Brown's syndrome
Encyclopedia
Brown's syndrome is a rare eye
disorder characterized by defects and errors in eye movement. The disorder may be congenital
(existing at or before birth), or secondary (for example, due to inflammation). Brown's syndrome is caused by a malfunction of the superior oblique tendon
, causing the eye to have difficulty moving upward, particularly during adduction
(when eye turns towards the nose).
In the United States, the prevalence of Brown's syndrome is 1 in every 400–450 strabismus
cases. 35% of the patients with congenital Brown's syndrome have a family member with Brown's syndrome. This indicates Brown's syndrome could potentially be a genetic trait
. The syndrome occurs in women more than men. Of the people who have the syndrome in the United States, 59% are female and 41% male. In 55% of patients the syndrome is found only in the right eye, 35% only in the left eye, and 10% bilaterally.
Harold W. Brown characterized the syndrome in many ways such as
He concluded that all of these features of Brown's syndrome were due to the shortening or tightening of the anterior superior oblique tendon. Because this syndrome can be acquired or occur at random and has spontaneous resolution, Brown hypothesized one major truth for this disorder — that the short tendon sheath was due to a complete separation, congenital paresis, of the ipsilateral
inferior oblique muscle
and secondary to a permanent shortening.
After further research, he 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's Syndrome. The real cause was a tight or short superior oblique tendon; studies have confirmed this and have labeled the tendon inelastic.
There are different types of congenital Brown's 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's 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.
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's 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 movement causing Brown
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.
Brown's syndrome has been researched more because it can be developed due to other diseases and disorders. A cause for scarring and adhesions is because during surgery you can receive scars from having a blepharoplasty, plastic surgery on the eye lid, and having fat removed. Reasons for the tightening or shortening of the superior oblique tendon are because of the muscles surrounding the tendon. An inelastic muscle would cause the tendon to shorten because its inflexible characteristic or a superior oblique tuck would because there is a section of the tendon removed.
. Another way to do this is to inject a steroid into the trochlea and oral corticosteroids. This is done because the trochlea and oral corticosteroids tend to limit movement and cause inflammation.
A few more methods to fix Brown's syndrome include: the superior oblique split tendon lengthening technique, tenotomy, and superior oblique recession.
All procedures aim to align patients' eyes properly when they are in the primary position — the ideal state.
Human eye
The human eye is an organ which reacts to light for several purposes. As a conscious sense organ, the eye allows vision. Rod and cone cells in the retina allow conscious light perception and vision including color differentiation and the perception of depth...
disorder characterized by defects and errors in eye movement. The disorder may be congenital
Congenital disorder
A congenital disorder, or congenital disease, is a condition existing at birth and often before birth, or that develops during the first month of life , regardless of causation...
(existing at or before birth), or secondary (for example, due to inflammation). Brown's syndrome is caused by a malfunction of the superior oblique tendon
Tendon
A tendon is a tough band of fibrous connective tissue that usually connects muscle to bone and is capable of withstanding tension. Tendons are similar to ligaments and fasciae as they are all made of collagen except that ligaments join one bone to another bone, and fasciae connect muscles to other...
, causing the eye to have difficulty moving upward, particularly during adduction
Adduction
Adduction is a movement which brings a part of the anatomy closer to the middle sagittal plane of the body. It is opposed to abduction.-Upper limb:* of arm at shoulder ** Subscapularis** Teres major** Pectoralis major** Infraspinatus...
(when eye turns towards the nose).
In the United States, the prevalence of Brown's syndrome is 1 in every 400–450 strabismus
Strabismus
Strabismus is a condition in which the eyes are not properly aligned with each other. It typically involves a lack of coordination between the extraocular muscles, which prevents bringing the gaze of each eye to the same point in space and preventing proper binocular vision, which may adversely...
cases. 35% of the patients with congenital Brown's syndrome have a family member with Brown's syndrome. This indicates Brown's syndrome could potentially be a genetic trait
Introduction to genetics
Genetics is the study of genes, and tries to explain what they are and how they work. Genes are how living organisms inherit features from their ancestors; for example, children usually look like their parents because they have inherited their parents' genes...
. The syndrome occurs in women more than men. Of the people who have the syndrome in the United States, 59% are female and 41% male. In 55% of patients the syndrome is found only in the right eye, 35% only in the left eye, and 10% bilaterally.
Background
Brown's syndrome was first documented by Harold W. Brown in 1950. He initially named it the "superior oblique tendon sheath syndrome". Since then, the name has changed, and the definition of the syndrome has become "limited elevation in adduction from mechanical causes around the superior oblique". This definition indicates that when the head is upright, the eye is restricted in movement due to 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
- 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
He concluded that all of these features of Brown's syndrome were due to the shortening or tightening of the anterior superior oblique tendon. Because this syndrome can be acquired or occur at random and has spontaneous resolution, Brown hypothesized one major truth for this disorder — that the short tendon sheath was due to a complete separation, congenital paresis, of the ipsilateral
Anatomical terms of location
Standard anatomical terms of location are designations employed in science that deal with the anatomy of animals to avoid ambiguities that might otherwise arise. They are not language-specific, and thus require no translation...
inferior oblique muscle
Inferior oblique muscle
The Obliquus oculi inferior is a thin, narrow muscle placed near the anterior margin of the floor of the orbit.-Action:Its actions are lateral rotation, elevation and abduction of the eye....
and secondary to a permanent shortening.
After further research, he redefined the sheath syndrome into the following divisions: true sheath syndrome, which categorized only the cases that had a congenital short anterior
Anatomical terms of location
Standard anatomical terms of location are designations employed in science that deal with the anatomy of animals to avoid ambiguities that might otherwise arise. They are not language-specific, and thus require no translation...
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's Syndrome. The real cause was a tight or short superior oblique tendon; studies have confirmed this and have labeled the tendon inelastic.
Types
Brown's 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.Congenital Brown's Syndrome
Present at birth. It is the normal elevation of the eye into adduction, such that when the head is upright, adduction, the eye is in its normal position. With Brown's Syndrome, there is an increase between the trochlea and the superior oblique tendon when the eye is straight up, causing them to position themselves differently.There are different types of congenital Brown's 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's 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 Brown's Syndrome
Acquired Brown's Syndrome (Wright) may occur as a result of another pre-existing disorder or the stretching of the tendon sheath.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's 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 movement causing Brown
Characteristics
There are some key characteristics of Brown's 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.
Causes
There are a few classifications and potential causes for Brown's syndrome. Congenital Brown's Syndrome could be caused by an inelastic muscle-tendon complex, differences of the superior oblique tendon fibers, abnormal inferior orbital attachments, and the posterior orbital bands.Brown's syndrome has been researched more because it can be developed due to other diseases and disorders. A cause for scarring and adhesions is because during surgery you can receive scars from having a blepharoplasty, plastic surgery on the eye lid, and having fat removed. Reasons for the tightening or shortening of the superior oblique tendon are because of the muscles surrounding the tendon. An inelastic muscle would cause the tendon to shorten because its inflexible characteristic or a superior oblique tuck would because there is a section of the tendon removed.
Medical Care
There are a few procedures that can be done to fix Brown's syndrome medically. When treating Brown syndrome with medical care the goal is to release the mechanical limitation to elevation in the eye. This can be solved by using anti-inflammatory medication. One approach is with ibuprofenIbuprofen
Ibuprofen is a nonsteroidal anti-inflammatory drug used for relief of symptoms of arthritis, fever, as an analgesic , especially where there is an inflammatory component, and dysmenorrhea....
. Another way to do this is to inject a steroid into the trochlea and oral corticosteroids. This is done because the trochlea and oral corticosteroids tend to limit movement and cause inflammation.
Surgical Care
The most effective method to fix Brown's syndrome is by the use of surgical care. The most important indication for surgery is the presence of chin elevation or the eye not being positioned in its normal place when the head is straight up and down.- The Wright silicone tendon expander technique can be used to fix chin elevation during adduction, head positioned normal, by lengthening the superior oblique tendon. This is done by performing tenotomy, cutting the tendon, and then inserting a segment of medical grade silicone 240 retinal band between the cut ends of the tendon. The problem with this procedure is that the silicone has to be placed within the tendon capsule without disrupting the floor of the tendon capsule. If this is done improperly the implant could be forced out of the tendon or the implant might attach to the outside of the tendon instead of holding the two tendons together. This procedure is very effective and is most commonly used when dealing with surgical repair.
A few more methods to fix Brown's syndrome include: the superior oblique split tendon lengthening technique, tenotomy, and superior oblique recession.
- The first method, superior oblique split tendon lengthening involves splitting the tendons on the section of the eye near the nose. This is done by removing the halves of the tendon, combining them together, and then eventually joining the halves that were made one onto the old tendon. The tendons are separated in a controlled manner and the superior oblique tendon remains as its original self. The reason this isn’t used more often is because it weakens the tendon. By cutting the tendon in half and combining it, the tendon will never be its original self because the new tendon from the old halves is now longer and weaker.
- Tenotomy, cutting of the tendon, is done by using a 5–6mm stitching that keeps the already cut tendons from expanding too far. The main issue with this type of surgery is controlling the cut tendons from separating too far. This stitched bridge helps control the tendon but often causes under corrections. The rate of success for this procedure is 50–85%.
- The superior oblique recession technique creates a controlled slackening of the tendon. This is used the least compared to all of the other procedures because of its high rate of failure and chance for under corrections. More problems with this procedure include a change with the characteristics of the superior oblique tendon and possibly limited depression (Wright).
- Facial reconstruction is the final option to help patients with Brown's syndrome. It is not recommend or used commonly because of the difficulty of the procedure and because of its low success rate. It is uncommonly used because freeing facial restrictions is usually unsuccessful.
All procedures aim to align patients' eyes properly when they are in the primary position — the ideal state.
See also
- Eye care professional
- International Orthoptic AssociationInternational Orthoptic AssociationThe International Orthoptic Association represents over 20,000 orthoptists, in over 20 countries.- History :The International Orthoptic Association was formed in 1967 after the first International Orthoptic Congress. The British Orthoptic Association were the founding members. - Registration and...
- Convergence insufficiencyConvergence insufficiencyConvergence insufficiency or Convergence Disorder is a sensory and neuromuscular anomaly of the binocular vision system, characterized by an inability of the eyes to turn towards each other, or sustain convergence.-Symptoms:...
- GlassesGlassesGlasses, also known as eyeglasses , spectacles or simply specs , are frames bearing lenses worn in front of the eyes. They are normally used for vision correction or eye protection. Safety glasses are a kind of eye protection against flying debris or against visible and near visible light or...
- DiplopiaDiplopiaDiplopia, commonly known as double vision, is the simultaneous perception of two images of a single object that may be displaced horizontally, vertically, or diagonally in relation to each other...
- Pediatric ophthalmologyPediatric ophthalmologyPediatric ophthalmology is a sub-speciality of ophthalmology concerned with eye diseases, visual development, and vision care in children.-Training:...
- StrabismusStrabismusStrabismus is a condition in which the eyes are not properly aligned with each other. It typically involves a lack of coordination between the extraocular muscles, which prevents bringing the gaze of each eye to the same point in space and preventing proper binocular vision, which may adversely...
- EyepatchEyepatchAn eyepatch or eye pad is a small patch that is worn in front of one eye. It may be a cloth patch attached around the head by an elastic band or by a string, or an adhesive bandage. It is often worn by people to cover a lost or injured eye, but it also has a therapeutic use in children for the...
- ExotropiaExotropiaExotropia is a form of strabismus where the eyes are deviated outward. It is the opposite of esotropia. People with exotropia often experience crossed diplopia. Intermittent exotropia is a fairly common condition. "Sensory exotropia" occurs in the presence of poor vision...
- EsotropiaEsotropiaEsotropia is a form of strabismus, or "squint", in which one or both eyes turns inward. The condition can be constantly present, or occur intermittently, and can give the affected individual a "cross-eyed" appearance...
- HaploscopeHaploscopeA haploscope is an optical device for presenting one image to one eye and another image to the other eye. The word derives from two Greek roots: haploieides, single and skopeo, to view. The word is often used interchangeably with stereoscope, but it is more general than that. A stereoscope is a...
External links
- Animation at mrcophth.com