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K H Chiappa

Publications and source records attributed to K H Chiappa.

68 records · Page 4Linked to original sources
PubMed1981

Brainstem auditory and short-latency somatosensory evoked responses in brain death.

Thirty-five patients who met all clinical criteria for brain death and 53 patients who did not were tested with brainstem auditory (BAER) and short-latency somatosensory (SER) evoked responses. Of the brain-dead patients, 77% had no waves present in the BAER, including wave I, whereas 69% had medullary components present in the SER. These data suggest that the SER has greater clinical utility in the brain-death setting, because it is important to have a wave present that established that the input signal has reached the central nervous system. No brain-dead patients had subsequent waves in either test. These results are correlated with neuropathologic findings and contrasted with data obtained in the comatose but not brain-dead patients.

Adolescent↗
PubMed1980

Brainstem auditory evoked responses in 200 patients with multiple sclerosis.

Brainstem auditory evoked responses (BAERs) were recorded from 202 patients with definite, probable, or possible multiple sclerosis (MS). Definitions of abnormality were based only on interwave separations and the wave I/wave V amplitude ratio. Thirty-two percent of the patients had abnormal BAERs, and the presence of clinically unsuspected lesions was revealed by BAER abnormalities in 7.4%. Thirty-five percent of the patients who had nystagmus and 53% of those who had internuclear ophthalmoplegia at the time of testing had BAER abnormalities. Forty-five percent of the abnormalities were elicited with stimulation of one ear only, stressing the importance of monaural stimulation. Click rates faster than 10 per second did not reveal abnormalities undetected at slower rates. BAERs were normal by these criteria in patients with labyrinthine diseases and amyotrophic lateral sclerosis. Thus, the BAER in MS can (1) confirm the presence of central lesions in patients with suspected brainstem involvement, (2) document the presence of clinically unsuspected lesions, and (3) be followed over time to provide possible assistance in evaluating the effectiveness of therapeutic measures. The BAER is a useful tool in the diagnosis and management of MS.

Acoustic Stimulation↗
PubMed1980

Pattern shift visual, brainstem auditory, and short-latency somatosensory evoked potentials in multiple sclerosis.

Pattern shift visual (PSVER), brainstem auditory (BAER), and short-latency somatosensory (SER) evoked potentials are practical and reliable clinical tests that provide objective measures of impulse conduction in the respective central nervous system (CNS) white matter tracts. In large groups of patients with multiple sclerosis (MS), the abnormality rates were 56, 32, and 60% (PSVER, BAER, and SER, respectively). Evidence of clinically unsuspected lesions was found in 42, 21, and 51%, respectively. Abnormality rates for a definite MS group alone were higher. The tests provide confirmatory and additional evidence for multiple lesions in CNS white matter. They may also provide an objective assessment of the efficacy of therapeutic regimens.

Amblyopia↗
PubMed1979

Brain stem auditory evoked responses: studies of waveform variations in 50 normal human subjects.

Brain stem auditory evoked responses (BAERs) were recorded in 50 normal adult subjects at various click rates. Attention was paid to absolute latencies, interwave latencies, interear interwave latencies, absolute amplitudes, and various amplitude ratios. The variability of waves VI and VII suggests that the clinical utility of these waves is restricted-their absence is not necessarily due to a CNS lesion. The wave IV-V complex appears with six different patterns. These variations must therefore be considered normal; none should be misconstrued as indicative of disease of the CNS. Repeated studies over a period of two to nine months showed no statistically significant changes in amplitude or latency measurements with the passage of time. Knowledge of these normal values and their variations, as a precondition for establishing criteria for abnormality, is essential to the interpretation of BAERs in clinical situations.

Acoustic Stimulation↗
PubMed1979

The effect of metrizamide on the electroencephalogram: a prospective study in 61 patients.

A prospective study was made of changes in the electroencephalogram after the use of metrizamide for myelography and posterior fossa cisternography in 61 patients (62 studies). The EEG changed in 21 patients (34%); 3 of these had had previously abnormal records, and the abnormalities were accentuated on the second recording. Eight developed paroxysmal activity, including spike and wave in 1. EEG changes appeared 24 to 48 hours after the use of metrizamide in 6 patients whose intervening EEGs were normal. The percentage of records that changed tended to increase as metrizamide was brought to more rostral levels. Symptoms following the use of metrizamide were reviewed in 58 patients. Although there were no seizures in the present series, seizures did occur with subsequent use of metrizamide in 3 other patients at our institution. Previous reports may have underestimated the frequency of EEG changes after metrizamide since these may require 24 to 48 hours to develop. The appearance of such activity suggests that the use of metrizamide in patients with known seizure disorders, the anatomical level to which metrizamide is brought during radiography, removal of contrast medium, and further investigation of premedication with anticonvulsants all require careful consideration when use of metrizamide is being contemplated.

Adult↗
PubMed1979

Impact of CT on EEG.

Explore the source record for details and available documents.

Electroencephalography↗
PubMed1978

Pattern shift visual evoked responses. Two hundred patients with optic neuritis and/or multiple sclerosis.

Fifty-one patients with clinically pure optic neuritis (ON) and 149 with possible, probable, or definite multiple sclerosis (MS) were tested with pattern shift visual evoked responses (PSVER) and compared with a group of 43 normal subjects. Attention was paid to response latency, intereye latency difference, as well as differences in amplitude or duration of the major positive peak (P100). Abnormal PSVER cannot be recorded from everyone with confirmed ON. Abnormal responses were recorded from 91% of all patients (including those with MS) who had a history of ON, 57% of all MS patients, and 36% of patients without a history of ON or an abnormal eye examination. Measurements of amplitude and duration proved to be of little value in this setting. Though abnormalities of PSVER are not "specific" for ON or MS, because they also result from other disease processes, they afford more reliable, quantitative documentation of abnormal conduction in visual pathways than any other clinical test.

Adolescent↗
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↗
PubMedDate not supplied

Pattern ERG: effects of reference electrode site, stimulus mode and check size.

We studied monocular pattern ERG (PERG) in 10 normal subjects and a patient with optic neuritis. No clinically significant PERG could be recorded from the occluded eye with any reference (ipsilateral ear or temple, or midfrontal), indicating that cross-contamination is not present with binocular testing. Ipsilateral temple reference minimized VEP (P100/N100) contribution to the PERG N95 which occurred with ipsilateral ear or midfrontal reference. The conclusions were confirmed by results from the patient, who had marked monocular delay of a normal amplitude P100. Twenty-four subjects were tested with monocular and binocular stimulation using an ipsilateral temple reference. There were differences in PERG latencies and amplitudes although the interside amplitude ratio showed smaller differences with binocular stimulation. Increasing check size (17, 35 and 70 min) decreased P50 and N95 latencies and increased P50 amplitude.

Adult↗
PubMedDate not supplied

EEG monitoring for induced hypotension for surgery of intracranial aneurysms.

EEG was monitored at bilateral scalp sites outside the operative field during hypotensive aneurysm surgery in 21 patients. Mean arterial blood pressure at axillary level was 50-60 mm Hg (average 55 mm) for 1.9-5.3 hours (average 3.6). Four new deficits were noted immediately post-operatively, all related to the operated site: these were attributable to intra-operative rupture with forced vascular clipping, vasospasm, or edema. In no instance was hypotension solely responsible for a new deficit. EEG showed persistent slowing in relation to surgery in only 1 patient, where aneurysmal rupture led to severe hypotension, forced clipping of 1 posterior cerebral artery, and subsequent brain stem infarction. In the 3 other patients with fresh focal postoperative deficits, no persistent intraoperative EEG changes were observed. EEG monitoring did not detect ischemia in these 3 patients because 1) hypotension was moderate and did not per se cause new deficit, and 2) EEG electrodes did not survey the area at maximal risk, namely the operative field. EEG scalp electrodes near but outside the operative site do not seem useful for monitoring cerebral function in the region of aneurysm surgery. Epidural or cortical electrodes in the operative field may prove to be more useful.

Adult↗
PubMedDate not supplied

Results of electroencephalographic monitoring during 367 carotid endarterectomies. Use of a dedicated minicomputer.

Three hundred sixty-seven carotid endarterectomies were monitored using routine electroencephalographic (EEG) techniques. In 9.8%, changes in the EEG followed clamping of the internal carotid artery and could roughly be grouped into 6 patterns. The most common (47%) was rapid unilateral or bilateral attenuation of background anesthetic-induced fast EEG activity. Conclusions drawn from studies of the 9 patients who had immediate postoperative neurological deficits of varying degrees are presented as they illustrate monitoring techniques that are useful for early recognition of cerebral ischemia. Thirty-five patients were monitored with both routine and computerized techniques--the latter proved more useful than the former on all counts.

Anesthesia↗
PubMedDate not supplied

Transcranial motor evoked potentials.

History, methodology and description of recording motor action potentials elicited by magnetic stimulation of the cortex through the skull. Summary of clinical results published in the literature and those carried out by the author.

Animals↗