Brainstem Auditory and Somatosensory Evoked Potentials in Neuro-Behqet's Syndrome

Abstract: Brainstem auditory evoked potentials (BAEPs) and somatosensory evoked potentials after median nerve stimulation (MN-SEPs) and after posterior tibial nerve stimulation (PTN-SEPs) were studied in 17 patients with neurolehget's syndrome (NB). Eleven patients (64.7%) showed an absence of wave I, III or V or a prolongation of the interpeak latency 1–111, or 111-V in BAEPs. Six patients (37.4%) showed a prolongation in the latency of cortical P37 of PTN-SEPs and/, or the interpeak latency EP-N13 or N13–N18 of MN-SEPs. The BAEP and SEP abnormalities indicated a conduction failure of the acoustic lateral lemniscus pathway and the medial lemniscus pathway in the brainstem of the patients with NB. Abnormal EPs can provide sensitive information which shows the presence of subclinical lesions in the central nervous system.     

支架置入术对椎基底动脉系统短暂性脑缺血发作患者诱发电位的影响

目的 观察支架置入术能否改善椎基底动脉系统短暂性脑缺血发作（TIA）患者的亚临床症状。方法 11例症状性椎基底动脉狭窄的椎基底动脉系统TIA患者,支架置入术前后分别检测体感诱发电位（SEP）、脑干听觉诱发电位（BAEP）、视觉诱发电位（VEP）,记录各诱发电位的潜伏期及波幅。结果 （1）术前诱发电位均异常,主要表现为SEP N20及P40潜伏期异常,BAEPⅠ、Ⅲ、Ⅴ波潜伏期延长,VEP P100潜伏期延长。（2）与术前相比,术后1周BAEP表现为Ⅰ～Ⅲ波潜伏期缩短（P =0.046）、Ⅲ波幅升高（P =0.05）;SEP表现为N20潜伏期缩短（P =0.012）,N13～N20间期缩短（P =0.013）,P14～N20间期缩短（P =0.005）;VEP表现为 P100潜伏期缩短（P =0.022）。结论 支架置入术后,椎基底动脉系统TIA患者的SEP、BAEP、VEP好转,提示患者的亚临床症状恢复。     

Brainstem auditory and somatosensory evoked potentials in neuro-Beh?et's syndrome

Brainstem auditory evoked potentials (BAEPs) and somatosensory evoked potentials after median nerve stimulation (MN-SEPs) and after posterior tibial nerve stimulation (PTN-SEPs) were studied in 17 patients with neuro-Beh?et's syndrome (NB). Eleven patients (64.7%) showed an absence of wave I, III or V or a prolongation of the interpeak latency I-III, or III-V in BAEPs. Six patients (37.4%) showed a prolongation in the latency of cortical P37 of PTN-SEPs and/or the interpeak latency EP-N13 or N13-N18 of MN-SEPs. The BAEP and SEP abnormalities indicated a conduction failure of the acoustic lateral lemniscus pathway and the medial lemniscus pathway in the brainstem of the patients with NB. Abnormal EPs can provide sensitive information which shows the presence of subclinical lesions in the central nervous system.     

The diagnostic value of sensory evoked potentials in pediatric Wilson disease

We studied the sensory evoked potentials in pediatric Wilson disease to verify their subclinical neurologic involvement and to elucidate the role of cirrhosis in abnormal evoked potentials in non-neurologic Wilson disease. Thirty children (17 male, 13 female), diagnosed with Wilson disease before 18 years, were enrolled. The mean age during studies was 15.8 +/- 6.3 years, and disease duration since diagnosis was 3.0 +/- 3.3 years. In 12 neurologic Wilson disease cases, there were prolonged interpeak latencies of brainstem auditory evoked potentials III-V, I-V, somatosensory evoked potentials N13-N20 (P < 0.01 vs controls and non-neurologic cases), and P100 latency (P < 0.01 vs controls). All 12 patients had at least one abnormal evoked potential, including 91.7% brainstem auditory, 58.3% somatosensory, and 25% visual evoked potentials. In 18 non-neurologic Wilson disease cases, there were still prolonged interpeak latencies for brainstem auditory evoked potentials I-V and somatosensory evoked potentials N13-N20 (P < 0.05 vs controls), with 27.8% of them having at least one abnormal evoked potential, including 16.6% brainstem auditory, 5.6% somatosensory, and 11.1% visual evoked potentials. In those with non-neurologic Wilson disease, there were no significant differences in all the evoked potential parameters between the cirrhotic and non-cirrhotic patients.     

Evoked potentials in patients with non-neurological Wilson's disease

Summary In Wilson's disease neurological manifestations result from the damage in the basal ganglia, even if a widespread degeneration of the brain occurs. The few studies performed using evoked potentials with the aim of identifying subclinical dysfunction in the three major sensory pathways have never shown abnormalities in patients without neurological manifestations. To verify this observation we studied 12 patients suffering from Wilson's disease in a pre-neurological stage by using pattern visual evoked potentials (VEPs), somatosensory evoked potentials (SEPs) to median nerve stimulation and brainstem auditory evoked potentials (BAEPs). Four of these patients had not yet been treated with penicillamine or trientine (triethylenetetramine dihydrochloride), while the remaining 8 patients were on treatment for at least 1 year. In 3 patients of this second group and in 1 patient of the first group we observed a significant (3 SD over the mean) increase in P100 wave latency, while SEPs and BAEPs were found to be abnormal in only 1 patient, respectively.     

The value of measuring saccadic eye movement in the investigation of non-compressive myelopathy.

Saccadic eye movement recording was performed in 53 patients with non-compressive myelopathy. Twenty one patients (40%) had subclinical abnormalities of saccadic movement, supporting a diagnosis of probable multiple sclerosis. When used in addition to the measurement of visual evoked potentials and brainstem auditory evoked responses, the detection of subclinical abnormalities increased from 40% to 57%. The detection rate of abnormalities by saccadic eye movement recording was equal to that of visual evoked responses, but more than of brainstem auditory evoked responses. Prolonged latency of gaze was the most common saccadic latency abnormality detected. The majority of saccadic velocity abnormalities could be explained by disease in the medial longitudinal bundle. An unusual finding was that abduction velocity was increased in six patients. It is concluded that the simple measurement of saccadic eye movement is a valuable addition to other ancillary investigations for the diagnosis of multiple sclerosis. It also allows analysis of oculomotor function, commonly disordered in multiple sclerosis, but rarely investigated.     

Multimodal evoked potentials in the early period after cranio-cerebral trauma]

In 83 patients aged 17-68 years somatosensory evoked potentials by median nerve stimulation, and visual and auditory evoked potentials were studied 5-28 days after craniocerebral trauma. Brain concussion was diagnoses in 43 cases on the basis of neurological examination, CT and duration of unconsciousness. In the remaining 40 cases brain contusion was diagnosed. In SSEP the latency was calculated of waves N9, N13, P16, N20, P22, N35 and P40: in the visual evoked potentials the latency of the P100 component, and in auditory evoked potential the latency of waves I, III and V, and interpeak latency I-III, III-V and I-V SSEP changes were found in 39% of cases of brain concussion and 52.9% of brain contusion cases. The abnormalities in both groups involved mainly the component of latency and deviation P100 of visual evoked potential P40 and N35. Prolongation of the latency of P100 of the visual evoked potential was recorded in 20% of patients with brain concussion and 16.7% with brain contusion. Auditory evoked potentials were abnormal in 10.3% of brain concussion and 26.5% of brain contusion cases. In 64 cases all three types of evoked potentials were studied and pathological changes in at least one of these types were found in 56.4% of brain concussion and 72% of brain contusion cases. The results show that as least in a part of cases diagnosed as brain concussion according to generally accepted criteria, central nervous system injury is present.     

Neurophysiological (evoked auditory and somatosensory potentials) and neuroradiological (cranial CT) study in patients with olivopontocerebellar atrophy

Thirteen patients affected by either dominant or recessive and/or sporadic olivopontocerebellar atrophy were studied. All patients were subjected to auditory evoked potential recordings including early and long latency components, CT scans, vestibular and EMG-ENG examinations. In nine patients somatosensory evoked potentials were also recorded. Clear-cut abnormalities in brainstem auditory evoked potentials were observed in only two patients while a slight reduction of the IV-V/I amplitude ratio was found in seven cases. N85 was increased in two patients. The main feature of somatosensory evoked potentials abnormalities was a delayed N20 in association with prolonged N13-N20 central conduction time (five patients). For all patients the CT scan varying degrees of cerebellar and brainstem atrophy. There was no clear correlation between the abnormalities revealed by neurophysiological and neuroradiological investigations and the severity and duration of the illness. It is noteworthy that auditory and/or somatosensory evoked potential changes were found in all dominant olivopontocerebellar atrophy patients.     

Evoked potentials in multiple system atrophy (MSA)

OBJECTIVES: To study the involvement of pyramidal tracts and sensory pathways in multiple system atrophy (MSA). MATERIALS AND METHODS: Evoked potential studies were performed in 45 MSA patients suffering from either MSA of cerebellar type (MSA-C) or MSA of parkinsonian type (MSA-P). RESULTS: Motor evoked potentials were normal in all MSA patients, whereas visual and somatosensory evoked potential abnormalities were found in about 40% of the MSA patients with no significant difference between the cerebellar (MSA-C) and parkinsonian (MSA-P) subgroup. Abnormal latencies of wave III in brainstem auditory evoked potentials were significantly more frequent in MSA-C. CONCLUSIONS: Abnormalities of somatosensory, visual and auditory evoked potentials are frequent findings in MSA, whereas abnormal motor evoked potentials are not a characteristic feature of the disease.     

Auditory brainstem evoked potentials in early-treated congenital hypothyroidism

To evaluate the effect of early treatment of congenital hypothyroidism on central nervous system development, auditory brainstem evoked potentials were determined in 32 patients with hyperthyrotropinemia diagnosed during neonatal screening. The patients included 27 with congenital hypothyroidism and 5 with transient hypothyroidism. Abnormal auditory brainstem evoked potential tracings were found in 8 patients (congenital hypothyroidism in 7 and transient hypothyroidism in 1). Four of these patients had increased peripheral conduction time (wave I prolongation), and the other 4 had increased central conduction time (wave III or V prolongation). The patients with abnormal auditory brainstem evoked potentials did not show increased initial manifestations, yet 6 of them had lower initial thyroxine levels. Specific auditory brainstem evoked potential abnormalities were found in 25% of early-treated patients with congenital hypothyroidism. The possible causal relationship between deviant auditory brainstem evoked potential patterns and later neurodevelopment demands further clarification. This study suggests the usefulness of auditory brainstem evoked potential assessment to provide information about electrophysiologic deviation of the auditory pathway in patients with early-treated congenital hypothyroidism.     

Correlation between disability and transcranial magnetic stimulation abnormalities in patients with multiple sclerosis

Multiple sclerosis (MS) is an idiopathic inflammatory demyelinating disorder of the central nervous system. Clinical evaluation, MRI, cerebrospinal fluid testing and evoked potentials (EP) are among the available methods utilized for disease diagnosis and monitoring. To date, no surrogate markers have been established to assess disease evolution and progression. The aim of this study is to assess motor evoked potentials (MEP) of MS patients by transcranial magnetic stimulation (TMS) and investigate the possible correlations between TMS abnormalities and disability in the patient group, which includes a subgroup with no apparent pyramidal tract dysfunction. A total of 131 clinically definite MS patients were included in the study. Motor responses to TMS stimulation were recorded. Absent values, decreases in amplitude, prolongation of latency and central motor conduction time (CMCT) were considered as abnormal. A total of 109 (83%) patients displayed abnormal MEP amplitude, 68 (52%) displayed MEP latency, and 64 (49%) displayed CMCT abnormalities. Abnormal CMCT, latency and amplitude results were correlated with Expanded Disability Status Scale scores (p < 0.001). Our results indicate that TMS-EP in MS patients is correlated with disability, and that these findings may support the role of EPs in predicting disability even in subclinical presentations.     

Neurotoxic effects of n-hexane on the human central nervous system: evoked potential abnormalities in n-hexane polyneuropathy.

An outbreak of n-hexane polyneuropathy as a result of industrial exposure occurred in printing factories in Taipei area from December 1983 to February 1985. Multimodality evoked potentials study was performed on 22 of the polyneuropathy cases, five of the subclinical cases, and seven of the unaffected workers. The absolute and interpeak latencies of patterned visual evoked potential (pVEP) in both the polyneuropathy and subclinical groups were longer than in the normal controls. The pVEP interpeak amplitude was also decreased in the polyneuropathy cases. Brainstem auditory evoked potentials (BAEP), showed no difference of wave I latency between factory workers and normal controls, but prolongation of the wave I-V interpeak latencies was noted, corresponding with the severity of the polyneuropathy. In somatosensory evoked potentials (SEPs), both the absolute latencies and central conduction time (CCT) were longer in subclinical and polyneuropathy cases than in the unaffected workers and normal controls. From this evoked potentials study, chronic toxic effects of n-hexane on the central nervous system were shown.     

Late infantile Krabbe leukodystrophy: MRI and evoked potentials in a Japanese girl

A Japanese girl showed deterioration in development from the age of 13 months. At the age of 16 months, there were mild spastic diplegia, increase in cerebrospinal fluid protein to 61.5 mg/dl and deficient galactosylceramidase I. Magnetic resonance imaging (MRI) demonstrated a high signal intensity with increased T2 in the centrum semiovale. Short latency somatosensory evoked potentials (SSEPs) showed a prolonged N13-N20 interpeak latency followed by abolition of N20. Brainstem auditory evoked potentials (BAEPs) were normally followed by prolonged interpeak latencies of wave I-V. This may be the first report of what we consider to be the late infantile form of Krabbe disease with MRI and evoked potential examinations.     

Somatosensory evoked potentials in progressive supranuclear palsy

We report median and digital nerve somatosensory evoked potentials (SEPs) in 14 patients with probable progressive supranuclear palsy (PSP) along with transcortical long-loop reflexes, motor evoked potentials, and auditory startle responses. Enlarged cortical responses were found in 14 median and 13 digital nerve SEP studies, while long-loop reflexes were increased in only one patient. All motor evoked potential studies were normal. Auditory startle responses were either absent or reduced in 11 patients. The observed neurophysiological abnormalities may reflect cortical hyperexcitability but are distinct from those in other disorders associated with giant SEPs, such as progressive myoclonus epilepsy. A number of groups reported widespread cortical changes in addition to the characteristic subcortical neurofibrillary degeneration in post-mortem confirmed PSP. However, clinical features reflecting cortical dysfunction such as ideomotor apraxia and cortical sensory loss are uncommon in classical PSP. Furthermore, frontal lobe dementia which is frequently present in PSP patients, is thought to be of subcortical origin resulting from striato-frontal deafferentation. We propose that cortical neurofibrillary pathology may lead to subclinical intracortical disinhibition accounting for the enlarged cortical SEPs in PSP.     

Multimodal evoked potentials in progressive external ophthalmoplegia with mitochondrial myopathy

Multimodal evoked potentials were studied in 13 patients affected by progressive external ophthalmoplegia with histologically proven mitochondrial myopathy. Progressive external ophthalmoplegia occurred with craniosomatic spreading in all the patients and with a varying degree of nervous and/or other system involvement in most of them. In all but one of the subjects, at least one evoked potential modality was abnormal; 11 of them demonstrated an abnormal visual evoked potential, but this finding might have been influenced by concurrent retinal dysfunction. Abnormalities in brainstem auditory evoked potentials and/or somatosensory evoked potentials, revealing an impairment of central sensory pathways, were detected in 7 subjects, 5 of whom lacked clinical evidence of central nervous system involvement. Thus, evoked potentials represent an useful tool for the detection of subclinical central nervous system involvement in patients affected by progressive external ophthalmoplegia with mitochondrial myopathy.     

Evoked potentials in HIV infection]

The study of the literature data on the multimodal evoked potentials in HIV infected patients shows many abnormalities as well in asymptomatic subjects without AIDS as in AIDS subjects with or without neurological signs. Visual evoked potentials (VEPs) reveal prolonged P100 wave latency in 22% of HIV asymptomatic subjects and in 26% of HIV symptomatic subjects; brainstem auditory evoked potentials (BAEPs) reveal an increase of the interpeak latency I-V in 16% of asymptomatic subjects and in 32% of symptomatic subjects; somatosensory evoked potentials (SEPs) by median nerve stimulation reveal prolonged central conduction time in 6% of asymptomatic subjects and in 11% of symptomatic subjects; somatosensory evoked potentials (SEPs) by tibial nerve stimulation reveal prolonged central conduction time in 4% of asymptomatic subjects and in 45% of symptomatic subjects; motor evoked potentials (MEPs) by magnetic stimulation reveal prolonged central motor conduction time in 46% of asymptomatic subjects.     

Correlation between morphological abnormalities of Chiari malformation and evoked potentials]

We studied correlation between morphological abnormalities of Chiari malformation and evoked potentials (short-latency somatosensory evoked potential [SSEP] and auditory brainstem response [ABR]). On SSEP the inter-peak latency prolongation of P3-N1 was revealed in 6 out of 8 cases with Chiari malformations. The feature of positive wave between P3 and N1 was divided into 2 groups. The tendency of the positivity between P3 and N1 was more marked in cases of prolonged P3-N1 latency and correlated with the medullary kink. On ABR the prolongation of III-V inter-peak latency was revealed in one side in 3 patients Chiari malformations with malformed pons and tegmentum.     

Sensory evoked potentials in herpes simplex encephalitis.

Flash visual potentials (FEPs), somatosensory evoked potentials (SEPs) and auditory brainstem responses (ABR) were recorded in a 66-year-old patient presenting with clinical, EEG and CT brain scan features of herpes simplex encephalitis (HSE). At the time of evoked potential study (10 days after onset of the disease) the patient was treated with iv barbiturate on controlled respiration (lidocaine and phenytoin were not utilized); core temperature was 37 degrees C and pupils were dilated and nonreactive. Cortical FEPs were not recognizable on 02 lead, whereas they were clearly evident on 01 with normal latency of early N1, P1, N2 waves and delayed P2 component. SEPs showed normal peripheral and central conduction times, but N20 peak was bilaterally absent with unrecognizable (on P3) or delayed (on P4) N33 wave. No ABR (including wave I) were found on stimulation of the right ear, whereas delayed wave V with prolonged interpeak I-V latency was found on stimulation of the left ear. In conclusion, changes in sensory evoked potentials in HSE seem to be caused either by necrotic-hemorrhagic damage (with the disappearance of some cortical responses), by coma (with alterations in middle-latency cortical responses) and by increased intracranial pressure (with subsequent ABR abnormalities).     

Multimodality evoked potentials in motor neuron disease

We performed median and tibial nerve somatosensory evoked potentials (SEPs), pattern-shift visual evoked potentials (PSVEPs), and brain-stem auditory evoked potentials (BAEPs) on 27 patients with motor neuron disease (MND). Median and tibial nerve SEPs were abnormal in 8 (30%) of 27 and 3 (14%) of 21 patients tested, respectively. Central and peripheral abnormalities were recorded in the absence of spondylosis. As a group, patients with MND and no evidence of cervical spondylosis had normal conduction to Erb's point following median nerve stimulation, but conduction times beyond this point were prolonged. The PSVEPs and BAEPs were within normal limits in all patients, excluding abnormalities attributable to other disease, but the group P100 latency was significantly prolonged in the group with MND. The BAEPs were normal in the group with MND. This study provides neurophysiological evidence of sensory system involvement in MND.     

Sympathetic skin response (SSR) is abnormal in multiple sclerosis

As the function of the autonomic nervous system is often compromised in multiple sclerosis (MS), different standardized tests are used to detect disseminated abnormalities in cardiovascular autonomic functions. Sympathetic skin response (SSR), a slow wave generated in deep layers of the skin, is induced by reflex activation of sudomotor sympathetic efferent fibers. SSR was studied in 70 patients classified into different categories according to the diagnostic criteria for MS. We also obtained pattern reversal visually evoked potentials and brainstem auditory evoked potentials as well as somatosensory evoked potentials (by median and posterior tibial nerve stimulation). SSR was abnormal in 66 patients (94.2%), including abnormal foot latency with normal hand latency in 30 (42.8%), delayed foot and hand latencies in 30 (42.8%), and no response in 6 (8.6%). The percentages of SSR abnormalities were similar in the different patient categories. Pathological SSR were more common than abnormal evoked potentials in suspected and probable MS. SSR appears to be a simple and effective means of assessing sympathetic sudomotor outflow disturbances in MS, providing a valuable addition to current electrophysiological procedures for the detection of MS lesions.© 1995 John Wiley &Sons, Inc.