Anita Pikus

Neurofibromatosis 1 (Recklinghausen Disease) and Neurofibromatosis 2 (Bilateral Acoustic Neurofibromatosis): An Update

The neurofibromatoses comprise at least two autosomal dominant disorders affecting an estimated 100,000 Americans with clinical manifestations that may require care from every type of clinician. Neurofibromatosis 1 and neurofibromatosis 2 have in common the occurrence of many neurofibromas but are distinctly different clinical disorders. The disease genes are on different chromosomes. Magnetic resonance imaging, particularly with gadolinium enhancement, has generally supplanted other techniques for visualizing brain, spinal, and other neural tumors in both disorders. The technique has rekindled the controversy over the nature and frequency of optic pathway tumors in patients with neurofibromatosis 1 and has revealed, throughout the brains of young patients, bright lesions that have uncertain clinical consequences and unknown pathologic bases. In patients with neurofibromatosis 2, small acoustic neuromas can be seen, leading to the possibility of excision with preservation of hearing and facial nerve function. Abnormal hearing may occur to excess in patients with neurofibromatosis 1, but acoustic neuroma has never been documented. In patients with neurofibromatosis 2, a battery of audiologic tests has a high positive predictive power. Lisch nodules or iris hamartomas, probably a universal sign in adults with the neurofibromatosis 1 gene, cause no problem with vision. Posterior capsular lens opacity in patients with neurofibromatosis 2 is a helpful diagnostic sign and a potential source of additional handicap in persons at risk for impaired hearing. Progress in the clinical delineation of the disorders has been matched with considerable research into the still obscure pathogenesis of the disorders. Such rapid advances may necessitate reconsideration of the conclusions of the National Institutes of Health Consensus Development Conference on Neurofibromatosis, especially those on the categories of persons in which a neurofibromatosis should be considered and the need for caution in recommending surgery. Watchful waiting may often be the best management for acoustic neuromas in neurofibromatosis 2.

Sensorineural hearing loss in Vogt-Koyanagi-Harada syndrome.

Background: Vogt‐Koyanagi‐Harada (VKH) syndrome is a systemic condition characterized by ocular inflammatory disease as well as skin, ear, and meningeal manifestations. Patients with VKH often report tinnitus and hearing loss, but these symptoms tend to be given secondary consideration because most undergo treatment with steroids to prevent blindness resulting from granulomatous uveitis, exudative retinal detachment, and optic nerve inflammation.

Neomycin and plasma lipoproteins in type II hyperlipoproteinemia

Neomycin, a nonabsorbable aminoglycoside antibiotic, has been shown to exert a hypocholesterolemic effect in man. In a 9‐mo, double‐blind, randomized, crossover, placebo‐controlled clinical trial, the effect of neomycin, 2 gm/day, on plasma lipoproteins, as well as its safety, was described in 20 subjects with type II hyperlipoproteinemia. A 15% (50 mg%) decline in plasma cholesterol concentration was observed with neomycin. Most of this effect resulted from a 41 mg% (16%) decrease in low‐density lipoprotein cholesterol concentration. No significant or consistent effect on the concentration of high‐density lipoprotein cholesterol was observed. Monthly audiologic and renal evaluation disclosed no oto‐ or nephrotoxicity. Neomycin treatment in patients with type II hyperlipoproteinemia is an inexpensive and effective means of lowering the concentration of low‐density lipoproteins and is free of significant side effects over a 3‐mo period.

Auditory evoked potentials in patients with dementia of the Alzheimer type.

Dementia of the Alzheimer type (DAT) disrupts the function of the central auditory nervous system as a result of temporal lobe pathology. Auditory brain stem response (ABR) and middle latency responses (MLR) were studied in a group of patients with DAT to determine whether a correlate of dementia existed in these electrophysiological potentials. Comparison of absolute and interwave latencies on ABR, and absolute latency and amplitude of the MLR in patients with DAT and normal aged controls showed no significant differences between groups for any measure. Further, no relationship with degree of dementia or temporal lobe involvement, as assessed through dichotic speech recognition studies, and auditory evoked potentials could be demonstrated. It was concluded that the temporal lobe atrophy and hypometabolism seen in DAT is not generally sufficient to disrupt the generating of ABR and MLR potentials; however, slow cortical and cognitive evoked potentials may be more sensitive to central auditory nervous system impairment in DAT.

Alterations in auditory processing of speech stimuli during aging in healthy subjects.

Studies of auditory processing during aging in man have not provided a consensus on whether aging affects the ability to process speech stimuli. To evaluate the relationship between speech recognition tasks and age, we examined 36 male subjects between the ages of 21 and 83 years, who were screened for the absence of disease, particularly in the cardiovascular and neurologic systems. Measures were obtained on the following tests: pure tone thresholds, speech reception threshold, speech discrimination, low-pass filtered speech, and binaural fusion. A statistically significant correlation was found between pure tone thresholds and age for all frequencies. When the effect of peripheral hearing loss was taken into account, speech measures did not correlate with age, with the exception of low-pass filtered speech in the left ear. Our findings suggest that the aging process in healthy man is not necessarily accompanied by deficits in the processing of speech stimuli beyond those which are due to peripheral hearing loss.

Disequilibrium and audiovestibular function in panic disorder: Symptom profiles and test findings

Patients with panic disorder commonly report symptoms of dizziness and imbalance. We studied the relationship between objective measures of audiovestibular function, phenomenologic, and self-report measures of dysequilibrium and related somatic symptoms in a sample of panic disorder patients with and without agoraphobia, unselected for the complaint of dysequilibrium. Of seventeen patients evaluated by electronystagmography, 71 percent exhibited abnormal vestibular test findings. These latter patients had higher total anxiety ratings than patients without vestibular abnormalities. We conclude that patients with panic disorder warrant evaluation of audiovestibular function.

ULTRASTRUCTURAL AND BIOCHEMICAL ANALYSIS OF SPERM FLAGELLA FROM AN INFERTILE MAN WITH A ROD-DOMINANT RETINAL DEGENERATION

This study examined the ultrastructural morphology and posttranslationally modified alpha-tubulin isoforms in the sperm flagella of a patient presenting with infertility and retinal degeneration. Clinical evaluation showed impaired motility and gross morphological abnormalities of the sperm and a rod-dominant retinal degeneration with midperipheral pigment clumping and scattered bone spicules. Other neurological indications included delayed neuroelectric transmission in the auditory brainstem and a temporal lobe seizure disorder. Ultrastructural analysis showed that 46% of sperm axonemes had missing and/or misplaced doublets compared with 10% to 12% in control subjects. ELISA analysis showed hypoacetylation of alpha-tubulin (30% of control) but normal levels of alpha-tubulin tyrosination. Tubulin acetyl-transferase specific activity was also 30% of control activity. These characteristics may be indicative of microtubule instability leading to the pathological consequences described.