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Biomedical subjects

A E Walker

Publications and source records attributed to A E Walker.

At least 55 records · Page 3Linked to original sources
PubMed1980

Continuous intracranial pressure recording in adult hydrocephalus.

An implantable intracranial pressure sensor was used to diagnose and monitor the treatment of 17 adults with hydrocephalus. The intracranial pressure sensor was implanted before shunting in most cases and patients were studied in a sleep laboratory for two nights during which the intracranial pressure was measured throughout the night. Cases included five examples of acute hydrocephalus secondary to tumor, subarachnoid hemorrhage or meningitis, and 12 cases of long standing hydrocephalus diagnosed as normal pressure hydrocephalus, aque-ductal stenosis, or hydrocephalus ex vacuo. Continuous intracranial pressure monitoring was a valuable adjunct in the diagnosis and management of these patients. Continuous overnight recordings of intracranial pressure were helpful in determining compromised cerebral compliance by observing the shape and the amplitude of the intracranial pressure waves during desynchronized sleep. A second method for checking cerebral compliance is also described.

Adult↗
PubMed1979

The prediction of posttraumatic epilepsy. A mathematical approach.

Simple mathematical equations can be used to estimate the probability of posttraumatic seizures. Risk factors and time since the injury are taken into consideration in the calculations. The equations are based on a constant probability model derived from published data. When these formulae are applied to data from a variety of published studies, the predicted incidence of posttraumatic epilepsy based on the mathematical model agrees well with the incidence observed in the study groups.

Brain Injuries↗
PubMed1979

Clinical evaluation of long-term epidural monitoring of intracranial pressure.

Forty-two epidural sensors for measuring intracranial pressure were implanted in 38 patients over the last four years. The sensor is a passive device consisting of an inductance and a pressure sensitive capacitance resonant at about 50 megahertz. The study involved 17 cases of hydrocephalus, nine of pseudotumor cerebri, and the remainder included cases of cranial trauma, brain tumors, and aneurysms. Four of the sensors failed in patients and were removed. Two of these had to be replaced to continue the pressure monitoring. The intracranial pressure is still being monitored in 22 patients, while 15 have been lost to follow-up for various reasons. Fourteen patients have been followed for about a year, and four for two years. The baseline drift rate in most sensors is between 1 and 2 mm H2O per day, with a few having greater rates of drift. Calibration errors were found in some of the sensors after implantation. These errors were corrected by direct measurement of the cerebral spinal fluid pressure via lumbar puncture. The sensors have proven to be a valuable adjunct in the management and diagnosis of neurosurgical patients by simplifying the intermittent and continuous recording of intracranial pressure. This was so despite the presence of calibration errors and a drift which necessitated an occasional lumbar puncture for making corrections.

Brain Diseases↗
PubMed1978

Pulsatile cerebral echo in diagnosis of brain death.

Conclusive diagnosis of brain death can be made by the demonstration of prolonged cessation of cerebral blood flow. This report describes a simple method to determine the presence or absence of the blood flow in the brain by recording the pulsatile midline echo on one channel of the electroencephalogram (EEG) or on any four-channel monitoring system in the intensive care unit. A firm transducer holder has been developed to eliminate artifacts caused by transducer motion, The pulsations of the midline echo are assumed to be the result of displacement of the midline structures by the arterial injection of each cardiac systole. Thus, the absence of these midline pulsatile echoes correlates with the absence of cerebral blood flow and, if the absence persists over 30 minutes in the presence of normal blood pressure, then the result is brain death. Twenty-eight cases of clinical brain death with electrocerebral silence of EEG and 18 obtained patients with various types of cerebral pathology were examined by the echo-pulsation technique. Twenty-six of the 28 cases showed no pulsation of the midline echo. The validity of the technique was documented in four cases by four-vessel cerebral angiogram.

Adolescent↗
PubMed1978

Pemphigus vulgaris in a 15-year-old girl.

Pemphigus vulgaris is uncommon in adolescence and only ten well documented cases in this age group were found in a recent review (5). Because the condition is often more severe in the younger age group it is important to consider it in the differential diagnosis of bullous eruptions of childhood and to perform direct and indirect immunofluorescence studies.

Adolescent↗