Heredopathia atactica polyneuritiformis (phytanic acid storage disease). A new case with special reference to dietary treatment.

A 33-year-old man with Refsum disease exhibited clinical features of night blindness, dysequilibrium, hearing loss, itchy dry skin, symmetrical polyneuropathy, distal muscle weakness, pes cavus, and hammer toe. His total serum protein was increased, nerve conduction velocities were slow, and serum phytanic acid levels were high. Dietary restriction of phytol resulted in a decrease in serum phytanic acid without any visual and autitory changes; however, coordination, skin lesions, and nerve conduction velocities definitely improved.

Preoperative and postoperative auditory brain-stem response results for patients with eighth-nerve tumors.

Preoperative and postoperative auditory brain-stem response results and audiologic data were reviewed for seven patients whose hearing was preserved after eighth-nerve tumor surgery. Auditory brain-stem response absolute latencies (I, III, and V) and interpeak intervals (I-III, III-V, and I-V) were identified more often postoperatively than preoperatively. Even though postoperative absolute latencies were usually abnormal, the interpeak intervals were usually normal following surgery. Postoperative hearing sensitivity was unchanged or slightly poorer for five of the seven patients, but postoperative speech discrimination was the same or better for six of the seven patients. All three patients having acoustic reflex testing showed improvement postoperatively.

Auditory brainstem response and magnetic resonance imaging for acoustic neuromas: costs by prevalence.

OBJECTIVE: To compare hypothetical costs for identification of acoustic tumors when using magnetic resonance imaging with gadolinium Gd 64 (MRI-(64)Gd) as a sole diagnostic test and when using auditory brainstem response (ABR) testing followed by MRI-( 64)Gd (ABR + MRI-(64)Gd) for those with positive ABR findings. PATIENTS AND METHODS: Retrospective review of the medical records of 75 patients having surgically confirmed acoustic neuromas to categorize them into 3 subgroups relative to their risk of having a cerebellopontine angle tumor based on history, symptoms, and routine pure-tone and speech audiometric findings. Hypothetical costs associated with identification of patients with acoustic neuroma in each subgroup were calculated for MRI-(64)Gd alone and ABR + MRI-( 64)Gd. Auditory brainstem response sensitivity and specificity data for the 75 patients with acoustic neuroma and 75 patients without a tumor matched for hearing loss were applied to the hypothetical subgroups. Tumor size was considered also. SETTING: Tertiary care center. MAIN OUTCOME MEASURE: Comparison of costs for MRI-(64)Gd and ABR + MRI-(64)Gd. RESULTS: Fouteen patients with acoustic neuroma were assigned to the high-risk category (30% probability); 45 were in the intermediate-risk category (5% probability); and 16 were in the low-risk category (1% probability). Auditory brainstem response testing correctly identified 100% of the large tumors (>2.0 cm), 93% of the medium-sized tumors (1.1-2.0 cm), and 82% of the small tumors (<1.0 cm). The hypothetical costs for identifying 14 patients with acoustic neuroma among 47 patients in the high-risk category using MRI-(64)Gd would be $70,500; ABR + MRI-(64)Gd costs for the 13 patients identified by ABR would be $39,600. Hypothetically 900 patients would be tested to identify the 45 acoustic neuromas in the intermediate-risk category. Magnetic resonance imaging with (64)Gd screening would reach $1.35 million for this sample. Auditory brainstem response testing and MRI-(64)Gd would be $486,000, but 4 acoustic neuromas would be missed. For the low-risk subgroup MRI-6(4)Gd screening of 1600 patients to identify 16 acoustic neuromas would total $2.4 million; ABR + MRI-(64)Gd to identify 15 of them would be $787,500. In this sample of 75 acoustic neuromas, large tumors were more prevalent in the low-risk subgroup than in the high- or intermediate-risk subgroups. CONCLUSIONS: Decisions regarding assessment of patients at risk for acoustic neuromas must be made on a case-by-case basis. Use of ABR + MRI-( 64)Gd allows considerable savings when patients are in the intermediate- or low-risk subgroups. New MRI and ABR testing techniques offer promise for reducing costs.

Masking level differences for cochlear and brain stem lesions.

Masking level differences (MLD) for 500 Hz pure tones and for spondees were obtained from 48 subjects. Twelve were without otologic or neurologic complaints (normal), 12 had high frequency, noise-induced hearing losses, 12 were diagnosed otologically as having Ménière's disorder, and 12 had neurologically diagnosed central nervous system (CNS) disorders. Results indicated that high frequency, noise-induced hearing losses do not affect MLD for 500 Hz stimuli, but do diminish the size of MLD for speech. Masking level differences for both 500 Hz and spondees were decreased for the Ménière's disorder group. The group of patients having CNS disorders attributed to multiple sclerosis, to inflammatory lesion of the pons, to degenerative processes of the cerebellum and adjacent nervous tissue, or to brain stem cerebrovascular accident had normal hearing according to conventional pure tone and speech testing, but attained smaller than normal MLD for 500 Hz and spondees. These findings agree closely with results obtained in an earlier study and continue to suggest that, given normal peripheral auditory function, MLD tests may have unique value in detection of subtle lesions of the central auditory nervous system.

Speech discrimination in quiet and in white noise by patients with peripheral and central lesions.

Speech-discrimination scores in quiet and in white noise (O dB S/N ratio) were obtained from six groups of subjects. Differences of 40% or more between scores in quiet and in white noise were observed for less than 1% of the normal ears tested but were found for 8.0% of ears with noise trauma, 48% of ears with Meniere's disease, 62% of ears with subsequently surgically confirmed 8th-nerve tumors, 14% of ears of patients with multiple sclerosis, and 42% of ears contralateral to the lesion in patients with temporal-lobe damage.

Presbycusis. When hearing wanes, is amplification the answer?

Many persons with sensorineural hearing loss can benefit from wearing a hearing aid. Of the approximately 1 million hearing aids sold in the United States in 1983, more than half were purchased by persons over age 65. Persons with presbycusis should have audiologic and otologic evaluations to determine whether medical or surgical treatment is possible and, if not, whether they can benefit from hearing aid use. The patient can better assess the benefits of hearing aid use by using an appropriately selected hearing aid on a trial basis. Patients and their families also benefit from receiving suggestions for easing communication difficulties.

Head trauma and mid-frequency hearing loss.

Numerous reports in the literature associate head trauma with high-frequency hearing losses, often mimicking "4K notches" attributed to noise exposure. We have observed that some patients with a positive history for head trauma may show midfrequency notches in their audiometric configurations.

Use of TEOAE, ABR, and Acoustic Reflex Measures to Assess Auditory Function Patients With Acoustic Neuroma.

Cochlear and neural auditory function for a series of 30 patients with acoustic neuroma was assessed pre- and postoperatively by transiently evoked otoacoustic emission (TEOAE), auditory brain stem response (ABR), and acoustic reflex measures. Employing a retrosigmoid surgical approach, physical integrity of the acoustic nerve was preserved for 22 patients. TEOAEs were observed preoperatively for 13 patients and postoperatively for 6 of them. Postoperative neural function remained unchanged or improved following surgery for 7 patients, and cochlear function decreased. TEOAE, ABR, and acoustic reflex measurements were considered valuable in providing information about site of lesion and probable mechanisms of injury associated with tumor removal.

Penetrating injury to the brainstem after a nailgun accident: a case study.

Nonfatal penetrating injuries to the brainstem offer a unique opportunity to assess subcortical auditory pathway function. A case study of a patient suffering a severe nailgun accident is presented. Hearing sensitivity and acoustic reflexes were normal bilaterally, but word recognition was reduced for one ear. Auditory brainstem response results indicated waves I-IV were present bilaterally, but wave V was absent bilaterally. Results of vestibular findings indicated central pathology also. Results of audiologic, vestibular, radiologic, neurologic, and physical medicine examinations are discussed.

Brief tone audiometry: a review.

This paper reviews a number of studies on temporal integration of acoustic power at threshold. A wide variety of results for normal-hearing individuals and for hearing-impaired patients is revealed. This variability limits the current clinical application of brief tone audiometry.

Dichotic test results for normal subjects and for temporal lobectomy patients.

Test results obtained with Dichotic Consonant-Vowel (CV) test materials are reported for 50 normal subjects as well as for a total of 67 patients who underwent removal of the anterior portion of the right or left temporal lobe for control of seizures. All patients were tested before and after surgery. Results demonstrated that not all patients with temporal lobe seizures with subsequent temporal lobectomy demonstrated performance below the lower limits of normal established by the sample of normal subjects. Comparison of Dichotic CV and Staggered Spondaic Word test results is made on a subset of the patient population.

Auditory brainstem responses as a function of average hearing sensitivity for 2,000-4,000 Hz.

Average hearing thresholds for 2,000, 3,000 and 4,000 Hz and ABR results were analyzed for 290 patients having some degree of cochlear hearing loss. As average hearing sensitivity in the 2,000- to 4,000-Hz range became poorer, the incidence of abnormal auditory brainstem responses (ABR) increased. When the 2,000-Hz threshold sensitivity was 0-40 dB and the three-frequency average hearing loss was less than 50 dB, nearly 80% of ABR tracings were normal. Steeply sloping audiograms above 2,000 Hz increased the percent of abnormal ABR results.

Signal monitor for audiometry.

Conventional volume unit (VU) and auditory monitors of signals generated by or fed through an audiometer do not allow monitoring of the signal after the attenuator or output selector. An amplifier-compressor circuit has been designed and constructed which allows auditory monitoring of the electrical signal at the transducer. The circuit and its use are described.

Comparison of monaural and binaural hearing aid use on a trial period basis.

Thirty hearing-impaired patients compared monaural and binaural hearing aid use for a period of 4 weeks. Most of them preferred binaural hearing aids in quiet situations, but monaural hearing aids in noisy environments. Follow-up at 6 months revealed that 17 had purchased monaural hearing aids, 8 had purchased binaural hearing aids.

The effect of 2000-4000 Hz hearing sensitivity on ABR results.

Pure-tone hearing sensitivity at 2000, 3000, and 4000 Hz and ABR results were reviewed for 458 patients with cochlear hearing loss. Wave V latency and waveform morphology data from the 916 ears yielded percentages of abnormal ABR results as a function of degree and slope of hearing loss. Threshold sensitivity at all three frequencies influenced ABR latency or waveform. A higher incidence of abnormal ABR results was observed when 3000 Hz thresholds were elevated than when 4000 Hz thresholds were elevated to the same levels. ABR results for various audiometric configurations are reported.

Comparison of ABR amplitudes with TIPtrode and mastoid electrodes.

ABR evaluations were completed for 36 adults (18 males, 18 females) having normal hearing sensitivity and for 91 adult patients having various degrees of sensorineural hearing loss. Amplitudes of waves I and V were compared for ear canal (TIPtrode) electrode and mastoid electrode recordings. Interpeak intervals (I-III, III-V, and I-V) were determined and upper 95% confidence limits defined for normative data. In general, amplitude of wave I was larger when TIPtrodes were used. Wave V amplitude was nearly identical for the two electrodes. Wave I was identified more frequently for TIPtrode than for mastoid recordings of ABR waveforms for the sensorineural hearing loss subjects.