Absent Waves Research Articles

Audiologic characterization using clinical physiological measures: Normative data from macaque monkeys

Clinical auditory physiological measures (e.g., auditory brainstem responses, ABRs, and distortion product otoacoustic emissions, DPOAEs) provide diagnostic specificity for differentially diagnosing overt hearing impairments, but they remain limited in their ability to detect specific sites of lesion and subtle levels of cochlear damage. Studies in animal models may hold the key to improve differential diagnosis due to the ability to induce tightly controlled and histologically verifiable subclinical cochlear pathologies. Here, we present a normative set of traditional and clinically novel physiological measures using ABRs and DPOAEs measured in a large cohort of male macaque monkeys. Given the high similarities between macaque and human auditory anatomy, physiology, and susceptibility to hearing damage, this normative data set will serve as a crucial baseline to investigate novel physiological measures to improve diagnostics. DPOAE amplitudes were robust at f2 = 1.22, L1/L2 = 65/55, increased with frequency up to 10 kHz, and exhibited high test re-test reliability. DPOAE thresholds were lowest from 2-10 kHz and highest < 2 kHz. ABRs with a standard clinical electrode montage (vertex-to-mastoid, VM) produced Waves I-IV with a less frequently observed Wave-I, and lower thresholds. ABRs with a vertex-to-tympanic membrane (VT) electrode montage produced a more robust Wave-I, but absent Waves II-IV and higher thresholds. Further study with the VM montage revealed amplitudes that increased with stimulus level and were largest in response to click stimuli, with Wave-II showing the largest ABR amplitude, followed by -IV and -I, with high inter- and intra-subject variability. ABR wave latencies decreased with stimulus level and frequency. When stimulus presentation rate increased or stimuli were presented in close temporal proximity, ABR amplitude decreased, and latency increased. These findings expand upon existing literature of normative clinical physiological data in nonhuman primates and lay the groundwork for future studies investigating the effects of noise-induced pathologies in macaques.

SONOGRAPHIC EVALUATION OF OUTFLOW VEINS IN SUDANESE LIVER TRANSPLANTS

The purpose of this study was to identify the specific Doppler criteria for the outflow vein (hepatic veins and inferior vena cava) obstruction in liver transplants. A case control study was done after performing venous Doppler sonographic studies in 300 normal (control) and 45 liver transplant cases (4 whole liver, 41 lobar) with no vascular obstruction. The ultrasonic Doppler study were classified as normal, occluded, or stenosed on the basis of gray scale and color flow mapping appearances as well as elevated or absent waves. The following Doppler parameters were evaluated: the outflow veins on color Doppler interrogation, venous pulsatility index on spectral trace. Receiver operating characteristic curves were constructed. There were no cases of outflow vein obstruction found in our sample (neither stenosis, nor occlusion). Mean venous pulsatility index for normal outflow veins was 0.75 and is found ranging between (0.55-0.75). A venous pulsatility index of &lt; 0.45 is specific for stenosis (5). The venous pulsatility index is a useful parameter for diagnosing venous stenosis in liver transplants.

A novel homozygous mutation in POLR3A gene causing 4H syndrome: a case report

Background4H syndrome is a congenital hypomyelinating leukodystrophy characterized by hypodontia, hypomyelination and hypogonadotropic hypogonadism belonging to the Pol III-related leukodystrophies which arise due to mutations in the POLR3A or POLR3B gene. The clinical presentation is of neurodevelopmental delay or regression with ataxia, dystonia, nystagmus, delayed deciduous dentition and abnormal order of eruption of teeth. MRI brain shows a characteristic hypomyelination pattern. Several mutations have been described in the implicated genes but there are no reports on mutations seen in patients from India.Case presentationWe report a 1½ year old girl, only child of a non-consanguinous couple who presented with delayed developmental milestones and delayed dentition. On physical examination she had downward slanting palpebral fissures, low set ears, smooth philtrum, hypodontia, prominent body hair and clitoromegaly. There was prominent horizontal nystagmus, hypertonia of both upper and lower limbs, exaggerated deep tendon jerks and flexor planter response. She had not attained complete head control and required support to sit. She showed absent waves on brainstem evoked response audiometry and her fundus examination showed bilateral optic atrophy with prolongation of P100 latencies on visual evoked potentials. MRI Brain showed hyperintensity of entire white matter with involvement of the internal and external capsule, frontal deep white matter and corpus callosum. Her karyotype was 46 XX and her endocrinal profile was unremarkable. Clinical exome sequencing identified an unreported mutation in the POLR3A gene. The same mutation was identified by Sanger sequencing in heterozygous state in both parents. The child is being managed with physiotherapy and developmental therapy. She has been provided with hearing aids and started on speech therapy. Parents were provided anticipatory guidance and genetic counselling about autosomal recessive nature of inheritance, risk of recurrence and need for follow-up.Conclusion4H syndrome is a rare congenital hypomyelinating leukodystrophy inherited as an autosomal recessive disorder due to mutations in the POLR3A and POLR3B gene. Delay or regression of milestones, abnormalities in dentition and endocrinal perturbations are its hallmark. A novel mutation in the POLR3A gene resulting in amino acid substitution of arginine for glutamine at codon 808 (p.R808Q) was detected in exon 18 in our case.

83. Isoelectric electroencephalogram as early marker of poor prognosis: A case report

Isoelectric electroencephalogram (EEG) in conformant with clinical findings is one of the criteria of brain death. In clinical practice, isoelectric EEG is rarely seen in patients who are not brain-dead. We present a case of a 66-year-old woman with headache and acute confusional state. Brain TC showed aneurysmal subarachnoid hemorrhage for the rupture of anterior communicating artery aneurysm. During anesthesia and intubation patient presented acute anisocoria. Brain CT showed rebleeding with subarachnoid blood in anterior interhemispheric cistern and intraventricular.Serial EEG were flat and somatosensory evoked potentials demonstrated absent waves at the cortical level but there was evidence of preserved cerebral blood flow on computed tomography angiography. Her neurological examination continued to show evidence of residual brainstem function (cranial nerve reflexes and coughing). He survived this condition for 5 days and afterward every criteria for brain death could be applied.EEG records activity from only the cortical layers immediately beneath the scalp; it does not record from subcortical structures but EEG can be a very early marker of diffuse cortical damage. This case demonstrates that isoelectric EEG can not be equated with brain death but can be a very early marker of poor prognosis.

Otorhinolaryngological, audiovestibular and swallowing manifestations of patients with Niemann–Pick disease Type C

ObjectivesThe aim of this study is to evaluate audiovestibular and swallowing impairment of patients with NPC. MethodsAudiovestibular and swallowing evaluation were performed on patients with Niemann–Pick disease type C (NPC) at Hacettepe University between 20013 and 2015 prospectively. Pure-tone audiometry (PTA), Auditory Brain stem response (ABR), Flexible endoscopic evaluation of swallowing (FEES) test and posturography were done. Hearing, swallowing and balance states were measured. ResultsThere were 16 patients (5 male and 11 female, with a median age of 6.5 years old). The most common ABR abnormalities observed were absent waves I and III (%70 absent I waves, %43.75 absent III waves). Twelve of sixteen patients (%75) had an ABR abnormality in at least one ear, of these, four patients had normal hearing and three of them had periferal hearing loss. 12 (75%) patients had complaint of postural imbalance. 11(69%) of patients had peripheral and one (6%) patient had central impairment. Nine of sixteen patients (56.25%) show some degree of dysphagia (either penetration or aspiration). Two patients (12.5%) showed aspiration both liquid and viscous nutrition. Three patients (18.75%) showed aspiration primarily in liquids and two of them had penetration with viscous nutrition. Three patients (18.75%) had penetration with no aspiration neither liquid nor viscous nutrition (PEN-ASP score was 3, 3, 5, respectively). ConclusionThere is no curative treatment for this devastating and fatal disorder and hearing impairment, balance and swallowing disorders can be seen especially late onset form of disease.

Saccular dysfunction in children with sensorineural hearing loss and auditory neuropathy/auditory dys-synchrony

Conclusion: There is a correlation between the AN/AD disorder and the saccular dysfunction in children with severe sensorineural hearing loss, which means that saccular dysfunction can be a concomitant sign of AN/AD. In conclusion, the term of audio-vestibular dys-synchrony (AVS) is a more suitable description for this condition. Objectives: Patients with auditory neuropathy/auditory dys-synchrony (AN/AD) characteristically demonstrate poor neural responses from the vestibulocochlear nerve and brainstem while displaying evidence of intact outer hair cells function. Therefore, the objective of this study is studying of the relationship of the saccular dysfunction with AN/AD disorder in children with sensorineural hearing loss. Methods: In this cross-sectional study, 100 children with bilateral severe-to-profound sensorineural hearing losses underwent audiologic tests and cervical vestibular-evoked myogenic potentials (cVEMPs) at the Audiology Department of Hamadan University of Medical Sciences (Hamadan, Iran). Results: Eleven children with bilateral severe sensorineural hearing loss were given to unilateral AN/AD disorder (11 ears), and two children (4 ears) had bilateral AN/AD (total = 13 children). The ears with AN/AD took the form of unrepeatable or absent waves of ABR and presence of OAEs. The statistical analysis of an independent t-test between AN/AD ears as compared to non-AN/AD ears of these 13 children showed that the mean latencies of p13 and the mean latencies of n23 and the mean peak-to-peak amplitude had significant differences.

Su1087 Heartburn and Condition of Distal Part of Esophagus in Pregnancy

Ineffective esophageal motility (IEM) has been observed in erosive and non-erosive reflux disease (NERD) patients and may account for delayed bolus transit and impaired esophageal reflux clearance. It has been demonstrated that conventional manometry findings cannot predict reflux clearance in GERD patients. High resolution manometry (HRM) allows an accurate analysis of esophageal motility. Distal contractile integral (DCI) integrates the length, contractile vigour, and duration of contraction of the first two segments of the distal esophagus. Aim: To assess the correlation between HRM findings and reflux clearance in GERD patients. Methods: Following a 3-week washout from PPI and/or H2 antagonists, HRM and 24-hour ambulatory multichannel pH-impedance (pH-MII) monitoring were performed in 37 consecutive GERD patients, with no evidence of hiatal hernia at endoscopy. Patients were analyzed in the supine position, a catheter with 36 solid state pressure sensors located at 1 cm intervals (MMS, HRIM, Enschede, The Netherlands) was used. Data were stored and analyzed using dedicated software. A total of 10 saline (5 ml) swallows, at 30sec intervals were analyzed in each subject. The pH-impedance assembly was positioned with the pH electrode at 5cm above the LES and impedance measuring segments at 3, 5, 7, 9, 15 and 17cm above LES (Sandhill Scientific, USA). Reflux episodes were classified according to standardized criteria. Mean reflux clearance time (RCT) and reflux exposure time (RET) were calculated using Bioview software analysis, after a manual analisys of each pH-MII tracing. DCI was calculated and correlated to RCT and RET values by means of linear regression analysis. HRM tracings were analyzed according to the Chicago classification. IEM was defined by the presence of hypothensive or absent peristaltic waves in >20% of deglutitions. Results: Of the 37 patients, 30 showed normal esophageal motility and 7 IEM. Mean DCI values were 1562 (95% CI, 1203-1921) mmHg*s−1*cm−1 in all patients and 182 (95% CI, 122-242) mmHg*s−1*cm−1 in the 7 patients with IEM (p<0.001). Mean RCT and RET were 12.2 sec. and 3.6% of total recording time in all 37 patients, 13.5 sec. and 6.5% in the 7 IEM patients. No correlation was found between DCI and mean RCT and RET (r= 0.3 and 0.25, respectively). Weak correlation was found between DCI and mean RCT in the subgroup of IEM patients (r= 0.65, p<0.05). Conclusions: failure of esophageal motility seems to play a weak role in the clearing of gastroesophageal reflux episodes. DCI is not correlated to impaired esophageal reflux clearing whose occurrence could depend on the balance between the magnitude of the motility weakness and of the flow resistance at esophago-gastric junction.

P.19.3 ESOPHAGEAL HIGH RESOLUTION MANOMETRY FINDINGS DO NOT CORRELATE WITH CLEARANCE OF GASTRO-ESOPHAGEAL REFLUX IN GERD PATIENTS

Ineffective esophageal motility (IEM) has been observed in erosive and non-erosive reflux disease (NERD) patients and may account for delayed bolus transit and impaired esophageal reflux clearance. It has been demonstrated that conventional manometry findings cannot predict reflux clearance in GERD patients. High resolution manometry (HRM) allows an accurate analysis of esophageal motility. Distal contractile integral (DCI) integrates the length, contractile vigour, and duration of contraction of the first two segments of the distal esophagus. Aim: To assess the correlation between HRM findings and reflux clearance in GERD patients. Methods: Following a 3-week washout from PPI and/or H2 antagonists, HRM and 24-hour ambulatory multichannel pH-impedance (pH-MII) monitoring were performed in 37 consecutive GERD patients, with no evidence of hiatal hernia at endoscopy. Patients were analyzed in the supine position, a catheter with 36 solid state pressure sensors located at 1 cm intervals (MMS, HRIM, Enschede, The Netherlands) was used. Data were stored and analyzed using dedicated software. A total of 10 saline (5 ml) swallows, at 30sec intervals were analyzed in each subject. The pH-impedance assembly was positioned with the pH electrode at 5cm above the LES and impedance measuring segments at 3, 5, 7, 9, 15 and 17cm above LES (Sandhill Scientific, USA). Reflux episodes were classified according to standardized criteria. Mean reflux clearance time (RCT) and reflux exposure time (RET) were calculated using Bioview software analysis, after a manual analisys of each pH-MII tracing. DCI was calculated and correlated to RCT and RET values by means of linear regression analysis. HRM tracings were analyzed according to the Chicago classification. IEM was defined by the presence of hypothensive or absent peristaltic waves in >20% of deglutitions. Results: Of the 37 patients, 30 showed normal esophageal motility and 7 IEM. Mean DCI values were 1562 (95% CI, 1203-1921) mmHg*s−1*cm−1 in all patients and 182 (95% CI, 122-242) mmHg*s−1*cm−1 in the 7 patients with IEM (p<0.001). Mean RCT and RET were 12.2 sec. and 3.6% of total recording time in all 37 patients, 13.5 sec. and 6.5% in the 7 IEM patients. No correlation was found between DCI and mean RCT and RET (r= 0.3 and 0.25, respectively). Weak correlation was found between DCI and mean RCT in the subgroup of IEM patients (r= 0.65, p<0.05). Conclusions: failure of esophageal motility seems to play a weak role in the clearing of gastroesophageal reflux episodes. DCI is not correlated to impaired esophageal reflux clearing whose occurrence could depend on the balance between the magnitude of the motility weakness and of the flow resistance at esophago-gastric junction.

The Relationship Between Dysphagia, Pump Function, and Lower Esophageal Sphincter Pressures on High-Resolution Manometry

IntroductionStudy objective was to compare high-resolution impedance manometry (HRIM) findings between patients with and without dysphagia. MethodsAfter Institutional Review Board approval, a prospectively maintained database was reviewed to identify patients who underwent HRIM. Patients without upper endoscopy within 7 days of manometry, patients with achalasia, history of previous foregut surgery, esophageal strictures, or a large hiatus hernia were excluded. A new parameter called lower esophageal sphincter pressure integral (LESPI) was compared between patients with and without dysphagia. For subanalysis, subjects were categorized: (a) group A: no dysphagia and <60% hypocontractile or absent waves, (b) group B: dysphagia and <60% hypocontractile or absent waves, and (c) group C: ≥60% hypocontractile or absent waves. ResultsOne hundred thirteen patients satisfied study criteria. Patients with dysphagia had a significantly higher LESPI and distal contractile integral (DCI). On multivariate regression analysis, the following were associated with dysphagia: (a) ≥60% hypocontractile or absent waves, (b) LESPI >400 mmHg s cm, and (c) DCI >3,000 mmHg s cm. However, 32% of patients with <60% hypocontractile or absent waves (group B) had dysphagia. These patients had a significantly higher DCI and LESPI than group A. Group C had a significantly lower DCI than all other patients. ConclusionsDysphagia in patients with ≥60% hypocontractile or absent waves is indicative of an intrinsic pump failure as they have low DCI, while dysphagia in patients with <60% hypocontractile or absent waves is more indicative of significant outflow obstruction as they have high LESPI and integrated relaxation pressure.

Predicting comatose patients with acute stroke outcome using middle-latency somatosensory evoked potentials

Objective To evaluate the prognostic value of middle-latency somatosensory evoked potential (MLSEP) in comatose patients with acute severe supratentorial stroke, considering both unfavourable outcome and death. Methods Eighty-eight patients with acute severe supratentorial stroke underwent MLSEP, short-latency somatosensory evoked potential (SLSEP), Glasgow Coma Scale (GCS) and cerebral computed tomography (CCT) within 1 week from onset. MLSEP and SLSEP were recorded in 25 normal controls. All patients were evaluated with two criteria of outcome as unfavourable outcome (modified Rankin Scale 4–6) and death 6 months after onset. N60 of MLSEP predictive value was compared with N20 of SLSEP, GCS and CCT. Results Sixty-seven patients (76.1%) suffered from cerebral infarction; and 21 patients (23.9%) suffered from intracerebral haemorrhage. Seventy-one patients (80.7%) had unfavourable outcomes and 39 patients (44.3%) died. The peak latencies of MLSEP were prolonged and some waves of MLSEP were absent in stroke patients, and the proportion of absent waves in lesion-ipsilateral MLSEP was higher than in contralateral MLSEP. By using the prognostic authenticity analysis of predictors, the lesion-ipsilateral absence of N60 showed the highest sensitivity for unfavourable outcome (97.2%, confidence interval (CI): 89.3–99.5%) and death (100%, CI: 88.8–100%), which was superior to GCS, CCT and N20. Bilateral absence of N60 showed a high specificity of 100% for unfavourable outcome, which was as good as bilateral absence of N20. However, it showed a specificity of 89.8% (CI: 77.0–96.2%) for death, not as good as bilateral absence of N20 (98%, CI: 87.8–99.9%). The false positive rate of lesion-ipsilateral absence of N60 for unfavourable outcome and death was 12.7% (CI: 6.6–22.5%) and 50.6% (CI: 39.2–62.0%), respectively, and that of bilateral absence of N60 was 0 (CI: 0–12.3%) and 14.3% (CI: 5.4–31.0%), respectively. Conclusions We confirm the high predictive value of MLSEP in severe stroke. MLSEP showed higher sensitivity than SLSEP for predicting unfavourable outcome and death. Combined MLSEP with SLSEP results produced even greater predictive value. Significance The combination of MLSEP and SLSEP would increase the sensitivity and maintain the high specificity not only for predicting outcome in coma after cardiopulmonary resuscitation but also after severe stroke.

Audiologic Outcomes and Management of Infants with Hyperbilirubinemia

AbstractThe present study aimed to investigate the time course of audiologic manifestations of infants with hyperbilirubinemia and examine the management strategies for these infants. Seven infants (6 male, 1 female) with hyperbilirubinemia or neonatal jaundice received audiologic assessments including auditory brainstem response (ABR) and transient evoked oto-acoustic emissions from birth. Their gestational age ranged from 26 to 40 weeks and chronologic age between 11 and 44 months (mean = 25; SD = 12.1) at the time of data collection. Initial ABR results for all participants showed poor waveform morphology, absent waves, delayed wave latencies, and raised thresholds. The ABR results improved over time for five participants. At least five of the seven children exhibited symptoms of auditory neuropathy. Of the seven children, two received binaural behindthe- ear hearing aids, two were found to have normal hearing sensitivity, one child was referred to Australian Hearing for management of hearing problems,...

Auditory brainstem responses in neonatal hyperbilirubinemia and effect of therapy

Objectives; To determine the effect of neonatal hyperbilirubinemia on auditory brainstem responses (ABRs) and evaluate ABR responses to lowering of bilirubin levels. prospective case control trial tertiary referral center. 60 neonates (40 cases & 20 controls). Term appropriate for date(AFD) neonates with uncomplicated birth history and bilirubin level of ≥ 13 mg/dL were included as cases, those with bilirubin value of < 13 mg/dL were taken as controls.Interventions; First BERA examination was carried out within 24 hrs of the diagnosis of hyperbilirubinemia and repeat examination was done when total serum bilirubin came down to < 13 mg/dL with treatment. Comparisons were made between cases (before & after therapy) and controlResults; No abnormality in neonates with bilirubin < 18 mg/dL. Abnormal ABRs were observed in 24(60%) of the 40 cases studied, with therapy it reverted back to normal in 15(62%). The commonest abnormality noted was prolonged latency of wave V(42.5%), followed by prolonged latency of wave III(35%) and wave I(22.5%). Prolonged latency of wave I was found in only those with bilirubin > 20mg/dL. Inter peak latency of wave IV (Brain stem conduction time) was prolonged in 8 cases; it reverted to normal in all cases. Prolonged inter peak latency of wave I-III was observed in 7 cases, of which it reverted to normal in 6. Absent waves reappeared in 4 out of 5 cases, but abnormal amplitude ratios reverted to normal in only one of the 7 cases in which it was abnormal.Conclusions; about 60% of term A FD neonates with serum bilirubin of > 18mg/dL will demonstrate ABR changes. Most of these changes revert to normal early after therapy, indicating need for aggressive therapy in this subgroup of neonates.

Auditory brain-stem response in zitter rats with genetic spongiform encephalopathy

Zitter rats with genetic spongiform encephalopathy and hypomyelination developed an abnormal auditory brain-stem response (ABR) before the appearance of spongy lesions in the central nervous system (CNS). The ABR abnormalities were characterized by a dual peak of wave I, with a longer latency than in normal rats, and decreased or absent waves III and IV. Hypomyelination in both peripheral and central nerves may have been responsible for these abnormalities. The slow negative wave became wide and obscure with aging. These changes accompanied age-dependent progression of spongy changes in the CNS. These findings suggest that at least two mechanisms, one involving hypomyelination and the other causing spongy lesions, are responsible for the brain-stem auditory pathway dysfunction in zitter rats.

Evoked potentials in children with oxidative metabolic defects leading to Leigh syndrome

We studied evoked potentials in 15 children (age range: 2 wks to 4 yrs; mean: 10 mos) with metabolic disturbances that led to Leigh syndrome. These disturbances included deficiencies of pyruvate dehydrogenase (N = 5), complex 1 (N = 7), complex 4 or cytochrome oxidase (N = 2), and complex 5 (N = 1) deficiencies. Subsequent studies were performed in 11 children. All of the children with pyruvate dehydrogenase deficiency had abnormal brainstem auditory evoked potentials (BAEPs) due to poor morphology and reproducibility of the waveforms; central conduction time was normal in 4 of 5 initial studies. The patients with complex 4 or cytochrome oxidase deficiency had abnormal BAEPs, due to increased interpeak latencies and low amplitude or absent waves IV/V. Six of 7 of the children with complex 1 deficiency had normal BAEPs. The remaining patient (the youngest, age 6 wks) had only waves I and II bilaterally and suffered from the rapidly progressive form of complex 1 deficiency; the other 6 with complex 1 deficiency had the slowly progressive form. The one patient with complex 5 deficiency had normal BAEPs when first tested at 4 mos; abnormal BAEPs with loss of later waves were observed 10 weeks later. The visual evoked potentials and somatosensory evoked potentials usually were abnormal in these patients, but the findings were not specific to the patient subgroups. In all but one patient, subsequent studies disclosed a lack of normal maturational changes and/or deterioration across all 3 modalities. The BAEPs appeared to covary with the specific metabolic findings in these patients and with the patient's clinical course, but no BAEP could be considered characteristic of Leigh syndrome.

Evoked potentials in motor system diseases.

We studied pattern-shift visual (PSVEP), brainstem auditory (BAEP), and somatosensory (SEP) evoked potentials in 38 unselected patients with motor system diseases (MSD) (28 sporadic, 10 familial). PSVEPs were normal in all patients, and BAEPs were normal in all except one with clinical hearing loss who had absent waves I and III and prolonged wave V latencies. Median and tibial SEPs revealed definite CNS conduction abnormalities in only 1 of 30 and 1 of 18 patients, respectively. In addition, four patients had peripheral and four had peripheral or central delays on tibial nerve testing. There were no or only small group differences in central conduction SEP, BAEP, and PSVEP values in patients with normal studies compared with controls. This study suggests that central conduction SEP, BAEP, or PSVEP abnormalities can rarely be attributed to MSD and that their presence in patients suspected of having this disorder should prompt a search for an alternative diagnosis.

Neurobiology of pain

We studied evoked potentials in 15 children (age range: 2 wks to 4 yrs; mean: 10 mos) with metabolic disturbances that led to Leigh syndrome. These disturbances included deficiencies of pyruvate dehydrogenase (N = 5), complex 1 (N = 7), complex 4 or cytochrome oxidase (N = 2), and complex 5 (N = 1) deficiencies. Subsequent studies were performed in 11 children. All of the children with pyruvate dehydrogenase deficiency had abnormal brainstem auditory evoked potentials (BAEPs) due to poor morphology and reproducibility of the waveforms; central conduction time was normal in 4 of 5 initial studies. The patients with complex 4 or cytochrome oxidase deficiency had abnormal BAEPs, due to increased interpeak latencies and low amplitude or absent waves IV/V. Six of 7 of the children with complex 1 deficiency had normal BAEPs. The remaining patient (the youngest, age 6 wks) had only waves I and II bilaterally and suffered from the rapidly progressive form of complex 1 deficiency; the other 6 with complex 1 deficiency had the slowly progressive form. The one patient with complex 5 deficiency had normal BAEPs when first tested at 4 mos; abnormal BAEPs with loss of later waves were observed 10 weeks later. The visual evoked potentials and somatosensory evoked potentials usually were abnormal in these patients, but the findings were not specific to the patient subgroups. In all but one patient, subsequent studies disclosed a lack of normal maturational changes and/or deterioration across all 3 modalities. The BAEPs appeared to covary with the specific metabolic findings in these patients and with the patient's clinical course, but no BAEP could be considered characteristic of Leigh syndrome.

CORRELATION BETWEEN PATHOLOGICALLY CONFIRMED SITES OF NEUROLOGICAL LESIONS AND ABNORMALITIES OF FAR-FIELD AUDITORY BRAINSTEM RESPONSES.

AMERICAN ASSOCIATION OF NEUROPATHOLOGISTS 159 CORRELAnON BEIWEEN PAntOLOCICALLY CONFIRMED SITES OF NEUROLOGICAL LESIONS AND ABNORMALITIES OF FAR-FIELD AUDITORY BRAINSTEM RESPONSES. A. Starr and A.E. Hamilton*. University of C4lifornia, Irvine, C4lifornia College of Medicine, Irvine, California. Far-field auditory brainstelll responses were recorded in nine patients in whom the distribution of the pathology was defined at autopsy in order to correlate the loss of the electrical components of the auditory res- ponse to the anatomic components of the auditory tract. lbe normal res- ponse consists of seven wave components in the initial ten miliseconds following click signals. A schwanoma of the eighth nerve resulted in the loss of the components after Wave I. Two patients with midbrain tumors had intact Waves I, II, and III, abnormal Waves IV and V, and absent Waves V and VI. A patient with a brainstem glioma which completely obliterated the midbrain and pons, a patient vbose pons and medulla vere completely infarcted. and a drug overdose patient with patchy brainstem encepbalomalacia and three patients with diffuse severe anoxic brainstem changes had clearly detectable Wave I's. The subsequent components were either absent or significantly altered in latency or amplibide. We con- clude that Wave I reflects the activity, Waves II and III reflect activity of the cochlear nucleus, trapezoid body and superior olive and Waves IV and V reflect the activity of the lateral lemniscus and inferior colliculus. The anatomic sources of Waves VI and VII vere not elucidated. (Supported in part by Grant PBS NS 11876 from the USPHS.)

Responsibility of manufacturers and consumers

Man's functions are probed, monitored, altered, and substituted for by machines. The most vital activities of life are sustained by artificial respiration and circulation; death is diagnosed by absent waves on the electroencephalogram. The authority to construct these devices and the privilege of using them places an awesome responsibility on the manufacturer and consumer if the subject is to be safeguarded against misfunction or misdirection. However, the failure of manufacturers and physicians to accept this burden of responsibility has aroused governmental interest. In these days of social conscience, governmental agencies have assumed a role as guardian angels over the welfare of the governed as groups or individuals. The delivery of appropriate medical care is a small but obvious segment of the programs influencing life from birth to death in the conflict between the individual and his world. The interplay between manufacturer, physician, and government with the public as the ball

Responsibility of Manufacturers and Consumers

Man's functions are probed, monitored, altered, and substituted for by machines. The most vital activities of life are sustained by artificial respiration and circulation; death is diagnosed by absent waves on the electroencephalogram. The authority to construct these devices and the privilege of using them places an awesome responsibility on the manufacturer and consumer if the subject is to be safeguarded against misfunction or misdirection. However, the failure of manufacturers and physicians to accept this burden of responsibility has aroused governmental interest. In these days of social conscience, governmental agencies have assumed a role as guardian angels over the welfare of the governed as groups or individuals. The delivery of appropriate medical care is a small but obvious segment of the programs influencing life from birth to death in the conflict between the individual and his world. The interplay between manufacturer, physician, and government with the public as the ball