Horner's syndrome

🦉 Horner’s Syndrome is caused by the loss of sympathetic nerve supply to the face and eye. It classically presents with ptosis, miosis, anhidrosis, and apparent enophthalmos. ⚠️ Important causes to exclude: lung apex malignancy (Pancoast tumour), carotid artery dissection, and lateral medullary infarct.

📍 Aetiology

• The sympathetic pathway originates in the hypothalamus, descends through the brainstem, exits at C8/T1, travels with the carotid artery, and finally enters the eye.
• Lesions along this 3-neuron pathway produce Horner’s syndrome.

🧠 Causes (By Neuron Level)

• First-order (Central): Brainstem and cervical cord lesions
  • Stroke (especially lateral medullary syndrome).
  • Tumours, demyelination (e.g., MS).
  • Syringomyelia, trauma.
• Second-order (Preganglionic): Apex of lung / chest outlet
  • Pancoast tumour (lung apex squamous carcinoma).
  • Thoracic trauma or post-surgical damage.
  • Schwannoma.
• Third-order (Postganglionic): Neck / carotid artery to the eye
  • Carotid artery dissection or aneurysm.
  • Base of skull tumours or infections.
  • Cluster headaches / migraines.
  • Birth trauma in children.

📊 Anatomy of Autonomic Supply

This 3-neuron oculosympathetic pathway runs: Hypothalamus → Spinal cord (C8–T1) → Superior cervical ganglion → Eye (pupil dilator, eyelid smooth muscle, facial sweat glands).

🩺 Clinical Features

• 👁️ Ptosis: Drooping of upper eyelid (loss of sympathetic innervation to Müller’s muscle).
• 🎯 Miosis: Constricted pupil that reacts normally to light.
• 💧 Anhidrosis: Reduced sweating on affected side (distribution depends on lesion level).
• ⚡ Apparent enophthalmos: Sunken eye appearance.
• Additional: Conjunctival injection; cough and cachexia if lung cancer-related.

📸 Case Studies

• Left Pancoast Tumour: Horner’s with ptosis from apical lung cancer.
  
• Idiopathic Horner’s: Left-sided, cause unknown.
  
• Classic Clinical Signs: Ptosis + miosis + anhidrosis.
  

🧪 Investigations

• Bloods: FBC, U&E; calcium or sodium derangements may suggest paraneoplastic lung cancer.
• Imaging:
  • MRI brainstem for stroke.
  • MRA neck for carotid dissection.
  • CT chest for apical lung tumour (Pancoast).
• Pharmacological Testing:
  • 1% cocaine drops: failure of pupil dilation confirms Horner’s.
  • Apraclonidine drops may also be used (denervation supersensitivity → pupil dilates).

🩹 Management

• 🎯 Treat the underlying cause:
  • Surgery / radiotherapy for lung cancer.
  • Anticoagulation or stenting for carotid dissection.
  • Stroke management if central cause.
• 👁️ Symptom management: Usually benign, but underlying pathology must never be missed.

💡 Clinical Pearls

• Think “Ptosis + Miosis + Anhidrosis = Horner’s until proven otherwise”.
• Always exclude 🚬 Pancoast tumour in a smoker with Horner’s + arm/shoulder pain.
• 🚑 Carotid dissection is a stroke emergency: look for ipsilateral head/neck pain + Horner’s.

Cases — Horner’s Syndrome

• Case 1 — Apical Lung Tumour (First-Order Neuron) 🫁: A 62-year-old man with a 40 pack-year smoking history presents with right-sided shoulder pain radiating to the arm. Exam: mild right ptosis, miosis, and anhidrosis. CXR shows a right apical mass. Diagnosis: Horner’s syndrome due to Pancoast tumour invading sympathetic chain. Management: Oncology referral; CT chest; biopsy for staging.
• Case 2 — Carotid Artery Dissection (Second-Order Neuron) ⚡: A 45-year-old man presents with sudden neck pain and headache after minor trauma. Exam: left ptosis and miosis without anhidrosis; no extraocular palsy. MRI angiography: left internal carotid artery dissection. Diagnosis: Painful Horner’s syndrome due to carotid dissection. Management: Urgent vascular input; anticoagulation/antiplatelets; stroke prevention.
• Case 3 — Cluster Headache (Third-Order Neuron) 💥: A 38-year-old man has recurrent severe left periorbital headaches lasting 1 hour, associated with ipsilateral lacrimation and nasal congestion. Exam during attack: mild ptosis and miosis on the left. Diagnosis: Horner’s syndrome associated with cluster headache. Management: High-flow oxygen, subcutaneous sumatriptan for acute attack; verapamil for prevention.
• Case 4 — Stroke-Related Horner’s 🧠: A 59-year-old man with vascular risk factors presents with acute vertigo, dysphagia, hoarseness, and loss of pain/temperature sensation on the right side of his face and left body. Exam: right-sided ptosis and miosis. MRI brain: infarct in right lateral medulla (posterior inferior cerebellar artery territory). Diagnosis: Horner’s syndrome secondary to lateral medullary (Wallenberg’s) syndrome. Management: Stroke care (antiplatelet therapy, risk factor modification, swallow assessment, rehab); supportive for Horner’s.

Teaching Commentary 🧠

Lateral medullary syndrome = classic brainstem stroke syndrome (PICA or vertebral artery occlusion). Key features: - Ipsilateral: facial pain/temperature loss (trigeminal nucleus), Horner’s syndrome (sympathetic tract), ataxia (cerebellar peduncle), palate weakness (nucleus ambiguus → dysphagia/hoarseness). - Contralateral: body pain/temperature loss (spinothalamic tract). Mnemonic: “Don’t PICA horse (hoarseness) that can’t eat (dysphagia)”. Management: same as ischaemic stroke (antiplatelets, risk factor control, swallow therapy). Prognosis depends on severity of bulbar dysfunction.