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J W Packwood

Publications and source records attributed to J W Packwood.

6 recordsLinked to original sources
PubMed1992

Asymptomatic HIV infection does not cause EEG abnormalities: results from the Multicenter AIDS Cohort Study (MACS)

We conducted EEG testing in 200 asymptomatic homosexual men, half of whom were HIV seropositive. We chose to include half of the subjects because they were rated as impaired on a neuropsychological screening test. We used both traditional visual EEG interpretation and quantitative EEG analysis. Abnormal EEGs and borderline degrees of EEG slowing occurred in 32% of these men. These EEG changes were not related to HIV serostatus. EEG changes did correlate with the impaired neuropsychological test performance. Clinicians faced with abnormal EEG results or borderline EEG slowing in an asymptomatic HIV-seropositive patient should not attribute the EEG change to effects of the serostatus itself but should look for other causes.

Acquired Immunodeficiency Syndrome↗
PubMed1987

Evoked potentials predict the clinical changes in a multiple sclerosis drug study.

Visual, brainstem auditory, and median nerve somatosensory evoked potential (EP) tests were performed annually during a 3-year, double-blind, placebo-controlled study of azathioprine with or without steroids in chronic progressive MS. Treatment-related visual and somatosensory EP changes became statistically different 1 year before corresponding differences were seen in the Standard Neurological Examination scores. The statistical significance of EP changes was substantially greater than seen for changes in other clinical scales. The degree of significance was increased by using EP latency values, rather than simple criteria for change. EPs are sensitive, objective measurements useful in MS therapeutic trials.

Adult↗
PubMed1985

Evoked potential testing in relatives of multiple sclerosis patients.

Evoked potential (EP) tests were obtained in 110 neurologically normal first-degree relatives of patients with multiple sclerosis. Visual EP tests were performed in all relatives; brainstem auditory and median nerve somatosensory EP tests were performed in 67 relatives. The relatives had a mean visual EP P100 latency that was significantly longer than that for normal subjects controlled for age and gender. Asymmetries were seen in results from individual MS relatives, including interocular visual EP P100 differences of up to 14 ms, and interarm somatosensory Erb-N18 differences of up to 3.0 ms. We identified 19 pairs of patients and relatives who were HLA identical and 18 other pairs who were HLA double nonmatched. EP asymmetries were seen more often in the HLA identical siblings than in the HLA double patients, especially if they share HLA types with the patients. Since less than 2% of siblings of MS patients would be expected to eventually develop clinical MS, these small subclinical electrophysiological changes are not expected to be a sign of the future appearance of clinical MS. Clinicians should be aware not to overinterpret small EP changes in relatives of MS patients.

Adolescent↗
PubMed1983

Evoked potential abnormalities in the various inherited ataxias.

Visual (VEP), brainstem auditory (BAEP), and somatosensory (SEP) evoked potential tests were performed in 45 patients representing ten types of inherited disorders in which ataxia was the most prominent symptom. Comparable VEP abnormalities were present among all types of patients. Normal BAEP tests were recorded in most patients except those with olivopontocerebellar atrophy. SEP results were often more severely abnormal in patients with Friedreich's ataxia. The observations emphasize the similarity in expression of different metabolic-degenerative disorders. When these tests are used clinically, certain features of evoked potentials (especially left-right symmetry) are typical of the inherited ataxias as a group. Few distinguishing features differentiate the individual disorders.

Ataxia↗
PubMedDate not supplied

A parametric scale for BAEP latencies in multiple sclerosis.

A parametric scale for measuring BAEP latencies is set forth here for use in multiple sclerosis (MS) therapeutic trials and similar longitudinal studies. Derived constants are used to create a synthetic I-V interpeak interval, needed for cases where V (or other waves) are absent. Transitional peaks (peaks on the verge of disappearing) were studied in MS patients and used to determine appropriate values for the weighting constants. The resulting scale or index makes use of latencies to whichever peaks are still present. In theory such a scale is more sensitive to small changes than either a simple ordinal scale of which peaks remain or a parametric scale of I-V interpeak intervals excluding the 25-40% of MS records with absent wave V. To test this synthetic I-V index in practice, we studied it in 100 MS patients entering a therapeutic trial. It was found to correlate appropriately with patients' history, physical examination, and clinical scales at entry into the trial. Parametric statistical analysis of the derived scale was able to show a statistically significant drug effect during the therapeutic trial, whereas 3 other data analysis techniques showed at best a trend that did not quite reach significance.

Adult↗