Description

• A constellation of neurologic signs and symptoms manifested as a classic triad of ipsilateral miosis, eyelid ptosis, and anhidrosis of the ipsilateral face and/or neck (with iris heterochromia in children).
• System(s) affected: nervous, skin/exocrine
• Synonym(s): Bernard syndrome, Bernard-Horner syndrome (HS); or oculosympathetic palsy, oculosympathoparesis, and Von Passow syndrome (triad with heterochromia iridis)

Epidemiology

Etiology and Pathophysiology

• Disruption of the sympathetic chain (first, second, or third order) may produce signs and symptoms of HS as a result of loss of sympathetic innervation to the eye and/or face.
  • Ptosis: Sympathetic innervation to the Müller muscle in the upper eyelid and the lower eyelid retractors helps to maintain normal eyelid position. When sympathetic innervation to these structures is interrupted, a subtle ptosis of both the upper lid (ptosis) and lower lid (reverse ptosis) may result and may persist with downward gaze. This ptosis may be subtle, often ≤2 mm. Lower lid may become elevated, which narrows the palpebral fissure or pseudo-enophthalmos.
  • Miosis: The radially oriented pupillary dilator muscle produces pupillary dilation in response to stimulation by the sympathetic nervous system. Anisocoria will be more pronounced in dim lighting, reflecting impairment of dilation in the affected eye. The affected eye will constrict normally in response to light but will be slower to dilate than the unaffected pupil.
  • Anhidrosis: When present, anhidrosis may assist in localizing a lesion; sympathetic fibers innervating sweat glands of the lower face and vasodilatory muscles branch off before the superior cervical sympathetic ganglion and travel along the external carotid artery; lesions affecting primary and secondary neurons are more likely to produce anhydrosis of both the upper and lower face.
• Etiologies in adults:
  • Arnold-Chiari malformation, basal meningitis (e.g., syphilis), cerebral vascular accident: lateral medullary (Wallenberg) syndrome, cervical cord trauma, cervical spondylosis, demyelinating disease (multiple sclerosis), intrapontine hemorrhage, neck trauma, syringomyelia/syringobulbia, tumor (basal skull, pituitary), unintended subdural placement of lumbar epidural catheter
  • Aneurysm/dissection of aorta, central venous catheterization, chest tubes, 1st rib fracture, lymphadenopathy (Hodgkin, leukemia, tuberculosis, sarcoid), mandibular tooth abscess, neuroblastoma, Pancoast tumor or infection of lung apex, proximal common carotid artery dissection, thoracic outlet obstruction (cervical rib, subclavian artery aneurysm), trauma/surgical injury, tumor (thyroid, mediastinum)
  • Carotid cavernous fistula or other pathology, carotid endarterectomy or carotid artery stenting, cluster headaches/paroxysmal hemicrania, internal carotid artery dissection, herpes zoster, lesions of the middle ear (acute otitis media), Lyme disease, tumor (nasopharyngeal, pituitary, paratrigeminal, metastasis, skull base), tonsillectomy, trauma/surgical injury, Raeder paratrigeminal syndrome
• Etiologies in children: perinatal injury to the brachial plexus—most common: brainstem glioma, neuroblastoma, vascular anomalies, surgical interventions in the neck/chest, idiopathic

Risk Factors

• Recent trauma to the head/neck/thorax (e.g., motor vehicle accident [MVA])
• Smoking (Pancoast tumor)
• Known aneurysm of the carotid or subclavian arteries
• Known malignancy/tumor/mass
• Previous surgery (neck/thoracic)
• Cluster headache