Detection of subclinical Harlequin syndrome in pediatric patients

Harlequin syndrome presents as differences in facial coloring due to unilateral flushing. This is the result of the inability to flush on the affected side due to the disruption of vasomotor and sudomotor sympathetic activity. The neurologically intact side appears flushed. A 2°C temperature difference between the flushed and nonflushed sides of the face has been detected in patients presenting with Harlequin syndrome. This difference in temperature might be detectable even in the absence of unilateral flushing, and this subclinical manifestation of the syndrome may occur more often than realized.

To measure and compare the difference in the change in temperature on both sides of the face in patients with a thoracic epidural.

Fifteen pediatric patients receiving thoracic epidurals for the correction of pectus excavatum via Nuss procedure were enrolled. Temperature measurements on each side of the face were collected at three time points: prior to epidural placement in the holding area, one hour after epidural analgesia had been instituted, and after the patient awakened in the recovery area. The primary outcome is whether or not a temperature difference occurred between the two sides of the face over time.

Comparing the pre-op temperature change to post-op temperature change for each side of the face, patient 2 had a large increase in temperature on the left side of the face with a decrease in temperature on the right side of the face. The largest observed difference between the changes in temperature from pre-op to post-op between the right and left sides of the face was 1.85°C in patient 2. This was more than two standard deviations from the mean difference in the patient population. Patient 15 also had a large difference in change in temperature from pre-op to post-op between the right and left sides of the face with an observed difference of 1.14°C, although this was not more than two standard deviations from the mean. None of the patients had unilateral facial flushing.

Asymmetric effects or distribution of local anesthetic used in thoracic epidurals may result in asymmetric blockade of efferent sympathetic nervous system activity. This may cause differences in temperature between the two sides of the face without unilateral flushing. This phenomenon has previously been termed subclinical Harlequin syndrome. Subclinical Harlequin syndrome may be more common than anticipated and may be detected by comparing temperature differences in patients.