Horner's Syndrome
Definition | Aetiology | Pathophysiology | Risk Factors | Signs and Symptoms | Investigations | Management
Definition
Horner's syndrome is a neurological disorder caused by disruption of the sympathetic pathway supplying the eye and face, leading to ptosis, miosis, and anhidrosis.
Aetiology
- Central causes: brainstem strokes, multiple sclerosis, syringomyelia.
- Preganglionic causes: Pancoast tumour, carotid artery dissection, cervical spinal trauma.
- Postganglionic causes: cavernous sinus thrombosis, migraine, internal carotid artery pathology.
Pathophysiology
- The sympathetic pathway consists of a three-neuron arc from the hypothalamus to the eye.
- Lesions along this pathway disrupt sympathetic innervation, leading to ptosis (loss of superior tarsal muscle function), miosis (unopposed parasympathetic activity), and anhidrosis.
Risk Factors
- Smoking (risk for Pancoast tumours).
- Hypertension and atherosclerosis (risk for carotid dissection and stroke).
- Recent head or neck trauma.
- History of malignancy.
Signs and Symptoms
- Ptosis: partial drooping of the upper eyelid.
- Miosis: small, non-reactive pupil.
- Anhidrosis: decreased sweating on the affected side of the face (not always present).
- Flushing: occasional due to loss of sympathetic vasoconstriction.
Investigations
- Pharmacological testing: apraclonidine or cocaine drop test to confirm diagnosis.
- MRI/MRA: to assess for central or preganglionic lesions.
- CT chest: if a Pancoast tumour is suspected.
Management
1. Treat Underlying Cause:
- Stroke management with thrombolysis if indicated.
- Anticoagulation for carotid dissection.
- Oncological treatment for Pancoast tumour.
2. Supportive Care:
- Observation for idiopathic cases.
- Regular ophthalmic follow-up if visual symptoms persist.
3. Referral:
- Neurology: for central or unexplained cases.
- Ophthalmology: for further assessment and monitoring.
- Vascular surgery: if carotid artery dissection is suspected.
- Oncology: if a malignancy such as a Pancoast tumour is suspected.