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Biomedical subjects

B L Ehrenberg

Publications and source records attributed to B L Ehrenberg.

31 records · Page 2Linked to original sources
PubMed1990

Asymmetries of sleep spindles and beta activity in pediatric EEG.

Unilateral suppression of beta activity, unilateral suppression of sleep spindles, and unilateral delta slowing on EEG have not been previously compared regarding accompanying neuroradiological (NR) and clinical neurological (CN) findings in children. We studied EEGs in children under age 10 years with unilateral beta suppression (n = 80), spindle suppression (n = 51) or unilateral delta slowing (n = 49). There were no significant differences between the three groups of abnormal EEGs in their relationships with NR and CN. Unilateral suppression of sleep spindles and beta activity are at least as accurate as focal slowing in lateralizing NR and CN findings.

Beta Rhythm↗
PubMed1989

Metamorphopsia and palinopsia. Association with periodic lateralized epileptiform discharges in a patient with malignant astrocytoma.

A patient with a right parietal glioma developed palinopsia and various forms of metamorphopsia that were temporally related to the electrographic presence of periodic lateralized epileptiform discharges. These symptoms occurred in an alert woman with normal visual fields. The literature shows that epileptic events can produce these symptoms. We believe that continuous repetitive electrical stimulation caused our patient's unusual symptoms by altering the association pathways through which visual data are experienced. To our knowledge, the association between periodic lateralized epileptiform discharges and metamorphopsia or palinopsia has heretofore not been reported.

Adult↗
PubMed1989

Pharmacokinetic and electroencephalographic study of intravenous diazepam, midazolam, and placebo.

Eleven healthy volunteers received a single intravenous dose of diazepam (0.15 mg/kg), midazolam (0.1 mg/kg), and placebo by 1-minute infusion in a double-blind, three-way crossover study. Plasma concentrations were measured during 24 hours after dosage, and the electroencephalographic (EEG) power spectrum was simultaneously computed by fast-Fourier transform to determine the percentage of total EEG amplitude occurring in the 13 to 30 Hz range. Both diazepam and midazolam had large volumes of distribution (1.2 and 2.3 L/kg, respectively), but diazepam's half-life was considerably longer (33 versus 2.8 hours) and its metabolic clearance lower (0.5 versus 11.0 ml/min kg) than those of midazolam. EEG changes were maximal at the end of the diazepam infusion and 5 to 10 minutes after midazolam infusion. Percent 13 to 30 Hz activity remained significantly above baseline until 5 hours for diazepam but only until 2 hours for midazolam. For both drugs, EEG effects were indistinguishable from baseline by 6 to 8 hours, suggesting that distribution contributes importantly to terminating pharmacodynamic action. The relationship of EEG change to plasma drug concentration indicated an apparent EC50 value of 269 ng/ml for diazepam as opposed to 35 ng/ml for midazolam. However, Emax values were similar for both drugs (+19.4% and +21.3%, respectively).

Adult↗
PubMed1989

Sleep disorders and depression with atypical features: response to valproate.

Symptoms of so-called atypical depression, such as hypersomnia and lethargy, may accompany specific sleep disorders. It is often difficult to determine which disorder is "primary". The authors examine three cases of depression with atypical features associated with specific sleep disorders and report a favorable response to valproate. Some clinical features of the cases suggest a primary sleep disorder with secondary affective symptoms. However, valproate may have direct mood-altering effects as well as effects on sleep physiology. The implications of these findings for diagnosis and treatment are discussed.

Adult↗
PubMed1989

Kinetic and dynamic study of intravenous lorazepam: comparison with intravenous diazepam.

Six healthy volunteers received a single i.v. dose of 'low dose' lorazepam (0.0225 mg/kg), 'high dose' lorazepam (0.045 mg/kg) and placebo by 1-min infusion in a double-blind three-way crossover study. Plasma concentrations were measured 24 hr after dosage, and the EEG power spectrum was simultaneously computed by fast-Fourier transform to determine the percentage of total EEG amplitude occurring in the 13-30-Hz range. Low and high dose lorazepam did not differ significantly in distribution volume (1.89 versus 1.81 l/kg) or elimination half-life (11.5 versus 12.2 hr); clearance was slightly although significantly reduced at the higher dose (2.08 versus 1.88 ml/min/kg, P less than .005). EEG effects were of relatively slow onset, reaching their maximum change over baseline 30 min after infusion. The duration of action was prolonged, with the fraction of EEG activity in the 13-30-Hz range still significantly above baseline 8 hr after the 0.045 mg/kg dose. Five of these subjects received 0.15 mg/kg of i.v. diazepam in a companion study of identical design. EEG effects of diazepam were shorter than those of lorazepam, probably because of the more rapid and extensive decline in plasma diazepam concentrations in the postinfusion distribution phase. In addition, the onset of diazepam's effect was immediate. In male CD-1 mice that received i.v. diazepam (8.3 mg/kg) or lorazepam (3.3 mg/kg), the brain:plasma concentration ratio was maximal 2.5 min after dosage for diazepam, but equilibration was delayed at least 30 min after dosage for lorazepam. Thus the slow onset of action of lorazepam is probably attributable to slow entry into brain.

Adult↗
PubMed1986

Globoid cell leukodystrophy: cranial computed tomography and evoked potentials.

The evoked potentials and cranial computed tomographic (CT) scan findings in a case of early infantile globoid cell leukodystrophy are presented. The brain stem auditory evoked responses (BAERs) and the flash visual evoked potentials (VEPs) were abnormal. Repeated cranial CT scans showed multiple areas of increased attenuation and progressive cerebral atrophy. These evoked potential and CT scan patterns occurring concomitantly in an infant are suggestive of globoid cell leukodystrophy.

Electroencephalography↗
PubMed1983

In vitro correlates of benzodiazepine cerebrospinal fluid uptake, pharmacodynamic action and peripheral distribution.

Factors influencing the rate and extent of benzodiazepine uptake into cerebrospinal fluid (CSF), peripheral tissue distribution and electroencephalographic (EEG) effects were evaluated in a model utilizing anesthetized male cats. A single (0.25-10 mg/kg) dose of the following eight benzodiazepines was administered i.v.: diazepam, desmethyldiazepam, midazolam, lorazepam, alprazolam, triazolam, flunitrazepam and clobazam. Multiple samples were simultaneously drawn from arterial blood and cisternal CSF over the next 4 hr and the EEG was continuously monitored. Concentrations of benzodiazepines in plasma and CSF samples were measured by electron-capture gas-liquid chromatography and plasma protein binding determined by equilibrium dialysis. Physicochemical properties of lipophilicity of each benzodiazepine were determined by measurement of the octanol/buffer partition ratio at physiologic pH and by the high-pressure liquid chromatographic (HPLC) retention on a reverse-phase C18 column at neutral pH. Disappearance of all benzodiazepines from plasma was consistent with a linear sum of two or three exponential terms. After correction for individual differences in protein binding, volume of distribution (Vd) of unbound drug was highly correlated with HPLC retention (r = 0.91), but not significantly related to octanol/buffer partition coefficient. Diazepam and midazolam, having the longest HPLC retention also had the largest unbound Vd. All benzodiazepines rapidly entered CSF, with peak concentrations usually attained within 15 min of dosage. More lipophilic drugs tended to enter CSF most rapidly, but associations of entry rate and in vitro lipophilicity were not significant. After distribution equilibrium was attained, disappearance of benzodiazepines from both plasma and CSF occurred in parallel. Equilibrium CSF/total plasma concentration ratios of all drugs were much less than unity.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1982

Pattern shift visual evoked response: application in neurology.

The technique that we use for pattern shift visual evoked response (PSVER) is described. PSVER is a non-invasive, practical and reliable clinical test in detecting anterior visual pathways lesions even when asymptomatic. The ability to find unsuspected lesions in multiple sclerosis, making possible an early diagnosis, is underscored. We also discuss some pathophysiologic aspects and the findings of the PSVER in some neurologic disorders with visual system involvement.

Adolescent↗
PubMed1982

Brainstem auditory evoked response: application in neurology.

The technique that we use for eliciting brainstem auditory evoked responses (BAERs) is described. BAERs are a non-invasive and reliable clinical test when carefully performed. This test is indicated in the evaluation of disorders which may potentially involve the brainstem such as coma, multiple sclerosis, posterior fossa tumors and others. Unsuspected lesions with normal radiologic studies (including CT-scan) can be revealed by the BAER.

Adult↗
PubMed1982

Somatosensory evoked response: application in neurology.

One technique used for short-latency somatosensory evoked response (SER) is described. SER following nerve stimulation is a unique non-invasive, clinical test used to evaluate the somatosensory pathways. It tests the physiological function of the median nerve, the brachial plexus, the C6-7 cervical roots, cervical spinal cord, the cuneate nuclei, the medial lemniscus, the thalamus, and the contralateral sensory cortex. It has been shown to be a reliable and useful clinical test particularly in multiple sclerosis and comatose patients. The promising technique of SER following peroneal nerve stimulation is mentioned.

Adult↗
PubMed1976

Computer recognition of generalized spike-wave discharges.

Twelve 12h daytime telemetered EEGs were read for generalized spike-wave (S-W) bursts by a computer and independently by three experienced electroencephalographers. The computer system was a hybrid of analog devices (tape-recorder, voltage summator, and high-pass filters) and a multipurpose laboratory digital device (PDP-12). The computer was programmed to identify only the location on the record and the duration of the generalized S-W paroxysms. From 1,462 discharges identified by both the readers and the computer, a consensus list of 609 was derived by selecting only those bursts identified by all three readers. The computer recognized 516 (85%) of those bursts on the consensus list; the computer's accuracy, as compared with the consensus, rose to 92% when portions of the EEG containing sleep were discounted. The computer also recognized as generalized S-W paroxysms 15 high-voltage transients, which none of the three readers selected. Ten of these, however, occurred during sleep. When the computer results were added to those of the three readers to permit a four-way inter-reader comparison, the computer was found to have had about as many isolated decisions as any of the three readers. In the number of bursts recognized, the computer tended to be about as conservative as the reader under whose guidance it was originally programmed. The computer's accuracy in measuring burst duration was not evaluated statistically.

Computers, Hybrid↗
PubMedDate not supplied

The health status of adults with epilepsy compared with that of people without chronic conditions.

STUDY OBJECTIVES: To examine the feasibility of administering and the psychometric properties of a general health status questionnaire in adults with epilepsy, and to assess the health status of these patients. DESIGN: Prospective, cross-sectional, observational study. SETTING: Neurology clinic of a tertiary care medical center. PATIENTS: One hundred forty-eight ambulatory adults with epilepsy. INTERVENTIONS: Patients completed the SF-36, a general health status questionnaire. Respondent burden and data quality as well as psychometric characteristics were evaluated. Patients' SF-36 scale scores, adjusted for comorbidities, were compared with those of 641 people without chronic conditions with the same sociodemographic characteristics. MEASUREMENTS AND MAIN RESULTS: Administering the SF-36 to adult outpatients with epilepsy is feasible and results are psychometrically sound. Compared with those who were not ill, patients had significantly (p < 0.001) lower (0 = worst, 100 = best) scores in six of the eight SF-36 domains: general health perceptions (57.7 vs 82.1), mental health (61.3 vs 79.6), vitality (53.5 vs 67.8), role limitations owing to physical (69.6 vs 95.0) and emotional problems (67.2 vs 88.4), and social functioning (75.2 vs 89.9). CONCLUSIONS: Lower SF-36 scores may reflect patients' assessments of the balance among epilepsy, seizures, and antiepileptic drug therapy-related effects. Incorporating health status information into therapeutic decision making may help to attain the ultimate goal of improving patients' health.

Adult↗