4 Things to Know About Horner’s Syndrome
Horner’s syndrome is a neurological condition that affects the nerves that control the size of the pupil in the eye. In addition to pupil size, these nerve fibers can control the eyelid position and sweating on the face, both of which are affected by Horner’s syndrome. There are many potential causes of Horner’s syndrome, and testing must be done to identify the exact cause of any Horner’s syndrome.
Sympathetic Nervous System in the Face
The sympathetic nervous system is a part of the autonomic nervous system which is not able to be controlled voluntarily.
This system of nerves controls things that engage the “fight or flight” reflexes. The neurotransmitter norepinephrine is responsible for triggering these nerves.
Among the functions of the sympathetic nervous system are increased heart rate, increased blood pressure, dilated pupils, and increased sweating.
Additionally, the sympathetic nervous system contributes to maintaining the eyes open and holding the upper eyelid open.
Route of the Nerves of the Sympathetic Nervous System
The nerves of the sympathetic nervous begin in the brain and course through the neck in the spinal cord before terminating in a ganglion in the lower neck region.
Once these nerves end, they connect to another set of nerves which continue up into the neck and to the structures of the head including the eye, eyelid, and face.
A problem at any location along this path can result in dysfunction that causes Horner’s syndrome.
Symptoms of Horner’s Syndrome
The classic symptoms of Horner’s syndrome are the triad of a small pupil, a slightly droopy eyelid, and a lack of sweating on one side of the face.
When the sympathetic nervous system does not provide any input to the pupil, it will become smaller than the other eye – particularly in dim lighting conditions when the pupil is typically the largest.
The muscle that assists the upper lid in remaining up and open is controlled by the sympathetic nervous system and if it does not function, the eyelid will droop by a few millimeters.
The sweat glands of the face are also innervated by the sympathetic nervous system and will not be functional in Horner’s syndrome.
If the face has no perspiration on one side, it is likely from Horner’s syndrome.
Potential Causes of Horner’s Syndrome
Horner’s Syndrome can be the result of damage to the sympathetic nervous pathway at any point in the pathway.
Common sites of damage include in the brain – due to a stroke or compressive tumor, in the neck – due to a carotid artery dissection or Pancoast tumor in the lungs, or in the head – due to inflammation in the ear or cluster headache.
Each of these possible causes will either damage sympathetic nerves by compressing the nerves or by decreasing blood flow and nutrition to these nerves and result in a loss of the sympathetic innervation of the face and eyes.
Our eye doctors at GHEye excel in the prescription of glasses, contact lenses and the diagnosis of a variety of eye diseases. Call our optometrists at (571) 445-3692 to schedule your appointment today to be evaluated for Horner’s syndrome. Our eye doctors, Dr. Ally Stoeger and Dr. Jennifer Sun, provide the highest quality optometry services and eye exams in the Gainesville VA and Haymarket VA areas.
Horner’s syndrome is a neurological condition that affects the nerves that control the size of the pupil in the eye. In addition to pupil size, these nerve fibers can control the eyelid position and sweating on the face, both of which are affected by Horner’s syndrome. There are many potential causes of Horner’s syndrome, and testing must be done to identify the exact cause of any Horner’s syndrome.
Sympathetic Nervous System in the Face
The sympathetic nervous system is a part of the autonomic nervous system which is not able to be controlled voluntarily.
This system of nerves controls things that engage the “fight or flight” reflexes. The neurotransmitter norepinephrine is responsible for triggering these nerves.
Among the functions of the sympathetic nervous system are increased heart rate, increased blood pressure, dilated pupils, and increased sweating.
Additionally, the sympathetic nervous system contributes to maintaining the eyes open and holding the upper eyelid open.
Route of the Nerves of the Sympathetic Nervous System
The nerves of the sympathetic nervous begin in the brain and course through the neck in the spinal cord before terminating in a ganglion in the lower neck region.
Once these nerves end, they connect to another set of nerves which continue up into the neck and to the structures of the head including the eye, eyelid, and face.
A problem at any location along this path can result in dysfunction that causes Horner’s syndrome.
Symptoms of Horner’s Syndrome
The classic symptoms of Horner’s syndrome are the triad of a small pupil, a slightly droopy eyelid, and a lack of sweating on one side of the face.
When the sympathetic nervous system does not provide any input to the pupil, it will become smaller than the other eye – particularly in dim lighting conditions when the pupil is typically the largest.
The muscle that assists the upper lid in remaining up and open is controlled by the sympathetic nervous system and if it does not function, the eyelid will droop by a few millimeters.
The sweat glands of the face are also innervated by the sympathetic nervous system and will not be functional in Horner’s syndrome.
If the face has no perspiration on one side, it is likely from Horner’s syndrome.
Potential Causes of Horner’s Syndrome
Horner’s Syndrome can be the result of damage to the sympathetic nervous pathway at any point in the pathway.
Common sites of damage include in the brain – due to a stroke or compressive tumor, in the neck – due to a carotid artery dissection or Pancoast tumor in the lungs, or in the head – due to inflammation in the ear or cluster headache.
Each of these possible causes will either damage sympathetic nerves by compressing the nerves or by decreasing blood flow and nutrition to these nerves and result in a loss of the sympathetic innervation of the face and eyes.