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Biomedical subjects

D W Klass

Publications and source records attributed to D W Klass.

At least 37 records · Page 2Linked to original sources
PubMed1988

The diagnostic specificity of triphasic wave patterns.

A blind analysis of 56 EEGs with triphasic wave patterns was performed to determine the diagnostic specificity of individual electrographic features. EEG and clinical variables analyzed included longitudinal topography, phase lags, symmetry, background activity, reactivity, longitudinal bipolar phase reversal sites, responses to photic stimulation and mental status at the time of recording. The only statistically significant finding for any of the diagnostic groups tested was the presence of severe background slowing in cases of hepatic encephalopathy (P less than 0.001). We found no evidence to suggest that other features may contribute to a more highly characteristic pattern for hepatic encephalopathy. None of the features studied reliably distinguished hepatic encephalopathy from other forms of metabolic encephalopathy.

Adult↗
PubMed1988

Seizures induced by exercise.

Three patients had a clinical history of epileptic seizures during exercise. In all three patients, generalized epileptiform EEG abnormalities were activated by exercise, whereas none had paroxysms during resting wakefulness or during hyperventilation, and only one had a paroxysmal discharge during sleep. Advice to epileptic patients about physical activity should be based on a careful history of individual tolerance. In doubtful cases, an EEG recorded during exercise can provide evidence for an epileptic mechanism.

Adolescent↗
PubMed1987

Transient global amnesia and epilepsy. Electroencephalographic distinction.

Electroencephalographic recordings were obtained during 13 episodes of transient global amnesia in 13 patients. Eight were entirely normal; none showed seizure discharges or other epileptiform activity. Electroencephalographic recordings were also obtained after 103 episodes of amnesia in 96 patients with transient global amnesia (TGA) alone, five patients who had both TGA and epilepsy independently, and three patients with amnesia related to epilepsy. The majority (60.8%) of waking records were normal during or after episodes of TGA. Mild or moderate and nonfocal abnormalities were found in a minority. Genuine epileptiform activity was observed only among patients who had seizure disorders. Amnestic episodes attributable to seizures were more brief and more apt to be repeated than TGA and usually responded to anticonvulsant drugs. Differentiation of TGA from epilepsy is essential for appropriate management.

Amnesia↗
PubMed1986

Midline theta rhythm.

Thirty-six patients had a midline theta rhythm in the electroencephalogram that consisted of a train of rhythmic waveforms in the theta frequency range (4 to 7 Hz), which occurred as a focal rhythm in the midline leads and was usually most prominent in the central vertex lead. The activity consisted of sinusoidal or arciform waveforms that waxed and waned. There was variable reactivity of the midline rhythm to eye opening, alerting, and limb movement. Of the 36 patients, 28 had a seizure disorder, while the other eight had various conditions unassociated with epilepsy. The pattern was not associated with epileptiform activity, mu activity, a drowsy pattern, or medication effect. Although its mechanism of origin is uncertain, the midline theta rhythm appears to represent a nonspecific electroencephalographic pattern that can occur in a mixed group of patients with various diagnoses.

Adolescent↗
PubMed1986

Chronic periodic lateralized epileptiform discharges.

Six patients with chronic epilepsy had persistent periodic lateralized epileptiform discharges (PLEDs) in their interictal electroencephalographic recordings. Three patients had complex partial seizures, two had infantile spasms, and one had multifocal seizures. Four patients had cerebral pathologic changes consisting of tuberous sclerosis (two patients), a porencephalic cyst (one patient), and a chronic brain abscess (one patient). Although PLEDs are usually seen in association with an acute or subacute disturbance of cerebral function, the findings in this group of patients show that chronic PLEDs also can occur in patients with long-standing seizure disorders or chronic brain lesions.

Adult↗
PubMed1986

Triphasic waves in cerebral carcinomatosis. Another nonmetabolic cause.

A 59-year-old woman with a metastatic adenocarcinoma of unknown origin and no metabolic abnormalities developed a diffuse encephalopathy, with generalized triphasic waves seen on the electroencephalogram. Postmortem examination revealed widespread, multifocal perivascular carcinomatosis of the cerebral cortices. Triphasic waves have been described with dementing processes, subdural hematomas, and cerebrovascular disease, but they are more commonly seen with metabolic encephalopathies. This case demonstrates an additional nonmetabolic cause of triphasic waves.

Brain Neoplasms↗
PubMed1985

Repetitive involuntary movement associated with episodic cerebral ischemia.

Clinical characteristics of 12 patients with carotid occlusive disease who experienced episodes of repetitive involuntary movement were analyzed and correlated with laboratory findings. The majority of patients had rhythmic involuntary movements of one or both extremities on one side, which were characteristically precipitated by standing, walking, or hyperextension of the neck and were promptly alleviated by assuming a sitting or supine position. Six patients had a history of a prior transient ischemic attack or stroke. Electroencephalograms contained no epileptiform activity at rest or during sleep in any patient or during the involuntary movements in 2 patients. Cerebral angiography revealed either occlusion or high-grade stenosis of the internal or common carotid artery on the side opposite the involuntary movement in all patients. We conclude that the repetitive involuntary movements result from transient hemodynamic ischemic episodes rather than partial (focal) epilepsy.

Aged↗
PubMed1985

Nonepileptogenic epileptiform electroencephalographic activity.

Accumulated experience has delineated numerous distinctive electroencephalographic (EEG) patterns that are morphologically epileptiform but have no relationship to the process responsible for generating epileptic seizures and have little or no practical value for diagnosis. These anomalous patterns need to be distinguished carefully from the highly abnormal types of EEG activity that continue to have important diagnostic value.

Adult↗
PubMed1985

Interobserver variability in EEG interpretation.

A random sample of 100 active electroencephalographers in the United States evaluated 10-second samples of 12 selected EEGs. The evaluations consisted of multiple-choice questions related to the age of the patient, EEG finding, artifact, and consciousness of the patient. The rate of reporting the "correct" response was examined in terms of various respondent characteristics such as EEG board certification, age, percent of time in clinical EEG work, and number of recordings interpreted annually. This study indicates that, even today, there is considerable variability in EEG interpretation, and that this variability is influenced by specific reader characteristics.

Action Potentials↗
PubMed1985

An acute syndrome with psychiatric symptoms and EEG abnormalities.

Four patients with abrupt onset of psychosis had prominent periodic EEG abnormalities with diffuse sharp waves. Other laboratory studies, including CSF and CT, were normal. The EEG abnormalities disappeared within 1 to 7 days. Clinical improvement was complete and commenced after the EEG showed improvement. The cause remains obscure, but it seems to be a transient organic disturbance of cerebral function that must be distinguished from primary psychiatric disorders.

Acute Disease↗
PubMed1981

Localized EEG abnormalities in acute carbon monoxide poisoning.

The EEG of a patient with acute carbon monoxide poisoning was characterized by lateralized sharp waves and a focal electrographic seizure discharge within hours of the exposure. These findings were associated with coma and focal motor seizures. The patient made a full clinical recovery, and the EEG was normal two months after the exposure. The association of a primarily diffuse cerebral insult after CO poisoning, with prominent lateralized epileptiform discharges in the EEG, is a distinctly unusual phenomenon.

Adolescent↗
PubMed1981

Computed tomography and EEG in cerebrovascular disease.

In three patients with cerebrovascular diseases, the EEG showed active dysfunction of varied extent and severity in one cerebral hemisphere, but computed tomography showed no demonstrable abnormalities in the corresponding areas. These patients had occlusion or severe stenosis of one or both internal carotid arteries, either extracranially or intracranially. Both clinical symptoms and the EEG abnormalities resolved or improved after surgical anastomosis of the superficial temporal artery to the middle cerebral artery.

Adult↗
PubMed1981

A distinctive rhythmic EEG discharge of adults.

An unusual transient electroencephalographic pattern consisting of repetitive sharp-contoured wave forms in the range of 4--7 c/sec was seen in recordings from 65 patients who were between 42 and 80 years of age. This pattern was usually predominant over the parietal and temporal regions. No clinical alteration was associated with the pattern. Although the pattern resembled a subclinical EEG seizure discharge, it did not correlate with clinical seizures. The pattern occurred in patients with diverse clinical complaints, and although its mechanism of origin remains uncertain, it appears to represent a benign EEG phenomenon that has little diagnostic significance.

Adult↗
PubMed1979

Recording small sharp spikes with depth electroencephalography.

Two patients with intractable seizures and focal temporal sharp waves also had small sharp spikes as incidental findings in their scalp electroencephalograms. Depth electroencephalography verified the intracerebral origin of the small sharp spikes and differentiated them from the more significant epileptiform abnormalities.

Adolescent↗