Database of benign positional paroxysmal nystagmus.

Classification of various manifestations of benign positional paroxysmal nystagmus, due to canalolithiasis or to cupulolithiasis, as a reaction to movements and to the site of detritus, is now possible due to the integration of theoretical knowledge (relationships between the semicircular canals and/or ampullae and the vestibulo-ocular pathways) with the forms of nystagmus induced when the head is placed in various positions. A comparison is made of results in patients examined in three Departments, during the past 3 years, and data presented in the literature. Findings are presented in a database which enables the clinician to compare the standard diagnostic manoeuvres (Dix-Hallpike, Pagnini-McClure, Rose) with results obtained by placing the head in alternative positions. This approach offers all the information needed to identify the site of onset and hence to formulate a correct diagnosis, thus directly indicating the most appropriate liberating or repositioning manoeuvre or--in the case of a suspected central lesion--to suggest further tests. Moreover, it is suggested that this table could become a useful tool for teaching purposes.

Effect of superoxide dismutase and allopurinol on impulse noise-exposed guinea pigs--electrophysiological and biochemical study.

OBJECTIVE: To investigate the protective effect of two anti-reactive oxygen species (ROS) substances, copper-zinc superoxide dismutase (CuZn-SOD) and allopurinol, in impulse noise-exposed guinea pigs. MATERIAL AND METHODS: Allopurinol or CuZn-SOD were administered intraperitoneally before exposure to 125 dB SPL noise centered at 2.0-3.0 kHz, with a repetition rate of 4/s, for 1.8 h. Hearing thresholds were tested by means of electrocochleography after implanting the animals with permanent electrodes. The presence of lipoperoxides in the guinea pig cochleae exposed to noise-induced oxidative stress was determined by means of the dosage of malondialdhyde, evaluated by measuring the content of thiobarbituric acid reactive substances in perilymph samples. RESULTS: Acoustic stress induced ROS formation and both allopurinol and CuZn-SOD exerted a protective effect on the cochlea. Comparison of compound action potential thresholds in different animal groups showed that the temporary threshold shift was significantly lower in treated animals than in those without pharmacological protection. CONCLUSION: The protective effect of the antioxidant agents demonstrates that, even at a high level of impulse noise exposure, a metabolic mechanism of cochlear damage may still play an important role in noise-exposed sensorineural hearing loss.

[Protective effect of allopurinol in the exposure to noise pulses]. / Effetto protettivo dell'allopurinolo nell'esposizione a rumore impulsivo.

Free oxygen radicals cause particularly severe tissues and organ damage. They appear to play an important role in the cochlea, mediating noise-exposure damage. In the present study 16 guinea pigs were implanted with permanent electrodes to record cochlear action potential. Eight animals were exposed to a 2-3 kHz, 125 dB SPL noise pulse, at a rate of 4 stimulations per second for 1.8 hours. Prior to noise exposure four out of eight animals were treated with a known dose of allopurinol. The remaining eight animals were used as controls. Endolymphatic malondialdehyde concentration was used as indicator of the lipid peroxidization processes exerted by the free radicals. No significant difference was found between the variations in hearing threshold and malondialdehyde concentration in the animals treated with allopurinol and then exposed to noise vs. the control group. The electophysiological and biochemical results have, therefore, demonstrated that preventative administration of allopurinol can provide valid protection vs. noise impulse damage.

A case of Dejerine-Sottas disease with prominent ataxia and brain stem involvement. A clinical, electrophysiological, otoneurologic, and ultrastructural study.

A case is presented of Dejerine-Sottas disease in a 12-year-old boy in which clinical signs made diagnosis of Friedreich's ataxia seem plausible. Based on marked slowing of motor conduction velocity, the sural nerve biopsy findings of a hypertrophic neuropathy with hypo- and demyelination of the nerve fibres, as well as the clinical history, the diagnosis of Dejerine-Sottas disease was made. ABR examination suggested involvement of brain stem at the roots and/or nuclei of the eighth cranial nerve, without involvement of higher structures.

Otoneurological findings in Friedreich's ataxia and other inherited neuropathies.

Fifteen cases of Friedreich's ataxia (FA) were examined using an otoneurological test battery that included tone and speech audiometry, the synthetic sentence identification (SSI) test, impedance audiometry, cortical auditory-evoked response (CAER), brainstem auditory-evoked response (ABR) and electronystagmography. We also obtained ABR and CAER findings in 2 cases of familial spastic paraplegia, in 5 cases of Charcot-Marie-Tooth disease and 6 in cases of atypical FA of uncertain classification. The results of puretone and impedance audiometry were normal in all cases. ABR could not be elicited in 11 FA patients and were abnormal at higher intensity levels in the remaining 4 patients. In these 4 cases, however, the latencies were normal. ABR did not show any marked abnormalities in patients with familial spastic paraplegia or Charcot-Marie-Tooth disease. CAERs were normal in all 28 patients. ABRs tended to be absent with the progression of FA. ABR thresholds were correlated with the Inherited Ataxias Clinical Rating Scale score, which is an index of the severity of the illness. ABRs contributed to the diagnosis or to excluding FA in patients with an atypical clinical picture. The absence of ABRs and the normal latencies of the waves, when evoked, agree with the pathological finding of a reduction of fibers in the spinal root ganglion. SSI abnormalities and vestibular findings agree with this hypothesis.