Horner Syndrome – Quick Consult
Last Updated / Reviewed: October 2024

Definition
Key History
Key Physical Exam
Differential Diagnosis
Diagnostic Testing
Clinical Risk and Safety Pearls

Definition

Ptosis, miosis, and anhidrosis resulting from an interruption of the sympathetic nerves that supply the eye. Horner syndrome is most often an acquired disorder, but it may also be congenital or iatrogenic. The syndrome may reflect serious systemic pathology such as Pancoast tumor or thyroid carcinoma.

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Key History

  • Unable to completely open affected eye
  • Lack of sweat on same side of face
  • Orbital pain
  • Migraine-like headache
  • Neck pain – painful Horner syndrome is associated with carotid artery dissection
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Key Physical Exam

  • Round constricted (miosis) pupil
  • Anisocoria greater in darkness
  • Ptosis
  • Appearance of enophthalmos
  • Loss of ciliospinal reflex – pupil fails to dilate when the skin on the back of neck is pinched – an unreliable test
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Differential Diagnosis

  • Argyll Robertson pupil
  • Holmes-Adie pupil
  • Miotic drugs
  • Senile miosis
  • Simple anisocoria
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Diagnostic Testing

Text / literature information and recommendations include:
  • Labs:
    • Obtain CXR – Atypical bronchogenic carcinoma (Pancoast tumor) is the most common cause of Horner syndrome.
  • Imaging:
    • Obtain an MRI angiography of the brain with cross-sectional imaging of neck to evaluate for carotid artery dissection.
    • Obtain a head CT if stroke is suspected.
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Clinical Risk and Safety Pearls

  • Apical bronchogenic carcinoma (Pancoast tumor) is the most common cause of Horner syndrome.
  • Carotid artery dissection may cause a painful Horner syndrome.
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    Kanagalingam S, Miller N. Horner syndrome: Clinical perspectives. Eye Brain. 2015;7:35-46.

    Khan Z, Bollu PC. Horner Syndrome. [Updated 2023 Apr 10]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2024 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK500000/.

    Martin TJ. Horner syndrome: A clinical review. ACS Chem Neurosci. 2018;9(2):177-186.

This is intended solely as reference material and is not a recommendation for any specific patient. The practitioner must rely upon his or her own professional judgment and medical decision-making to determine whether it is relevant in a particular case. Materials are derived from medical and nursing texts, medical literature and national guidelines and should not be considered complete or authoritative. Users must rely on specific patient presentation, experience and judgment when utilizing any of the information contained herein relative to an actual patient.
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