Evoked potentials, saccadic velocities, and computerized tomography in diagnosis of multiple sclerosis

Correlation between spinal cord MRI and clinical features in patients with demyelinating disease

Localisation of spinal cord lesions by MRI was correlated with neurological symptoms and signs in 16 patients with clinical and laboratory evidence of multiple sclerosis. There was good correspondence between spinal cord lesions and motor tract signs. On the other hand, superficial or deep sensory disturbances correlated with spinal cord lesions in only about a quarter of the patients. MRI of the spinal cord appeared to explain the myelopathy in 11 patients, while in 3 there was strong clinical evidence of more extensive demyelinating lesions. In 7 of the 16 patients MRI of the brain was normal.

Cortical somatosensory magnetic responses in multiple sclerosis

Somatosensory evoked magnetic fields (SEFs) to contralateral median and ulnar nerve stimulation were analyzed in 10 patients with multiple sclerosis and in 8 healthy controls. SEFs were recorded with a 24-channel SQUID gradiometer over both hemispheres. Seven patients showed abnormally large-amplitude SEF deflections at 60-80 msec; 5 of them had multiple lesions around lateral ventricles in magnetic resonance imaging. In 2 patients with plaques at the level of 3rd and 4th ventricles and medulla, the 30 msec responses were enlarged. The equivalent sources of 20 msec and 30-80 msec responses were in the primary hand sensorimotor cortex both in patients and in control subjects. The results suggest that early and middle-latency SEFs reflect parallel processing of somatosensory input. Recording of middle-latency evoked responses, electric or magnetic, may give additional information about the somatosensory function in multiple sclerosis.

Latency and amplitude abnormalities of the scalp far-field P14 to median nerve stimulation in multiple sclerosis. A SEP study of 122 patients recorded with a non-cephalic reference montage

The frequency and characteristics of P14 abnormalities were investigated in 122 patients with probable (68), or definite (54) multiple sclerosis by recording SEPs to median nerve stimulation with a non-cephalic reference montage. The most frequent SEP abnormality found in our series (62% of abnormal results) combined latency increase and amplitude reduction of P14. Interindividual variability, inherent in absolute amplitude measurements, was by-passed by calculating the ratio between the amplitudes of far-field P9 and P14 components, which proved to be normally distributed in controls. In spite of the strong association (P much less than 0.001) between the P9-P14 interpeak interval (IPL) and the P9/P14 amplitude ratio in MS patients, the latter parameter was found to be the only abnormality in 12 patients whose P9-P14 and P14-N20 IPLs were normal. Also IPLs were increased in 12 patients with normal P14 amplitudes. These results suggest that adding the P9/P14 amplitude criterion to standard IPL data might be useful to detect conduction troubles in MS patients.

Multiple sclerosis: diagnostic value of computerized tomography with delayed scanning after a double-dose of contrast medium in comparison with other diagnostic tests

In 63 cases of clinical definite or suspected MS we compared the results of CSF analysis, VEP, BAEP, CT scanning without and after double dose contrast, in 17 cases also those of MRT. We found that CSF analysis had the highest rate of abnormal findings, followed by MRT. VEP and CT with double dose contrast showed similar sensitivity, while BAEP and CT without contrast had disappointing results. We think that CT with delayed scanning after double dose contrast can be a very useful investigation in early and doubtful cases of MS, until MRT will become a more widespread and less expensive investigation.

Vestibular neuronitis. An otoneurological evaluation

Eighty-one cases with vestibular neuronitis were examined. The diagnostic criteria were a sudden onset of vertigo without previous symptoms, spontaneous nystagmus towards the healthy side, totally extinguished caloric responses with 44 degrees C and 30 degrees C water irrigation and no involvement of hearing associated with the onset of the disease. The series was divided into a prospective and a retrospective group. The prospective group A was examined at the acute stage, about 1 month and 1 year afterwards. The retrospective group B fulfilled the same criteria as group A and was examined 1-8 years after the acute stage. The results of the acute stage in group B were analysed from the case history reports, electronystagmo- and audiograms. The preceding and predisposing factors and symptoms were inquired. The examination scheme included the clinical otoneurological examination, the nystagmographic, audiological and clinical neurophysiological measurements and the serological and hematological specimens were collected at the acute stage of group A to examine the role of virus infections in the etiology of vestibular neuronitis. The liquor specimens of 16 cases available in group A were analysed. A recent respiratory infection was reported by 9 cases (27.3 percent) in group A and by 18 cases (37.5 percent) in group B. The serological evidence (increase of IgM-antibodies) was observed in 1 case against influenza A and in 1 case against parainfluenza 3 and the hematological examinations revealed clues of virus infection in 6 cases (18.2 percent) of group A. Cell counts and protein analyses of the liquor specimens were within normal limits. Cases with arterial hypertension under medical control were observed in 15.2 percent of group A and 14.6 percent in group B. These figures do not exceed the age- and sex-correlated prevalence of arterial hypertension in Finnish population. The clinical symptoms included an acute chiefly rotatory vertigo associated with nausea and vomiting without subjective involvement of hearing. The prominent symptoms lessened gradually during the first week and most of the patients were able to their earlier work after one month. The prognosis of the disease was good. The clinical otoneurological findings of the acute stage included spontaneous nystagmus with Frenzel's glasses and disturbances of the vestibulospinal tests. These abnormalities improved markedly during the follow-up period. The results of electronystagmography were characteristic of a pure peripheral vestibular disorder. Nystagmic beats were observed almost regularly in the pendular eye-tracking test at the acute stage examination.(ABSTRACT TRUNCATED AT 400 WORDS)

The diagnosis of multiple sclerosis. Contribution of non-clinical tests

A group of 89 patients in whom multiple sclerosis (MS) has been clinically diagnosed with varying degrees of certainty, and 25 patients with optic neuritis (ON), were subjected to the following electrophysiological tests: visual evoked response (VER), auditory brainstem-evoked response (ABER), somatosensory-evoked response (SSER), blink reflex and electronystagmography (ENG). All these patients also underwent computerized tomography (CT scan) and analysis of cerebrospinal fluid (CSF). A new diagnostic procedure is proposed, combining optimum detection of definite MS with optimally economical use of the above-mentioned non-clinical tests. The results for the MS patients show that definite MS can be diagnosed much more frequently (72%) if abnormal results in the above-mentioned tests are accepted as evidence of a (subclinical) CNS lesion. Application of the clinical diagnostic criteria of McAlpine yielded "definite MS" only in 27% of our patient material. Our diagnostic criteria showed evidence for MS in 36% of the patients clinically diagnosed as having ON. The test results were inconclusive as regards the possibility of the remaining ON patients developing MS in the future.

An evaluation of laboratory investigations in patients with multiple sclerosis

The contribution of VEP, CT and oligoclonal bands (OB) to the diagnosis of MS was studied in a group of 213 hospitalized patients. Whereas the diagnostic values of VEP and OB were both in the same range, the combination of both methods increased the proportion of cases with "definite MS" from 58 to 75%, whereas CT did not contribute significantly to diagnostic ascertainment. Vitamin B12 absorption was less than 10% in 27% of cases. A slight tendency towards increased serum IgG and IgM levels was found, and the rheumatoid factor was demonstrated in 6% of cases.

The blink reflex and somatosensory evoked potential in optic neuritis in south India

Optic Neuritis (ON) proceeds to multiple sclerosis (MS) in a considerable number of patients. The blink reflex (BR) and somatosensory evoked potential (SSEP) are useful non-invasive tests that can detect silent lesions in the central nervous system in patients with clinically suspect MS. In the present study, the BR and SSEP were done in 20 healthy controls and 20 patients with ON. Abnormalities of the SSEP were seen in 20%, and of the BR in 30% of the patients with ON. On combining the results of SSEP and BR studies, 45% of the ON patients were seen to have abnormalities. Over a short period of follow-up, 2 of the 20 ON patients developed clinical MS and both of them had had abnormalities of the BR. These findings suggest that ON proceeding to MS in India may be more common than suspected at present.

The diagnostic challenge of multiple sclerosis

Multiple sclerosis is a common cause of many neurological complaints and disabilities among young, adult Canadians. In the absence of a reliable and specific laboratory test for the disease, the diagnosis is established primarily by clinical criteria, which are outlined in this article. Recent advances in immunology, neurophysiology and neuroimaging have provided techniques to improve diagnostic confidence, particularly in early or atypical cases.

Short-latency somatosensory evoked potentials in dystrophia myotonica

Somatosensory evoked potentials (SEPs) were recorded in a group of 21 patients with dystrophia myotonica and in a group of controls. Those with dystrophia myotonica had longer absolute peak latencies due to slower peripheral conduction. SEP abnormalities revealed peripheral and/or central conduction delays in 33% of the dystrophia myotonica subjects. There was no apparent relationship between the clinical severity of the disease and SEP abnormality.

Visual evoked responses and immunoglobulin abnormalities in the diagnosis of multiple sclerosis

Visually evoked responses (VERs), CSF IgG/albumin ratio and CSF oligoclonal IgG were examined in 136 patients with multiple sclerosis (MS) admitted to hospital for investigation, and compared to the CSF findings in 87 patients with other neurological diseases (OND). 33% of patients with OND had abnormal CSF IgG/albumin ratios but only 9% had CSF oligoclonal IgG banding. In clinically definite MS, VERs were abnormal in 87% and CSF oligoclonal banding was found in 80% of patients, but CSF oligoclonal banding was found significantly more frequently than abnormal VERs in patients with suspected MS. We were unable to show any relationship between benign MS and the absence or presence of CSF oligoclonal IgG. The significance of CSF oligoclonal IgG in the less clinically definite forms of MS will only emerge with prolonged follow-up.

CT findings in acute MS

In 5 patients with definite or highly probable MS, unusually large hypodense plaques are seen by computerized tomography (CT scan). The active plaques all show enhancement after i.v. contrast medium injection, suggestive of blood-brain-barrier-damage, and differ from the well-known CT findings in chronic MS patients, causing diagnostic difficulties between glioma and infarction.

Nuclear magnetic resonance imaging of the orbit

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Evoked potentials. With special reference to the diagnostic value in multiple sclerosis

A survey is given of my studies of evoked potentials in patients with multiple sclerosis (MS) and in control subjects. Potentials were recorded following random low-rate auditory stimulation (BAEP), checker-board pattern-reversal stimulation (VEP), somatosensory stimulation (SEP); blink reflexes (BR) were recorded following electrical stimulation of the supraorbital nerve. Normal data had to be related to age and sex in evaluating BAEPs and VEPs. In 160 MS patients, a total of 421 recordings were obtained. Changes by repeated BAEP and VEP tests might reflect changes in the clinical state, but they also did occur in clinically stable patients. In patients with definite MS, high incidences of abnormality were shown, supporting the clinical findings. The diagnostic value was greatest when clinically silent lesions were demonstrated in patients with suspected or possible MS. In these patients, either BAEP or VEP gave evidence of subclinical lesions in about 50%, and when combined, in 71% of the patients, thus making a transfer to a more certain diagnostic classification possible and invasive examinations unnecessary. When SEP and BR tests were added, subclinical lesions were found in 74% of the patients. The SEP recordings did show a high incidence of abnormality, but only few silent lesions; the BR test was the least sensitive. The VEP was abnormal in all patients with signs of optic neuritis and in all but one with a history of optic neuritis. The present results are compared to those obtained in other laboratories and with other types of examinations in MS patients. It is concluded that although the tests are not specific for MS, they give valuable information in the majority of patients with a clinically uncertain diagnosis. This information will most often not be given by other types of examination. The combination of VEP and BAEP is recommended, but it should be supplemented by SEP recording in patients without spinal signs.

Spinal and cortical somatosensory evoked potentials in Japanese patients with multiple sclerosis

Twenty-seven Japanese patients with multiple sclerosis (MS) were studied by recording the spinal and cortical somatosensory evoked potentials (SEPs) in response to median nerve and/or posterior tibial nerve stimulation. The median nerve SEPs were abnormal in half the cases whereas the tibial nerve SEPs were abnormal in 90% of cases. SEP abnormalities, especially absence or amplitude depression of components, were highly correlated with proprioceptive impairment of hands or legs tested. With regard to the usefulness of SEP in detecting subclinical lesions of the sensory system, the tibial nerve SEP was found more useful than the median nerve SEP. Absence or depressed amplitude of SEP components was seen more commonly with tibial nerve stimulation as compared with median nerve stimulation.

Steady-state and transient visual evoked potentials in clinical practice

The electrophysiological analysis of visual evoked responses is a powerful tool for the study of visual function. The combined application of pattern-reversal transient visual evoked potentials, critical frequency of photic driving, and visual evoked spectrum array has enhanced the reliability and the yield of these tests for the diagnosis of visual dysfunctions. Prechiasmatic and retrochiasmatic lesions are characterized by different abnormalities. Prechiasmatic lesions often can be further differentiated into retinal and optic nerve lesions by the simultaneous recording of retinal and cortical potentials.

Success and failure of evoked potentials in detecting clinical and subclinical lesions in multiple sclerosis patients

The value of visual, brain stem auditory and somatosensory potentials in detecting clinical and subclinical lesions as compared to the routine neurological, ophthalmological and vestibular examinations was investigated in 100 M.S. patients. It would appear that the VEP and SEP are far superior to the routine techniques in demonstrating lesions. On the other hand, the BAEP is inferior to the clinical and vestibular test as an indicator of brain stem lesions. All clinically manifest posterior column lesions are associated with abnormal SEP. However a substantial proportion of clinically evident lesions in the visual pathways or the midbrain and pons are not detectable by the VEP and BAEP.

Pattern-reversal visual evoked potentials in the hereditary ataxias and spinal degenerations

Pattern-reversal visual evoked potentials (PRVEP) were evaluated in 24 patients from 18 separate families with various forms of hereditary ataxia and spinal degeneration. Abnormally delayed latencies were found in 3 of 5 patients with classic Friedreich's ataxia, 1 patient with dominant spastic paraparesis, and 1 patient with recessive dentatorubrospinal degeneration. Fifteen other patients with several different types of dominant and recessive hereditary ataxias had normal PRVEP latencies, including 1 patient with bilateral optic atrophy. Testing of PRVEP will be useful in the clinical delineation of the genetic ataxias and spinal degenerations, and, when interpreted with caution, should be an additional variable evaluated in the differentiation of these disorders from multiple sclerosis.

The value of brain stem auditory, visual and somatosensory evoked potentials and blink reflexes in the diagnosis of multiple sclerosis

Cervical and cortical somatosensory evoked potentials (SEP) following electrical stimulation of the median nerve and blink reflexes (BR) following electrical stimulation of the supraorbital nerve were recorded in 30 normal subjects aged 20-49 years. Subjects aged 40-49 had longer SEP latencies than subjects aged 20-39 years. A total of 29 slightly affected patients with multiple sclerosis (MS) aged 26-49 years, including four patients without clinical signs (suspected MS) and 19 patients with signs indicating only one lesion (possible MS) were examined by low-rate random-stimulated brain stem auditory (BAEP), checkerboard pattern-reversal visual evoked potentials (VEP), SEP and BR. Abnormal recordings by at least one of the examinations were found in all but three patients, and by all four tests in five patients. In patients with definite or probably MS, demonstration of clinically recognized or subclinical lesions was of minor diagnostic value, in contrast to the importance such findings had in patients with suspected or possible MS. Silent lesions were shown by at least one of the tests in the four suspected and in 13 of the possible MS patients, so these 17 patients could be transferred to a more certain diagnostic category. This reclassification was most often due to the BAEP recording. In patients with spinal signs, the combination of BAEP and VEP recording was sufficiently efficient. In patients with optic neuritis a combination of BAEP and SEP was preferred. No abnormal recordings were found in 15 normal subjects examined by all four tests.

Diagnostic techniques in multiple sclerosis

Although multiple sclerosis (MS) has been an area of great interest and effort in numerous scientific disciplines, its etiology, pathogenesis and therapy remain mysterious. Perhaps the most significant advances have resulted from the ability to be more precise in establishing the diagnosis of MS. Among the most important of the new diagnostic tools are electrophysiological techniques for examination of the visual and oculomotor systems. Tests such as the visually evoked potential (VEP) can confirm the existence of clinically suspected lesions and document the presence of asymptomatic ones. Various electrophysiological techniques for detection and evaluation of MS, as well as CSF analysis, psychological and neuroradiological procedures, and immunological observations are described. The relationship between optic neuritis and MS is reviewed, as are therapeutic regimens in use and under study.

Evaluation of various brain structures in multiple sclerosis with multimodality evoked potentials, blink reflex and nystagmography

Pattern reversal visual evoked potentials (VEP), blink reflexes, auditory brainstem evoked potentials (ABEP), spinal and scalp recorded somatosensory evoked potentials (SSEP), and nystagmographic records were investigated in 55 patients with multiple sclerosis (MS), who were separated in different categories of probability according to the clinical history, symptoms, and signs. The combined use of different electrophysiological methods forms a sensitive battery for investigating clinically uncertain cases of MS. It was stressed that care should be taken in the interpretation of the electrophysiological findings, since a single lesion in the central nervous system, particularly in the brainstem, may affect different functional systems simultaneously and therefore mimic a disseminated disease.

Effects of induced hyperthermia on visual evoked potentials and saccade parameters in normal subjects and multiple sclerosis patients

A convenient method for raising body temperature has been developed and used to evaluate temperature effects on visual evoked potentials and saccade reaction time and velocity in five normal subjects and five patients with multiple sclerosis.

Electroretinogram (ERG) and visual evoked response (VER) studies in patients with optic disc drusen

Non-corneal ERGs, recorded from infraorbital skin electrodes to flash stimulation and mid-occipital and parasagittal VERs to both flash stimulation and pattern reversal were performed in 26 patients with optic disc drusen. ERGs were normal in all patients. The mean VER amplitude was lower in the eyes with optic disc drusen than the mean amplitude of VERs in the normals but the interindividual variation was also so great in normals that the difference was not significant. The waveform of the major positive peak was quite often broad or split. VER latencies were usually in normal range although the visual field defects could be rather severe. Some other cause was present when the major positive peak was delayed.

Somatosensory central latencies and disc discrimination in multiple sclerosis

1. Somatosensory evoked potentials are abnormal in a large percentage of patients with severe multiple sclerosis if amplitude, latency and right-left asymmetry are all considered. Mild disease has remained difficult to identify. This screening test employing two stimulus sites in the same arm did not improve the yield. 2. Stimulation of the median nerve at the elbow is not often likely to justify the associated discomfort, except in patients with known disease in the forearm. 3. Measuring the central conduction velocities from easily recorded low cervical potentials up to the parietal scalp deflections eliminates the need to consider the length and health of the peripheral nerve stimulated. 4. Central conduction velocities were not significantly related to age or total body height in this population. Extremely old or tall subjects may still deserve special consideration if the cervical responses are truly nerve propagated waves. 5. One restricted measure of stereogno-sis--disc size discrimination, correlated well with conduction times from the low cervical region to short-latency deflections in the post-central parietal area, but patients with delayed onset of deflections still maintained normal interpeak latencies. 6. more precise correlations between components of stereognosis, and the integrity of mediating neurons, will be possible when the electrical generators of the SER are better delineated.

Central and peripheral conduction times in multiple sclerosis

Somatosensory evoked potentials (SEPs) were recorded simultaneously from the cervical spine and scalp in 25 normal subjects and 105 patients with established or suspected multiple sclerosis (MS) using median nerve stimulation. The normal latency of the main peak of the cervical SEP (N14) following median nerve stimulation at the wrist was 13.7 +/- 0.8 msec. The peak latency of the first cortical event of the scalp SEP (N20) was 19.1 +/- 0.9 msec. The difference in these latencies (N20 -- N14) reflects a conduction time between the dorsal column nuclei and cortex. It measured 5.45 +/- 0.7 msec. The conduction times between the wrist and Erb's point and Erb's point and N14 measured 8.6 +/- 0.7 msec and 5.1 +/- 0.6 msec respectively. There was a 68.6% overall incidence of abnormalities of N14, N20 or (N20 -- N14) in the patients. This incidence was over 80% in definite and early probable or latent MS, 68.2% in progressive spinal MS and 40.0% in suspects. SEPs were also simultaneously recorded from the lower thoracic spine (T12) and scalp in a different group of 25 normal subjects using tibial nerve stimulation. The latency of the thoracic SEP (N21) was 21.4 +/- 1.5 msec and that of the first cortical event of the scalp SEP (P40) was 38.6 +/- 2.2 msec. The difference in these latencies (P40 -- N21) which reflects conduction between T12 and the cortex measured 17.2 +/- 1.7 msec. Conduction between the ankle and popliteal fossa was 7.0 +/- 0.65 msec and between the popliteal fossa and N21, it was 14.5 +/- 1.1 msec. All of a small group of MS suspects showed abnormality of P40 or (P40 -- N21).

The early diagnosis of multiple sclerosis

An outline of modern views on the aetiology of multiple sclerosis is followed by a discussion of diagnosis. Examination of the cerebrospinal fluid, visual evoked potentials, and other electrophysiological tests are considered. The special problems of optic neuritis, spastic paraparesis, and psychological disorder receive more detailed attention. It is concluded that while the supplementary tests are valuable the diagnosis remains essentially clinical.

Crossed acoustic response combined with visual and somatosensory evoked responses in the diagnosis of multiple sclerosis

The crossed acoustic response, (CAR), a recently introduced test of brainstem function, has been studied in 66 patients with multiple sclerosis and 53 control subjects, and compared with conventional visual and somatosensory evoked responses (VER, SER). A latency abnormality was found in the CAR in 73% of patients, in the VER in 63%, and in the SER in 37%. Abnormalities have been related to the presence or absence of clinically detectable signs. All three responses detected subclinical lesions by showing abnormality in a proportion of multiple sclerosis patients who had no corresponding abnormal clinical signs (CAR 69%, VER 42%, SER 29%). The best diagnostic combination of responses was VER and CAR. Ninety per cent of patients had at least one of these two responses abnormal.

Visual and somatosensory evoked cortical potentials in multiple sclerosis

The diagnostic value of the pattern reversal evoked cortical potential (VEP) and the somatosensory evoked cortical potential (SEP) has been compared in 50 patients with established or suspected multiple sclerosis. A prolonged latency of VEP was found in 96% of definite cases of multiple sclerosis, 58% of probable cases, and 20% of possible cases. A prolonged latency of SEP by stimulation of median or peroneal nerves or both was found in 86% of definite cases of multiple sclerosis, 83% of probable cases, and 50% of possibe cases. When combining the results of all three tests the diagnostic yield increased to 100%, 92%, and 50%, respectively.

Computerized tomography of brain and optic nerve in multiple sclerosis. Observations in 100 patients, including serial studies in 16

Computerized tomography (CT) of the brain was carried out in 100 patients with established or suspected multiple sclerosis (MS). The optic nerves were also examined in 53 of these patients. Areas compatible with demyelinating lesions were found in the cerebral hemisphere white matter and less frequently in the brain stem in 47% of cases. The hemisphere lesions were commonly multiple, typically situated in the deep white matter and periventricular regions, and were often asymptomatic. Small areas with unduly low attenuation coefficients were found in one or both optic nerves in 52% of patients in whom the optic nerves were examined. While these areas may represent demyelinating lesions their significance remains uncertain in view of poor correlation with clinical and electrophysiological parameters of optic nerve damage. Cerebral cortical atrophy and/or ventricular dilatation was found in 44% of cases, the frequency and severity of atrophy increasing with age and duration of disease. Serial studies after intervals of up to 21 months were performed in 16 patients, providing the opportunity to study the natural history of the cerebral lesions. While in some cases no significant change occurred, in others white matter lesions underwent an increase or a reduction in size, and in some cases new lesions appeared. In some patients minor degrees of atrophy became apparent over the period of the study. The value of CT in the investigation of patients with suspected MS and as a means of studying the natural history of the disease is discussed.

Pattern-reversal visual evoked potential. Method of analysis and results in multiple sclerosis

A detailed method of analysis of the pattern-reversal visual evoked potential is presented. This method takes into account a number of parameters in addition to the latency of the major surface-positive component (P2) and has been tested in a group of 50 normal subjects and in 98 patients with established or suspected multiple sclerosis (MS). It was found that this more detailed form of analysis improved the detection rate of abnormal responses in the MS subjects particularly in those classified in the suspected category. The potential value of this form of analysis, particularly in clinical neurophysiology laboratories where the recording of visual evoked potentials is the only technique employed in the investigation of patients with suspected MS, is discussed.