Brainstem involvement in multiple sclerosis: a clinical and electrophysiological study

Clinical and electronystagmographical evaluation of vestibular symptoms in relapsing remitting multiple sclerosis

OBJECTIVE

Multiple sclerosis (MS) may give rise to a variety of clinical signs and symptoms including vertigo and/or other problems related with equilibrium. In this study, we aimed to evaluate clinical and electronystagmographical (ENG) characteristics of relapsing remitting MS (RRMS) patients.

DESIGN

This is a prospective controlled study consisting of 30 patients who were diagnosed as definite RRMS according to McDonald's diagnostic criteria and 30 healthy individuals.

SETTING

Entire population of patients were examined and followed up at the same tertiary centre during the period of September 2003 and March 2005. Clinical examination and detailed electronystagmographic investigations were performed in each group.

METHODS

Vestibular laboratory testing was carried out by a computerized ENG system. All ENG subtests including tracking, saccade, optokinetic, gaze, positional and Dix-Hallpike tests were performed in each group but caloric, which is relatively an invasive test, was performed only in the patient group.

MAIN OUTCOME MEASURES

We aimed to find the ratio of abnormal tests indicating, central and/or peripheral pathology in ENG. We also analyzed the correlation of total number of abnormal tests in ENG with clinical parameters.

RESULTS

Differences of ENG abnormality indicating central and/or peripheral pathology and ENG abnormality indicating only central pathology between the two groups were statistically significant. Correlation of total number of abnormal tests in ENG with EDSS score was statistically significant.

CONCLUSION

ENG is sensitive in detecting the vestibular system involvement in RRMS patients if all subtests are performed and evaluated in detail with clinical symptoms and signs.

The roles of blink reflex and sympathetic skin response in multiple sclerosis diagnosis

The neurological history and examination are important in multiple sclerosis (MS) diagnosis, but early and accurate diagnosis of MS often requires judicious use of paraclinical information. Electrophysiologic techniques have an important role in demonstrating lesions that are clincally silent but magnetic resonance imaging (MRI) is accepted as the most sensitive paraclincal test for detecting asymptomatic dissemination in space for MS patients. In order to test the sensitivity of electrophysiologic techniques in diagnosing asymptomatic MS lesions, we performed blink reflex (BR) and sympathetic skin response (SSR) studies on 13 female (mean age 39 -/+ 9 years) and 8 male (mean age 35 -/+ 14 years) patients with a diagnosis of definite MS who do not have any clinical symptoms nor signs referable to brainstem or autonomic system dysfunction. Forty three percent of patients on SSR testing and 40% of patients on BR testing demonstrated abnormal results. In countries with unfavorable economic conditions, diagnosis, especially the follow-up evaluation of MS patients, poses a major dilemma. The role of diagnostic techniques in MS diagnosis when MRI is available is an economic problem. Diagnostic evaluation adds to the cost of health expenses. We usually choose to perform MRI only at the initial diagnosis of MS and perform follow-up evaluations during remissions and exacerbations with the aid of electrophysiologic techniques. We stress the importance of electrophysiologic screenings in MS patients because they provide data that cannot be obtained through clinical evaluations only with a little cost.

Multiple sclerosis: a cause of sudden hearing loss

Sudden hearing loss is a clinical entity which has numerous aetiologies. In cases where the aetiology is not determined, evaluation and treatment of sudden hearing loss are very difficult. A case of probable multiple sclerosis with sudden hearing loss as the initial symptom is reported. The pure-tone audiometry showed a quasi-total sensorineural hearing loss in the left ear; the left side displayed only wave I in the auditory brainstem response (ABR). Electronystagmographic examination revealed hypometric dysmetria and saccadic pursuit abnormalities. Magnetic resonance imaging (MRI) showed high-intensity lesions with multiple foci. After steroid therapy, the patient's hearing loss, vertigo and visual problems improved, but the ABR findings remained unchanged. We have decided to present this case because of the interesting ABR finding revealing the presence of wave I and the absence of all other waves after the normalization of the hearing.

Saccade metrics in multiple sclerosis: versional velocity disconjugacy as the best clue?

We studied the parameters (latency, amplitude, peak velocity) of horizontal saccades in 32 patients with multiple sclerosis (MS) and 20 healthy, age matched control subjects. Saccades were recorded by direct-current electro-oculography technique (EOG). The patients were divided in 2 groups according to the absence or the presence of clinical internuclear ophthalmoplegia (INO). In both groups, we found increased latency, hypometria and reduced velocity. The disconjugacy of saccades was measured by calculating the ratio of abduction and adduction peak velocities (the versional disconjugacy index: VDI). Though the absolute value of this index might be dependent on the recording technique, its variation is not. Interestingly, the VDI was significantly increased in the groups of MS patients without clinical INO, indicating a more severe slowing in adduction. We concluded that VDI may be a very useful index in detecting subtle disorders in saccades conjugacy.

Evoked potentials and CSF-immunoglobulins in MS: relationship to disease duration, disability, and functional status

In 100 MS patients, BAEP and tibial SEP abnormality rates increased significantly with disease duration and clinical disability. VEP correlated non-linearly with disease duration, and median nerve SEP correlated with disability. In multifactorial analysis, however, BAEP correlated significantly only with clinical brainstem and cerebellar signs. These results suggest that evoked potentials correlate more strongly with neurological status of the functional subsystems than either overall disability or disease duration. These findings indirectly suggest that evoked potentials may be useful monitors during large therapeutical trials in MS patients.

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.

Electronystagmography in the diagnosis of multiple sclerosis

The aim of our study was to define the diagnostic importance of a complete electronystagmographic (ENG) examination (visual-vestibular, vestibular and visual suppression tests on caloric nystagmus) in patients affected by MS. Of 144 patients examined, 116 were definite and 28 possible. Descriptive data of the instrumental findings showed very frequent alterations of one or more subtests: pursuit movements and visual suppression test were especially pathological, in respectively 56% and 58% of the cases; spontaneous and/or evoked nystagmus was present in 45%. A comparison between clinical and instrumental evidence of brainstem/cerebellar involvement indicated that 18% of the definite and 32% of the possible MS cases presented a negative clinical examination with positive instrumental findings. The usefulness of including a comprehensive ENG examination to obtain paraclinical evidence of a second lesion in the CNS in early MS is discussed.

Brainstem impairment in multiple sclerosis: an assessment by multimodal evoked potentials

The usefulness of multimodal evoked potentials for the diagnosis of Multiple Sclerosis (MS) is established. Our purpose was to try to set of 3 EPs (BAEP, median SEP and trigeminal SEP) in the evaluation of brainstem dysfunction. 53 definite and probable MS patients have been examined; they were allotted to 3 groups according to the duration of the disease. Our results showed that median SEP is the most sensitive investigation, while BAEP and trigeminal SEP were abnormal in a smaller number of cases. The combined use of median and trigeminal SEPs supplied sufficient information on brainstem function, without using the complete set of EPs. No significant relation between EP abnormalities and duration of the disease was found.

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.