ANESTHESIA FOR EAR SURGERY

Safe, comfortable operating conditions can be provided for ear surgery by infiltration of a local anesthetic or by administration of general anesthesia. ^[244]

Local Anesthesia

Procedures such as premeatal operations, stapedectomy, and uncomplicated middle ear surgery can be performed on selected patients with the use of a local anesthetic and titrated sedation. Patients should be able to understand and communicate and be cooperative. The anesthesiologist should perform the same thorough preoperative medical evaluation as for general anesthesia. Light sedation can be achieved by titrating intravenous propofol (0.5 to 0.7 mg/kg) during the injection of local anesthetic and, if necessary, adding midazolam (0.02 to 0.04 mg/kg IV) during the procedure.

Nerve Block

Four nerves provide sensory innervation of the ear.

1. The auriculotemporal nerve supplies the outer auditory meatus. It is blocked by the injection of 2 mL of local anesthetic into the anterior wall of the external auditory meatus.
2. The great auricular nerve supplies the medial-lower aspect of the auricle and part of the external auditory meatus.
3. The auricular branch of the vagus nerve runs between the mastoid process and the external auditory meatus and supplies the concha and external auditory meatus. The great auricular and auricular (vagus) nerves can be blocked by the injection of 2 to 3 mL of local anesthetic posterior to the ear canal.
4. The tympanic nerve supplies the tympanic cavity and can be blocked topically by the instillation of sterile 4% lidocaine. When a large perforation of the tympanic membrane has occurred, care must be taken to not place toxic substances into the auditory canal and damage the middle ear cavity.

The addition of epinephrine to the local anesthetic increases the intensity and duration of the effect and provides some local vasoconstriction, thereby decreasing bleeding. A safe dose of epinephrine is 0.1 mg (10 mL of a 1:100,000 concentration) and may be repeated after 20 minutes.