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Biomedical subjects

S R Wiener-Vacher

Publications and source records attributed to S R Wiener-Vacher.

8 recordsLinked to original sources
PubMed2004

[Vertigo in children].

Vertigo and dizziness in children, when these symptoms are recognized, worry physician and children's families and urge them, before doing a good otological, neurological and vestibular clinical examination, on a prescription of CT scan or an NMR which are unnecessary test in most of the cases and expensive tests. A better knowledge of the clinical signs of vestibular deficit and of the most frequent origins of vertigo and dizziness in children (migraine equivalent, ophthalmological disorders, benign paroxysmal idiopathic pediatric vertigo, temporal bone fracture) permits a better and more adapted procedure for diagnosis and therapy.

Child↗
PubMed2000

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.

Child↗
PubMed1999

Vestibular function in children with the CHARGE association.

BACKGROUND: Histopathological examinations and computed tomographic scans of the temporal bone in patients with the CHARGE association (a malformative syndrome that includes coloboma, heart disease, choanal atresia, retarded development, genital hypoplasia, and ear anomalies, including hypoplasia of the external ear and hearing loss) have shown an absence of semicircular canals and a Mondini form of cochlear dysplasia. Until recently, no information was available concerning a possible loss of vestibular function, which could be a factor in retarded posturomotor development. To our knowledge, this is the first report of otolith tests done on patients with the CHARGE association. OBJECTIVE: To test residual vestibular function in patients with the CHARGE association. STUDY DESIGN: In 7 patients with the CHARGE association, we made electro-oculographic recordings of vestibulo-ocular responses to earth-vertical and off-vertical axis rotations to evaluate the function of the canal and the otolith-vestibular systems. RESULTS: None of the 7 patients had semicircular canals in the computed tomographic scan, and none had canal vestibulo-ocular responses to earth-vertical axis rotation, but all had normal otolith vestibulo-ocular responses to the off-vertical axis rotation test. CONCLUSIONS: These results support the hypothesis of a residual functional otolith organ in the hypoplastic posterior labyrinth of children with the CHARGE association. The severe delays in psychomotor development presented by these children are more likely a consequence of multiple factors: canal vestibular deficit, visual impairment, and environmental conditions (long hospital stays and breathing and feeding problems). The remaining sensitivity of the otolith system to gravity and linear acceleration forces in these children could be exploited in early education programs to improve their posturomotor development.

Abnormalities, Multiple↗
PubMed1999

Motoneuron axon distribution in the cat stapedius muscle.

Stapedius-motoneuron cell bodies in the brainstem are spatially organized according to their acoustic response laterality, as demonstrated by intracellular labeling of physiologically identified motoneurons [Vacher et al., 1989. J. Comp. Neurol. 289, 401-415]. To determine whether a similar functional spatial segregation is present in the muscle, we traced physiologically identified, labeled axons into the stapedius muscle. Ten labeled axons were visible in the facial nerve and five could be traced to endplates within the muscle. These five axons had 39 observed branches (others may have been missed). This indicates an average innervation ratio (> or = 7.8) which is much higher than that obtained from previous estimates of the numbers of stapedius motoneurons and muscle fibers in the cat. One well-labeled stapedius motor axon innervated only a single muscle fiber. In contrast, two labeled axons had over 10 endings and innervated muscle fibers spread over wide areas in the muscle. Two of the axons branched and coursed through two primary stapedius fascicles, indicating that the muscle zones innervated by different primary fascicles are not functionally segregated. In another series of experiments, retrograde tracers were deposited in individual primary nerve fascicles. In every case, labeled stapedius-motoneuron cell bodies were found in each of the physiologically identified stapedius-motoneuron regions in the brainstem. These observations suggest there is little, if any, functional spatial segregation based on separate muscle compartments in the stapedius muscle, despite there being functional spatial segregation in the stapedius-motoneuron pool centrally.

Animals↗
PubMed1998

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.

Case-Control Studies↗
PubMed1996

Canal and otolith vestibulo-ocular reflexes to vertical and off vertical axis rotations in children learning to walk.

In order to determine the characteristics of the vestibulo-ocular reflexes (VORs) as a function of age and posturo-motor development, a group of 26 normal children (6 to 25 months old) were tested at three different stages of posturo-motor control: prior to as well as during the first attempts to walk without support, and during the first year of independent walking. The test consisted of electro-oculographic (EOG) recordings of the VOR responses to horizontal semi-circular canal and otolith stimulations. The canal VOR was elicited in seated subjects by rotatory impulsions about a vertical axis (acceleration and deceleration both at 40 degrees/s2, separated by a rotation at 60 degrees/s velocity). The otolith VOR was elicited by inclining the rotating chair by 9 degrees respect to gravity. For the canal VOR, the time constant and the highest initial slow phase velocity were measured. The otolith VOR was characterized by the amplitude of the modulation and the bias (offset of baseline from zero) of the slow phase velocity averaged over 10 to 20 rotation cycles, for both the horizontal and vertical components of the response. The pooled values of these data show that canal VOR parameters did not vary significantly either with age of the children or with their stage of posturo-motor control. However, the otolith VOR parameters changed during the period of learning to walk: the modulation of the horizontal component increased and the modulation of the vertical component decreased significantly. Thus the ability to walk without support is marked by a significant change in the otolith but not canal responses; since the vestibular sensory organs develop anatomically at the same rate these results indicate that central nervous system processors of canal and otolith information develop independently.

Electrooculography↗
PubMedDate not supplied

Audiological assessment of infants and children with preauricular tags.

A previous study found sensorineural hearing loss in 13% of 178 children with solitary preauricular tags. The present results are quite different. Audiological assessment was performed on 42 children (median age of 2 months) with preauricular tags as the sole anatomical malformation. Tests included behavioral audiometry and transient evoked otoacoustic emissions. Twenty-two subjects were also tested with auditory brainstem recording while under general anesthesia during surgical excision of the tag. None of the children had a sensorineural hearing loss, but 4 had a bilateral or unilateral conductive hearing loss due to secretory otitis media. It is concluded that solitary ear tags are not a high risk factor for sensorineural hearing loss if not associated with a family history of hearing loss.

Acoustic Impedance Tests↗