Horner's syndrome

(medicine) A complex of symptoms due to unilateral destruction of the cervical sympathetics.

Key Terms: Congenital, Hypothalamus, Neuroblastoma.

Description

William Edmonds Horner (1793–1853) first described a small muscle at the angle of the eyelid (tensor tarsi) as well as a description of an ingenious operation to correct problems with the lower lid in 1824 in the American Journal of the Medical Sciences. Since that time, his name has been associated with the syndrome of a small, regular pupil, drooping of the eyelid on the same side and occasional loss of sweat formation on the forehead of the affected eye. In appearance, it occurs on one side of the face with a sinking in of the eyeball (enophthalmos), drooping upper eyelid (ptosis), slight elevation of the lower lid, excessive contraction of the pupil of the eye (miosis), narrowing of the eyelid, and an absence of facial sweat on the affected side (anhidrosis). Other symptoms may include a variation in eye color of the iris and changes in the consistency of tears.

Causes

Horner's syndrome is caused by damage or interruption of the sympathetic nerve to the eye. There are two major divisions of the nervous system: the voluntary (conscious control) and involuntary (without conscious control). The involuntary (autonomic nervous system) has two divisions: sympathetic and parasympathetic nervous systems. Under normal conditions, there is a fine balance between sympathetic and parasympathetic stimulation. If an individual is threatened by a situation, the pupils dilate, blood is shifted to the muscles and the heart beats faster as the person prepares to fight or flee. This is sympathetic stimulation. The eye has both sympathetic (responds to challenges) and parasympathetic (slows the body down) innervation. The nerve that carries the sympathetic innervation travels down the spinal cord from the brain (hypothalamus), emerges in the chest cavity, and then finds it way up the neck along with the carotid artery and jugular vein through the middle ear and into the eye. If these sympathetic impulses were blocked, the eye would have an overbalance of parasympathetic supply, which would result in a constriction of the pupil, relaxation of all the muscles around the eye and a sinking of the eye into the orbit—Horner's syndrome. Thus, damage that occurs anywhere along the course of this nerve's route from the brain to the eye can evoke this syndrome.

If the syndrome exists from birth (congenital), it is typically noted around the age of two years with the presence of a variation in the color of the iris and the lack of a crease in the drooping eye. Since eye color is completed by the age of two, a variation in color is an uncommon finding in Horner's syndrome acquired later in life.

The common causes of acquired Horner's syndrome include aortic dissection (a tear in the wall of the aorta to create a false channel where blood becomes trapped), carotid dissection, tuberculosis, Pancoast tumor (a tumor in the upper end of the lung), brain tumors, spinal cord injury in the neck, trauma to the cervical or thoracic portions of the spinal cord, cluster migraine headache, vertebrae destruction or collapse, compression of the spinal cord by enlarged lymph nodes, and neck or thyroid surgery.

The diagnosis and localization of this disorder is made with the use of pharmacological testing by an ophthalmologist. The physician places drops of a 10% liquid cocaine into the eyes, blocking the parasympathetic nerves so the sympathetic nervous system can be evaluated. After thirty minutes, the dilation of the pupils is noted and a Horner's pupil dilates poorly. A positive cocaine test does not, however, localize the area of the damage. After waiting for 48 hours, other medications are used to determine where the nerve interruption occurs. This solution routinely has been hydroxyamphetamine bromide. However, it has not been routinely available and in 2004, a study reported that a phenylephrine solution works as well. An individual's urine can test positive for cocaine up to two days following the initial test.

Treatments

Treatment for Congenital Cases

Children who are diagnosed with Horner's syndrome of a congenital origin may undergo surgical correction to strengthen the muscle of the eyelid and give it an appearance similar to the unaffected eye. The surgery improves the appearance of the child but does not alleviate the syndrome. For these cases a plastic surgeon may be preferred. Occasionally Horner's syndrome may be seen in a newborn with a neuroblastoma (tumor originating from nerve cells). This is almost always a sign of a localized tumor and is associated with a relatively good prognosis. In these cases, a neurologist may be consulted for treatment since their specialty is the nervous system.

Treatment for Acquired Cases

The treatment for acquired Horner's syndrome depends upon the cause and is focused toward eliminating the disease that produces the syndrome. Frequently, there is no treatment that improves or reverses the condition, but recognition of the signs and symptoms is extremely important for early diagnosis and treatment. Early detection of the syndrome may facilitate treatment related to those caused by tumors as they can be removed before extensive damage is done. Causes related to an interruption in nerve transmission once the nerve leaves the spinal cord are usually related to blood circulation and are easier to treat. Any numbness or paralysis on one side of the body means the problem is within the spinal cord or brain and is more difficult to treat. Some acquired Horner's may be corrected slightly by plastic surgery for appearance changes.

Alternative and Complementary Therapies

Acupuncture may be utilized to enhance disruptions in nerve transmissions and herbs or supplements that improve circulation may benefit some cases of acquired syndrome. These herbs and supplements would include Gingko biloba and vitamin E. As with any complementary treatment, patients should notify their physician of any herbal or over-the-counter medications they are taking.

Resources

Books

Jarvis, Carolyn. Physical Examination and Health Assessment. Philadelphia: W.B. Saunders Company, 2000.

Periodicals

Danesh-Meyer, H.V., P. Savino, and R. Sergott. "The Correlation of Phenylephrine 1% With Hydroxyamphetamine 1% in Horner's Syndrome." British Journal of Ophthalmology April 2004: 592–594.

Other

Handbook of Ocular Disease Management. [cited July 6, 2005]. .

—Linda K. Bennington, C.N.S., M.S.N.; Teresa G. Odle

A tetrad of symptoms resulting from paralysis of the cervical sympathetic trunk: pupillary constriction, ptosis of the upper eyelid, dilation of the orbital blood vessels (redness of conjunctiva), and blushing and anhidrosis of the side of the face.

Enophthalmos, ptosis of the upper eyelid, slight elevation of the lower lid, constriction of the pupil, and narrowing of the palpebral fissure caused by paralysis of the cervical sympathetic nerve supply.

Horner's syndrome. By permission from Nelson RW, Couto CG, Small Animal Internal Medicine, Mosby, 2003

• first order (central) H's s. — caused by lesions within the parenchyma of the brain or spinal cord, before the synapse of sympathetic fibers within gray matter of thoracic segments T1 to T3.
• second order (peripheral) H's s. — involves the sympathetic trunk from its origin at T2 to T4 to the cranial cervical ganglion.
• third order H's s. — involves sympathetic fibers distal to the cranial cervical ganglion. Middle and inner ear disease can affect these fibers, which pass close to the tympanic bulla.

Horner's syndrome
Classification and external resources
Left-sided Horner's syndrome
ICD-10	G90.2
ICD-9	337.9
OMIM	143000
DiseasesDB	6014
MedlinePlus	000708
eMedicine	med/1029 oph/336
MeSH	D006732

Horner's syndrome or Horner syndrome is a clinical syndrome caused by damage to the sympathetic nervous system. It is also known by the names Bernard-Horner syndrome or oculosympathetic palsy.

Contents 1 Signs 2 History 3 Causes 4 Pathophysiology 5 Diagnosis 6 See also 7 References

Signs

Signs found in all patients on affected side of face include; ptosis (which is drooping of the upper eyelid from loss of sympathetic innervation to the superior tarsal muscle, also known as Müller's muscle ^[1]), upside-down ptosis (slight elevation of the lower lid), and miosis (constricted pupil) and dilation lag (slow response of the pupil to light). Enophthalmos (the impression that the eye is sunk in) and anhydrosis (decreased sweating) on the affected side of the face, loss of ciliospinal reflex and bloodshot conjunctiva may occur depending on the site of lesion. Sometimes there is flushing of the face is on the affected side of the face due to dilation of blood vessels under the skin.

In children Horner syndrome sometimes leads to a difference in eye color between the two eyes (heterochromia).^[2] This happens because a lack of sympathetic stimulation in childhood interferes with melanin pigmentation of the melanocytes in the superficial stroma of the iris.

History

It is named after Johann Friedrich Horner, the Swiss ophthalmologist who first described the syndrome in 1869.^[3][4] Several others had previously described cases, but "Horner's syndrome" is most prevalent. In France and Italy, Claude Bernard is also eponymised with the condition ("Claude Bernard-Horner syndrome").

Causes

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

• Due to lesion or compression of one side of the cervical or thoracic sympathetic chain which generates symptoms on the ipsilateral (same side as lesion) side of the body.
• Lateral medullary syndrome
• Cluster headache - combination termed Horton's headache^[5]
• Trauma - base of neck, usually blunt trauma, sometimes surgery.
• Middle ear infection
• Tumors - often bronchogenic carcinoma of the superior fissure (Pancoast tumor) on apex of lung
• Aortic aneurysm, thoracic
• Neurofibromatosis type 1
• Goitre
• Dissecting aortic aneurysm
• Thyroid carcinoma
• Multiple sclerosis
• Cervical rib traction on stellate ganglion
• Carotid artery dissection
• Klumpke paralysis
• Cavernous sinus thrombosis
• Sympathectomy
• Syringomyelia
• Nerve blocks, such as cervical plexus block, stellate ganglion or interscalene block
• As a complication of tube thoracostomy

Pathophysiology

Horner syndrome is due to a deficiency of sympathetic activity. The site of lesion to the sympathetic outflow is on the ipsilateral side of the symptoms. The following are examples of conditions that cause the clinical appearance of Horner's syndrome:

• First-order neuron disorder: Central lesions that involve the hypothalamospinal pathway (e.g. transection of the cervical spinal cord).
• Second-order neuron disorder: Preganglionic lesions (e.g. compression of the sympathetic chain by a lung tumor).
• Third-order neuron disorder: Postganglionic lesions at the level of the internal carotid artery (e.g. a tumor in the cavernous sinus).

If someone has impaired sweating above the waist affecting only one side of the body, yet they do not have a clinically apparent Horner's syndrome, then the lesion is just below the stellate ganglion in the sympathetic chain.

Diagnosis

Three tests are useful in confirming the presence and severity of Horner syndrome:

1. Cocaine drop test - Cocaine eyedrops block the reuptake of norepinephrine resulting in the dilation of a normal pupil. Due to the lack of norepinephrine in the synaptic cleft, the pupil will fail to dilate in Horner's syndrome. A more recently introduced approach that is more dependable and obviates the difficulties in obtaining cocaine is to apply the alpha-agonist apraclonidine to both eyes and observe the reversal of miosis on the affected side of Horner syndrome (the opposite effect to cocaine).
2. Paredrine test:- This test helps to localize the cause of the miosis. If the 3rd order neuron (the last of 3 neurons in the pathway which ultimately discharges norepinephrine into the synaptic cleft) is intact, then the amphetamine causes neurotransmitter vesicle release, thus releasing norepinephrine into the synaptic cleft and resulting in robust mydriasis of the affected pupil. If the lesion itself is of the aforementioned 3rd order neuron, then the amphetamine will have no effect and the pupil remains constricted. There is no pharmacological test to differentiate between a 1st and 2nd order neuron lesion.
3. Dilation lag test

It is important to distinguish the ptosis caused by Horner's syndrome from the ptosis caused by a lesion to the oculomotor nerve. In the former, the ptosis occurs with a constricted pupil (due to a loss of sympathetics to the eye), whereas in the latter, the ptosis occurs with a dilated pupil (due to a loss of innervation to the sphincter pupillae). In an actual clinical setting, however, these two different ptoses are fairly easy to distinguish. In addition to the blown pupil in a CNIII (oculomotor nerve) lesion, this ptosis is much more severe, occasionally occluding the whole eye. The ptosis of Horner syndrome can be quite mild or barely noticeable.

When anisocoria occurs and the examiner is unsure whether the abnormal pupil is the constricted or dilated one, if a one-sided ptosis is present then the abnormally sized pupil can be presumed to be the one on the side of the ptosis.

See also

• Anisocoria

References

1. ^ Adams, Raymond Delacy; Victor, Maurice; Ropper, Allan H. (2001). Adam and Victor's principles of neurology. New York: McGraw-Hill. ISBN 0-07-067497-3. 
2. ^ Gesundheit B, Greenberg M (2005). "Medical mystery: brown eye and blue eye--the answer". N Engl J Med 353 (22): 2409–10. doi:10.1056/NEJM200512013532219. PMID 16319395. 
3. ^ Horner JF. Über eine Form von Ptosis. Klin Monatsbl Augenheilk 1869;7:193-8.
4. ^ synd/1056 at Who Named It?
5. ^ Graff JM, Lee AG (February 21, 2005). "Horner's Syndrome (due to Cluster Headache): 46 y.o. man presenting with headache and ptosis.". Ophthalmology Grand Rounds. The University of Iowa. http://webeye.ophth.uiowa.edu/eyeforum/cases/case22.htm. Retrieved 2006-09-22. 

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