Brown syndrome is the inability of upwards movement of the eye. Previously it was considered as a dysgenesis of the superior oblique muscle's tendon sheath, that's why it's still known as "superior oblique tendon sheath syndrome", nowadays however its believed that the problem is not the sheath but the tendon itself, that undergoes increased tension.
The patient shows inability of upwards rotation and is divided in congenital/ primary form in which the superior oblique has decreased tendon length, or acquired during which the malfunction of the muscle can due to inflammation (like Idiopathic Rheumatoid Arthritis), trauma or previous strabismus operation.
In 90% of patients the disease is unilateral, while hereditary predisposition is present in some cases, like most cases of childhood strabismus.
As previously mentioned, the main cause is considered the dysgenesis of the muscle tendon whilst secondary causes such as systemic inflammation, trauma in the trochlear region and other operations can be also causes of the secondary disease. Genetic predisposition is also present.
The diagnosis should be put on physical examination grounds, including among others "V" phenomenon, inability of upward turn, absence of amblyopia and a passive traction test and compensatory head position.
In primary position patients don't usually show vertical deviation. A few of them however develop hypotropia in the effected eye, in which case a compensatory head position is developed, in which the head leans to the affected side.
In either case both eyes provide equal stimulation to the ophthalmic cortex, this results in absence of amblyopia.
Clique syndrome: In secondary disease the patient can, after some effort, turn the affected eye upwards. During this movement they hear a snapping sound due to the friction of the thickened tendon.
During upwards rotation of the affected eye, the palpebral fissure is wider and during adduction we observe a downwards turn that imitates hyperactivity of the superior oblique. This however is not the case since during upwards turn we observe "V" phenomenon and not "A" as it would have been the case in an actual superior oblique hyperactivity.
The disease should be differentiated from inferior oblique muscle palsy, and from the combined palsy of the upwards rotating muscles.
The definite diagnosis will be given with a passive traction test (under local anesthesia) in which it is impossible to turn the affected upwards. This happens because the obstruction of the muscle in Brown syndrome is mechanical, in addition saccadic movements are not affected.
Early, primary Brown syndrome is often intermittent. This can go on for many years, after which the disease subsides in a significant portion of patients and in 75% of cases there is some improvement. Therefore early surgery is not recommended.
Secondary cases, due to inflammation in the trochlear notch can benefit from steroid treatment.
The treatment is surgical but its indicated only in cases of hypotropia in primary position or in cases in which the compensatory position causes significant cosmetic problem.
The following surgical procedures could be followed
- The surgery which is believed to be of most benefit, is considered to be either tendonotomy of the superior oblique, or tendonectomy with preservation of the sheath, additionally,
- Placing a silicon expander on the tendon. The expander is a 5mm (#240 retinal band) silicon band.
- "Chicken suture" in which a nonabsorbable suture is placed to connect the cut ends of the superior oblique tendon.
- Superior oblique split tendon lengthening: In this technique, the tendon on the nasal side of the superior rectus muscle is split into half and the halves of the tendon are removed and then joined to lengthen the tendon.
- In Iatrogenic Brown Syndrome due to muscle plication, reversal of the plication is indicated.
- In case the primary cause is a muscle cyst, removal of the cyst is indicated.
- American Academy of Ophthalmology. Pediatric Ophthalmology/Strabismus: Brown syndrome/superior oblique tendon sheath syndrome Practicing Ophthalmologists Learning System, 2017 - 2019 San Francisco: American Academy of Ophthalmology, 2017.
- Alexandros Damanakis, Stabismoi 2nd edition, Litsas medical editions, Athens-Greece.
- American Academy of Ophthalmology. Pediatric Ophthalmology and Strabismus BCSC, Leo, 2011-2012.
- Jack J. Kanski- Brad Bowling, Clinical Ophthalmology- A systematic approach, Seventh Edition, Elsevier, 2011.
- JS Crawford, Surgical treatment of true Brown's syndrome, American journal of ophthalmology, 1976
- Wright KW, Brown's syndrome: diagnosis and management, Trans Am Ophthalmol Soc. 1999;97:1023-109.