Maurizio Versino

Vestibular evoked myogenic potentials in multiple sclerosis patients

OBJECTIVES Vestibular evoked myogenic potentials (VEMPs) are saccular responses to loud acoustic stimuli and are recordable from the sterno-cleido-mastoid muscle ipsilaterally to the stimulated ear. This study aimed to investigate VEMPs in patients suffering from multiple sclerosis (MS), and to compare these findings with both clinical and instrumental data. METHODS We recorded VEMPs from 70 MS patients, whose clinical data were retrospectively evaluated for the possible occurrence of: past and current (with respect to VEMP recording) brainstem and/or cerebellar symptoms; current brainstem and/or cerebellar signs. Sixty-five patients underwent brainstem auditory evoked potentials (BAEPs) recording; 63 of the same patients underwent saccadic eye movement recording and subjective visual vertical (SVV) evaluation. RESULTS VEMPs were abnormal in 31%, BAEPs in 38% and SVV in 21% of the patients. Saccadic eye movements showed a possible brainstem dysfunction in 44.4% of the patients. There was no correlation between the occurrence of abnormalities and the technical means of detection. The same held true for correlations with clinical data, with the exception of the BAEPs; these proved to be more frequently abnormal in patients presenting at neurological examination with brainstem and/or cerebellar signs that were possibly related to the complaint of dizziness. CONCLUSIONS VEMPs should be considered a useful complementary neurophysiological tool for the evaluation of brainstem dysfunction.

ICHD‐II diagnostic criteria for Tolosa–Hunt syndrome in idiopathic inflammatory syndromes of the orbit and/or the cavernous sinus

A bibliographical search was conducted for papers published between 1999 and 2007 to verify the validity of International Classification of Headache Disorders (ICHD)-II criteria for the Tolosa-Hunt syndrome (THS) in terms of (i) the role of magnetic resonance imaging (MRI); (ii) which steroid treatment should be considered as adequate; and (iii) the response to treatment. Of 536 articles, 48, reporting on 62 patients, met the inclusion criteria. MRI was positive in 92.1% of the cases and it normalized after clinical resolution. There was no evidence of which steroid schedule should be considered as adequate; high-dose steroids are likely to be more effective both to induce resolution and to avoid recurrences. Pain subsided within the time limit required by the ICHD-II criteria, but signs did not. We conclude that THS diagnostic criteria can be improved on the basis of currently available data. MRI should play a pivotal role both to diagnose and to follow-up THS.

Guillain-Barré syndrome

Guillain-Barré syndrome (GBS) is an autoimmune acute peripheral neuropathy. Frequently a flu-like episode or a gastroenteritis precede GBS, and the cross-reactivity between microbial and neural antigens partly explains the pathophysiology of the disease and the possible detection of antiganglioside antibodies. The weakness reaches its nadir in 2–4 weeks: the patients may be chair- or bed-bound, may need artificial ventilation and frequently experience dysautonomic dysfunction; 5–15% of the patients die and more patients are left with a disabling motor deficit and/or fatigue. Electrophysiology and cerebrospinal fluid evaluation support the diagnosis. The treatment of GBS is multidisciplinary, and both plasma exchange and high dose immunoglobulin (IVIg) are effective in reducing both the severity of the disease and the residual deficits. Finally, steroids are not effective in GBS.

Saccade latency toward auditory targets depends on the relative position of the sound source with respect to the eyes

The latency of saccadic eye movements evoked by the presentation of auditory and visual targets was studied while starting eye position was either 0 or 20 deg right, or 20 deg left. The results show that for any starting position the latency of visually elicited saccades increases with target eccentricity with respect to the eyes. For auditory elicited saccades and for any starting position the latency decreases with target eccentricity with respect to the eyes. Therefore auditory latency depends on a retinotopic motor error, as in the case of visual target presentation.

[Vestibular migraine: diagnostic criteria: consensus document of the Bárány Society and the International Headache Society].

This paper presents diagnostic criteria for vestibular migraine, jointly formulated by the Committee for Classification of Vestibular Disorders of the Bárány Society and the Migraine Classification Subcommittee of the International Headache Society (IHS). The classification includes vestibular migraine and probable vestibular migraine. Vestibular migraine will appear in an appendix of the third edition of the International Classification of Headache Disorders (ICHD) as a first step for new entities, in accordance with the usual IHS procedures. Probable vestibular migraine may be included in a later version of the ICHD, when further evidence has been accumulated. The diagnosis of vestibular migraine is based on recurrent vestibular symptoms, a history of migraine, a temporal association between vestibular symptoms and migraine symptoms and exclusion of other causes of vestibular symptoms. Symptoms that qualify for a diagnosis of vestibular migraine include various types of vertigo as well as head motion-induced dizziness with nausea. Symptoms must be of moderate or severe intensity. Duration of acute episodes is limited to a window of between 5 minutes and 72 hours.

Myasthenia gravis in a patient with chronic active hepatitis C during interferon-alpha treatment.

Batocchi et all recently reported the occurrence of autoimmune myasthenia gravis during interferon-a (INF-a) treatment in two patients with malignancies. We report a patient who developed myasthenia gravis after INF-a treatment for chronic hepatitis C. A previously healthy 54 year old man developed malaise and dyspepsia three years ago. Increased serum concentrations of alanine aminotransferase and aspartate aminotransferase led to a serological diagnosis of hepatitis C infection. Liver biopsy showed a histological picture of chronic active hepatitis. Two years later, in March 1993, the patient received INF-a-nl (Wellferon, Wellcome, UK) subcutaneously at a dose of

EYE-HEAD COORDINATION TOWARD AUDITORY AND VISUAL TARGETS IN HUMANS

Eye-head coordination during gaze orientation toward auditory targets in total darkness has been examined in human subjects. The findings have been compared, for the same subjects, with those obtained by using visual targets. The use of auditory targets when investigating eye-head coordination has some advantages with respect to the more common use of visual targets: (i) more eccentric target positions can be presented to the subject; (ii) visual feedback is excluded during the execution of gaze displacement; (iii) complex patterns of saccadic responses can be elicited. This last aspect is particularly interesting for examining the coupling between the eyes and the head displacements. The experimental findings indicate that during gaze orientation toward a visual or an auditory target the central nervous system adopts the same strategy of using both the saccadic mechanism and the head motor plant. In spite of a common strategy, qualitative and quantitative parameters of the resulting eye-head coordination are slightly different, depending on the nature of the target. The findings relating to patterns of eye-head coordination seem to indicate a dissociation between the eyes and the head, which receive different motor commands independently generated from the gaze error signal. The experimental findings reported in this paper have been summarized in a model of the gaze control system that makes use of a gaze feedback hypothesis through the central reconstruction of the eye and head positions.

Ocular neuromyotonia with both tonic and paroxysmal components due to vascular compression

Sirs: Ocular neuromyotonia (ONM) is characterized by brief spells of diplopia occurring spontaneously or after eccentric gaze holding due to tonic involuntary ocular muscle contraction [9]. ONM is a rare disorder, described in only 41 patients according to a recent review paper [10]. In most cases ocular neuromyotonia follows months or years after radiotherapy to the sellar or parasellar region [1, 2, 5, 8, 11, 13, 15], but it may be idiopathic [5, 6, 12, 13] or it may be secondary to differing pathological conditions [3–5, 7, 13, 15] including vascular compression [14]. We describe a patient in whom the neuromyotonic phenomenon was associated with a subclinical tonic component between the spells of diplopia, and was attributable to a vascular compression. It subsided with carbamazepine, but not with gabapentin administration. The patient was a 45-year-old healthy woman who suddenly had the onset of brief spells of vertical diplopia in all positions of gaze. The spells lasted about 30 seconds and consisted of left eye depression with pure vertical diplopia and without a clinically evident torsional component, pupil size modification or lid or horizontal eye movement involvement. The spells could be triggered by asking the patient to look down for about 20 seconds or by a prolonged hyperventilation. Between the spells she only showed a slight right hyperphoria. Cranial MRI disclosed a vascular compression between the left III cranial nerve and the P1 tract of the posterior cerebral artery (Fig. 1). Vertical saccades were recorded monocularly by means of the scleral magnetic search coil technique before (both between and during the spells) and after carbamazepine (CBZ) treatment. The patient had to make 10 and 20 degrees up and down saccades starting from and getting back to the primary position. The analyses focused on the phoria (right eye minus left eye position) and on the velocity-velocity ratio (vvr: the ratio of right to left eye peak velocity). The patient data were compared with those obtained from three normal subjects and from a 51 year-old patient presenting with a left superior rectus paresis. Between the spells, eye movement recording confirmed the vertical heterophoria slightly greater during upgaze (Fig. 2). This finding suggested a possible left superior rectus paresis, but this was incompatible with other data. The vvr was significantly greater than one (the peak velocity was greater in the right than in the left eye) for downward (both centrifugal and centripetal) rather than for upward saccade. These two findings were at variance both with those detectable in normal subjects and with those shown by the patient with the left superior rectus paresis (Fig. 2). The spells modified both left eye position and peak velocity, and increased both the phoria and and the vvr mainly below primary position within the lower ocular motor hemifield (Fig. 2). The patient was initially treated with gabapentin 400 mg t. i. d. unsuccessfully, and the spells subsided only after a few days of carbamazepine therapy (200 mg b. i. d.). Fourteen days later eye movement recording still showed a vertical misalignment, but consisted in a small left hyperphoria and the vvr pattern was similar to pre-treatment between spell recording. We hypothesize that vascular compression was likely to be the cause of ONM. Accordingly, all the ocular motor signs and symptoms were attributable to ephaptic transmission and axonal hyperexcitability that in our patient showed both a tonic and a paroxysmal component. The tonic component, already reported in ONM [14, 15], consisted of a small and slightly incomitant vertical misalignment explainable by a left inferior rectus spasm on the basis of the larger vvr LETTER TO THE EDITORS

Vestibuläre Migräne: diagnostische Kriterien

This paper presents diagnostic criteria for vestibular migraine, jointly formulated by the Committee for Classification of Vestibular Disorders of the Bárány Society and the Migraine Classification Subcommittee of the International Headache Society (IHS). The classification includes vestibular migraine and probable vestibular migraine. Vestibular migraine will appear in an appendix of the third edition of the International Classification of Headache Disorders (ICHD) as a first step for new entities, in accordance with the usual IHS procedures. Probable vestibular migraine may be included in a later version of the ICHD, when further evidence has been accumulated. The diagnosis of vestibular migraine is based on recurrent vestibular symptoms, a history of migraine, a temporal association between vestibular symptoms and migraine symptoms and exclusion of other causes of vestibular symptoms. Symptoms that qualify for a diagnosis of vestibular migraine include various types of vertigo as well as head motion-induced dizziness with nausea. Symptoms must be of moderate or severe intensity. Duration of acute episodes is limited to a window of between 5 minutes and 72 hours.

A New Tool for Investigating the Functional Testing of the VOR

Peripheral vestibular function may be tested quantitatively, by measuring the gain of the angular vestibulo-ocular reflex (aVOR), or functionally, by assessing how well the aVOR performs with respect to its goal of stabilizing gaze in space and thus allow to acquire visual information during the head movement. In recent years, several groups have developed clinical and quantitative approaches to functional testing of the vestibular system based on the ability to identify an optotype briefly displayed on screen during head rotations. Although the proposed techniques differ in terms of the parameters controlling the testing paradigm, no study has thus far dealt with understanding the role of such choices in determining the effectiveness and reliability of the testing approach. Moreover, recent work has shown that peripheral vestibular patients may produce corrective saccades during the head movement (covert saccades), yet the role of these eye movements toward reading ability during head rotations is not yet understood. Finally, no study has thus far dealt with measuring the true performance of their experimental setups, which is nonetheless likely to be crucial information for understanding the effectiveness of functional testing approaches. Thus we propose a new software and hardware research tool allowing the combined measurement of eye and head movements, together with the timing of the optotype on screen, during functional testing of the vestibulo-ocular reflex (VOR) based on the Head Impulse Test. The goal of such tool is therefore that of allowing functional testing of the VOR while collecting the experimental data necessary to understand, for instance, (a) the effectiveness of the covert saccades strategy toward image stabilization, (b) which experimental parameters are crucial for optimizing the diagnostic power of the functional testing approach, and (c) which conditions lead to a successful reading or an error trial.