IntroductionHorner syndrome (HS) in the emergency department (ED) is never a trivial finding. While it often signals catastrophic vascular or neoplastic disease such as carotid dissection or apical lung cancer, spinal cavernous hemangioma (SCH) is an extraordinarily rare etiology. Its recognition is critical, as missing this subtle sign may delay lifesaving intervention.Case PresentationWe describe a 21-year-old previously healthy male who presented with acute neck pain, progressive right upper limb weakness, and contralateral lower limb paresthesia. Careful examination revealed right-sided ptosis and miosis, unveiling HS. Urgent cervical MRI demonstrated a 47 × 11 mm intradural lesion at C6–C7, consistent with a cavernous hemangioma. The patient underwent emergent microsurgical resection, resulting in rapid neurological recovery. By two months, all deficits—including HS—had completely resolved.ConclusionThis case underscores that even the most subtle ocular sign can unmask life-threatening spinal pathology in the ED. HS should be approached as a clinical alarm bell, mandating immediate imaging and multidisciplinary coordination. Recognizing SCH as a potential—though rare—culprit expands the emergency physician’s diagnostic horizon and illustrates how prompt diagnosis and timely surgery can transform an impending catastrophe into full recovery.References1. Chen J, Lee H, Park H, et al. Horner syndrome as a presenting sign of carotid artery dissection: diagnostic challenges in the ED. Emerg Med J. 2021;38(5):372-5.2. Kline LB, Bajandas FJ. Neuro-ophthalmology review manual. 8th ed. Thorofare (NJ): Slack Inc; 2020.3. Nielsen JK, Olsen LH, Schroeder TV. Acute Horner syndrome in emergency settings: importance of rapid differential diagnosis. Eur J Emerg Med. 2022;29(1):8-13.4. Chen L, Li Y, Liu J, et al. Emergency presentations of Horner syndrome: a multicenter analysis. Am J Emerg Med. 2021;44:118-24.5. Song J, Park JH, Lee HS. Clinical spectrum of Horner syndrome in acute care: diagnostic pitfalls. Front Neurol. 2020;11:611.6. Gross BA, Du R. Spinal cavernous malformations: clinical features and surgical management. Neurosurg Focus. 2021;50(6):E15.7. Li D, Hao SY, Wu Z, et al. Clinical features and surgical outcomes of intramedullary cavernous malformations. Neurosurgery. 2020;87(2):314-23.8. Rajasekaran S, Soundararajan DCR, Kabir SM, et al. Spinal cavernous hemangiomas with atypical findings: case series. Spinal Cord Ser Cases. 2019;5:101.9. Matsumoto K, Takahashi T, Saito T, et al. Rare presentation of spinal cavernous hemangioma with Horner syndrome. World Neurosurg. 2020;137:287-90.10. Lee SH, Park KS, Choi JH. Emergency imaging of Horner syndrome: when to suspect spinal pathology. Clin Neurol Neurosurg. 2021;207:106768.11. Kim HJ, Cho Y, Koo HW. Multidisciplinary approach in rare causes of Horner syndrome: lessons from case reviews. Hong Kong J Emerg Med. 2022;29(6):345-52.12. Zhang Y, Wu L, Zhou Y, et al. Rapid recognition and treatment outcomes of spinal cavernous malformations: a 10-year single-center experience. Spine J. 2021;21(11):1784-92.
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