RESUMEN
BACKGROUND: Harlequin syndrome is a rare autonomic condition consisting of unilateral facial flushing and sweating induced by heat, emotion or physical activity. The affected side presents anhidrosis and midline facial pallor due to denervation of the sympathetic fibers. CASE DESCRIPTION: This case describes a patient who reported right-side redness of the face associated with hyperhidrosis during physical activity. She had two previous major motor vehicle accidents. The patient demonstrated difficulties in the visual accommodation of the left eye, but cranial nerve assessment was unremarkable; the patient was then referred to an ophthalmologist, who excluded any autonomic dysfunction as the primary cause of convergence and visual acuity. OUTCOMES: A left-sided sympathetic dysfunction with Harlequin sign diagnosis was made followed by a progressive compensatory adaptation of the right face. The patient was educated and reassured about the benign nature of her problem. DISCUSSION: Knowledge of the autonomic nervous system is still limited in clinical practice. Although challenging, physiotherapists should develop the knowledge and ability needed to perform appropriate assessment of autonomic dysfunctions. CONCLUSION: A dispositional reasoning model should be considered in differential diagnosis.