When should I refer a patient with Horner's syndrome for further investigation or specialist assessment?

Guideline-aligned answer with reasoning, red flags and references. Clinically reviewed by Dr Kola Tytler MBBS CertHE MBA MRCGP.

Posted: 22 August 2025Updated: 22 August 2025 Guideline-Aligned (High Confidence) Clinically Reviewed
Dr Kola Tytler MBBS CertHE MBA MRCGPClinical Lead • iatroX

Refer a patient with Horner's syndrome for further investigation or specialist assessment if:

  • There is any suspicion of an underlying serious cause such as a stroke, tumour, or carotid artery dissection, given Horner's syndrome can be a sign of these conditions.
  • Neurological examination reveals additional abnormalities or progressive neurological symptoms.
  • The presentation is acute or associated with other red-flag neurological signs that require urgent neuroimaging or specialist evaluation.
  • There is persistent or unexplained facial pain, numbness, or other cranial nerve involvement alongside Horner's syndrome.

In general, Horner's syndrome warrants prompt referral for neurological assessment to exclude serious underlying pathology, especially if the cause is not already known or if symptoms are new or worsening.

Educational content only. Always verify information and use clinical judgement.