Does the stapes reflex remain the same after Bell's palsy?

The authors investigated the integrity and function of nervus stapedius 1 year after facial paralysis.

Patients with Bell's palsy were observed prospectively for 1 year and compared with healthy patients.

The follow-up of patients was done in the outpatient clinic and tests were applied in the audiology unit.

The mean age of 32 patients was 41.03 years. Eight of 32 patients were grade II (25%), 11 were grade III (35%), and 13 were grade IV (40%) according to House-Brackman grading system. The mean age of the control group (10 persons) was 36.5 years.

Contralateral stimulus was used in acoustic reflex test at 500 and 1,000 Hz with 80-, 90-, 100-, and 110-dB stimulus intensity. Tests were applied in three ways: normal position, eye-closed position, and grin position. Tests were done in the first 15 days of facial paralysis and repeated at least 1 year thereafter. The millimeter difference in amplitude of impedance recording of middle ear between the normal ear and paralyzed ear was accepted as criterion.

There were 6- to 9-mm amplitude differences between normal side and healed side of grade IV patients with 100- and 110-dB stimuli.

In the second test (after 1 year), statistically significant differences were present between control group and grade IV patients on 1,000 and 500 Hz frequencies with 100- and 110-dB stimulus intensity (p < 0.05). There were no significant differences between grade II and control group and between grade III and control group.

A permanent partial denervation is present on the stapedial nerve, especially after grade IV paralysis, and it affects the function of stapes muscle in high decibel sounds. But it does not affect the stapes reflex threshold. No synkinetic innervation was found in the authors' patient group with their test method.