Horner Syndrome After Radiofrequency Ablation of a Benign Thyroid Nodule.

A 56-year-old woman presented for evaluation of a right thyroid nodule causing dysphagia. Thyroid function tests were normal. Ultrasound showed an isoechoic right thyroid nodule measuring 3.6 × 2.1 × 3.5 cm. After fine needle biopsy demonstrated benign pathology, ultrasound-guided radiofrequency ablation (RFA) of the nodule was performed. One day after the procedure, the patient developed a miotic, non-reactive right pupil, right upper eyelid and cheek swelling, right upper eyelid ptosis, and injection of the right eye. The patient was diagnosed with Horner syndrome (HS). RFA is a safe, minimally invasive procedure for the treatment of benign thyroid nodules. However, providers performing RFA should be aware of the possibility of HS in the immediate post-procedural period and beyond.