Harlequin Syndrome Associated with Erector Spinae Plane Block
Bibliographic record
Abstract
Harlequin syndrome represents a partial autonomic neuropathy.1 The characteristic appearance is sharply demarcated hemifacial erythema (arrow) and diaphoresis. The underlying pathologic process involves ipsilateral interruption of the autonomic pathway between the hypothalamus, intermediolateral column of the spinal cord, cervical sympathetic ganglia, and postganglionic sympathetic fibers, resulting in relative ipsilateral facial pallor and anhidrosis with contralateral overcompensation.1,2The patient pictured was noted to have right-sided facial erythema and right upper limb diaphoresis with concomitant hypotension after receiving a left-sided T3 erector spinae plane block with 20 ml of adrenalized 0.5% ropivacaine for radical mastectomy and axillary dissection. The patient’s symptoms were transient. The image, acquired at 6 h, followed partial resolution. Complete resolution of the hemodynamic and sudomotor/vasomotor features occurred within 4 h and 12 h, respectively.Sympatholysis after erector spinae plane block implies paravertebral local anesthetic spread with activity at the rami communicantes or sympathetic chain. Oculomotor fibers exit the spinal cord at T1, whereas sudomotor and vasomotor fibers supplying the face and upper limb exit the spinal cord at T2–T3 and T4, respectively.2 Harlequin syndrome with upper limb symptoms in the absence of Horner’s syndrome indicates sympathetic blockade from T2–T4, which correlated with the T2–T5 sensory block observed.To the best of our knowledge, Harlequin syndrome has not previously been reported after erector spinae plane block. We present this image to educate fellow clinicians about this rare, self-limiting condition which, in the absence of additional neurologic findings, warrants gentle reassurance, and to support the hypothesis that erector spinae plane block is a paravertebral block by-proxy3 that potentially predisposes to similar hemodynamic consequences.The authors declare no competing interests.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.001 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.000 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.000 | 0.001 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.003 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".