Timo Hirvonen

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Gentamicin is toxic to vestibular hair cells, but its effects on vestibular afferents have not been defined. We treated anesthetized chinchillas with one injection of gentamicin (26.7 mg/ml) into the middle ear and made extracellular recordings from afferents after 5-25 (early) or 90-115 days (late). The relative proportions of regular, intermediate, and(More)
Mammalian vestibular-nerve afferents innervating the semicircular canals have been divided into groups according to their discharge regularity, gain at 2-Hz rotational stimulation, and morphology. Low-gain irregular afferents terminate in calyx endings in the central crista, high-gain irregular afferents synapse more peripherally in dimorphic (bouton and(More)
OBJECTIVE Determine the change in vestibular function in patients receiving a unilateral cochlear implant, and to compare these results with other signs and symptoms. STUDY DESIGN Prospective cohort study. SETTING Academic tertiary referral center. PATIENTS Forty-four adults (mean age, 55 yr; range, 30-76 yr) receiving their first cochlear implant. (More)
HYPOTHESIS Afferents innervating the superior semicircular canal are rendered especially sensitive to acoustic stimulation when there is a dehiscence of the superior canal. Other vestibular end organs are also more sensitive to acoustic stimulation. BACKGROUND Dehiscence of the superior semicircular canal is associated with vertigo and nystagmus caused by(More)
The objective was to study the applicability and repeatability of visual feedback posturography (VFP) in assessing postural control of 23 healthy subjects. The subjects had to move their center of gravity (COG) marker on a computer screen to chosen targets by leaning their body on the platform, and the accuracy, velocity, and side difference of these(More)
OBJECTIVE The vestibulo-ocular reflex (VOR) stabilizes gaze during head movements by producing compensatory eye movements. Gain of the VOR can be defined as the difference between the eye and corresponding head movement amplitudes. The objective of the study was to compare the gain of postoperative vestibular schwannoma (VS) patients with that of healthy(More)
Vestibular symptoms are common after stapes surgery and may prevent outpatient treatment. The cause of vestibular symptoms is unclear, and in previous studies objective measurements have been obtained few days after the surgery. The aim of the study was to evaluate the existence and nature of any early, and possibly temporary vestibular irritation that(More)
Intratympanic and systemic dexamethasone treatment of Ménière's disease (MD) was evaluated in a prospective study. Seventeen patients (6 men and 11 women) with MD (5 right-sided, 11 left-sided and 1 bilateral) were treated with three 0.2- to 0.4-ml injections of intratympanic dexamethasone hyaluronate (16 mg/ml) during a week and with an initial(More)
OBJECTIVE To evaluate the existence of vestibular irritation with video-oculography before and after stapes surgery and to examine whether there would be signs of specific end-organ irritation. STUDY DESIGN A prospective study of preoperative and postoperative nystagmus, vertigo, and hearing thresholds. SETTING University hospital, tertiary referral(More)