Impact of Interscalenous Block Anesthesia on Hearing

Interscalene brachial plexus block (ISBPB) is used for both anesthesia and analgesia purposes in shoulder, clavicle and upper arm surgeries. It is also frequently used to obtain analgesia in the postoperative period especially in patients undergoing shoulder surgeries. Thus, it provides decrease in opioid need and opioid related side effects in the perioperative period. The effect of IBPB on hearing is probably not caused by an effect on the vestibulocochlear nerve because of its central location. The innervation area of the greater auricular nerve, a derivative of the cervical plexus, is often involved in an IBPB. However, this nerve is not known to affect hearing. The nerves supplying the outer ear canal and the tympanic membrane (branches of the mandibular, facial and vagal nerves) are located far enough from the IBPB injection site to make their involvement unlikely. However, sound conduction through the middle ear to the inner ear, and functioning of the spiral organ of the cochlea may be indirectly affected by regional sympathetic block that is most likely seen after IBPB. Sympathetic block may cause vasodilatation and swelling of the mucosal membranes of the middle ear and the eustachian tube with deterioration of hearing.

The patient will be examined by ENT physician on the morning of the operation, after a detailed anamnesis. otoscopic examination will be performed, pure tone audiometry, speech audiometry and tympanometric examination will be performed and recorded.The same tests will be performed at the next day after the surgery but before the discharge and also when he/she applies for the first week check-up. Ultrasaoun guided Interscalene block anesthesia will be applied to all patients. Each patient will be treated with the same multimodal analgesia method at the postoperative period.

Inclusion criteria

• participants are undergoing a shoulder surgery.
• ASA I and II patients without uncontrolled diabetes and hypertension
• participants have normal or near-normal hearing thresholds in the un-operated ear

Exclusion criteria

• participants have hearing loss (PTA > 35 dB HL) in pure tone audiometry testing before surgery in any side
• participants have medical conditions after the surgery which prevents having hearing tests
• participants have abnormal tympanometric results
• participants with chronic otitis media or a history of ear surgery