Exploration of sleep quality and rest-activity rhythms characteristics in Bilateral Vestibulopathy patients.

Sleep and circadian timing systems are constantly regulated by both photic and non-photic signals. Connections between the vestibular nuclei and the biological clock raise the question of the effect of peripheral vestibular loss on daily rhythms, such as the sleep-wake cycle and circadian rhythm. To answer this question, we compared the sleep and rest-activity rhythm parameters of 15 patients with bilateral vestibulopathy (BVP) to those of 15 healthy controls. Sleep and rest-activity cycle were recorded by a device coupling actimetry with the heart rate and actigraphy at home over 7 days. Subjective sleep quality was assessed by the Pittsburgh Sleep Quality Index (PSQI). Sleep efficiency and subjective sleep quality were significantly reduced, and sleep fragmentation was increased in BVP patients compared to controls. BVP patients displayed a damped amplitude of the rest-activity rhythm and higher sleep fragmentation, reflected by a higher nocturnal activity compared to controls. These results suggest that both rest-activity and sleep cycles are impaired in BVP patients compared to healthy controls. BVP patients seem to have greater difficulty maintaining good sleep at night compared to controls. BVP pathology appears to affect the sleep-wake cycle and disturb the circadian rhythm synchronization. Nevertheless, these results need further investigation to be confirmed, particularly with larger sample sizes.

Vestibulo-sympathetic reflex in patients with bilateral vestibular loss.

This study assessed cardiovascular control during head-down neck flexion (HDNF) in a group of patients suffering from total bilateral idiopathic vestibular loss (BVL) for 7 ± 2 yr. Nine adult patients (age 54 ± 6 yr) with BVL were recruited. Calf blood flow (CBF), mean arterial pressure (MAP), and heart rate (HR) were measured with subjects' eyes closed in two lying body positions: ventral prone (VP) and lateral (LP) on the left side. Vascular resistance (CVR) was calculated as MAP/CBF. The HDNF protocol consisted in passively changing the head position: head up (HU)-head down (HD)-HU. Measurements were taken twice at each head position. In VP CBF significantly decreased in HD (3.65 ± 0.65 mL·min-1·100 mL-1) vs. HU (4.64 ± 0.71 mL·min-1·100 mL-1) (P < 0.002), whereas CVR in VP significantly rose in HD (31.87 ± 6.93 arbitrary units) vs. HU (25.61 ± 6.36 arbitrary units) (P < 0.01). In LP no change in CBF or CVR was found between the two head positions. MAP and HR presented no difference between HU and HD in both body positions. Age of patients did not significantly affect the results. The decrease in CBF of the BVL patients was similar to the decrease observed with the same HDNF protocol in normal subjects. This suggests a sensory compensation for the lost vestibular inputs that could originate from the integration of inputs from trunk graviceptors and proprioceptive and cutaneous receptors. Another possibility is that the HDNF vascular effect is evoked mostly by nonlabyrinthine sensors.NEW & NOTEWORTHY The so-called vestibulo-sympathetic reflex, as demonstrated by the head-down neck flexion (HDNF) protocol, is present in patients with total bilateral vestibular idiopathic loss, equally in young and old subjects. The origin of the sympathetic effect of HDNF is questioned. Moreover, the physiological significance of the vestibulo-sympathetic reflex remains obscure, because it acts in opposition to the orthostatic baroreflex. It may serve to inhibit the excessively powerful baroreflex.

[Late and sudden recovery of sudden deafness or vestibular neuronitis].

INTRODUCTION: Vestibular neuronitis (VN) and sudden deafness (SD) are well-defined entities. The abrupt appearance of symptoms in both disorders represents an important element for the diagnosis. In cases of VN, symptoms regress gradually over time as the peripheral function recovers, or the central nervous system compensates for the balance deficit. In cases of SD, the recovery occurs in about half the cases and is generally progressive. The chances to recover normal levels of hearing are better if the recovery occurs early after the onset of the deficit. The goal of the paper is to present new insights of these disorders based on four unusual cases and on an evaluation of the delay for the function's recovery. MATERIAL AND METHODS: 1) We report two cases of VN and two of SD whose the recovery was late and sudden; 2) The recovery time after a SD was retrospectively analysed using the chart of 36 patients seen

[Exploration of the otolith function]. / L'exploration de la fonction otolithique.

The analysis of our vertiginous patients reveals that the likely existence of a pattern of symptoms related to a disturbance of the otolith organ responsible for detection of linear accelerations. Very often otolith pathology affects only certain directions of movement or tilting in relation to gravity. The various tests of the otolith function do not seem to identify all of these otolith deficits. It is possible that each individual test explores only partially the 4 otolith organs. Our otolith tests are still either too general, or, only focused on a part of a multi-directional function (and wrongly emphasizing a partial pathology). Thus, the history remains the finest diagnostic tool. The exploration of the otolith function has improved. These tests are not redundant. The subjective visual vertical tests the otolith function up to the vestibular cortex whilst the off-vertical axis rotation (OVAR) test explores the ocular otolith reflex. The myogenic otolith evoked potentials are saccule-collic. The cerebral cartography shows the various zones of cortical saccular activity and the tilt suppression test explores a reflex involving the cerebellar nodulus. However all of these tests are still nonspecific. There 'non-specificity' is similar to the non-specific nature of a free field hearing or the rotatory vestibular tests. The analysis of patient symptoms, using diagrams summarizing the principal clinical findings, or using a 3D software, facilitates the identification of the involved side, the affected organ (utricle or saccule) and to some extent the possible site of the lesion (just as a visual field would assist in identification of the retinal area affected prior to fundoscopy). Some otolith tests can be very sensitive albeit non-specific like the subjective visual vertical test. Others are more specific in identification of the organ and side affected like the otolith sacculo-collic evoked potentials. The choice of vestibular function tests is best based on the patient's particular symptoms. Thus a patient complaining of falling outwards is to be tested by offset rotations. A patient complaining of falling while going down in a lift is best investigated by the cortical vestibular otolith evoked potentials.

Nonlinear analysis of orthostatic posture in patients with vertigo or balance disorders.

The stabilometry signals involve irregular and unpredictable components. In order to identify the hidden dynamics that underlie the multi-link networks consisted of the multiple sensory systems, motor components and central integration, we applied a nonlinear analysis to these signals. We evaluated the postural control differences between eyes open and closed by means of the dynamical closeness between two states, known as similarity index, for the patients with vestibular disorders. We were able to demonstrate that some patients (eight of 21) showed a difference between the conventional and nonlinear measures. Especially, the similarity index tended to reflect the clinical course of the vestibular compensation and the findings in the patients with benign paroxysmal positional vertigo (BPPV) demonstrated that its vestibular function may include various pathologies besides canalithiasis. These results suggest that nonlinear analysis can elucidate the complex postural control networks and this procedure may also be able to provide the new findings of the stabilometry examinations.

[Rotatory impulse test does not replace caloric tests]. / L'épreuve rotatoire impulsionnelle ne remplace pas les tests caloriques.

We sought to determine whether the rotatory impulsional test was capable of exploring the canalar function with sufficient precision to replace the caloric test, as it has been recently affirmed. We first compared the observed preponderance from this test with that measured during a sinusoidal (20 and 4 s) test. We observed that, in the case of a significant preponderance for a given test, there was complete redondance with the preponderance observed with any other test. The rotatory impulsional test does not present any specific advantage compared to other kinetic test as far as the observation of the preponderance phenomenon. We then compared the preponderance with the results of the caloric tests and came to the following conclusions i) the absence of preponderance does not allow us to predict the absence of vestibular deficit, due to the fact that 37% of the deficits were compensated for including acoustic neuroma; ii) the presence of a preponderance does not allow a priori to say whether it is of vestibular, cervical, or central origin and systematic caloric tests shows that almost one fourth of preponderance observed is not associated with unilateral weakness iii) supposing that a clinical argument allow us to conclude as to the probable vestibular origin of a vestibular preponderance, the direction of this preponderance does not allow us to determine which side is involved. In fact, if the undercompensated deficits are 3 times more frequent than overcompensated deficits, the proportion of preponderance not linked to a significant deficit indicates that the probability of encountering a preponderance related to a specific undercompensated deficit is approximately 50%. We thus did not find in the rotatory impulsional test any specific advantage allowing us to predict the laterality of a vestibular lesion.

Unilateral vestibular neuritis with otolithic signs and off-vertical axis rotation.

Off-vertical axis rotation (OVAR) at constant velocity is a dynamic otolith stimulus that induces horizontal and vertical eye movement responses. To determine the value of this examination as a test for unilateral otolithic hypofunction, we compared the OVAR responses of patients suffering from acute vestibular neuritis (VN) without any sign of otolith affection, with those of patients suffering from acute VN with otolithic signs. The horizontal eye movement bias component shows directional preponderance (DP) significantly higher in patients with otolithic signs than in patients not presenting them. However, as bias DP also reflects the imbalance between right and left horizontal canals activity, this greater bias DP could be explained by the more severe canals impairment-evaluated by caloric test-found in patients with otolithic signs. No significant difference can be shown on horizontal modulation. The DP of vertical modulation is significantly higher in patients presenting otolithic signs than in patients not presenting them: in the case of otolithic signs, the responses are smaller during rotations toward the affected side. Therefore, this variable could be used as an indication of unilateral otolithic hypofunction.

Unilateral peripheral semicircular canal lesion and off-vertical axis rotation.

Off vertical axis rotation (OVAR) is a stimulus that can be used to assess the otolith-ocular reflex. However, experimental data suggest that isolated unilateral lesion of the lateral semicircular canal (SCC) nerve could modify responses to OVAR. Thus, to determine what nystagmus variables are not affected by SCC dysfunction and might be used as indices of otolithic disease, responses to OVAR were compared in 39 healthy controls and in 19 patients suffering from acute unilateral vestibular neuritis (VN), without any sign of otolith dysfunction. Horizontal and vertical slow phase velocities (SPV) were measured during earth vertical axis rotation (EVAR), and during OVAR at a tilt angle of 9 degrees and rotation velocity of 60 degrees/s. During OVAR, horizontal SPV consists of a sinusoidal modulation superimposed on a sustained bias opposite to the rotation. Vertical SPV consists of a sinusoidal modulation without bias. In patients, the bias shows directional preponderance (DP) toward the healthy side, strongly correlated to EVAR nystagmus DP. It would therefore simply reflect an imbalance, produced by the unilateral peripheral vestibular lesion, between right and left vestibular nuclei activity. On the other hand, vertical and horizontal modulations are not significantly different in patients and controls. Since the cause and the site of VN are not known, we cannot be sure that patients had pure SCC deafferentation. However, as all of them had SCC paresis it is concluded that OVAR modulations are not affected by a strong dysfunction of the pathways issued from the SCCs.

[Vertigo in children]. / Le vertige chez l'enfant.

Oto-neurologic investigation in the child with vertigo is fundamentally important. In 3% of cases, it reveals the presence of a cerebral tumour. Technical difficulties in examining a child under 5 years of age stem from their fear of the dark, insecurity in a medical setting and a labile attention span. Major causes are migraine (in 28% of cases) and childhood idiopathic paroxysmal vertigo, and recurring vestibular disorders (13% of cases). Classic disorders such as Ménière's disease are rare in the child (3% of cases), as are benign paroxysmal positional vertigo and cupulolithiasis (only 5% of children with vertigo).

Orthostatic postural control in vestibular neuritis: a stabilometric analysis.

Posturographic data for 182 vestibular neuritis patients were recorded on a static posturographic platform (stabilometry) with the patients' eyes both open and closed. Three of the parameters studied are presented here: mean position of the center of pressure, area of the statokinesigram, and Romberg's quotient. Vestibular neuritis modifies the performance of the fine-postural system in unpredictable ways, varying with the subject. It may disturb either the mean position of the center of pressure or the integration of visual input. Sixty of the patients in this study did not use visual input to stabilize their position in relation to their surroundings. The value of stabilometry as a method for observing the integration of visual input in the control of orthostatic posture is discussed.

[Evaluation of cochleovestibular sequelae of craniocervical injuries]. / Evaluation des séquelles cochléo-vestibulaires des traumatismes cranio-cervicaux.

After reviewing the elements of cochleovestibular assessment designed to demonstrate objective disorders, the authors try to evaluate the principal sequelae of cranio-cervical trauma.

Menière's disease in children.

Fourteen children (aged 14 years or younger) with typical Ménière's triad with cochlear sensorineural hearing loss, tinnitus, and intermittent vertigo attacks lasting from minutes to hours were investigated in four different neuro-otologic centers. Nine children, labeled as having "idiopathic Ménière's disease," developed the auditory and vestibular symptoms without any detectable causative factor. Five children, labeled as suffering from "secondary Ménière's syndrome," had histories of an initial hearing loss following mumps, hemophilus influenza meningitis, temporal bone fracture, or congenital or embryopathic complications in the ear that developed into the full Ménière's triad 5 to 11 years later. The 14 children represent 1% of all cases affected with idiopathic or secondary Ménière's disease (or syndrome) that have been detected during the past five years in the four collaborating centers.

[Posturography should be included in the vertigo test]. / La posturographie doit être incluse dans l'examen du vertigineux.

After a brief review of different systems involved in postural control, we describe a method of posturography for exploring vestibulospinal pathways, in which postural oscillations of subject standing on a platform are recorded with eyes open then with eyes closed, and in different head and gaze positions. In normals, only closing of eyes interferes significantly with balance. Posturography is important in vertigo examinations, because it can show: vestibuloocular and vestibulospinal pathway lesions, associated or not; whether there is compensation for imbalance by visual input; cervical origin of vertigo, if any; and, in acute vestibular deficit, that good test results suggest a favorable prognosis.

[Neurinomas with normal brain stem auditory evoked potentials]. / Les neurinomes à BERA normaux.

Of 145 neurinomas operated upon, 2% had normal brain stem auditory evoked potentials (BERA). Potentials were obtained by means of a special technique allowing extraction every 600 ms and its follow up with time (brain stem temporal dynamic). This score of 2% was also that reported by some American authors who associate electrocochleography with BERA. The latter provide an accurate diagnosis in 96% of cases of all types of tumors taken together and in 91% of cases of small tumors. Furthermore, the performance of conventional scan imaging is accurate in only 25% of small tumors whereas gas meatocysternography detects more than 95% of cases. The latter method is therefore the most sensitive one but it possesses the disadvantage of being invasive and of costing much more than BERA, which remains therefore the least invasive examination providing the best and earliest diagnosis.

[Does proprioception of the extrinsic eye muscles participate in equilibrium, vision and oculomotor action?]. / La proprioception des muscles extrinsèques de l'ceil participe-t-elle à l'équilibre, à la vision et à l'oculomotricité?

Extrinsic eye muscles respond to both proprioceptive and visual impulses. Histology of ocular proprioceptive receptors shows them to be qualitatively and original, neuromuscular bundles are found in primates, and so called "palisade sensory nerve endings" in felines. Golgi's osteotendinous receptors are apparently absent. The number of muscle receptors is high and their proportion in relation to muscle weight even more so. The afferent pathway for this sensory system initially accompanies the motor fibers of oculomotor III, IV, ans VI nerves. Some fibers continue with these nerves to the brain stem while others join the ophthalmic branch of the trigeminal nerve (probably in the cavernous sinus). Cell bodies of proprioceptive fibers are located either in the mesencephalic root of the trigeminal nerve and in the Gasserian ganglion. The superior colliculus, center of eye-head coordination integration, also receives proprioceptive data. Proprioceptive afferent signals also project on two cerebellar cortex regions, one in the VI th and VII th lobules of the posterior lobe vermis, the other in the flocculus, all major centers for control and interaction of visuocervicovestibular activity. Extraocular proprioceptive impulses play an important role as do visual influx, in the maturation of the visual cortex in mammalia. Moreover, maintenance of binocular integration appears to require both coherent binocular vision and balanced bilateral, extraocular afferent impulses. Clinical consequences are multiple. Proprioceptive imbalance due to oculomotor dysfunction could explain the attendant visual deficit, which is reversible after correction of they motor disorder. Forced excentration of gaze provokes equilibrium disturbances in normal subjects. In cases of oculomotor palsy, the accompanying vertigo often observed could thus be due à lack of coordination between the intention of movement and its execution. Many oculomotor signs are dependent on the position of gaze alone, in the absence of any visual guide: end-position nystagmus gaze nystagmus, rebound nystagmus, gaze drift, periodic alternating and vertical superior nystagmus, ocular flutter and opsoclonus, nystagmus retractorius, etc. Proprioceptive impulses from extrinsic eye muscles are probably necessary for assessment of orbital coordinates of the ocular globe position during target fixation: this emphasizes the importance of this proprioceptive factor in the origin of ocular jerks. Proprioceptive impulses may play a crucial role in the triggering of the rapid phase of nystagmus, thus conditioning the variations in amplitude seen in provoked nystagmus tests.