Harlequin syndrome is defined by the presence of hemifacial flushing and diaphoresis [1]. This rare condition is likely a malfunction of the sympathetic network in the upper thoracic region (with the exception of the first segment) [1] [2]. Although the exact cause of this disorder is not clear and the majority of cases are idiopathic, some are iatrogenic [2] [3]. For example, Harlequin syndrome is associated with the removal of neck lesions, lung resection, paravertebral thoracic block, catheterization of the jugular vein, dissection of the carotid artery, and thoracic sympathectomy [3] [4]. Moreover, cases have been described to develop after resection of superior mediastinal neurinoma [5] and other types of compression tumors on the sympathetic chain [6] [7]. Additionally, Harlequin syndrome can also result following a stroke, Horner's syndrome [1], and even autoimmune hyperthyroidism [4].

Report of a patient who underwent resection of a ganglioneuroma located on the thoracic spine developing a midline mark on the face with asymmetric flushing and warmth appearing on half of the face, neck, as well as the chest has been highlighted in the literature [3]. The onset in such situation was shortly after surgery and discovered in the postoperative unit. Crying worsened these findings [3], which is consistent with the fact that Harlequin syndrome is precipitated by emotion, physical activity, and elevated temperature [1] [2] [3]. Symptoms resolved 3 hours following surgery and did not recur. While this ailment is generally benign and resolves without medical intervention a few hours after onset, some patients have been spoken about to have chronic symptoms [3].

Physical exam

In the case discussed above, there were no abnormalities in vital signs or the neurologic or cranial nerve exams [3]. Note that a thorough neurologic exam, including the pupillary response as well as the deep tendon reflexes, should be performed [8].

Anyone who appears with asymmetric facial flushing and sweating following thoracic surgery warrants assessment of the clinical presentation, a physical exam with a neurologic focus, imaging, and possibly other studies. The laboratory tests are usually normal [3]

Imaging

The workup should include imaging modalities to rule out other conditions that may cause a clinical picture similar to Harlequin syndrome. Specifically, the brain and the cervicothoracic segments of the spine should be assessed for tumors or other pathologies with computed tomography (CT) scan and magnetic resonance imaging (MRI) [8] [9].

Other

Chronic idiopathic cases may require a sweat test for evaluation of involved body parts [10]. Other studies include cardiovascular autonomic reflex tests, microneurography for assessment of sympathetic nerve function, and biopsy of affected skin [10]. Very importantly, the pupillary and deep tendon reflexes should be tested as noted earlier [8].

There is no specific treatment for Harlequin Syndrome, as it is generally a benign condition. Management focuses on addressing any underlying causes, if identified, and alleviating symptoms. In cases where the syndrome is associated with significant psychological distress, counseling or support groups may be beneficial. For those who find the flushing particularly bothersome, medications that reduce sweating, such as anticholinergics, may be considered.

The prognosis for individuals with Harlequin Syndrome is generally good. The condition is not life-threatening and does not typically progress to more serious health issues. However, the symptoms can persist over time. In some cases, if an underlying cause is identified and treated, the symptoms may improve or resolve.

The exact cause of Harlequin Syndrome is not well understood. It is believed to result from damage or dysfunction in the autonomic nervous system, particularly affecting the sympathetic nerves that control sweating and blood flow. This damage can be due to various factors, including:

• Surgical Procedures: Especially those involving the chest or neck.
• Trauma: Physical injury to the nerves.
• Tumors: Growths that may compress or damage the nerves.
• Idiopathic: In many cases, no specific cause is identified.

Harlequin Syndrome is considered a rare condition, with only a limited number of cases reported in the medical literature. It can occur in individuals of any age, but there is no clear data on its prevalence or incidence. Both males and females can be affected, and there does not appear to be a significant gender predisposition.

The pathophysiology of Harlequin Syndrome involves a disruption in the sympathetic nervous system, which is part of the autonomic nervous system responsible for regulating involuntary bodily functions. In this syndrome, there is an imbalance in the sympathetic nerve supply to the face and body, leading to the characteristic one-sided flushing and sweating. This imbalance may be due to nerve damage or dysfunction, but the precise mechanisms remain unclear.

As the exact cause of Harlequin Syndrome is often unknown, specific preventive measures are not well established. However, minimizing risk factors that could potentially damage the autonomic nervous system, such as avoiding unnecessary surgical procedures or protecting against trauma, may be beneficial. Early detection and management of any underlying conditions that could contribute to nerve damage are also important.

Harlequin Syndrome is a rare neurological disorder characterized by asymmetric facial flushing and sweating. It results from a disruption in the autonomic nervous system, often due to nerve damage or dysfunction. While the condition is generally benign, it can cause significant psychological distress. Diagnosis involves clinical evaluation and tests to rule out other conditions. There is no specific treatment, but management focuses on symptom relief and addressing any underlying causes. The prognosis is typically good, with symptoms persisting but not progressing to more serious health issues.

If you or someone you know is experiencing symptoms of Harlequin Syndrome, such as one-sided facial flushing and sweating, it is important to seek medical evaluation. While the condition is not life-threatening, understanding the symptoms and potential underlying causes can help manage the condition effectively. Support from healthcare professionals, as well as counseling or support groups, can be valuable in coping with the social and psychological impacts of the syndrome.

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