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Acoustic-reflex responses in patients with insulin-dependent diabetes mellitus
J Virtaniemi1, M Laakso, J Nuutinen
1Department of Otolaryngology, University of Kuopio, Finland.
Purpose:
Patients with insulin-dependent diabetes mellitus (IDDM) are especially susceptible to microangiopathic complications such as nephropathy, retinopathy, and neuropathy. Microangiopathic changes are also the most important findings in histopathologic studies of the inner ear and central nervous systems in diabetic subjects. No previous studies have measured acoustic-reflex latencies (ARL) or amplitudes (ARA) in patients with IDDM. ARL and ARA reflect the function of the acoustic-reflex arch. Furthermore, possible changes in the tympanic membrane, ossicular chain, and stapedius muscle may affect the shape of acoustic-reflex.
Subjects And Methods:
Acoustic-reflex thresholds, latencies, and amplitudes were studied in 53 patients with IDDM and 42 randomly selected nondiabetic control subjects, aged between 20 and 40 years, using the Madsen Model ZO 73 Impedance Bridge (Madsen Electronics, Copenhagen, Denmark). Subjects with an abnormal tympanic membrane, conductive hearing loss, and known cause for hearing impairment eg, noise damage, were excluded from the study.
Results:
There were no differences between control and diabetic subjects in the contralateral acoustic-reflex thresholds. In contrast, patients with IDDM had longer ARLs and decreased ARAs compared with those of control subjects. ARA amplitude had linear correlation with the amplitude of tympanogram, whereas ARL had no linear correlation with auditory brainstem latencies in the same study subjects. Acoustic-reflex responses in insulin-dependent diabetic patients were not associated with the duration of diabetes, metabolic control, microangiopathy, or neuropathy.
Conclusions:
Prolonged ARLs and decreased ARAs in patients with insulin-dependent diabetes are probably caused more by the stiff middle ear system than disturbances in the brainstem.
Insights
Patients with insulin-dependent diabetes mellitus (IDDM) show prolonged acoustic-reflex latencies and decreased amplitudes, suggesting middle ear stiffness rather than brainstem issues. This impacts auditory function in diabetics.
Area of Science:
- Otolaryngology
- Endocrinology
- Audiology
Background:
- Insulin-dependent diabetes mellitus (IDDM) is linked to microangiopathic complications affecting various organs.
- Histopathologic studies show microangiopathic changes in the inner ear and central nervous system of diabetic individuals.
- Acoustic-reflex latencies (ARL) and amplitudes (ARA) reflect acoustic-reflex arch function, but haven't been studied in IDDM.
Purpose of the Study:
- To investigate acoustic-reflex thresholds, latencies, and amplitudes in patients with IDDM.
- To compare these auditory parameters between IDDM patients and non-diabetic controls.
- To explore potential correlations between ARL/ARA and diabetes-related factors.
Main Methods:
- Acoustic-reflex thresholds, latencies, and amplitudes were measured in 53 IDDM patients and 42 controls (aged 20-40).
- Measurements were performed using the Madsen Model ZO 73 Impedance Bridge.
- Exclusion criteria included abnormal tympanic membrane, conductive hearing loss, or known hearing impairment causes.
Main Results:
- No significant differences in contralateral acoustic-reflex thresholds were found between groups.
- IDDM patients exhibited significantly longer ARLs and decreased ARAs compared to controls.
- ARA amplitude correlated linearly with tympanogram amplitude, but ARL did not correlate with auditory brainstem latencies.
Conclusions:
- Prolonged ARLs and decreased ARAs in IDDM patients likely stem from middle ear system stiffness.
- These findings suggest middle ear changes, rather than brainstem disturbances, are primarily responsible for altered acoustic reflexes in IDDM.
- The study highlights potential subclinical auditory pathway involvement in IDDM.