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Brain-stem auditory evoked response: Its application in South African paediatric practice
S157 mission electron microscopy. The platelet morphology, the serotoninergic granules (5HT granules) and the changes induced by antiepileptic drug were studied in each case. Dendritic shaped activated platelets were found predominantly. Microtubules were absent or fragmented. The sol-gel zone and the organelle zone exhibit submicroscopic features similar to those observed in normal platelets. The 5HT granules were depleted in most patients. The findings suggest alternations in binding, storage a n d / o r release of serotonin and the probable role of diphenylhydantoine and phenobarbital in the modulation of platelet activation, release of serotonin and disassemblage of microtubules is discussed. The association of epilepsy with other neurological entities and the centrifugation technique used for isolation of platelet rich-plasma fraction partially limit the evaluation of the blood platelet as a model of serotoninergic neurones.
EPs AND EEG IN P A E D I A T R I C S AND GERIATRICS. P25.01 BRAIN-STEM A U D I T O R Y EVOKED R E S P O N S E : ITS A P P L I C A T I O N IN S O U T H AFRICAN P A E D | A T R I C PRACTICE. M. Pietersen and C. Palmer
(Rondebosch, South Africa) The clinical neurology laboratory at the Children's Hospital in Cape Town presents two years clinical experience with this relatively new technique. The technology and methodology is presented with definition of normal standards. Clinical application is demonstrated with examples of normal recordings and recordings depicting neurological and audiological pathology. These examples include sensorineural deafness, conductive deafness, brain-stem death, and recordings of focal pathology involving the auditory pathways in the brain-stem. During the period under review there were 468 requests for the investigation. Two thirds of these requests were on account of suspected hearing impairment and one third for suspected pathology affecting the central auditory pathways within the brain-stem. Requests are tabulated to give an idea of the clinical application of this technique. The BAER may be used to monitor both the effects of treatment and the progression of pathology. By way of an illustration, a case with a pontine tuberculoma is presented, showing change in brain-stem transmission time in response to anti-tuberculous treatment.
P25.02 VARIABLE S E N S I T I V I T Y T O P E R I P H E R A L S T I M U L A T I O N IN CHILDREN: S S E P s D U R I N G WAKEF U L N E S S AND SLEEP. R. Gilmore
(Lexington, KY, USA) The cortical and subcortical SSEPs after posterior tihial nerve stimulation (PTN-SSEP) vary during sleep in children. This study examined the effect of wakefulness and sleep on absolute latencies, interpeak intervals (IPls) and conduction velocity (CV) of P28 and N41 (recorded from Cz'-Fz), N20 (spinous process seventh cervical vertebra referred to Fz) and N14 (spinous process first lumbar vertebra referred to spinous process sixth thoracic vertebra) in 6 children aged 2 6 years old. Sleep stage was established by EEG and polygraphic variables. Using wakefulness as baseline, the latency of the P28 (primary scalp positivity) lengthened by 2.41 _+0.95 msec (p < 0.05) during stage II sleep. The morphology of the waveform also changed with either attenuation or disappearance of N41. The latency of N20 shortened by 1.10+_0.72 msec (p < 0.05). Although the IPIs N41-P28, P28-N20, N41-N20, P28-NI4, and N 2 0 - N I 4 did not change significantly, the ('V (height/P28 latency) during sleep decreased 2.91+_0.82 msec (p < 0.05). These differences may reflect physiologic differences in subthalmic and thalamic transmission a n d / o r cortical sensitivity to peripheral stimulation during wakefulness and sleep.
P25.03 HEARING IN O L D AGE: E L E C T R O P H Y S I O L O G I CAL AND A U D I O M E T R I C R E S U L T S IN RELATION T O PATHOLOGY. D.K. Prasher, S. Souckova and L. Michaels
(London, UK) At present there are conflicting reports regarding the pathogenesis of presbycusis which has been variously reported as resulting from degeneration of peripheral a n d / o r central auditory pathways. Brain-stem and electrocochleographic potentials together with detailed audiometry (with a measure of the reliability of the tests) are being investigated to establish the functional integrity of the cochlea and brain-stem auditory pathways in elderly patients. Brain-stem potentials in the 25 patients with symmetrical hearing loss tested to date (mean age 87 years) were normal in morphology with the inter-wave intervals within normal limits indicating absence of any central brainstem involvement in these patients. The latency/intensity function of the brain-stem responses was found to be in agreement with the subjective audiogram in both indicating the threshold and the presence of recruitment. Histo-pathological studies of the temporal bone and brain-stem of some 8 patients are in progress and will be reported in full. Correlation between the electrophysiological and histopathological data from the temporal bone and brain-stem of the patients previously tested will
EPs AND EEG IN P A E D I A T R I C S AND GERIATRICS. P25.01 BRAIN-STEM A U D I T O R Y EVOKED R E S P O N S E : ITS A P P L I C A T I O N IN S O U T H AFRICAN P A E D | A T R I C PRACTICE. M. Pietersen and C. Palmer
(Rondebosch, South Africa) The clinical neurology laboratory at the Children's Hospital in Cape Town presents two years clinical experience with this relatively new technique. The technology and methodology is presented with definition of normal standards. Clinical application is demonstrated with examples of normal recordings and recordings depicting neurological and audiological pathology. These examples include sensorineural deafness, conductive deafness, brain-stem death, and recordings of focal pathology involving the auditory pathways in the brain-stem. During the period under review there were 468 requests for the investigation. Two thirds of these requests were on account of suspected hearing impairment and one third for suspected pathology affecting the central auditory pathways within the brain-stem. Requests are tabulated to give an idea of the clinical application of this technique. The BAER may be used to monitor both the effects of treatment and the progression of pathology. By way of an illustration, a case with a pontine tuberculoma is presented, showing change in brain-stem transmission time in response to anti-tuberculous treatment.
P25.02 VARIABLE S E N S I T I V I T Y T O P E R I P H E R A L S T I M U L A T I O N IN CHILDREN: S S E P s D U R I N G WAKEF U L N E S S AND SLEEP. R. Gilmore
(Lexington, KY, USA) The cortical and subcortical SSEPs after posterior tihial nerve stimulation (PTN-SSEP) vary during sleep in children. This study examined the effect of wakefulness and sleep on absolute latencies, interpeak intervals (IPls) and conduction velocity (CV) of P28 and N41 (recorded from Cz'-Fz), N20 (spinous process seventh cervical vertebra referred to Fz) and N14 (spinous process first lumbar vertebra referred to spinous process sixth thoracic vertebra) in 6 children aged 2 6 years old. Sleep stage was established by EEG and polygraphic variables. Using wakefulness as baseline, the latency of the P28 (primary scalp positivity) lengthened by 2.41 _+0.95 msec (p < 0.05) during stage II sleep. The morphology of the waveform also changed with either attenuation or disappearance of N41. The latency of N20 shortened by 1.10+_0.72 msec (p < 0.05). Although the IPIs N41-P28, P28-N20, N41-N20, P28-NI4, and N 2 0 - N I 4 did not change significantly, the ('V (height/P28 latency) during sleep decreased 2.91+_0.82 msec (p < 0.05). These differences may reflect physiologic differences in subthalmic and thalamic transmission a n d / o r cortical sensitivity to peripheral stimulation during wakefulness and sleep.
P25.03 HEARING IN O L D AGE: E L E C T R O P H Y S I O L O G I CAL AND A U D I O M E T R I C R E S U L T S IN RELATION T O PATHOLOGY. D.K. Prasher, S. Souckova and L. Michaels
(London, UK) At present there are conflicting reports regarding the pathogenesis of presbycusis which has been variously reported as resulting from degeneration of peripheral a n d / o r central auditory pathways. Brain-stem and electrocochleographic potentials together with detailed audiometry (with a measure of the reliability of the tests) are being investigated to establish the functional integrity of the cochlea and brain-stem auditory pathways in elderly patients. Brain-stem potentials in the 25 patients with symmetrical hearing loss tested to date (mean age 87 years) were normal in morphology with the inter-wave intervals within normal limits indicating absence of any central brainstem involvement in these patients. The latency/intensity function of the brain-stem responses was found to be in agreement with the subjective audiogram in both indicating the threshold and the presence of recruitment. Histo-pathological studies of the temporal bone and brain-stem of some 8 patients are in progress and will be reported in full. Correlation between the electrophysiological and histopathological data from the temporal bone and brain-stem of the patients previously tested will