Allergic reaction to hyaluronidase after a peribulbar injection

Hyaluronidase is a testicular protein, which hydrolyses hyaluronic acid, a structural component of the intercellular ground substance. It is often mixed in the local anaesthetic solutions used in ophthalmic regional anaesthetic techniques in order to improve the anaesthetic action in terms of speed of onset and spread of block. It is known to be a potential cause of allergic adverse events although there are few reports and little detail in the literature. Consequently, we are reporting a recent case at our institution. A 41-year-old, 56 kg female presented for removal of a circumferential explant placed a year previously to treat a left sided retinal detachment. Her past medical history included breast carcinoma, treated 2 years ago with mastectomy, irradiation and chemotherapy. Her only regular medication was tamoxifen and she had no known allergies. She reported severe postoperative nausea and vomiting following general anaesthesia, so after discussion it was decided to use a local anaesthetic technique. Sub-Tenon's anaesthesia was impossible due to the explant positioning, so an infero-temporal peribulbar injection using a 25 gauge 25 mm needle was performed. A solution of 2 ml prilocaine 3% with felypressin 0.03 iµ.ml−1 and 3 ml levobupivacaine 0.75%, containing 15 iµ.ml−1 hyaluronidase was injected. Within 5 min of the injection, she developed marked periorbital erythema and then oedema, which spread to the contralateral side (Fig. 8). Hemorrhage was considered briefly, but excluded as the appearances were more consistent with an allergic response. There was no systemic evidence of anaphylaxis. Intravenous chlorpheniramine 10 mg and dexamethasone 8 mg were administered. The swelling settled over the next 20 min, and it was possible to remove the explant uneventfully. Allergic reaction to the local anaesthetic. Her postoperative course was unremarkable and at last follow-up she had a flat retina with 6/6 visual acuity. In view of the implications for further surgery and anaesthesia, she was referred to an immunologist who performed skin prick testing to chloramphenicol, hyaluronidase, levobupivacaine and prilocaine with felypressin. This test showed a marked positive reaction to hyaluronidase consistent with Type 1 IgE mediated hypersensitivity. She had no known prior exposure to hyaluronidase. Although allergy to hyaluronidase is a known side-effect, there have been only three case reports of adverse events during ocular anaesthesia [1-3]. Similar to our case, the reactions were limited locally, and terminated following treatment with antihistamines. However, in one, the rapid rise in orbital pressure led to vitreous loss during surgery [1]. Rapid peri-orbital swelling following an orbital injection suggests haemorrhage, but although rare, the possibility of hyaluronidase allergy should be considered and appropriate investigations performed even in individuals with no known prior exposure.