Horner's Syndrome

Horner's syndrome is a favoured topic of the college examiners, appearing in several: past paper SAQs:

Some of these questions ask details about the possible position of the lesion. It is important to be intimately familiar with this syndrome, and with its differentials.

Features of Horner's Syndrome

  • Ptosis
  • Myosis
  • Anhidrosis
  • Enophthalmos
Causes of Horner's Syndrome


Associated clinical findings:

Cluster headache
  • Transient Horners; comes and goes
  • Severe headache, with rhinorrhoea and excessive tear production
Cortical stroke (hemispheric)
  • weakness, sensory deficit, homonymous hemianopia, diplopia, or ataxia
  • No sensory or motor level (instead, hemiplegia)
Brainstem stroke (lateral medullary syndrome)
  • Contralateral pain and temperature sensory loss
  • Ipsilateral facial sensory loss
  • Ipsilateral nystagmus
  • Dysphagia
  • Ipsilateral V, IX and X cranial nerve lesions
Cavernous sinus pathology
  • An associated sixth nerve palsy
  • Everything in the cavernous sinus may have been taken out (that being upper facial branches of the 5th nerve, the 4th nerve and the 3rd nerve)
  • Dysphagia
  • Nystagmus
  • Pharyngeal and palatal weakness
  • Asymmetric weakness and atrophy of the tongue
  • Sensory loss involving primarily pain and temperature senses in the distribution of the trigeminal nerve
  • Bilateral signs!
  • Dissociated sensory loss: lost pain and temperature sensation, but preserved light touch, vibration and proprioception
  • Cape-like distribution of pain
  • Hand weakness
  • Bowel and bladder incontinence, sexual dysfunction
Spinal injury or infarction
  • Weakness, sensory deficit; with a distinct sensory or motor level
  • No diplopia or hemianopia
Malignancy in the apex of the lung
  • Wasting of small muscles of hand and clubbing
  • Cervical and axillary lymph nodes
Thyroid cancer
  • Suprasternal mass, goitre
  • Thyroid bruit
  • Cervical and supra/infraclavicular lymph nodes
  • Signs of retrosternal goitre, eg. stridor
Neck trauma or surgery
  • Various scars, signs of head / neck surgery/trauma (it wouldn't be subtle)
Lower trunk brachial plexus injuries
  • Motor deficit isolated to the affected arm
  • Weakness in all median and ulnar innervated hand muscles
  • Weakness in radial innervated distal forearm and wrist muscles.
  • Sensory loss in the medial aspect of the arm, forearm and hand
Carotid aneurysm or dissection
  • Sudden onset of the syndrome
  • Pain of the neck or face
  • A carotid bruit which is unilateral

Causes of Horners Syndrome, arranged in order of anatomical location

  • Hemispheric lesion (hemispherectomy, massive hemispheric CVA, thalamic CVA)
  • Brainstem   lesion   (brainstem   infarct,   multiple   sclerosis,   brainstem   tumour   or encephalitis)
  • Central cord lesion (syringomyelia, glioma, ependymoma, traumatic)
  • T1 root  lesion  (Pancoast  tumour,  cervical  rib, brachial  plexus  avulsion,  aortic  or subclavian aneurysm
  • Sympathetic chain (laryngeal, pharyngeal, thyroid or parathyroid surgery, carotid artery lesion, malignancy at base of skull)


The LITFL summary of cranial nerve lesions is without peer in terms of useful information density.