[Iatrogenic anisocoria after using a scopolamine patch for PONV prophylaxis]

This is a case report of a 29-year-old female patient who developed unilateral mydriasis following the use of a scopolamine patch for the prevention of postoperative nausea and vomiting (PONV).Given a medical history showing multiple risk factors for PONV, a preauricular scopolamine patch was applied prior to the induction of anesthesia. General anesthesia was induced with 150 mg propofol and 25 μg sufentanil and maintained with total intravenous anesthesia, using propofol (5 mg/kg per h) and remifentanil (2-3 μg/kg per h).Following an uneventful surgery of 90min duration, the patient was extubated and transferred to the recovery room, where the patch was removed. During the orthopedic ward round the following day, the clinical examination revealed anisocoria of the left eye in the form of unilateral mydriasis. In order to determine the cause of this clinical presentation, further neurological and ophthalmological examinations and investigations were carried out. In addition, magnetic resonance imaging was conducted to rule out a central nervous cause. The results of the investigations were negative and no pathology was identified. In addition, the symptoms resolved within 24 h of onset without any therapeutic intervention. Therefore, a suspected diagnosis of a pharmacologically induced anisocoria from the scopolamine patch was made, whereby the substance accidentally reached the affected left eye.Previous studies showed that scopolamine patches may reduce early emetic symptoms. Case reports describing the occurrence of anisocoria following the application of scopolamine patches have been previously published. In all of these cases the patches were used to prevent PONV and each case was comprehensively investigated using various diagnostic and clinical tools. It should be noted, however, that a dysfunctional accommodation is listed as a common side effect of the drug, affecting more than 1 in 10 patients.Even though the efficacy of scopolamine patches for the prevention of PONV is proven, clinicians should be aware of the common ophthalmological side effect. Particularly with respect to various surgical disciplines, where anisocoria may indicate an underlying surgery-related complication, the application of scopolamine patches should be well- considered.

Keywords: Accommodation; Postoperative nausea and vomiting; Side effect; Transdermal scopolamine; Unilateral mydriasis.