Lesion Detection in MS Patients with and without Clinical Brainstem Disorders: Magnetic Resonance Imaging and Brainstem Auditory Evoked Potentials Compared

Abstract

The findings of the present study can be summed up in the following points: (1) brainstem auditory evoked potentials (BAEP), as compared with magnetic resonance imaging (MRI), has a greater capacity and a lower cost in disclosing brainstem plaques both in MS patients with symptoms or signs of actual brainstem involvement and in clinically silent ones. This makes BAEP a useful technique for the neurologist, who can confirm the clinical suspicion of a brainstem lesion and follow the evolution of the disease in the patient. (2) The sensitivity of BAEP is lower than that of MRI as far as the anterior lesions of the brainstem are concerned. (3) MRI is more specific than BAEP, inasmuch as several types of injuries can alter the BAEP, while the demyelinating plaque has a specific image and can only be confused with little lacunar infarcts. (4) Plaques that produced symptoms or signs in the past can eventually disappear and be no longer detected by a subsequent MRI.

Brain Stem Magnetic Resonance Imaging and Evoked Potential Studies of Symptomatic Multiple Sclerosis Patients

“…The preva lence of BAEP and mSEP abnormalities found in this study is similar to the results in previous reports [3,4,[6][7][8], The lesser sensitivity of EPs than of MRI can be explained by the relatively high anatomic specificity of these tests which analyze BS acoustic pathways and the medial lemniscus. The use of a more extensive battery of neurophysiological techniques, such as electronystagmographic examination, blink reflex, or trigeminal SEP. could probably produce greater sensitivity of neurophysi ological evaluation, as reported by other groups [24][25][26], Our patients had a variety of clinical signs suggestive of focal involvement of BS structures, but in most cases the clinical features cannot be definitely referred to welllocalized lesions.…”

“…The lower values of BS MRI abnormalities reported in previous papers [6][7][8]10] can be essentially explained by technical difficulties. Several factors may have contrib uted to our positive results: the thickness of the slice, the strength of the field, the combined examination of sagittal and axial planes, and the use of the GMR technique.…”

“…Comparing abnormal BS MRI and abnormal BAEPs, no correlations have been found in most studies [2-4. 30], Only Capra et al [8] reported a significant cor relation between MRI and BAEPs. Although MRI was much more sensitive, in our study the correlations were statistically significant for both BAEP and mSEP results.…”

“…Clinical signs of brain stem (BS) dysfunction are de tectable in the majority of clinically definite multiple scle rosis (MS) patients, and they are the onset manifestation Some studies demonstrated that BS auditory EPs (BAEPs) were more sensitive than MRI in detecting BS lesions [7,8]. Combined use of BAEPs and median soma tosensory EPs (mSEPs) further increased the sensitivity of EPs [6].…”

Three-dimensional mapping of brainstem functional lesions

“…Conversely, areas of actual dysfunction may escape MRI detection. The functional correlation of MRI findings is notably poor in inflammatory diseases of the brainstem (ORMEROD et al, 1984;CAPRA et al, 1989;TURANO et al, 1991). Neurophysiological investigations (evoked potentials and trigeminal reflexes) add important topodiagnostic information not obtainable by clinical examination alone (CAPLAN et al, 1993;ONGERBOER DE VISSER and CRUCCU, 1993;HOPF, 1994;KIMURA et al, 1994).…”