Bilateral hearing loss following a retrobulbar block

Abstract

Purpose: Regional anesthesia is the most commonly used ophthalmological anesthetic technique in Canada and the United States. Brainstem anesthesia is not an uncommon complication of retrobulbar blocks. Anesthesiologists are a prominent element in the ophthalmology suite, in part due to the complications possible with regional anesthesia. This is the first reported case of complete bilateral hearing loss following a retrobulbar block. Clinical features: A 46-yr-old male with type 1 diabetes mellitus presenting for ophthalmological surgery had a retrobulbar block performed by the ophthalmologist. Local anesthetic was injected through a 25 G, 1.5 inch needle, entering the orbit inferiorly on the temporal third of the lower lid. Shortly after the block was completed the patient experienced sudden hearing loss. On examination the hearing loss appeared to be complete and bilateral. The patient was alert and oriented; the remainder of the cranial nerve exam was normal. The patient's hearing loss gradually improved and three hours after the block his hearing had subjectively returned to normal. Conclusion: Brainstem anesthesia is not a rare complication of regional anesthesia for ophthalmological surgery. Symptoms include confusion, mental agitation, dizziness, blurred vision or blindness, ophthalmoplegia, deafness, tinnitus, dysphagia, dysarthria, respiratory depression to apnea, and/or limb paralysis. A connection between the subdural and subarachnoid spaces and the optic sheath exists. The effect on the central nervous system depends upon the amount of local anesthetic injected and the area to which it spreads.