Hearing disturbances in hypertrophic cardiomyopathy. Is the sensorineural disorder neurogenic or myogenic?

BACKGROUND: In a previous study, we demonstrated that a hidden hearing defect is present in about 50% of patients with hypertrophic cardiomyopathy (HCM). Such defects were found significantly less frequently in age and clinical stage-matched patients with dilated cardiomyopathy (DCM), and were practically absent in patients with valvular aortic stenosis, and in patients taking beta-receptor blockers for different reasons (such as hypertension, ischemic heart disease, etc.). The hearing disturbances were first examined by means of brain-stem evoked response audiometry (BAEP). This method permitted only a rough differentiation between the origins of cochlear (myogenic) and retrocochlear (neurogenic) hearing disturbances, and did not allow us to establish their myogenic or neurogenic nature with certainty. AIMS: Our present aim was to determine whether the hearing disturbances present in HCM and DCM patients are myogenic or neurogenic in origin. METHODS: The neurogenic function of the inner ear was examined by BAEP as before, and the myogenic function by the distortion product otoacoustic emission technique. RESULTS: Myogenic abnormalities were found in 39/69 ears (57%) and neurogenic abnormalities in 19/69 (28%) ears among the HCM cases, as compared with 14/39 (36%) and 8/39 (21%) ears respectively among the DCM cases (p<0.005). Healthy controls displayed the lowest incidence of both types of hearing abnormalities. CONCLUSION: Our results lead us to conclude that myogenic lesions are more frequent than neurogenic lesions in patients with HCM. Both myogenic and neurogenic lesions are more frequent in HCM patients than in DCM patients or healthy controls. It may be hypothesized that abnormal sarcomeric proteins present in the muscular structures of the inner ear in HCM are possibly responsible for the hearing disorders in these patients, and that this is not merely a neurological defect.

ALA (5-aminolevulinic acid)-induced protoporphyrin IX fluorescence in the endoscopic diagnostic and control of pharyngo-laryngeal cancer.

Photodynamic diagnosis is a modern method for the fluorescence imaging of superficial pharyngeal and laryngeal tumours. 5-aminolevulinic acid (ALA)-induced protoporphyrin IX fluorescence benefits the tumour selective accumulation of protoporphyrin; therefore, tumours can be differentiated from healthy tissue. ALA-induced fluorescence of laryngo-pharyngeal tumours and precancerous and benign lesions were evaluated by endoscopy. At the Department of Otorhinolaryngology, Head and Neck Surgery, Szeged, Hungary, 31 patients underwent ALA-induced protoporphyrin fluorescence imaging. After topical application of ALA, mesopharyngeal tumours were visualised by direct fluorescence endoscopy. Laryngeal and hypopharyngeal tumours were examined with a laryngomicroscope with the patients under general anaesthesia after inhalation of an ALA solution. Intensity of PPIX fluorescence was classified and compared with pathological findings. The examination of all 13 laryngeal and 12 pharyngeal tumours resulted in a middle or strong intensity of red fluorescence, but for one cancer, four precancerous and two benign lesions. Healthy tissues showed green autofluorescence. Margins of mesopharyngeal and vocal cord tumours were clearly outlined under fluorescent vision, giving a helpful contribution to diagnosis and therapy even in clinically non-visible tumours. Laryngomicroscopy combined with laser surgery also indicated PPIX fluorescence examination visualising margins of the tumour intermediately with the endoscope. The ALA-induced PPIX fluorescence imaging method revealed a sensitivity of 96%. This method is applicable for detecting early superficial tumours, margins of tumours and follow-up after surgery/radiation therapy in the laryngo-pharynx.

Investigation of auditory brainstem function in diabetic patients.

We performed brainstem auditory evoked potential (BAEP) examinations in 15 patients with long-standing type 1 diabetes mellitus. We applied cardiovascular reflex tests for assessment of autonomic neuropathy. The aim of our investigation was to compare the BAEP results of this patient group with those of controls and to look for the possible correlation between alteration of the auditory brainstem function and cardiovascular autonomic neuropathy. Analysis of the latencies (waves I, II, III, and V) and the interpeak latencies (I-III and I-V) of BAEP revealed a significant difference between those of diabetics and those of healthy controls. The amplitudes of waves I, III, and V were definitely lower in comparison with amplitudes of healthy controls. We observed a positive correlation between the overall autonomic score and the latencies (waves III and V) and interpeak latencies (I-III, I-V). These data support the hypothesis that long-standing diabetes mellitus and diabetic neuropathy might be revealed as a cause of certain dysfunctions of the central auditory pathways.

Neural response telemetry in cochlear implant users.

Programming of multichannel cochlear implants requires subjective responses to a series of sophisticated psychophysical percepts. It is often difficult for cochlear implant patients (especially young prelinguistically deaf children) to provide adequate responses for device fitting. However, the neural response telemetry (NRT) system renders possible the measurement of the compound action potential threshold. We performed NRT examinations in 27 cochlear implant users with Nucleus 24-channel cochlear implants. Measurements were obtained from five electrodes (3, 5, 10, 15, and 20) in each patient. Our goal was to look for correlation between behavioral subjective thresholds and compound action potentials. The action potentials could be elicited in 23 patients in all measured electrodes. The NRT threshold values were highly correlated with electrical threshold levels obtained through subjective responses. Our results suggest that the electrically elicited neural responses may yield very important information for device fitting in patients with cochlear implants.