Acoustic reflex patterns in amyotrophic lateral sclerosis.

Area of Science:

• Neurology
• Audiology
• Otoacoustic Emissions

Background:

• Amyotrophic lateral sclerosis (ALS) is a progressive neurodegenerative disease primarily affecting motor neurons.
• Auditory pathway involvement in ALS is not fully understood, necessitating further investigation into subclinical manifestations.
• Acoustic reflex testing can provide insights into the function of the stapedial reflex pathway, which involves cranial nerves.

Purpose of the Study:

• To investigate acoustic reflex parameters (amplitude, latency, rise time) in patients with amyotrophic lateral sclerosis (ALS).
• To compare acoustic reflex measures between ALS patients (bulbar and spinal subtypes) and healthy controls.
• To determine the sensitivity of acoustic reflex parameters in detecting subclinical bulbar involvement in ALS.

Main Methods:

• Fifty-one ALS patients and ten age- and sex-matched controls underwent acoustic reflex testing.
• Stapedial reflex was recorded for 500 Hz and 1000 Hz contralateral acoustic stimuli.
• Statistical analysis utilized the Wilcoxon test with a significance level of 5%.

Main Results:

• All ALS patients exhibited present stapedial reflexes.
• ALS patients showed statistically significant differences in mean amplitude, latency, and rise time compared to controls.
• Lower amplitude and longer rise time were observed in both bulbar and spinal ALS patient groups compared to controls (p < 0.05).

Conclusions:

• Abnormal acoustic reflex patterns are present in ALS patients, particularly those with bulbar signs.
• The findings suggest potential subclinical involvement of the stapedial motor neuron even in spinal ALS patients.
• Acoustic reflex amplitude and rise time appear to be sensitive indicators for detecting subclinical bulbar involvement in ALS.