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Biomedical subjects

J J Stockard

Publications and source records attributed to J J Stockard.

18 recordsLinked to original sources
PubMed1979

Brainstem auditory-evoked responses. Normal variation as a function of stimulus and subject characteristics.

Brainstem auditory-evoked responses (BAERs) were elicited from 64 neurologically and audiometrically normal adults and 77 normal, full-term neonates with broadband rarefaction or condensation clicks at sensation levels (hearing levels in neonates) of 30 to 70 dB and at rates of ten and 80 clicks per second. In addition to the known effects of rate, previously unrecognized effects of acoustic phase and stimulus intensity on BAER interpeak latencies (IPLs), and an interaction of all three stimulus parameters, were found. Stimulus characteristics, age, and sex can account for much of the inter- and intrasubject variability of BAER IPLs and morphology. The BAER effects of many of these variables and their interactions have not been appreciated in clinical applications of BAER. Recognition and control of such reducible, methodological sources of BAER variability will enhance the sensitivity and specificity of the test in neurologic diagnosis.

Acoustic Stimulation↗
PubMed1978

Effects of hypothermia on the human brainstem auditory response.

Latency measurements between three potentials (waves I, III, and IV/V) of the human brainstem auditory response can allow early detection of certain posterior fossa lesions. The diagnostic use of these interwave latencies requires knowledge of what factors may prolong them in the absence of disease. Hypothermia appears to be one such factor--in 5 neurologically and audiometrically normal patients, mean esophageal temperatures as high as 34.5 degrees C resulted in prolongations of central auditory conduction time. Interwave latency prolongations that were abnormal relative to an age-matched normal population were seen at 32.1 degrees +/- 0.3 degrees C in patients with both spontaneous and induced hypothermia, and these abnormalities disappeared after rewarming to normothermia. Hypothermia often accompanies intoxication and coma and should therefore be considered when brainstem auditory response abnormalities are being interpreted in these two clinical conditions.

Adult↗
PubMed1977

EEG correlations with biochemical abnormalities in Reye syndrome.

A patient with Reye syndrome was studied throughout the course of the illness with continuous EEG monitoring, and these patterns were correlated with serial determinations of serum ammonia and short-chain fatty acid concentrations. There was high correlation between degree of EEG abnormality, clinical symptoms, and elevations of the short-chain fatty acids, while serum ammonia concentrations correlated poorly with the EEG and with the clinical state.

Ammonia↗
PubMed1977

Central pontine myelinolysis. A clinical reappraisal.

We discuss three patients with clinical findings of central pontine myelinolysis (CPM). Two patients survived with minimal neurological deficits, and one patient died from medical complications while recovering from his neurological deficit. Postmortem examination showed the typical lesion of CPM. Brain stem auditory evoked potential studies in two of our patients indicate that there was impairment of function in auditory pontine pathways that returned to normal as the patients improved clinically. We conclude that CPM can be diagnosed clinically and that patients may recover if intercurrent illnesses are vigorously treated.

Alcoholism↗
PubMed1977

Clinical and pathologic correlates of brain stem auditory response abnormalities.

Short-latency auditory evoked responses were recorded in over 100 neurologic patients. Abnormalities of each response component were correlated with postmortem or radiologic localization of different brain stem lesions. These findings suggested that waves I-VII largely reflect activity at the following levels of the auditory pathway: acoustic nerve (I), pontomedullary junction (II), caudal pons (III), rostral pons or midbrain (IV), midbrain (V), thalamus (VI), and thalamus or auditory radiation (VII). When this information was applied prospectively to the evaluation of brain stem dysfunction, response abnormalities proved useful in detecting and localizing certain lesions not revealed by other tests. Serial recordings provided information about the evolution of brain stem lesions and their response to therapy.

Adult↗
PubMed1977

Detection and localization of occult lesions with brainstem auditory responses.

Seven vertex-positive potentials--the brainstem auditory response--can be recorded from the human scalp within 10 milliseconds of an appropriate acoustic stimulus. The first of these potentials is generated in the acoustic nerve, the third in the pons, and the fifth in the midbrain. Measurement of the relative latencies and amplitudes of these potentials allowed detection of subclinical lesions in 37 (53 percent) of 70 patients with suspected multiple sclerosis who had no signs or symptoms of brainstem involvement by the disease. Abnormalities in the brainstem auditory response provided the first evidence of the pressence of multiple lesions in 14 (35 percent) of 40 patients with suspected multiple sclerosis who had clinical evidence of only a single spinal or cerebral lesion. Response abnormalities also suggested the presence of tumors of the posterior fossa in three patients with nonspecific symptoms and normal neurologic examinations, the test indicated the need for contrast studies, which then led to the correct diagnosis of infratentorial neoplasm.

Acoustic Stimulation↗
PubMed1976

Electroencephalographic findings in phencyclidine intoxication.

The first report of electroencephalographic findings in clinically encountered phencyclidine intoxication is presented. When first seen, the patient was in a coma, initially distinguished only by nystagmus, waxy rigidity of the extremities, and an EEG with a widespread, sinusoidal theta rhythm interrupted every few seconds by periodic slow-wave complexes. The similarity of the EEG to that of deep ketamine anesthesia suggested intoxication with a ketamine-related (phenylcyclohexylamine) drug. Phencyclidine, the prototype of the phenylcyclohexylamine compounds and a widely abused hallucinogen, was subsequently identified in the urine and blood.

Adult↗
PubMed1976

Brain stem auditory-evoked responses in suspected central pontine myelinolysis.

Central pontine myelinolysis was suspected in two chronic alcoholics who developed and recovered from a progressive spastic paresis of all muscles, that derived innervation at and below the level of the pons. In both cases, short-latency auditory-evoked responses aided in the diagnosis by indicating a slowing of conduction in the pontine auditory pathway, which varied in degree with the severity of the clinical manifestations of pontine demyelination.

Alcoholism↗
PubMed1975

Neurologic and electroencephalographic correlates in glutethimide intoxication.

Neurologic and electroencephalographic (EEG) examinations were performed every two hours during a case of severe glutethimide intoxication resulting from the acute ingestion of at least 15 grams of glutethimide. Neurologic data were reduced to 10 measurements of brainstem function and plotted as an index that varied cyclically in amplitude during the clinical course. Electroencephalographic data were computer-processed by power spectral methods and related to the brainstem function index. Good positive correlation existed between the frequency and reactivity of EEG activity and the level of brainstem function as reflected in the index. The cyclic and, sometimes, unilateral nature of the clinical findings previously reported in glutethimide coma was confirmed and seen to be reflected in the EEG. The present case also indicates that, in the absence of cerebral ischemia or hypoxemia secondary to cardiopulmonary depression, complete clinical recovery from glutethimide-induced coma is possible no matter how severe the presenting neurologic and EEG signs.

Brain Stem↗
PubMed1975

Effects of acute and chronic paleocerebellar stimulation on experimental models of epilepsy in the cat: studies with enflurane, pentylenetetrazol, penicillin, and chloralose.

Effects of acute and chronic paleocerebellar stimulation were evaluated in four experimental models of epilepsy in 24 adult cats chronically implanted with bilaterally symmetric parasagittal electrocorticographic electrodes and anterior lobe cerebellar stimulation electrodes. Pentylenetetrazol was given intraveneously in 50-mg increments or 4% enflurane was inspired until grand mal seizures occurred spontaneously or were triggered by photic or auditory stimuli. Alpha-chloralose, 50 mg/kg, was injected intraperitoneally to produce a model of stimulus-sensitive myoclonus and sodium penicillin G, 350,000 units/kg, was injected intramuscularly to produce a model of petit mal epilepsy. One- to 250-Hz electrical stimulation of paleocerebellar cortical surfaces was performed with constant-voltage or constant-current stimulators at threshold and suprathreshold intensities with average intensities of 8 V and 2.5 mA, respectively. Acute or chronic, threshold or suprathreshold paleocerebellar stimulation did not predictably alter the electrographic or clinical manifestations in any of these four models.

Acoustic Stimulation↗
PubMedDate not supplied

Monitoring of cerebral perfusion during anesthesia by time-compressed Fourier analysis of the electroencephalogram.

Time-compressed Fourier analysis of the electroencephalogram has proven to be a useful analytical procedure during anesthesia and surgery which simplifies data interpretation by presenting the EEG in a time-compressed frequency domain rather than the conventional time domain. This method of data analysis graphically accentuates the electroencephalographic correlates of ischemia-induced cerebral dysfunction and other cerebral oxygen consumption abnormalities. The ability to accentuate trends in frequency and power is derived from sequential plotting of spectra to produce a graph with three dimensional axes of frequency, time, and power. In carotid endarterectomies the system has proven more useful than the conventional EEG in assessing the need for a vascular shunt to maintain internal carotid flow during endarterectomy. In open-heart surgery time-compressed EEG spectral analysis has allowed early recognition of cerebral ischemia resulting from arterial hypotension and venous hypertension. Five cases are presented which demonstrate the ability of our system to reflect developing cerebral ischemia.

Aged↗
PubMedDate not supplied

Electroencephalographic abnormalities following halothane anesthesia.

In 7 subjects, serial EEGs, serum bromide determinations, and psychological tests were done prior to and following 13.83 +/- 0.74 (SEM) MAC-hours of halothane anesthesia. Significant psychological impairment demonstrated 2 days following anesthesia in these subjects was absent 2 weeks following exposure to halothane. Nonspecific postanesthetic slowing of the EEG was found, qualitatively similar to but more marked than that following exposure to enflurane. Generalized EEG slowing, with a tendency toward posterior delta activity and significant reduction of frequency and amplitude of the alpha rhythm, persisted for 6 to 8 days following anesthesia. Rare sharp-wave activity developed in 3 subjects in the 1st week after halothane. A potentially psychoactive postanesthetic serum bromide level of 2.97 +/- 0.17 mEq/L (SEM) was found 5 days following anesthesia. Electroencephalographic changes characteristic of mild bromide intoxication were absent, suggesting that the psychological impairment noted after halothane anesthesia is probably not due to this metabolite; these psychological changes are probably due instead to persistence in the circulation of unchanged halothane.

Adult↗