Makindo Medical Notes

About

• Loss of sympathetic nerve supply to the face and eye.
• Important to exclude lung malignancy and carotid dissection and lateral medullary infarct.

Aetiology

• The sympathetic pathway begins in the hypothalamus, descends through the brainstem, exits at C8/T1, joins the carotid artery, ascends, and enters the eye.

Causes Differentiated Anatomically

• First-order Neuron (FON) - Central: Lateral brainstem and cervical cord involvement due to syringomyelia, stroke, tumours, demyelination, or inflammation.
• Second-order Neuron (SON) - Preganglionic: Involves the lung apex, such as Pancoast tumour, SCC tumour, or trauma.
• Third-order Neuron (TON) - Postganglionic: Involves the neck and carotid artery, such as carotid dissection, aneurysm, or tumours.

Anatomy of Autonomic Supply to the Eye

The image above demonstrates the autonomic innervation to the eye, highlighting how sympathetic and parasympathetic pathways interact.

Causes

• First-order Neurons: Hypothalamus, brainstem, spinal cord
  • Stroke: Usually lateral medullary syndrome.
  • Tumors, demyelination.
  • Neck trauma, spinal column cyst (syringomyelia).
  • Congenital (e.g., lack of iris pigmentation).
• Second-order Neurons: Spinal cord to the side of the neck
  • Lung cancer (Pancoast tumour).
  • Schwannoma (tumour of the myelin sheath).
  • Damage to the aorta or trauma from surgery.
• Third-order Neurons: Side of the neck to carotid and eye
  • Damage to carotid artery or jugular vein.
  • Tumor or infection near the base of the skull.
  • Migraines or cluster headaches.
  • Birth or neck trauma in children.

Anatomy

The anatomy diagram demonstrates the involvement of sympathetic nerve pathways in Horner’s syndrome.

Case Studies

• Left Pancoast Tumor with Horner's: The image shows a less pronounced ptosis due to a left-sided Pancoast tumour.


• Left Horner's (Cause Unknown): An example of a left-sided Horner’s syndrome, with no clear etiology.


• Clinical Signs: Slight ptosis, miosis, endophthalmos, and absence of sweating on the affected side.

Clinical Features

• Slight ptosis, miosis, and endophthalmos.
• Conjunctival injection.
• Absence of sweating on the face, especially when the lesion is proximal to the divergence of fibers along the internal and external carotid vessels.
• Cachexia and cough, especially if a lung tumour is present.

Investigations

• Blood Tests: Full blood count (FBC), U&E, elevated calcium if lung tumour, low sodium (Na) if lung tumour.
• Imaging: MRI of the brain to investigate lateral medullary syndrome, MRA to check for carotid artery dissection, CT chest for suspected apical lung neoplasm.
• Pharmacological Testing: 1% cocaine will cause pupillary dilation if the lesion is preganglionic.

Management

• Identify and treat the underlying cause (e.g., tumour, trauma, vascular issues).