Brainstem Auditory Evoked Responses . in Progressive Supranuclear Palsy Eduardo S. Tolosa, MD, and James A. Zeese, M D
F i g 2.Microscopic section of cerebral cortex shows senile plaques and neurojibrillary tangles. (Bielschowsky; x575 bejove 3 0 % reduction.)
resemblance of some cases of anatomically verified Alzlreimer disease to Jakob-Creutzfeldt disease.
,?derences AL, Johnson PC: Rapidly evolving EEG changes in a case of Alzheimer disease. Ann Neurol 1:593-595, 1979 Faden AL, Townsend JJ: Myoclonus in Alzheimer disease. Arch Neurol 33:278-280, 1976 i. Jacob H: Muscular twitching in Alzheimer's disease, in Wolstenholme GEW, O'Connor M (eds): Alzheimer's Disease and Related Conditions. London, Churchill, 1970, pp 75-93 . Ehle
.)_
Progressive supranuclear palsy (PSP) is known to produce widespread neuronal changes in the brainstem. Therefore, we studied brainstem auditory evoked responses (BAER) in 7 patients with typical PSP, 4 with moderate and 3 with severe symptoms of brainstem dysfunction. All patients were female; the mean age was 65 years and the age range, 50 to 74. Clicks generated by 0.1-msec square waves with alternating polarity were delivered to each ear separately at 10 per second, 60 d b above the patient's hearing threshold. The BAER was recorded between Cz and the ipsilateral ear lobe, and at least two repeatable trials (less than 0.08 msec difference in interwave latencies) were obtained. Satisfactory recordings were achieved for 12 of 14 ears. For each patient the individual interwave latencies fell within the normal range (99% tolerance limits) of our young normal subjects using the same technique, and the amplitude ratio of wave IV/V to wave I exceeded 1.0 in all repeatable trials. The patient's mean 1-111 latency was 2.26 msec (SD 0.18) and 111-V, 1.86 msec (SD 0.21), values not significantly different from those reported by Rowe [ 11 for a group of normal older subjects (mean 1-111, 2.19 msec, SD 0.27; mean 111-Y, 1.82 msec, S D 0.21) using similar technique. There was no correlation between interwave latencies and the severity of the patient's brainstem symptoms. The results indicate that BAERs can be normal in PSP regardless of the severity of disease. This is probably because the auditory pathways are intact, or because slight neuronal changes in the central auditory nuclei seen in some PSP patients [2] are not reflected in an abnormality. The frequent disorders in BAER seen in multiple sclerosis indicate that white matter tracts are necessary for the conduction, if not the generation, of BAER waves; the relative contribution of ceptral nuclei is less clear. O u r results indicate that mild central neuronal changes may not alter BAER generation o r conduction.
References 1. Rowe MJ: Normal variability of the brain-stem auditory evoked response in young and old adult subjects. Electroencephalogr Clin Neurophysiol 44:459-470, 1978 2 . Steele JC, Richardson JC, Olszewski J: Progressive supranu-
clear palsy. Arch Neurol 10:333-359, ' 9 6 4 From the Department of Neurology, University of Minnesota Hospitals, Minneapolis, MN 55455. Accepted for publication June 9, 1979.
Notes and Letters
369
F i g 2.Microscopic section of cerebral cortex shows senile plaques and neurojibrillary tangles. (Bielschowsky; x575 bejove 3 0 % reduction.)
resemblance of some cases of anatomically verified Alzlreimer disease to Jakob-Creutzfeldt disease.
,?derences AL, Johnson PC: Rapidly evolving EEG changes in a case of Alzheimer disease. Ann Neurol 1:593-595, 1979 Faden AL, Townsend JJ: Myoclonus in Alzheimer disease. Arch Neurol 33:278-280, 1976 i. Jacob H: Muscular twitching in Alzheimer's disease, in Wolstenholme GEW, O'Connor M (eds): Alzheimer's Disease and Related Conditions. London, Churchill, 1970, pp 75-93 . Ehle
.)_
Progressive supranuclear palsy (PSP) is known to produce widespread neuronal changes in the brainstem. Therefore, we studied brainstem auditory evoked responses (BAER) in 7 patients with typical PSP, 4 with moderate and 3 with severe symptoms of brainstem dysfunction. All patients were female; the mean age was 65 years and the age range, 50 to 74. Clicks generated by 0.1-msec square waves with alternating polarity were delivered to each ear separately at 10 per second, 60 d b above the patient's hearing threshold. The BAER was recorded between Cz and the ipsilateral ear lobe, and at least two repeatable trials (less than 0.08 msec difference in interwave latencies) were obtained. Satisfactory recordings were achieved for 12 of 14 ears. For each patient the individual interwave latencies fell within the normal range (99% tolerance limits) of our young normal subjects using the same technique, and the amplitude ratio of wave IV/V to wave I exceeded 1.0 in all repeatable trials. The patient's mean 1-111 latency was 2.26 msec (SD 0.18) and 111-V, 1.86 msec (SD 0.21), values not significantly different from those reported by Rowe [ 11 for a group of normal older subjects (mean 1-111, 2.19 msec, SD 0.27; mean 111-Y, 1.82 msec, S D 0.21) using similar technique. There was no correlation between interwave latencies and the severity of the patient's brainstem symptoms. The results indicate that BAERs can be normal in PSP regardless of the severity of disease. This is probably because the auditory pathways are intact, or because slight neuronal changes in the central auditory nuclei seen in some PSP patients [2] are not reflected in an abnormality. The frequent disorders in BAER seen in multiple sclerosis indicate that white matter tracts are necessary for the conduction, if not the generation, of BAER waves; the relative contribution of ceptral nuclei is less clear. O u r results indicate that mild central neuronal changes may not alter BAER generation o r conduction.
References 1. Rowe MJ: Normal variability of the brain-stem auditory evoked response in young and old adult subjects. Electroencephalogr Clin Neurophysiol 44:459-470, 1978 2 . Steele JC, Richardson JC, Olszewski J: Progressive supranu-
clear palsy. Arch Neurol 10:333-359, ' 9 6 4 From the Department of Neurology, University of Minnesota Hospitals, Minneapolis, MN 55455. Accepted for publication June 9, 1979.
Notes and Letters
369
