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C W Vanderzant

Publications and source records attributed to C W Vanderzant.

9 recordsLinked to original sources
PubMed1993

Correlation of evoked potential and MRI findings in Wilson's disease.

We recorded brainstem auditory evoked potentials (BAEPs) and somatosensory evoked potentials to median nerve stimulation (MSEPs) within 10 days of brain MRI in 20 patients with Wilson's disease (WD). MRI was abnormal in 90% of patients, demonstrating symmetric striatum and brainstem lesions with or without thalamic lesions. MSEPs were abnormal in 65% of patients, usually showing bilaterally prolonged N/P13-N20 latencies. BAEPs were abnormal in 40%, most often with bilateral prolongation of the III-V latency. The III-V and N/P13-N20 interpeak latencies correlated significantly with the severity of MRI lesions in the caudal pons, rostral pons, and caudal midbrain. Our results indicate that subclinical sensory dysfunction is common in WD, and that auditory and somatosensory pathways are most severely affected at the brainstem level. Both the localization and severity of evoked potential abnormalities correspond closely to the morphologic changes in the pons and caudal midbrain shown by MRI.

Adult↗
PubMed1991

Polarity reversal of N20 and P23 somatosensory evoked potentials between scalp and depth recordings.

From depth and scalp electrodes, we recorded MN-SSEPs of a 33-year-old man with right parietal dysfunction and refractory right temporal seizures. A depth lead with 8 electrodes was implanted deep in each parietal-temporal region. Stimulation and recording parameters followed American EEG Society guidelines. Scalp recordings had well-defined P9, P13-14, N18, N20, and P23 potentials with normal conduction times bilaterally. Depth recordings showed potentials of greater number, voltage, and coherence. P13-14 and N18 were recorded at all depth sites with latencies similar to those at the scalp. N18 had markedly greater voltage and duration near the thalamus, with multiple fast components on its ascending phase. In the deep parietal region there was a positivity corresponding to the scalp N20 and a negative potential equal in latency to scalp P23. These findings support an origin of P13-14 caudal to the thalamus, multiple thalamic and possibly rostral brain-stem generators for N18, and generation of N20 and P23 in sensory cortex of subjacent white matter.

Adult↗
PubMed1991

Multimodality evoked potential testing in acute mild closed head injury.

Multimodality evoked potential (MEP) testing, including brainstem auditory, visual, and somatosensory evoked potentials, have been reported to be useful in predicting outcome in severe closed head injury. Brainstem auditory evoked potentials have been demonstrated to be abnormal in 10% to 40% of acute mild head injury. A prospective study of 18 patients with mild closed head injury was undertaken to determine the usefulness of MEP screening within two weeks of the acute event. Long latency event-related potentials (P300s), in response to auditory stimuli with an oddball paradigm, were included in the screening. The subjects had several symptoms consistent with the postconcussive syndrome at the time of the evoked potential testing. Only one patient had an abnormal evoked potential response (greater than three standard deviations from the mean) from all the testing done. The standard methods of MEP testing were insensitive to quantifying the possible physiologic changes that are associated with memory deficits, lethargy, and emotional irritability after mild closed head injury.

Adolescent↗
PubMed1989

Somatosensory evoked potentials of the dog: recording techniques and normal values.

Median and tibial nerve somatosensory evoked potentials (SSEPs) of 5 sedated dogs were studied to determine their normal features and optimal stimulation and recording techniques. Cortical potentials were mapped from an extensive array of skull electrodes as each limb was independently stimulated with subdermal needles. The effects of bandpass and stimulus intensity and rate were also assessed. Three cortical components (P1, N1, P2) were evoked by median or tibial nerve stimulation and were localized along the coronal suture at lateral and medial electrodes, respectively. SSEP voltage varied much more than morphology, topography, or latency. The inion was a stable, indifferent reference site. Cortical SSEP frequency content was mostly below 250 Hz. Maximal SSEP voltage was achieved only at stimulus intensities 2-3 times motor threshold. Appropriate methods minimize technical difficulties and consistently yield legible SSEPs.

Animals↗
PubMed1987

Differential effects of isoflurane on human median nerve somatosensory evoked potentials.

The effect of isoflurane on median nerve somatosensory evoked potentials (MN-SSEPs) was studied in 15 patients. Anesthesia was induced with thiamylal and maintained with oxygen and isoflurane. MN-SSEPs were recorded in awake patients and after achieving 0.5, 1.0, 1.5, and 2.0% stable end-tidal concentrations of isoflurane. Peak latencies and amplitudes of EP, N13, and N20 and conduction times EP-N13, N13-N20, and EP-N20 were measured. Peak latencies of all components increased after all concentrations of isoflurane compared with control values. N20 peak latencies after 1% and 1.5% isoflurane differed significantly, whereas EP and N13 latencies showed no significant difference. No significant change in conduction time EP-N13 resulted from 1% and 1.5% concentrations of isoflurane compared with control values. Isoflurane increased conduction time N13-N20 significantly when compared with control values, and this increase was dose related. Amplitude of EP and N13 did not show significant change with 1% and 1.5% isoflurane when compared with control values. Amplitude of N20 decreased significantly following isoflurane anesthesia compared with control values, and the difference between 1% and 1.5% isoflurane recordings was also statistically significant. N20 was not discernible in one out of 14 patients after 1.5% and in three out of ten patients after 2% isoflurane. These results indicate that subcortical potentials are less affected by isoflurane anesthesia than cortical potentials. Amplitude reduction of cortical potentials was more noticeable than either prolongation of peak latency or conduction time.(ABSTRACT TRUNCATED AT 250 WORDS)

Evoked Potentials, Somatosensory↗
PubMed1986

Personality of patients with pseudoseizures.

We studied personality features of 19 patients with pseudoseizures (PS) only. Scores on a personality inventory (MMPI) were compared with those of adults with generalized seizures and correlated to cognitive measures (Halstead-Reitan). Mean MMPI scores did not differ significantly, and no profile distinguished PS and epilepsy patients. MMPI abnormalities of PS patients were diverse and seldom characteristic of hysteria. Eight PS patients had cognitive impairment, two without MMPI evidence of personality disorder. These findings suggest that the etiology of pseudoseizures is multifactorial, involving different psychopathologies and sometimes cerebral dysfunction.

Adolescent↗
PubMed1985

Patients with pseudoseizures: intellectual and cognitive performance.

We compared cognitive and intellectual performance of patients with pseudoseizures (pseudoseizure-only group), pseudoseizures and epilepsy (mixed seizure group), and generalized epileptic seizures (generalized seizure group). The pseudoseizure-only group performed significantly better on all measures except those of simple motor function. There were no significant differences between those with mixed and generalized seizures. Therefore, cognitive and intellectual performances of patients with pseudoseizures are influenced by the presence or absence of concomitant epilepsy, and suggest that it is necessary to distinguish patients with and without epilepsy in studies of pseudoseizures.

Adolescent↗
PubMedDate not supplied

Ictal cortical blindness with permanent visual loss.

Cortical blindness is rarely an ictal manifestation. We report the case of a man who developed transient cortical blindness followed by permanent visual deficits during repeated partial seizures. Intermittent visual impairment began at age 14 years. After he had the first generalized seizure at age 28 years, neurologic, ophthalmologic, angiographic, and brain computed tomographic (CT) examinations were normal. Several EEGs showed almost continuous biposterior spike-waves. Over the next several years, frequent partial seizures were associated with transient visual loss and left body twitching or paresthesias. When he was 32, transient blindness occurred during several days of repeated occipital seizures. Permanent left homonymous hemianopia, right homonymous central scotoma, dyschromatopsia, and altered stereopsis followed these seizures. Brain CT demonstrated a new right occipital lesion. Partial seizures arising posteriorly may cause transient cortical blindness and result in permanent visual deficits.

Adult↗