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Brown Syndrome is a rare eye disorder characterized by defects and errors in eye movements. Some people may be born with this disorder, congenital, or the disorder may be developed because of a pre-existing disorder. Tendons and muscles surround the eye and control its movements. These tendons move the eye ball up and down, side to side, and allow the eyeball to move freely in its socket. Brown Syndrome is caused by malfunctions of the tendon sheath. The superior oblique tendon sheath surrounds the eyeball and when it is not working properly the patient will experience Brown Syndrome (Strabismus). What happens is the tendon is too short, long, thick, or inflamed. This effect causes the eye to move upward. Sometimes a Brown Syndrome patient will tilt their head and their chin will rise in order to feel comfortable. When this occurs their eyes roll into their original place and the person is able to see much more clearly. Brown Syndrome, in the United States of America, is found in every 1 to 400-450 strabismus cases. A strabismus case is the inability of the eye to focus on an object because of the problems with the muscles controlling eye movement. It is proven that 35% of the patients with congenital Brown syndrome have a family member with Brown Syndrome. This fact indicates Brown syndrome could potentially be a genetic trait. The syndrome occurs in women more than men. Of the people that have the syndrome in the United States 59% of them are female and 41% male. The syndrome is right eye bias; it is found 55% of the time in the right eye, 35% in the left eye, and 10% bilateral.
Brown Syndrome was first documented by Harold W. Brown. He published it in his first book Brown Sequard Syndrome naming it the superior oblique tendon sheath syndrome. Since then the name has changed and the definition of the syndrome has changed to limited elevation in adduction from mechanical causes around the superior oblique. Meaning that when the head is upright, there is a restriction of how the eye moves because of problems with muscles and tendons that surround the eye. Harold W. Brown characterized the syndrome in many ways such as; limited elevation in the eye when head is straight up, the eyes point out in a straight up gaze; greater separation of the upper and lower eyelids when the head is straight up; near normal elevation in adduction; and chin elevation for binocular fusion, to see one clear image instead of two blurry images. (Wright). These ways are the main characteristics and signs of Brown Syndrome. Harold W. Brown concluded that all of these features of Brown Syndrome were due to the shortening or tightening of the anterior superior oblique tendon, which is why he first named it superior oblique tendon sheath syndrome. Because this syndrome can be acquired or occur at random and has spontaneous resolution, Brown hypothesized one major truth for this disorder. He hypothesized that the short tendon sheath was because of a complete separation, congenital paresis, of the ipsilateral inferior oblique muscle and secondary to a permanent shortening.After more research Brown redefined the sheath syndrome into the following divisions: true sheath syndrome which categorized only the cases that had a congenital short anterior sheath of the superior oblique tendon, and simulated sheath syndrome which characterized all cases in which the clinical features of a sheath syndrome caused by something different other than a congenital short anterior sheath of the tendon. The clinical features of the two categories are correct but true sheath syndrome is always congenital. However, in 1970 it was discovered that a tight sheath tendon was not the cause of Brown Syndrome. The real cause was a tight or short superior oblique tendon; studies have confirmed this and have labeled the tendon inelastic.
Brown Syndrome can be divided in two categorizes based on the restriction of movement on the eye itself and how it effects the eye excluding the movement. The syndrome can be separated into congenital Brown Syndrome or acquired Brown Syndrome (Wright). Congenital is present at birth and is described as the normal elevation of the eye into adduction. Meaning when the head is straight up, adduction, the eye is in its normal position. With Brown Syndrome there is an increase between the trochlea and superior oblique tendon when the eye is straight up causing the eyes to position themselves differently. Acquired may occur as a result of another pre-existing disorder or the stretching of the tendon sheath.
Congenital There are different types of congenital Brown Syndrome within each class. The first one, Halveston’s theory of abnormal telescoping, forced, mechanism, is described as the tendon-slackening from its center attachment to the trochlea comes from a forced stretching of the central tendon. The stretching of the central tendon is mainly caused by the movement of the central tendon fibers. Another theory is the Wright hypothesis of congenital inelastic superior oblique muscle-tendon complex. This theory found that a tight or inelastic muscle-tendon complex was the best situation for a Brown Syndrome patient. If the tendon was stretched about 250% there was a drop in elevation and the syndrome could be cured. Another fact from this experiment was that the attachment of the inferior orbital fibrous to the posterior glove would restrict eye movement.
Acquired Abnormal forcing mechanism explains a reduced lengthening of the superior oblique tendon is caused by stretching of the tendon sheath. Tight or inelastic superior oblique tendon describes how a tight superior oblique tendon can be caused. It is caused by a displacement of the tendon or a superior oblique tendon tuck. However, tissue built up around the superior oblique tendon could be a sign of thyroid disease or Hurler-Sheie syndrome. Brown Syndrome patients who have inflammatory conditions are described as having superior oblique click syndrome. Stenosing tenosynovitis or the trigger-thumb analogy theory is the most detailed theory for all acquired theories. In this theory the frequent movement of the superior oblique tendon can result in tendon swelling surrounding the tendon sheath. Scarring occurs around the trochlea because the anterior superior oblique tendon has limited movements causing Brown syndrome.
There are some key characteristics of Brown syndrome that are not just obvious but also a disadvantage for the person. The first sign is when the chin points up and to the opposite side of the eye with the disorder. Another sign is when the head is straight up, the eye with the disorder is not aligned correctly in the eye socket, and is usually pointed at the nose because of the problems with the superior tendon sheath. Some other ones that are not so common and mentioned are; the eye does not move up in a straight up gaze, greater separation of the upper and lower eyelids when the head is straight up, the eye may be down shot when involved in adduction, there may also be some pain for the person with the syndrome. These characteristics are clear because they are on the outside of the body which also makes them disturbing to the unknown
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