Miosis, ptosis, enophthalmos, anhidrosis are symptoms of Horner's Syndrome

Result of brachial plexus injury (C8-T1)

Deep petrosal nerve could cause Horner's Syndrome

Horner's Syndrome is a clinical syndrome caused by damage to the sympathetic nervous system.

Signs found in all patients on affected side of face include: Partial ptosis (which is drooping of the upper eyelid from loss of sympathetic innervation to the superior tarsal muscle, also known as Muller's muscle), upside-down ptosis (slight elevation of the lower lid), and anhidrosis (decreased sweating on the affected side of the face), enophthallmos (the impression that the eye is sunk in), loss of ciliospinal reflex and bloodshot conjunctiva may occur depending on the site of lesion.

Sometimes there is flushing on the affected side of the face due to dilation of blood vessels under the skin. The pupil's light reflex is maintained as this is controlled via the parasympathetic nervous system.

In children, Horner syndrome leads to a difference in eye color between the two eyes (heterochromia). This happens b/c the lack of sympathetic stimulation in childhood interferes with melanin pigmentation of melanocytes in the superficial stroma of the iris.

Horner Syndrome is acquired as a result of disease but may also be congenital (inborn) or iatrogenic (caused by medical treatment). Although most causes are relatively benign, Horner syndrome may reflect serious disease in the neck or chest (such as Pancoast Tumor (tumor in the apex of the lung)) or thyrocervical venous dilatation.

Horner syndrome is due to a deficiency of sympathetic activity. The site of lesion to the sympathetic outflow is on the ipsilateral side (same side) of the symptoms.

Postganglionic lesions at the level of the internal carotid artery (e.g., a tumor in the cavernous sinus) can cause the appearance of Horner Syndrome.

Horner's Syndrome results from the interruption of the sympathetic fibres to the eyelids and pupil. The pupil is constricted (myosis, due to unopposed parasympathetic innervation via the oculomotor nerve), there is ptosis (partial paralysis of the levator palpebrae) and the face on the affected side is dry and flushed (sudomotor and vasoconstrictor denervation). Enophthalmos is said to occur, but this is not confirmed by exophthalmometry. The syndrome may follow spinal cord lesions at the T1 segment (tumor or syringomyelia), closed, penetrating, or operative injuries to the stellate ganglion or the cervical sympathetic chain, or pressure on teh chain or stellate ganglion produced by enlarged cervical lymph nodes, an upper mediastinal tumor, a carotid aneurysm or a malignant mass in the neck.
 

• Results from any injury along C5 to T1 of the vertebra.
  
  - Horner's Syndrome is present if the lesion in Brown-Sequard is above the T1 vertebrae level.
  - 3 classic symptoms of Horner's Syndrome include ptosis, miosis, and anhydrosis.