Vestibular dysfunction in Gulf War syndrome.

METHODS: Vestibular complaints of Gulf War veterans were characterized by a nested case-control study of 23 veterans with 3 different Gulf War syndromes and 20 matched control subjects. All subjects completed a standardized symptom questionnaire and underwent standard audiovestibular tests administered by audiologists blinded to group identities. RESULTS: The prevalence of reported dizzy spells was higher in veterans with Gulf War syndromes 1 (100%), 2 (85%), and 3 (100%) than in controls (25%, P < 0.0001). Dizzy spells were more frequent, lasted longer, and involved a wider variety of accompanying symptoms in veterans with syndrome 2 than in those with syndromes 1 and 3. Audiovestibular testing showed greater interocular asymmetry of nystagmic velocity on sinusoidal harmonic acceleration in syndromes 1 (P = 0.015) and 2 (P = 0.002), greater asymmetry of saccadic velocity in syndrome 2 (P = 0.4), diminished nystagmic velocity after caloric stimulation bilaterally in syndrome 3 (P = 0.02 to 0.04), more subjects with pathologic nystagmus (P = 0. 09), and greater interside asymmetry of wave I to III interpeak latency on auditory brain stem response in syndromes 1 (P = 0.005) and 2 (P = 0.07). Asymmetry of gain on sinusoidal harmonic acceleration and pathologic nystagmus were most strongly associated with symptoms of paroxysmal vertigo (P = 0.002 and 0.07, respectively); asymmetry of saccadic velocity, with the severity of vertigo (P = 0.004); and abnormal caloric response, with chronic dysequilibrium (P = 0.006). CONCLUSIONS: The findings are compatible with a subtle neurologic injury from organophosphate-induced delayed neurotoxicity.

The effect of profound umbilical artery acidemia in term neonates admitted to a newborn nursery.

OBJECTIVE: To determine whether there were immediate adverse effects of an umbilical artery pH < or = 7.0 in term and near-term infants. STUDY DESIGN: All infants triaged to the newborn nursery with an umbilical artery pH < or = 7.0 from May 1993 through April 1994 (n = 37) were prospectively identified; 35 of the 37 infants were enrolled and matched with nonacidemic control infants (n = 35). Organ system dysfunction (neurologic, renal, hepatic, gastrointestinal) was evaluated either clinically or biochemically with selected blood and urine parameters. RESULTS: Acidemic and control groups were similar for pregnancy complications before labor, but acidemic infants were more often delivered by cesarean section (20/35 vs 6/35, p = 0.001). No differences existed between acidemic and control infants in gestational age, birth weight, neurologic evaluations, hearing deficits, feeding tolerance, and hepatic function. The acidemic group had a higher mean serum creatinine than control infants on day 2 of life (0.90 +/- 0.34 vs 0.71 +/- 0.12 mg/dl, p = 0.005) and a greater number of infants with a urine Chemstrip positive for heme (14/35 vs 3/35, p = 0.005). No differences existed between groups in time to first void, urine specific gravity, and number of infants with microscopic hematuria. CONCLUSION: Term and near-term infants born with an umbilical artery pH < or = 7.0 and triaged to the newborn nursery on the basis of a stable appearance in the delivery room do not have clinical manifestations of hypoxia-ischemia in the 48 hours after birth. The higher mean serum creatinine for acidemic compared with control groups is presumably prerenal in origin and results from processes responsible for profound fetal acidemia. Infants with an umbilical artery pH < or = 7.0 and assessed to be clinically well can be treated similar to nonacidemic infants.

Use of an implantable hearing device.

PURPOSE: The purpose of this paper was to discuss our experiences with an implantable bone conduction hearing prosthesis, the XOMED Audiant Bone Conductor (Jacksonville, FL). PATIENTS AND METHODS: Twenty-four patients who had been implanted with the Audiant Bone Conductor were interviewed by telephone following implantation. Questions were asked regarding use of the device and subjective benefit. RESULTS: Eleven patients are using their devices, 12 patients are not using their devices, and one patient has been lost to follow-up. Patients using the device report satisfaction and prefer the Audiant to other amplification systems, whereas those not using the device indicate that insufficient amplification or weak magnetic attraction prevent its use. CONCLUSIONS: Analysis of failures has altered our criteria for implantation. With improvements that have been made by XOMED and stricter patient criteria, the Audiant should be considered a viable amplification alternative for certain hearing-impaired patients.

Vestibular evaluation in patients with early multiple sclerosis.

Multiple sclerosis (MS) is a chronic, debilitating disease characterized by multiple areas of focal demyelination that develop throughout the white matter of the central nervous system at varying times. Most patients report disequilibrium at some point in the course of their disease. When balance disturbance occurs early in the course of the disease prior to diagnosis, the patient may present to the otolaryngologist for evaluation. Are there any patterns of balance dysfunction that might suggest the diagnosis to the evaluating physician? An evaluation of ten patients with known early MS suggests that platform posturography and ENG is the test most likely to provide useful diagnostic information in patients with early MS.

Intrasubject test-retest variability in clinical electrocochleography.

Seventeen healthy volunteers without a history of auditory or vestibular difficulty and with normal screening audiometry had bilateral (34 ears) electrocochleography performed repeatedly at 1-week intervals. Each subject had from four to seven electrocochleograms performed on each ear. Measurements were made in the external auditory canal using a gold-foil "TIPtrode." Amplitude and latency for the summating potential (SP) and action potential (AP) were measured and SP/AP ratios were calculated. Averages and standard deviations for amplitude, latency, and SP/AP ratios were computed. The average SP/AP ratio was 0.22 with a standard deviation of 0.06. The range was 0.04 to 0.50. The average difference between the highest and lowest SP/AP ratio for a given individual was 0.155 (i.e., the range 0.03 to 0.31) with a standard deviation of 0.07. These normative data are useful in assessing the results of dehydration electrocochleography and in establishing how much test-retest variation is required to suggest pathology.

Audiologic threshold monitoring of patients receiving ototoxic drugs. Preliminary report.

An effort was made to determine the efficacy of auditory threshold monitoring of patients receiving ototoxic drugs. Forty-four patients treated with either tobramycin or vancomycin for osteomyelitis were tested at the beginning of treatment, following treatment, and twice weekly during treatment when possible. All patients had renal function carefully monitored. Peak and trough drug levels were kept out of the toxic range throughout the study. In no patient did indisputable ototoxicity occur, and therefore, no conclusion about the most efficacious schedule for auditory monitoring of patients receiving ototoxic drugs was made, and what constitutes a significant intratherapeutic threshold shift is still in question. Until further data are collected, monitoring of renal function and peak and trough drug levels, as well as patient counseling, is recommended. Pretherapy and posttherapy auditory monitoring and intratherapeutic monitoring of high-risk patients and those who develop aural symptoms may prove beneficial.