Case report: A Unique Case of Brainstem Anesthesia and Contralateral Amaurosis Following a Sub-Tenon Block.

Purpose: To report and discuss a case of brainstem anesthesia and contralateral amaurosis following a sub-Tenon block.

Methods: Single surgical case report of a patient who underwent an uncomplicated pars plana vitrectomy for an epiretinal membrane peel in the left eye following a sub-Tenon anesthesia technique.

Results: Post-operatively, the patient experienced symptoms of brainstem anesthesia as well as akinesia, a non-reactive pupil, and reduced visual acuity in the contralateral eye which gradually resolved within 24 hours. Imaging was within normal limits and did not reveal any anatomic abnormalities.

Conclusion: Despite the use of a blunt-ended cannula in a sub-Tenon block, there is a non-negligible risk of it penetrating surrounding structures such as the optic nerve sheath. This case emphasizes the importance of monitoring for brainstem anesthesia and contralateral eye affections in patients both intra- and post-operatively.