HORNER’S SYNDROME

FAKHRUDDIN HAFIY BIN HAMAD WAHID

101303139

GROUP C1

INTRODUCTION Horner’s syndrome results from an interruption of the sympathetic nerve

supply to the eye

Characterized by the classic triad of miosis (ie, constricted pupil), partial

ptosis, and loss of hemifacial sweating (ie, anhidrosis).

Causes of Horner syndrome include the following:

Lesion of the primary neuron

Brainstem stroke or tumor or syrinx of the preganglionic neuron – In one study,

33% of patients with brainstem lesions demonstrated Horner syndrome

Trauma to the brachial plexus

Tumors (eg, Pancoast) or infection of the lung apex

Lesion of the postganglionic neuron

Dissecting carotid aneurysm – In one study, 44% (65/146) of patients with

internal extracranial carotid artery dissections had painful Horner syndrome,

which remained isolated in half the cases (32/65)

Carotid artery ischemia

Migraine

Middle cranial fossa neoplasm

ANATOMY

First-order central sympathetic fibers arise from the posterolateral

hypothalamus, descend uncrossed through the midbrain and pons,

and terminate in the intermediolateral cell column of the spinal cord

at the level of C8-T2 (ciliospinal center of Budge).

Second-order preganglionic pupillomotor fibers exit the spinal cord at the

level of T1 and enter the cervical sympathetic chain, where they are in close

proximity to the pulmonary apex and the subclavian artery.

The fibers ascend through the sympathetic chain and synapse in the superior

cervical ganglion at the level of the bifurcation of the common carotid artery

(C3-C4).

Postganglionic pupillomotor fibers exit the superior cervical ganglion and

ascend along the internal carotid artery. Shortly after the postganglionic fibers

leave the superior cervical ganglion, vasomotor and sudomotor fibers branch

off, traveling along the external carotid artery to innervate the blood vessels

and sweat glands of the face.

The third-order pupillomotor fibers ascending along the internal carotid artery

enter the cavernous sinus. The fibers then leave the carotid plexus briefly to join

the abducens nerve (cranial nerve [CN] VI) in the cavernous sinus and enter the

orbit through the superior orbital fissure along with the ophthalmic branch (V1) of

the trigeminal nerve (CN V) via the long ciliary nerves. The long ciliary nerves

then innervate the iris dilator and the Müller muscle.

ETIOLOGY Horner syndrome can be congenital, acquired, or purely hereditary

(autosomal dominant).

The interruption of the sympathetic fibers may occur centrally (ie, between the hypothalamus and the fibers’ point of exit from the spinal cord [C8 to T2]) or peripherally (ie, in cervical sympathetic chain, at the superior cervical ganglion, or along the carotid artery)

Causes of Horner syndrome may also be classified as involving first-order, second-order, or third-order neuron lesions

First order lesions:

Basal meningitis (eg, syphilis)

Basal skull tumors

Cerebral vascular accident (CVA)

Demyelinating disease (eg, multiple sclerosis)

Lesions in the hypothalamus or medulla

Intrapontine hemorrhage

Neck trauma (eg, traumatic dislocation of cervical vertebrae or traumatic dissection of the vertebral artery) - Horner syndrome occurring in association with spinal cord trauma suggests a high cervical cord lesion because it does not occur with lesions below T2 or T3

Pituitary tumor

Syringomyelia-development of a fluid-filled cavity or syrinx within the spinal cord

Second-order neuron lesions that may give rise to Horner syndrome

include the following:

Pancoast tumor (tumor in the apex of the lung, most commonly squamous

cell carcinoma)

Birth trauma with injury to lower brachial plexus

Cervical rib

Aneurysm or dissection of the aorta

Lesions of the subclavian or common carotid artery

Central venous catheterization

Trauma or surgical injury (eg, from radical neck dissection, thyroidectomy,

carotid angiography, or coronary artery bypass grafting)

Chest tubes

Lymphadenopathy (eg, Hodgkin disease, leukemia, tuberculosis, or

mediastinal tumors)

Mandibular tooth abscess

Lesions of the middle ear (eg, acute otitis media)

Neuroblastoma

Third-order neuron lesions that may give rise to Horner syndrome include the

following:

Internal carotid artery dissection (associated with sudden ipsilateral face or neck pain)

Carotid cavernous fistula

Cluster or migraine headache

Herpes zoster

CLINICAL FEATURES Abnormalities found in all patients, regardless of the level of interruption, include

the following:

Mild-to-moderate ptosis, owing to denervation of the sympathetically controlled Müller

muscle

Due to paralysis/impairment of superior tarsal muscle (maintenance of upper lid

elevation)

Slight elevation of the lower lid (upside-down ptosis), owing to denervation of the lower

lid muscle (analogous to the denervation of the Müller muscle in the upper lid)

Miosis and dilation lag, where pupillary dilation after psychosensory stimuli is slower in

the affected pupil than in the unaffected pupil

Due to impairment in the dilator muscles innervated by the sympathetic nerve

Depending on the level of the lesion, impaired flushing and sweating may be

found ipsilaterally. Patients with preganglionic lesions may have facial flushing.

This symptom (ie, harlequin effect) occurs with physical exercise in some

patients. Patients with postganglionic lesions may have ipsilateral orbital pain or a

migrainelike headache.

With central first-order neuron lesions, anhidrosis affects the ipsilateral side of

the body

Lesions affecting second-order neurons may cause anhidrosis of the ipsilateral

face. With postganglionic lesions occurring after vasomotor and sudomotor fibers

have branched off the sympathetic chain, anhidrosis is either absent or limited to

an area above the ipsilateral brow. The pupils react normally to light and

accommodation

Iris heterochromia (with the affected eye being hypopigmented) is seen in

congenital Horner syndrome or Horner syndrome that occurs in children younger

than 2 years. Iris heterochromia also may occur in long-standing Horner

syndrome

The pupil on the affected side may be round and constricted (ie, miosis) due to

unopposed action of iris spinchter muscle innervated by parasympathetic nerve.

Patients’ anisocoria is greater in darkness.

The affected pupil dilates more slowly than the normal pupil does because the

affected pupil lacks the pull of the dilator muscle (ie, dilation lag).

Apparent enophthalmos-illusion created by narrowing of palpebral fissures

resulted from weakness of Muller muscles (upper and lower eyelids)

TREATMENT In general, appropriate treatment of Horner syndrome depends on the underlying

cause.

The goal of treatment is to eradicate the underlying disease process. In many

cases, however, no effective treatment is known.

Prompt recognition of the syndrome and expedient referral to appropriate

specialists are vital.

Whether surgical care is indicated and what type is appropriate depend on the

particular cause of Horner syndrome. Potential surgical interventions include

neurosurgical care for aneurysm-related Horner syndrome and vascular surgical

care for causative conditions such as carotid artery dissection or aneurysm.

REFERENCES Colledge N.R., Walker B.R., Ralston S.H. Davidson’s Principles & Practice of

Medicine, 21st edition, 2010; United Kingdom

Tripathi KD. Essentials of Medical Pharmacology, 6th edition. 2006; New Delhi

Bardorf CM, Stavern GV, Valenzuela EG., Horner Syndrome, Medscape.com,

2014