Thirteen of 29 patients with meningitis had a complicating ventriculitis (white blood cell count > 200/cu mm or positive ventricular fluid culture), including eight of 12 neonates. Ventriculitis should be considered a brain abscess and treated with the direct instillation of antibiotics. Periodic irrigation and drainage may be necessary. Very high antibiotic levels can be obtained in the ventricular fluid using the recommended dose schedule. A Salmon-Rickham ventriculostomy reservoir was placed in the lateral ventricle to obviate repeated puncture of the brain. Seven of ten patients with ventriculitis given antibiotics intraventricularly and systemically are normal including four of six neonates. The ratio of head circumference to cerebral mantle is used as a rough estimate of the ventricular fluid volume to aid in selecting the proper antibiotic dose. r Mhe fatality rate of neonatal J-meningitis at university hospi¬ tals is 60%. Significant sequelae are present in one half of the survivors.1

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Normal speech as well as an improved airway is now an achievable goal in the treatment of laryngeal webs. Seven acquired webs and 3 congenital webs were seen at the North Carolina Baptist Hospital/Bowman Gray School of Medicine. The speech of 6 patients was tested preoperatively and again postoperatively: speech was considered normal postoperatively in 5 patients without the need for speech therapy; normal in the sixth patient after 6 sessions of speech therapy. The authors' preferred method of treatment is development of an endolaryngeal mucosal flap with a variable beam CO2 laser under operating microscopic control.

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SUMMARY Intracranial hypotension increases cerebral blood flow. In dogs the average increase in cortical blood flow was 30 ml./100 g/min (47%) when the intracranial pressure was lowered acutely from 100 to 40 mm CSF. Permanent intracranial hypotension was established in seven demented patients using a ventriculoatrial shunt. The mean post shunt pressure was 50 mm CSF. In this group, the cerebral vascular resistance decreased 32%, the cortical blood flow increased 37 %, and the relative weight offunctional grey matter increased 44 %. The systemic blood pressure was 8% lower. The increase in cerebral blood flow is the result of an increase in the pressure differential between the precapillary arterioles and the veins. In addition, the vessels dilate in response to the decreased external pressure. This increase in cerebral blood flow may be the mechanism for improvement in patients with normal pressure hydrocephalus who are shunted. This is the report of an experimental and clinical study of the effects of lowering intracranial pressure on cerebral blood flow. The study is an attempt to determine the mechanism of improvement in patients with normal pressure hydrocephalus. METHODSCerebral blood flow was determined using the inert radioactive gas 133Xe. This isotope is a gamma emitter which permits counting through the intact skull. After its injection into the carotid artery, xenon diffuses in a known ratio between the blood and brain tissue. This is a purely physical process and depends only on diffusion and solubility. The gas is almost completely cleared in the lung as it is approximately 10 times more soluble in air than blood. On completion of the injection the carotid arterial blood contains virtually no xenon. The rate at which the xenon is washed out of the brain tissue varies with the quantity of blood perfusing the brain. The faster the flow of blood, the faster the radioactive material is removed from the brain. This is the basic principle for determining cerebral blood flow using the clearance technique (Harper, Glass, Steven, and Granat, 1964 to a standard arterial pCO2 (apCO2) of 40 mm Hg. Using the systolic blood pressure and CBFG, the cerebral vascular resistance (CVRc) of the cortical vessels was determined.In previous studies of 54 dogs using this technique, little variation in CBF was found on sequential determination in an individual dog. Our values in normal animals (Salmon, 1969) were comparable with those from other laboratories (Harper, Glass, and Glover, 1961).Seven animals were studied. After the dog was anaesthetized with pentobarbital and an endotracheal tube inserted, a small catheter was placed in the carotid artery and a no. 18 gauge needle in the cisterna magna. A scintillation detector, collimated to cover the estimated area of one cerebral hemisphere, was placed high on the cranial convexity. The intracranial pressure (ICP), the systolic (SBP) and mean (MBP) blood pressure, and the arterial pCO2 were monitored. However, in two dogs the apCO2 was not within the range of 35 to 50 mm H...