Horner syndrome is a neurological disorder in which the nerve signals from the brain to one side of the body including eye and face is disrupted. It would cause decreased sweating on the affected side of the body and decrease in size of the eyelid on one side. Horner syndrome is not a disorder but is the side effect of another neurological problem like stroke or injury in the brain. Often this syndrome would affect the size of the pupil and does not cause any difficulty in vision. In medical terms, Horner syndrome is known as oculosympathetic palsy.
Horner syndrome can cause decrease in size of the pupil in one of the eyes. Some of the other signs of this syndrome are dropping of affected eyelid, delay in opening of affected pupil and slight lifting of lower lid. In case one side of the body gets affected it can cause decreased sweating or no sweating on the affected side. Often, there are no obvious symptoms and if at all present, it would be subtle.
In children, Horner syndrome may cause slight change in color of the iris on the affected eye. In rare cases, symptoms of Horner syndrome can appear suddenly after an accident or trauma. If there is any impairment in vision and dizziness you need to consult your doctor immediately.
Exact cause of Horner syndrome is not known (idiopathic) and in some cases it can develop due to damage caused in the sympathetic nervous system. This system is responsible for controlling heartbeat, perspiration and blood pressure. It also checks on the pupil size and induces the body to adjust quickly to any change in the environment. Three groups of neurons can get affected due to Horner syndrome.
Any damage in the pathway of first order neurons can occur due to stroke, trauma in the neck and formation of cavity or cyst in the spinal column. First order neurons runs from hypothalamus region to the upper part of the vertebral column. Sometime, nerve damage can develop in the second order neurons due to presence of tumor in the myelin sheath, lung cancer and trauma or sudden injury in the spine.
For some people, third order neurons may get damaged due to tumor in the skull, migraine, and damage to the jugular vein. In children, Horner syndrome is caused by slight injury in the neck portion during delivery or any defect in the aorta (blood vessel of the heart) at birth.
Your doctor would look into the above symptoms after collecting your medical history and asking series of questions about the possible injury of the neck or spine. He would refer to an ophthalmologist for thorough eye examination to check the condition of pupil size. She would try to find out the cause of nerve damage using additional tests like CT or MRI scan. She may look for any abnormality in the nerve path or presence of any tumor or lesion.
No treatment is usually required for Horner syndrome. If the doctor could find out the underlying medical cause he would give suitable treatment for clearing the disruption of nerve pathway.