Auditory evoked responses in multiple sclerosis. Wave I abnormality.

Far-field short latency auditory evoked potentials (AEPs) were obtained in 40 patients with definite multiple sclerosis (MS) and 20 normal control subjects. Nine of 40 patients had abnormal wave I and normal hearing as established by pure tone audiometry. It is concluded that, in the population of patients with MS tested, slightly more than one fifth had AEP evidence of subclinical involvement of the auditory portion of the eighth cranial nerve.

Latency of the P3 event-related potential: normative aspects and within-subject variability.

A growing body of research has focused on the P3 (P300) event-related potential as an electrophysiological correlate of selective attention. The present investigation examines the intrasubject test-retest reliability of the auditory evoked P3 latency measure for neurologically and audiologically normal young adults aged 22-34 years across test sessions separated by 2-4 weeks (N = 9) and across trials within one test session (N = 20). In a target-selection ('oddball') paradigm, subjects mentally counted infrequent 2 kHz tone bursts (targets) randomly interspersed within a sequence of 1 kHz tone bursts (non-targets). A strong positive correlation was demonstrated between latencies of test sessions I and II. An analysis of variance did not demonstrate statistically significant latency differences as a function of either tests or trials for the test-retest group (N = 9). Although analysis of variance demonstrated a statistically significant difference between trials within one test session for 20 subjects, the small mean latency difference between trials (4.7 msec) is interpreted as being clinically unimportant. The stability of P3 latency found in this study over a period of 2-4 weeks supports its application to the study of normal and disordered cognitive processes.

Binaural masking-level differences in neurological disorders.

Binaural, speech detection masking-level differences (MLDs) were measured in 26 patients with documented brainstem and cerebral level lesions and in ten control subjects with normal hearing to determine the lesion's effects on the size of the MLD. Lesion level was determined on the basis of clinical findings, roentgenographic studies, auditory evoked potential recordings, and surgical findings when appropriate. Results showed there were no significant differences between MLDs of normal subjects and of patients with cerebral level or rostral pontine, midbrain, or thalamic level lesions, MLDs were significantly smaller than for other groups. Findings support the hypothesis that speech MLDs may originate from auditory centers at the pontomedullary region of the brainstem and may be a useful test to aid in the localization of central auditory dysfunction.

Autopsies on two native American Mummies.

An interdisciplinary team performed autopsies on an adult male and an infant male mummy from the American Southwest. Cause of death has not been determined for the infant. The presence of an unhealed skull fracture associated with an apparent hematoma in the adult male is suggestive of trauma as the cause of death in the adult. Evidence of disease is minimal. Analysis of powder thought to be dried blood from the thoracic cavity of the adult suggests the presence of human IgG. The instability of this protein may indicate the presence of proteolytic activity by enzymes that degrade immunoglobulins upon rehydration. The possibility of enzymatic degradation of proteins will be an important factor in future studies of such immunoglobulins in mummy remains and also indicates the importance of maintaining the desiccated condition of mummy tissues.

Computerized tomography and auditory-evoked potentials. Use in the diagnosis of olivopontocerebellar degeneration.

The pneumoencephalogram has been the only diagnostic test available to confirm the diagnosis of olivopontocerebellar degeneration during life. This study suggests that pneumoencephalography may be obsolete and that the diagnosis of olivopontocerebellar degeneration may be established by abnormalities seen during computerized tomography (CT) and by abnormal responses to auditory-evoked potentials (AEPs). The combination of CT scans and AEPs provides a completely nontraumatic method of diagnosis in olivopontocerebellar degeneration and eliminates the need for pneumoencephalography.

Auditory evoked brain stem potentials in a case of "locked-in" syndrome.

Auditory evoked brain stem potentials were measured in a patient with occlusion of the basilar artery about 7 mm above its origin, resulting in the "locked-in" syndrome due to infarction at the junction of the lower one third and upper two thirds of the pons. The first three waves of the evoked response originating from the acoustic nerve and auditory nuclei in the caudal pons were normal in wave form, peak latency, and voltage level. Waves IV and V, generated in the region of the lateral lemniscus and inferior colliculus in rostral pons and caudal midbrain, demonstrated prolonged peak latency and reduced voltage, indicative of slowed neural conduction in the pons above the level of the superior olivary complex. These findings suggest that auditory evoked potential recordings may have considerable value in the localization of brain stem disorders.

Temporal bone studies: findings with undecalcified sections in a 2,600-year-old Egyptian mummy.

Roentgenologic studies by polytomography of the temporal bones of a 2,600-year-old Egyptian mummy (PUM-II) revealed an increase in radiographic density throughout the left temporal bone. The superior portions of the petrous bones were removed with an electric saw for study by undecalcified techniques. For histological control, a similar specimen was removed from a cadaver immediately after autopsy. Light microscopy of sections showed excellent preservation of the Haversian systems. The vascular channels were clearly seen, and they were similar in appearance to those of the fresh specimen. The lacunae contained osteocytes with good preservation of the nucleus. Osteoid seams were identified and the osteon activity was described for the first time in an Egyptian mummy. There was a low turnover type of bone, but there was no evidence of metabolic bone disease. We postulate that the increased radiological density of the left temporal bone was due to a greater amount of resin infiltration in this bone as compared to the right. It appeared that the resin acted as a fixative preserving the bone cells and related elements.

Temporal bone preservation in a 2600-year-old Egyptian mummy.

Perforated eardrums in the preserved temporal bones of a mummified Egyptian male in otherwise normal middle ears offer new evidence of acute otitis media and probable defective hearing among ancient Egyptians.