Brainstem anaesthesia following single medial canthal peribulbar block: A case report and review

Abstract

Brainstem anaesthesia, the most dreaded complication of regional opthalmic anaesthsia has been reported with all routes with the exception of medial canthal peribulbar blocks. We report the first case of brainstem anaesthesia following a single medial canthal peribulbar block in a patient scheduled for cataract surgery and explore the factors that set the stage for this life-threatening complication. These include: A relatively short axial length of the globe, needle trajectory, position of the needle tip in relation to the posterior plane of the globe,and, the optic nerve. We introduce the concept of ‘Cornea to Canthus distance’ and urge that it is factored in when estimating the depth of needle tip during medial canthal peribulbar approach to avoid inadvertent retrobulbar intraconal injection. This case highlights that the ingress of local anaesthetic into subarachnoid space is unpredictable, and can occur without a direct neural breach. This case, unfortunately, was also complicated with a challenging airway. We reiterate the importance of the immediate availability of advanced resuscitative facilities, and, an experienced anaesthetist for all units providing regional ophthalmic anaesthesia.