Horners syndrom

Horner's syndrom er en kombination af symptomer der skyldes påvirkning af grænsestrengen (truncus sympaticus) sympathetic trunk is damaged.

Symptomer

Horners syndrom er karakteriseret af ensidige fund og symptomer i form af:

• Miosis (pupil kontraktion)
• Ptose partiel (hængende øjenlåg)
• Anhidrose (nedsat svedproduktion lokalt)
• Enoftalmus (indsunket øje - ikke et obligatorisk fund)

Anatomi

Den sympatiske innervation af øjet er en 3-neuron kæde startende:

• 1. Centrale sympatiske fibre fra del posterolaterale del af hypothalamus descenderer ukrydset til C8-Th2 niveau i medulla spinalis
• 2. Præganglionære fibre træder ud fra Th1 niveau træder ind i grænsestrengen og askenderer til ganglion cervikale på niveau C3-4 ud for carotis bifurkaturen
• 3. Postganglionære fibre fra ganglion cervikale danner netværk omkring a. carotis interna og fortsætter med denne gennem sinus cavernosus

Årsager

Fil:Horner's Syndrome and Autonomic innervation of the eye.svg

Scheme showing sympathetic and parasympathetic innervation of the pupil and sites of a lesion in Horner's syndrome.

Horner syndrome is acquired as a result of disease but may also be congenital (inborn, associated with heterochromatic iris) 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 a Pancoast tumor (tumor in the apex of the lung) or thyrocervical venous dilatation).

Causes can be divided according to the presence and location of anhidrosis:

• Central (anhidrosis = face, arm and trunk)
  • Syringomyelia
  • Multiple sclerosis
  • Encephalitis
  • Brain tumors
  • Lateral medullary syndrome
• Preganglionic (anhidrosis = face)
  • Cervical rib traction on stellate ganglion
  • Thyroid carcinoma
  • Thyroidectomy
  • Goiter
  • Bronchogenic carcinoma of the superior fissure (Pancoast tumor) on apex of lung
  • Klumpke paralysis
  • Trauma - base of neck, usually blunt trauma, sometimes surgery.
  • As a complication of tube thoracostomy
  • Thoracic aortic aneurysm
• Postganglionic (no anhidrosis)
  • Cluster headache - combination termed Horton's headache
  • A Horner's syndrome may occur during a migraine attack and be relieved afterwards<ref>Skabelon:Cite journal.</ref>
  • Carotid artery dissection/carotid artery aneurysm
  • Cavernous sinus thrombosis
  • Middle ear infection
• Sympathectomy
• Nerve blocks, such as cervical plexus block, stellate ganglion or interscalene block

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 tract (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) that releases acetylcholine.
• Third-order neuron disorder: Postganglionic lesions at the level of the internal carotid artery (e.g. a tumor in the cavernous sinus or a carotid artery dissection) that releases norepinephrine.
• Partial Horner's syndrome: In case of a third-neuron disorder, anhidrosis is limited to the middle part of the forehead or can be absent, resulting in a partial Horner's syndrome.<ref name="Lee">Skabelon:Cite journal</ref>

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

Fil:Example of Horner's syndrome in a cat.jpg

Left-sided Horner's syndrome in a cat as a result of trauma, demonstrating miosis in left pupil.

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

• Cocaine drop test: Cocaine eyedrops block the reuptake of post-ganglionic norepinephrine resulting in the dilation of a normal pupil from retention of norepinephrine in the synapse. However, in Horner's syndrome the lack of norepinephrine in the synaptic cleft causes mydriatic failure. 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 increased mydriatic effect (due to hypersensitivity) on the affected side of Horner syndrome (the opposite effect to what the cocaine test would produce in the presence of Horner's).Skabelon:Citation needed
• Paredrine test: This test helps to localize the cause of the miosis. If the third order neuron (the last of three 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 third order neuron, then the amphetamine will have no effect and the pupil remains constricted. There is no pharmacological test to differentiate between a first and second order neuron lesion.<ref name="Lee"/>
• Dilation lag testSkabelon:Clarify

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 a clinical setting, these two 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 (partial ptosis).Skabelon:Citation needed

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 on the side of the ptosis.Skabelon:Citation needed

In children

The most common causes in young children are birth trauma and a type of cancer called neuroblastoma.<ref name=":0">Skabelon:Cite book</ref> The cause of about a third of cases in children is unknown.<ref name=":0" />

History

It is named after Johann Friedrich Horner, the Swiss ophthalmologist who first described the syndrome in 1869.<ref>Skabelon:Cite journal</ref><ref>Skabelon:WhoNamedIt</ref> Several others had previously described cases, but "Horner's syndrome" is most prevalent. In France and Italy, Claude Bernard is also eponymized with the condition ("Claude Bernard-Horner syndrome").

See also

• Anisocoria
• Harlequin syndrome

Video om Horners syndrom

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