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.     

Evoked potentials in olivopontocerebellar atrophy

Pattern-reveral visual evoked potentials, far-field and cortical somatosensory evoked potentials, and auditory brainstem potentials were recorded in two patients with olivopontocerebellar atrophy. In one patient, visual evoked potentials exhibited prolonged latency and interocular latency differences in the absence of clinical visual dysfunction. Median and tibial nerve evoked cortical potentials were severely attenuated in the absence of somatosensory deficit or peripheral nerve slowing. The far-field somatosensory potentials, however, were well preserved. All components of the auditory brain-stem potentials had latencies within normal limits. In the other, more severely afflicted, patient, all visual, somatosensory, and auditory evoked potentials were abnormal.     

Evoked potential abnormalities in the various inherited ataxias

Visual (VEP), brainstem auditory (BAEP), and somatosensory (SEP) evoked potential tests were performed in 45 patients representing ten types of inherited disorders in which ataxia was the most prominent symptom. Comparable VEP abnormalities were present among all types of patients. Normal BAEP tests were recorded in most patients except those with olivopontocerebellar atrophy. SEP results were often more severely abnormal in patients with Friedreich's ataxia. The observations emphasize the similarity in expression of different metabolic-degenerative disorders. When these tests are used clinically, certain features of evoked potentials (especially left-right symmetry) are typical of the inherited ataxias as a group. Few distinguishing features differentiate the individual disorders.     

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.     

Study of multimodal evoked potentials in patients with type 1 Gaucher's disease

To detect early subclinical nervous dysfunction in Gaucher's disease type 1, we carried out motor, brainstem auditory, visual, and somatosensory evoked potentials in 17 patients with Gaucher's disease type 1. Central motor evoked potential abnormalities were found in nine patients (69.2%), consisting of an increased motor threshold in all, with prolonged central motor conduction time in two patients. Brainstem auditory evoked potentials were abnormal in five patients (31.2%), and the most frequent abnormality was a bilateral increased I-III interpeak latency. Visual evoked potentials showed a delayed latency of the P100 wave in four patients (25%). Somatosensory evoked potential abnormalities were found in three patients (18.7%), consisting of an increased N13-N20 interval in two patients and a not reproducible N13 wave in one patient. Our findings suggest that the multimodal evoked potential approach provides information about nervous subclinical damage in Gaucher's disease type 1; transcranial magnetic stimulation proved to be the most sensitive tool. Early detection of subclinical neurologic dysfunction can be useful in view of more effective therapeutic strategies.     

Wilson's disease: evoked potentials and computed tomography

Summary Multi-modality evoked potentials and computed cranial tomography (CT) were performed in ten patients with Wilson's disease to determine if any of these studies would correlate reliably with neurologic status. While all four patients with CT abnormality had neurologic signs, two additional patients with neurologic findings had normal scans. Evoked responses were normal in nine patients. The remaining patient displayed abnormal visual, brainstem, and somatosensory evoked potentials, and follow-up studies after clinical deterioration revealed worsening of the brainstem and visual evoked potentials. This patient died unexpectedly from a subdural hematoma, and postmortem examination confirmed the radiographic findings of cortical atrophy of the cerebrum and cerebellum and bilateral cystic degeneration of the basal ganglia. However, localized demyelination in the visual, auditory, and sensory pathways was not present. We conclude that the clinical neurologic status of patients with Wilson's disease cannot be reliably predicted by either CT or multi-modality evoked potentials.     

Early onset cerebellar ataxia with retained tendon reflexes (EOCA) and olivopontocerebellar atrophy (OPCA): a computed tomographic study

Computed tomographic (CT) studies in olivopontocerebellar atrophies (OPCA) and 'early onset cerebellar ataxia with retained tendon reflexes (EOCA)' are few and vary widely in methodology and criteria for cerebellar and brainstem atrophy. In this prospective study, CT scan observations on 26 patients (EOCA-11, OPCA-15) were compared with 31 controls using qualitative and quantitative assessment of cisterns, ventricles and atrophy of brain. Vermian and/or cerebellar hemispheric (predominantly anterior) atrophy was present in 80.8% and both were equally common. Cerebral cortical atrophy (26.9%) and leukoariosis (15.4%) were less frequently seen. Statistically significant atrophy of pons, brachium pontis, cerebellum and midbrain was noted in patient group. No significant differences were observed between EOCA and OPCA groups. Evidence of atrophy did not correlate with either the duration of illness or the severity of cerebellar ataxia in both the groups. The severity of brainstem atrophy in 14 patients with and 12 patients without abnormal brainstem auditory evoked response did not differ significantly. This study highlights the methodology of CT evaluation for brainstem and cerebellar atrophy, draws attention to cerebral atrophy and emphasizes the lack of significant differences in CT morphology between OPCA and EOCA patients.     

Visual, early auditory and somatosensory evoked potentials in multiple sclerosis (917 cases)

Visual (VEP), brainstem auditory (BAEP) and somatosensory (SEP) evoked potentials were recorded over a 6 year period in 917 patients with or suspected of multiple sclerosis according to Mc Alpine's criteria. Evoked potentials provided information of diagnostic relevance in detecting clinically unsuspected lesions (spatial dissemination). They also gave valuable informations in patients with atypical or borderline clinical features. When abnormal, VEP indicated clinically silent lesions in 45.1 p. 100 of patients with definite MS, 66 p. 100 of those with probable MS and 78 p. 100 of the possible MS. Less than 15 p. 100 of SEP and/or BAEP abnormalities were found in 83 patients with a simple or recurring retrobulbar optic neuritis. Thirteen patients with acute transverse myelopathy and no prior history of neurological disease were studied. All had normal visual and brainstem auditory evoked potentials. Abnormal VEPs helped to the clinical assessment of 88 patients with progressive spastic paraparesis 46,6 p. 100 of whom had abnormal VEPs demonstrating disseminated lesions and 36,1 p. 100 had abnormal BAEPs. The frequency of the various types of VEP, BAEP and SEP abnormalities was studied as well as their course on repeated recordings. Results of multivariate analysis are given. It was found that the longer the time interval between the first MS relapse and the evoked potential recording, the higher the incidence of abnormalities. The incidence of evoked potentials abnormalities was lower in patients with normal CSF and higher in patients with inflammatory CSF. The abnormalities were more frequent when patients had clinical evidence of lesions of the sensory pathways explored by the tests.     

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。     

Further evidence of involvement of central and peripheral sensory pathways in olivopontocerebellar atrophy

We report the electrophysiological findings of the central and peripheral somatosensory pathways in 20 patients with olivopontocerebellar atrophy. Changes in sensory action potentials of the median nerve were observed in 14 patients and consisted of reduced sensory potential amplitudes associated in 10 cases with an increase in distal latencies. Sixteen out of 20 patients also showed changes in somatosensory evoked potentials after stimulation of the median nerve, consisting of decreased amplitude of N13 (13 cases) and N20 (16 cases) components, associated with increased N9-N13 interpeak latency in 9 and N13-N20 in 14 patients. The origin of these alterations is discussed.     

Neurophysiologic study of olivopontocerebellar atrophy with or without glutamate dehydrogenase deficiency

By neurophysiologic investigations, we evaluated 20 patients with olivopontocerebellar atrophy (OPCA), comprising 8 with glutamate dehydrogenase (GDH) deficiency and 12 with normal GDH activity. We found sensorimotor, predominantly sensory axonal neuropathy distally in the legs, and peripheral auditory nerve dysfunction (prolonged wave I but normal interpeak latencies in brainstem auditory evoked response) in GDH-deficient patients. These findings seem distinctive enough to serve as the electrophysiologic marker for diagnosis and monitoring of treatment and progression of the disease. The pattern-reversal visual and median nerve somatosensory evoked responses did not differ among the patients and controls.     

Present criteria for the diagnosis in vivo of olivopontocerebellar atrophy

We present 6 cases of olivopontocerebellar atrophy (OPCA) of Dèjérine-Thomas type. The diagnosis was based on an appropriate clinical picture, anomalous brainstem auditory evoked potentials (BAEP) and computerized tomography (CT) and/or magnetic nuclear resonance (MNR) imaging which demonstrated atrophy of the cerebellum and the pons. We believe that these methods will provide greater uniformity in the diagnosis of such an heterogeneous entity as OPCA.     

Evoked potential studies in Friedreich's ataxia and progressive early onset cerebellar ataxia

We recorded somatosensory evoked potentials (SEP) in 15 patients affected by Friedreich's ataxia (FA) and in 9 patients with progressive early onset cerebellar ataxia (PEOCA). Brainstem auditory evoked potentials (BAEP) were also recorded in 14 FA patients and in five PEOCA patients. SEP results showed clear differences between groups of FA, evidence of peripheral involvement was seen in all patients, with absence of the N9 potential or a major reduction of its amplitude. In patients in whom central responses could be recorded, conduction velocity was normal or near normal up to the brainstem but was reduced from brainstem to cerebral cortex. Four patients with PEOCA had SEP abnormalities similar to those seen in FA. In the five other patients, the amplitude and latency of N9 were normal but conduction velocity was reduced from brainstem to cerebral cortex. In FA, BAEP were abnormal in all patients with a disease duration of four years or more but were normal in four of the five PEOCA patients. Systematic evoked potential recording is useful in the investigation of hereditary ataxias.     

Evoked potentials in spinal muscular atrophy

Visual evoked potentials, brainstem evoked responses, and somatosensory evoked potentials were evaluated in 22 children with spinal muscular atrophy, types I and II. Eleven of the children had the severe form of spinal muscular atrophy (type I) and 11 children had the intermediate form (type II). The results of visual evoked potentials, brainstem evoked responses, and somatosensory evoked potentials were compared with those obtained in a control group. Statistical analysis showed abnormalities in the different sensory modalities. A significant increase in the visual evoked potential latencies was observed and was found more often in patients with spinal muscular atrophy type I. Alterations of the somatosensory thalamocortical responses were also observed, as well as a delay in the central conduction time. Although spinal muscular atrophy is usually considered to be a purely motor disorder involving neurons of the spinal anterior horn and nuclei of the lower cranial nerves, lesions of the posterior roots, spinal ganglia, ascending tracts, lateral geniculated corpus, and thalamus have been reported. Our results suggest that sensory neuron degeneration occurs more commonly in spinal muscular atrophy than previously thought and that this process probably develops more slowly than motoneuron degeneration. Such degeneration may be associated with brain atrophy.     

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.     

Prospective studies of multimodal evoked potentials in patients after cranio-cerebral injury]

In 42 patients aged 18-68 years somatosensory, visual and brainstem auditory evoked potentials were studied in the first month after trauma and after 6-8 months after craniocerebral trauma for evaluation of their diagnostic importance in less severe craniocerebral trauma. On the basis of the results of neurological examination, CT of the head, and duration of unconsciousness in 22 cases brain concussion and in 20 cases brain contusion was diagnosed. In patients after brain concussion the frequency of early and late abnormalities after head trauma was as follows: for SSEP 36.4% and 27.3% respectively, for visual evoked potentials 21.1% and 5.3%, for auditory potentials 9.5% and 4.8%. In cases of brain contusion abnormalities were found in the 1st month and 6-8 months after trauma in SSEP in 60% and 20% respectively, in visual EP in 11.1% and 22.2%, and in auditory EP in 30% and 40%. In the group of concussion the greatest and most persistent changes developed in the later components od SSEP. Among certain patients with brain contusion deterioration of the results of visual and auditory evoked potentials were noted late after trauma.     

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).     

Clinical and electrophysiological studies of human immunodeficiency virus-seropositive men without AIDS

Motor weakness and ataxia of lower limbs and abnormalities of somatosensory evoked potentials occur in many patients with the acquired immunodeficiency syndrome (AIDS). We studied 15 human immunodeficiency virus-seropositive subjects without AIDS and found no clinical neurological abnormalities. The mean latency of the brainstem auditory evoked potential (peak V) was increased, suggesting a central defect. Despite normal peripheral nerve conduction along the tibial nerve, the mean latency of the spinal cord potential of the twelfth thoracic vertebra was increased compared with normal, possibly indicating an incipient conduction defect at or near the spinal root ganglion or lumbar spinal cord.     

Electrophysiologic study of 10 cases of Miller Fisher syndrome

The association of ophthalmoplegia, ataxia and areflexia was described by Miller Fisher in 1956. It is postulated as a variant of the Guillain Barré syndrome. We report 10 Miller Fisher syndrome patients admitted in an intensive care unit between June 1990 and February 1999 who were selected according to clinical criteria of Ropper and Wijdicks. All patients had motor and sensory nerve conduction studies and electromyography, nine had visual and brainstem auditory evoked potentials and two had short latency somatosensory evoked potentials. Peripheral neuropathy was found in all patients. All had sensory nerve changes and some were severe. Motor nerve conduction abnormalities were observed in 7 only cases with moderate increase of F latency in 3 cases and compound muscle action potential reduction in 3 other cases. In the last case, motor conduction abnormalities was more severe, characterized by conduction velocity slowing in both distal and proximal sites and by temporal dispersion of action potentials. All brainstem auditory evoked studies were normal. In 4 patients, MRI studies were normal. These data support that brainstem is preserved in MFS. Only one patient had visual evoked potential abnormalities. Optic neuropathy is debated in Miller Fisher and in Guillain Barré syndrome. As a conclusion, in MFS peripheral neuropathy is always present with severe sensitive changes and moderate motor changes (This is different as compared to Guillain Barré syndrome according to electrophysiological data). We did not find involvement of brainstem in our patients with Miller Fisher syndrome.     

Clinical, multimodal electrophysiological study of a family with progressive cerebellar ataxia and late deafness and an autosomal recessive inheritance]

We described the clinical, electrophysiological (electromyography, sensory and motor nerve conduction study, somatosensory evoked potentials, brainstem auditory evoked potentials, visual evoked potentials) and neuroradiological (brain magnetic resonance) data in 3 siblings (2 males and 1 female, age range: 54-48 years) affected by autosomal recessive late onset cerebellar ataxia. The 3 patients showed at the electrophysiological examination: mild peripheral neuropathy, involvement of somatosensory pathways both on central and peripheral side. A mild cerebellar atrophy, most evident in the female more severely disabled, was found by magnetic resonance.