Sylvette Wiener-Vacher

Asymmetric otolith vestibulo-ocular responses in children with idiopathic scoliosis☆☆☆★★★

OBJECTIVE A suggested cause of idiopathic scoliosis (IS) in children is a disequilibrium in the vestibulospinal control of trunk muscles. We sought a correlation between otolith vestibular dysfunction and IS. METHODS A recently developed test for evaluation of otolith vestibular function (off-vertical axis rotation, OVAR) was applied to 30 children with IS, 12 control subjects, and 3 with congenital scoliosis as a result of spinal deformities. RESULTS Of the patients with IS, 67% had significantly greater values of directional preponderance on the OVAR test (a measure of otolith system imbalance) compared with control subjects. Patients with congenital scoliosis showed normal responses on the OVAR test. No correlation was found between the direction of the preponderance and the side of the spine imbalance, or between the directional preponderance and the curve magnitude. The rate of progression of the scoliosis was not significantly correlated with the amplitude of the directional preponderance. CONCLUSION These results support the hypothesis that central otolith vestibular system disorders lead to a vestibulospinal system imbalance, and may be a factor in the cause of IS.

Vestibular disorders in children

When vertigo and dizziness are diagnosed in a child, this is a matter of concern for the physician and the childs family. Prior to a comprehensive otological, neurological, and vestibular clinical examination, physicians often request CT or MRI scanning, although in most cases such expensive testing is unnecessary. The present work is based on the results of a 14-year study conducted with a sample of more than 2,000 children referred for vertigo and balance disorders to the functional vestibular evaluation unit of the ENT pediatric department at Robert Debré Hospital (Paris). The clinical signs of vestibular deficit and the most frequent aetiologies of vertigo and dizziness in children are detailed (migraine equivalent, ophthalmologic disorders, benign paroxysmal idiopathic pediatric vertigo, and temporal bone fracture), which has been helpful in determining the best diagnostic procedure and therapy for vertigo in children.

Vestibular impairments pre- and post-cochlear implant in children

OBJECTIVES Determine prevalence and types of vestibular impairments in sensorineural hearing loss (SNHL) in a large population of pediatric candidates for cochlear implants. Evaluate impact of cochlear implants on vestibular function. STUDY DESIGN Retrospective and prospective study. METHODS Children with profound SNHL (n=224) underwent complete vestibular testing (clinical vestibular examination, bicaloric test, earth vertical axis rotation, off vertical axis rotation and vestibular evoked myogenic potentials) before cochlear implant. Changes in vestibular responses were measured after implants in 89 of these patients. RESULTS In the SNHL population only 50% had normal bilateral vestibular function, while 20% had bilateral complete areflexia, 22.5% partial asymmetrical hypoexcitability and 7.5% partial symmetrical hypoexcitability. In the 71/89 follow-up patients showing vestibular responses prior to implant, 51 (71%) had changes in vestibular function including 7 (10%) who acquired ipsilateral areflexia. Others developed ipsilateral hypo- or hyperexcitability. Vestibular modifications occurred during the 3 months after surgery and were not clearly associated with clinical signs except for ipsilateral areflexia cases. In long-term follow-up, two of the 7 patients with ipsilateral areflexia partially recovered vestibular function. CONCLUSION Since half of pediatric cochlear implant candidates have vestibular deficits and 51% of implants induce modifications of existing vestibular function, each implant should be preceded by canal and otolith functional tests to assure that the least functional vestibule is implanted. The tests provide baselines for follow-up monitoring of subsequent losses and recovery. This could be easily implemented with a clinical vestibular examination including the head thrust test associated with a bicaloric test and vestibular-evoked-myogenic-potentials.

Vertigo is an underestimated symptom of ocular disorders: dizzy children do not always need mri

Vertigo, instability, dizziness, or equilibrium disorders are not usually considered as consequences of ophthalmologic problems. We present data indicating that ocular disorders can be responsible for these symptoms in children. In a population of 523 pediatric patients with vertigo or disequilibrium and referred for vestibular testing in our otolaryngology department during a 5-year period, 27 children presented with normal vestibular and somatic neurologic examinations but with ophthalmologic disorders (vergence insufficiency or latent strabismus with binocular vision in 70% and anisometropia in 41%). These patients represented 24% of all vergence insufficiencies detected and 4% of all orthoptic examinations performed in the pediatric ophthalmology department. These ocular abnormalities were considered to be the initial cause of the problems. In two thirds of these patients the symptoms were completely resolved by simple ophthalmologic treatment. No other additional tests, such as magnetic resonance imaging, were required. Therefore we propose that every child complaining of vertigo or dizziness but with normal clinical somatic neurologic and vestibular examinations should have a complete ophthalmologic examination before additional, more costly, investigations. This should lead to better screening and more appropriate care of ocular disorders in children and avoid unnecessary magnetic resonance imaging.

Abnormality of vergence latency in children with vertigo.

Abstract.It is well known that vergence movements are important for distance appreciation, depth vision and stereopsis. Moreover, vergence movements are very probably used by the CNS during head and body motion to adjust the gain of the vestibulo-ocular reflex (VOR) according to the viewing distance. A recent clinical study of Anoh-Tanon et al. suggested that vertigo in children with normal vestibular function could be associated with abnormal vergence clinically assessed. The purpose of this study was to test this hypothesis with objective vergence eye movement recordings. We examined the latency of vergence, saccades and combined movements in twelve children with the complaint of vertigo but without vestibular abnormality. Convergence and saccades combined with convergence or with divergence had abnormally long latencies (relative to normal children of matched age). In contrast, divergence and isolated saccades showed only mild latency increase relative to normals. Lengthening of latency could be due to impaired cortical control. Orthoptic vergence training reduced all latencies; however, even the reduced latency of vergence and of combined movements was still abnormal. The improvement after orthoptic vergence training could be due to increased visual attention, although such mechanism cannot eliminate completely the initiation deficit of vergence movements. Objective eye movement recordings are thus useful for a diagnosis and treatment of children with vertigo.

Speed-accuracy of saccades, vergence and combined eye movements in children with vertigo

Vergence abnormalities could lead to inappropriate vestibulo-ocular reflex (VOR), causing vertigo and imbalance (Brandt 1999). Indeed, a recent study by Anoh-Tanon et al. (2000) reported the existence of a population of children with symptoms of vertigo in the absence of vestibular dysfunction but with abnormal vergence findings in orthoptic tests. The purpose of this study was to examine in such children the accuracy, duration and mean velocity of vergence and saccades; additionally, for a few subjects, the effect of orthoptic vergence training on these parameters was also investigated. LEDs were used to stimulate saccades, pure vergence along the median plane and combined saccade-vergence movements. Movements from both eyes were recorded with a photoelectric device (Bouis). The results show that children with vertigo perform saccades as normal subjects of comparable age. In contrast, vergence, particularly convergence, shows abnormalities: poor accuracy, long duration and low speed. During combined movements, the well known reciprocal interaction between the saccade and the vergence is present only for saccades combined with divergence; for saccades combined with convergence such interaction is abnormal: the saccade is slowed down by the convergence but the convergence is not accelerated by the saccade. Orthoptic training improves significantly the accuracy of all eye movements; such improvement was significant for all types of eye movements except for divergence (pure and combined). Furthermore, convergence remains abnormal and the lack of acceleration by the saccade persists. These specific convergence deficits could be of both subcortical and cortical origin. Orthoptic training improves the accuracy presumably via visual attentional mechanisms, but cannot completely override deficits related to subcortical deficiencies.

Evaluation of vertiginous children

Our objective was to evaluate, using a structured approach method, the history and findings in vertiginous children as compared with a group of healthy children. We evaluated 24 vertiginous children (15 girls, 9 boys) with episodes of true vertigo of unknown etiology and 12 healthy age- and gender-matched controls. A detailed medical history was obtained using a structured approach technique. Vertiginous and healthy children underwent general and otoneurologic examinations, including audiogram, electronystagmography, and tympanometry, at the Helsinki University Hospital ENT clinic. Characteristics of patient histories and clinical findings were compared between the groups. The vertiginous children reported significantly more head traumas and headaches than the controls. The structured data collection approach improved the evaluation process. The predominant diagnoses were benign paroxysmal vertigo of childhood, otitis media-related vertigo, and migraine-associated dizziness.

Vestibular Impairment after Bacterial Meningitis Delays Infant Posturomotor Development

OBJECTIVE To examine the findings and impact of postmeningitis vestibular dysfunction on early posturomotor development. Meningitis in children is frequently associated with postural instability, which is often attributed to an undefined neurologic disorder but it could actually be due to vestibular impairment. STUDY DESIGN In a retrospective cohort study, we compared groups with vestibular loss before versus after independent walking: 37 children (18 girls, 19 boys; median age: 2.3 years) hospitalized for bacterial meningitis and referred for postural instability. A complete vestibular evaluation included 3 tests for function of the 6 semicircular canals (caloric, earth vertical axis rotation, head impulse tests), 2 tests for otolith function assessment (vestibular evoked myogenic potentials, off vertical axis rotation), audiologic evaluation, neurologic examination, and brain and temporal bone imaging. RESULTS Twenty-nine children (10.5% of the 276 children hospitalized with bacterial meningitis) had vestibular impairment. Vestibular loss was complete bilaterally in 16 of 37 children and partial in 13 of 37, and 8 cases had normal vestibular responses. Neurologically normal children who had meningitis before they walked independently and had complete bilateral vestibular loss walked significantly later and their postural instability lasted longer than children in the other groups. The degree of vestibular impairment correlated with the postural instability duration and with the degree of hearing loss. CONCLUSIONS Bacterial meningitis in young children can impair vestibular function completely, leading to delayed posturomotor development if meningitis occurs before independent walking, even in absence of neurologic impairment. Vestibular evaluations are encouraged for postmeningitis evaluation, particularly in cases with postural instability exceeding 8 days, hearing impairment, and programmed cochlear implant.

Poor Postural Stability in Children with Vertigo and Vergence Abnormalities

PURPOSE An earlier study suggested that deficits of vergence can influence postural control via the efferent and afferent proprioceptive signals. In this study, postural control in 28 children with vertigo with normal vestibular function but with vergence abnormalities and in 19 normal children of comparable age was assessed with orthoptic tests. METHODS A posturography platform was used to examine posture in quiet stance. The child was asked to fixate a target at 40 cm or at 200 cm, either with eyes open (vision condition) or with eyes covered by a black mask (no vision condition). In a complementary test in 15 of 28 children with vertigo and in all 19 normal children, postural control was evaluated during monocular viewing (dominant and nondominant eye viewing). RESULTS For all children examined, postural stability was better when fixating a target at near than at far distance and with both eyes than with one eye or with eyes covered. In all conditions, the children with vertigo were more unstable than were the control children. CONCLUSIONS Binocular visual information, such as vergence disparity, is essential in stabilizing posture at near distance. Postural instability reported in children with vertigo and vergence abnormalities could be due to poor vergence inputs and/or to immature compensatory mechanisms controlling postural stability (vestibular, somatosensory inputs and/or cerebellar processes).

Binocular coordination of saccades in children with vertigo: dependency on the vergence state.

The present study examines the quality of binocular coordination of saccades at far and near distance in 15 children with symptoms of vertigo headache and equilibrium disorders; these children show normal vestibular function but abnormal convergence eye movements (e.g., long time preparation, slow execution and poor accuracy, see ). The results show normal binocular saccade coordination at far distance, but large abnormal disconjugacy for saccades at near distance. During combined saccade-vergence movements (studied in six of these children), convergence remains abnormally slow. This supports the interpretation according to which poor binocular yoking of the saccades is linked to the reduced ability to produce fast convergence during the saccade; a learning mechanism based on rapid vergence would help to reduce the abducting-adducting asymmetry of the saccades. An alternative interpretation would be reduced learning ability for monocular adjustment of the saccade signals.