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OBJECTIVE: To characterize the audiological and vestibular changes associated with a mitochondrial DNA mutation in an Arab-Israeli family and in other families with mitochondrial predisposition to aminoglycoside-induced hearing loss. DESIGN: Evaluation of audiological (pure tone thresholds, speech reception thresholds, speech discrimination, tympanometry, acoustic reflex thresholds, tone decay, and auditory brain-stem evoked response recording) and vestibular (complete history, physical examination, and 2-channel electronystagmography) systems. In 5 patients, structural evaluation of the inner ear was done by magnetic resonance imaging. PATIENTS: Fifteen members of an Arab-Israeli family, and 1 Chinese woman with the same mitochondrial DNA mutation who experienced hearing loss after short-term exposure to streptomycin. RESULTS: Most of the patients had a profound hearing loss due to cochlear involvement. The hearing loss usually was not accompanied by notable peripheral vestibular dysfunction. In the patient with severe hearing loss after exposure to aminoglycoside, the vestibular function was completely normal. CONCLUSIONS: In most of the Arab-Israeli patients with congenital deafness, the vestibular system function was normal, in contrast to the frequency of vestibular abnormality among deaf children, which was described in the literature. This may be related to genetic predisposition to aminoglycoside-induced deafness.Arch Otolaryngol Head Neck Surg. 1996;122:1001-1004

OBJECTIVES: The contributions of each of the vertical semicircular canals (SCCs) and otoliths to the short-latency vestibular evoked potentials in response to angular acceleration impulses were studied in the cat. DESIGN: The experiments were conducted on unilateral labyrinthectomized cats. Vestibular activation was achieved by delivering angular acceleration impulses to the animal's head, held in the position presumed to be optimal for maximal stimulation of either the anterior or the posterior SCCs before and after obliteration of the SCC studied, and before and after obliteration of the other SCCs and ablation of the maculae. INTERVENTIONS: Unilateral labyrinthectomy, obliteration of the SCCs, and ablation of the otoliths and section of the commissural vestibular fibers in the brain stem with histologic confirmation were carried out in the experiments. RESULTS: Following selective obliteration of either the anterior or the posterior SCC of the remaining ear and stimulation in the presumed optimal plane of the obliterated canal, the early prominent waves (P1 and P2) disappeared, leaving only much smaller-amplitude waves. These were severely depressed after ablation of the maculae. On the other hand, the vestibular evoked potentials in response to excitatory stimuli were not affected by obliteration of the other two SCCs and ablation of the maculae. CONCLUSION: These results indicate that when the head is stimulated in the optimal plane of each of the SCCs, the vestibular evoked potentials are generated mainly by the cristae ampullaris being stimulated, while the otoliths contribute smaller responses.(Arch Otolaryngol Head Neck Surg. 1995;121:34-38)

• Whether or to what extent loop diuretics, eg, ethacrynic acid and furosemide, affect the vestibular system is controversial. We studied this problem by recording in cats the short-latency vestibular evoked response (VsER) to acceleration stimuli by skin electrodes before and after local or systemic administration of loop diuretics. The effect on the VsER was minimal in contrast to the major changes that appeared in the auditory evoked response, in which, among the waves known to originate from the brain stem, the most affected was N1. These findings suggest that the vestibular endorgan function is minimally affected by loop diuretics and that the changes in the vestibulo-ocular reflex reported by several authors might be due to the effect of the drugs on the central nervous system. Thus, recording of the VsER in experimental animal models might serve as a useful tool for direct evaluation of the effect of certain drugs and conditions on the vestibular system.(Arch Otolaryngol Head Neck Surg 1986;112:836-839)

• Simultaneous recording of the electromyographic activity of the pharyngeal muscles and the intraluminal pressure in the upper sphincter zone was performed routinely in patients with swallowing problems for the first time, to our knowledge. This technique was found to be very useful for the localization of the "site of lesion." The procedure is safe, easy to master, and causes minimal inconvenience. It can reveal, in the most direct way, whether the disturbance is in the hypopharyngeal musculature (represented by the inferior constrictor muscle), in the cricopharyngeal muscle (spasm or lack of relaxation), or in the synchronization between them. Simultaneous recording of intraluminal pressure adds valuable information about the mechanical events associated with electromyographic activity. It was found that in pathologic cases there is quite often no correlation between the electrical and mechanical events. Thus, simultaneous recording of both electrical and mechanical events is essential for the understanding of the pathophysiology of disturbances of deglutition.(Arch Otolaryngol Head Neck Surg. 1990;116:910-913)