Horner syndrome

Aka oculosympathetic paresis

The syndrome produced by compression of the sympathetic chain along the pathway that supplies the head, eye and neck

Etiology of Horner syndrome in adults based on the location of the lesion

Central (first order) Hypothalamus Stroke (most common - lateral medullary infarction - Wallenberg syndrome) Tumor Brainstem (lateral medulla) Stroke Demyelination Tumor Spinal cord (cervicothoracic) Trauma Tumor (intramedullary) Myelitis Syringomyelia Demyelination Arteriovenous malformation Infarction

Preganglionic (second order) Pulmonary apical lesions Subclavian artery aneurysm Apical lung tumor (Pancoast tumor) Mediastinal tumors Cervical rib Iatrogenic (jugular cannulation, chest tube placement, thoracic surgery) Thyroid malignancies

Postganglionic (third order) Superior cervical ganglion Trauma Jugular venous ectasia Iatrogenic (surgical neck dissection) Internal carotid artery Dissection (acute Horner with neck or facial pain) Aneurysm Trauma Arteritis Thrombosis Tumor Skull base lesions Nasopharyngeal carcinoma, lymphoma Cavernous sinus lesion Tumors Invasive pituitary tumor Inflammation Thrombosis Carotid aneurysm Miscellaneous (cluster headache)

Pathophysiology

• Interruption to the sympathetic innervation to Mueller's muscle of the eyelids and the dilator muscle of the iris, as well as sweat fibres to the face
• No functional impairment, but there can be significant cosmetic concerns for the patient
• Anatomic considerations
  • Can result from a lesion anywhere along a three-neuron sympathetic pathway that originates in the hypothalamus
    • First-order neurons from the hypothalamus to the first synapse, which is in the cervical spinal cord
    • Second-order neurons from the sympathetic trunk, through the brachial plexus, over the lung apex, and up to the superior cervical ganglion
    • The third-order neuron ascends within the adventitia of the ICA, through the cavernous sinus
  • Inferior and middle cervical ganglions are often fused and are known as the stellate ganglion; found at the level of the vertebral artery origin
• Clinical signs may sometimes resolve once the underlying cause has been addressed, but most commonly do not

Presentation

• Ipsilateral:
  • Ptosis of both upper and lower eyelids - usually only mild - as a result of paralysis of Muller's muscle
  • Miosis (constriction)
  • Facial anhidrosis (only seen in first or second-order lesions)
  • Enophthalmos (sunken eyeball)