SUMMARY

Horner's syndrome is a rare condition that results from damage to the oculosympathetic chain. The classical presentation consists of miosis, unilateral ptosis and hemifacial anhidrosis due to a deficiency of sympathetic activity. Although it has been described as a result of different types of trauma, we present the first clinical report of Horner's syndrome that was developed after a fine-needle aspiration puncture of a thyroid nodule. A 48-year-old woman with a non-toxic multinodular goiter underwent an ultrasound-guided fine-needle aspiration for the second time for a nodule located at the right thyroid lobe. Four hours after the procedure, she developed homolateral eyelid ptosis, miosis and enophthalmos and went to the emergency department for observation. Structural causes potentially related to the manifestations were excluded. Horner's syndrome was diagnosed and the patient was discharged with symptomatic measures. Three months after the event, the patient reported partial improvement. We discuss the pathophysiology associated with Horner's syndrome, the association with thyroid diagnostic and therapeutic procedures, clinical presentation, patient management and prognosis. Although fine-needle aspiration of a thyroid nodule has few associated complications, Horner's syndrome should be considered when the patient develops ophthalmologic symptoms. Preventive measures should be observed to minimize its occurrence.

LEARNING POINTS

Horner's syndrome is a potential complication of diagnostic and therapeutic procedures directed at the thyroid gland, including ultrasound-guided fine-needle aspiration. It is characterized by eyelid ptosis, miosis, enophthalmos and anhidrosis homolateral to the lesion. The diagnosis of Horner's syndrome is clinical after excluding structural causes and establishing the temporal relationship between the procedure and the manifestations. There is no targeted treatment for Horner's syndrome, but it can be prevented.