Introduction to Horner's syndromeHorner's syndrome is medical condition that features with the characteristic trias including enophtalmus, miosis and ptosis. The condition develops as a consequence of the damage of sympathetic nervous system. The patient may additionally complain about the swelling of the affected eyelids. Heterochromia, which is a difference in coloration of the iris, and cut in sweat production on the affected side of the face are present as well.
Human nervous system can be divided into the voluntary and the involuntary. The involuntary nervous system is also known as autonomic nervous system. Further classification of autonomic nervous system includes sympathetic and parasympathetic nervous system. Human organs, blood vessels, muscles, and glands are innervated by both sympathetic and parasympathetic nervous system. Still these two systems act like antagonists. The sympathetic nerves that innervate the eye come from the brain. There are three neuronal pathways of sympathetic nervous system that are in charge with innervations of the eye. Horner's syndrome occurs if the damage occurs at any point of this pathway.
Causes of Horner's Syndrome
The fact is that Horner's syndrome is not an actual medical condition but it is a consequence of some other serious medical condition. The causes of Horner's syndrome are divided into three groups according to the neurons that have been damaged. The First Neuron Horner's SyndromeThe conditions that are connected to the damage of the first neuronal pathway of sympathetic nervous system include Arnold-Chiari malformation (descending dislocation of cerebellar tonsils into foramen magnum; this condition may lead to hydrocephalus), Wellenberg syndrome and strokes. Tumors such as basal scull tumor or pituitary tumors can be another cause of the first neuron Horner's syndrome. Certain infection such as basal meningitis can be additional cause. The problems with myelin that always occur in case of multiple sclerosis can also result in Horner's syndrome. Syringomyelia, the bleeding into the pons and sometimes even the trauma of the cervical vertebrae can be additional causes of Horner's syndrome. The Second Neuron Horner's SyndromeIn this case the damage affects the second neuronal pathway. It is causes by the tumor of the apical part of the lungs, damage of the brachial plexus, the presence of the cervical rib and phrenic nerve syndrome.
Additionally it can be caused by aortic aneurysm, mandibular tooth abscess and infections of the middle ear. Osteoarthritis of the neck or neck trauma can also result in Horner's syndrome. As for tumors, neuroblastoma can affect the second neuronal pathway. The Third Neuron Horner's SyndromeIn this case Horner's syndrome may be caused by Raeder syndrome or Herpes Zoster. Cluster headaches or even migraines in rare cases can result in Horner's syndrome. Carotid cavernous fistula is another cause of Horner's syndrome.