cystic fibrosis survive into adulthood, the risk of developing a brain abscess appears to increase.

A simplified method for measuring regional blood flow

A method of measuring regional blood flow (RBF) that is simple in procedure and calculations is described. By arresting flow promptly after a short pulse of diffusible tracer, it is feasible to equate the tracer retained in the tissue (Cfi) with that delivered by the blood. If the arterial pulse is characterized by its mean concentration (Ca) over a known duration (delta t), RBF can be estimated from Cif/Ca delta t). The error involved is relatively small and can be corrected for. If the amount of tracer injected is known, this procedure also provides an estimate of cardiac output and its fractional distribution to the regions sampled. The values obtained for RBF in 4 regions of brain were similar to those previously reported.

Cerebral blood flow immediately following brief circulatory stasis

Cerebral blood flow was studied in rabbits immediately following complete circulatory stasis of varying duration. Systemic arterial pressure was measured continuously. The postischemic circulation was examined both by an infusion of carbon black and, in separate experiments, by injection of 14C-antipyrine into the blood. We examined the relationship between the duration of stasis, the postischemic arterial pressure, and the amount of cerebral reperfusion. As stasis increased from 5 to 30 min the pressure required to achieve reperfusion of the entire brain rose from 20 to 100 torr. Following even temporary exposure to arterial pressures above 110 torr all areas of the brain were generally reperfused. Blood flow in reperfused brain varied directly with arterial pressure, indicating failure of autoregulation. At normal (preischemic) arterial pressure, postischemic cortical flow was twice the normal rate. The data indicate that the pressure required to initiate flow in ischemic brain increases as the duration of stasis is lengthened and that once flow occurs there will be a significant hyperperfusion unless systemic arterial pressure is lowered to the low normal or hypotensive range.

Syringomyelia following lumboureteral shunting for communicating hydrocephalus. Report of three cases

Three patients are described in whom syringomyelia was identified long after the treatment of communicating hydrocephalus by a lumboureteral shunt. The reason for syrinx formation in these cases could not be determined. In two there was either autopsy-proven or presumed evidence for arachnoiditis, and in the third patient the symptoms of syringomyelia were acutely aggravated by temporary obstruction of shunt. The development of a pressure drop from the intracranial compartment to the spinal compartment with crowding at the foramen magnum is also a suggested mechanism.

Neurologic complications of cardiac catheterization

A retrospective survey was made of neurologic complications of cardiac catheterization. Of 10 patients, only one had a diffuse disorder, with seizures of a type associated with reaction to contrast agents. Disorders in the other nine patients appeared to be embolic in nature. Five of these nine involved deficits indicating damage in the vertebrobasilar territories, suggesting local trauma to vessels as a source of the embolic material.

Reassessment of cerebral capillary changes in acute global ischemia and their relationship to the "no-reflow phenomenon"

Electron and light microscopic studies were performed on rabbit brain to re-examine the structural changes of endothelial cells and perivascular glia following ischemia. Although swelling of perivascular glia occurred, earlier findings of extreme perivascular glial swelling and bleb formation leading to luminal collapse and plugging could not be confirmed. Ischemic brains, however, had a higher proportion of small-diameter capillaries than controls. It is felt that structural changes in ischemic capillary walls in themselves are not sufficient to explain failed cerebral reperfusion, or the no-reflow phenomenon.

Physiological aspects of visual perception. II. The subcortical visual direction of behavior

The second part of the Bennett Lecture for 1975 by Denny-Brown examined the subcortical representation of the dissociation of function described by Denny-Brown and Chambers. Complete removal in the macaque monkey of the corticomesencephalic fibers where they pass from pulvinar to colliculus, and of the colliculus, resulted in the same loss of visual object identification, binocular fixation, and visuosocial behavior that followed removal of area 17. Vision for peripheral movement and spatial orientation ("panoramic vision") remained excellent, with release of catatonia. Conversely, unilateral electrolytic lesions of the mesencephalic tegmentum produced visuospatial distortion, asymmetry of optic righting, and directional difficulties in eye movement (Parinaud syndrome and skew deviation). When bilateral, tegmental lesions produced great constriction of visual field with release of convergence and fixation spasm. Suppression of peripheral attention resulted from perceptual rivalry.

Dandy-Walker syndrome: an evaluation of surgical treatment

✓ Twenty-seven patients with Dandy-Walker syndrome surgically treated between 1947 and 1972 are reviewed. The results of treatment and the ultimate functional status of the patients are evaluated. The initial treatment in 17 cases was excision of cyst membranes; 15 of these patients required further surgery to control hydrocephalus, while the other two, one of whom had normal pressure preoperatively, still have large heads. Ten patients were treated by ventricular shunting alone. Thus far 11 patients have died; the commonest causes of death have been CSF infection, uncontrolled hydrocephalus, and acute shunt obstruction. In a 1½- to 20-year follow-up, eight patients have normal or near-normal mental function; these results seem to correlate with the absence or control of increased intracranial pressure. Six patients who are alive are clinically retarded; two of these had severe, diffuse neurological deficits before treatment, two had multiple shunt problems and revisions, and two were either retarded or had severe behavior problems before treatment.

Studies on mechanisms of impairment of cerebral circulation following ischemia: effect of hemodilution and perfusion pressure

Reperfusion of cerebral vessels is impaired following total cerebral ischemia of more than five minutes; this is possibly the initial factor responsible for neurological sequela. Failure of cellular ion transport mechanisms during ischemia was thought to lead to swelling of endothelial cells and perivascular glia and this, in turn, was thought to be the primary cause of the impairment of recirculation. A method of quantitating this circulatory impairment in rabbits was devised after infusing carbon black into the ischemic cerebral vasculature in a standardized way. The amount of circulatory impairment was shown to be unaffected by heparin, inversely related to the infusion pressure of the carbon black, and greatly reduced by acute hemodilution with saline. This latter observation does not support the theory that cellular swelling is the major cause of the postischemic vascular impairment, but rather implicates changes in the blood itself, possibly erythrocyte aggregation which is responsible for increased blood viscosity in low flow and no flow states.

Ventriculo-direct atrial shunts. A clinical evaluation

✓ Ventriculoatrial shunts were performed on 10 patients by placing the cardiac tube directly into the right atrium via the auricular appendage at thoracotomy, and the long-term results after 3 to 6 years were analyzed. Complications included distractions of the upper part of the shunt, pleural cyst formation, pleural effusion, and phrenic nerve injury. The procedure is not recommended for the primary treatment of hydrocephalus, but is useful when simpler shunts are no longer possible or desirable.

Treatable extramedullary cord compression. Meningioma as a cause of the Brown-Séquard syndrome

The Brown-Séquard syndrome is infrequently reported. Though widely considered indicative of intramedullary spinal cord disease, in the absence of penetrating spinal cord trauma, the syndrome is frequently an early stage of extramedullary spinal cord compression, as an extensive analysis of diverse literatures reveals. We describe two cases resulting from compression of the spinal cord by a meningioma. While previous reviews emphasize that radicular or vertebral pain is a prominent feature of spinal cord compression by intradural tumors, our patients had no pain referable to tumor. Awareness that painless extramedullary spinal cord compression can produce the Brown-Séquard syndrome, early myelography, and surgical intervention are necessary to prevent progressive deficit. Even when encountered in a patient who has previously well-documented demyelinating disease, the syndrome should not be written off as a relatively untreatable intramedullary process.