Brown's Syndrome Flashcards
Mechanical
browns Definition
Superior oblique tendon sheath syndrome
Condition with limited elevation of the eye in adduction and a positive
forced duction test (FDT) due to a tight superior oblique anterior tendon sheath.
browns characteristics
Restricted elevation in adduction, but normal depression in adduction.
Possible acquired cases showing defective depression in adduction as well as defective elevation.
Most patients maintain binocular single vision (BSV); associated esotropia or exotropia possible.
browns incidence
Incidence:
Unilateral in most cases; less than 10% of cases are bilateral.
Prevalence: More common in females (59% cases).
browns Aetiology:
Assumed to be congenital initially, now believed to develop in infancy; may be acquired later in life due to inflammation or trauma affecting the trochlear region, which can trap the superior oblique tendon.
Trochlear Complex Involvement: Abnormalities of the superior oblique tendon and/or trochlear complex.
browns theroies
Developmental Anomaly: Failure of embryological trabeculae remodeling may cause the condition.
Tendon/Sheath Issues: Distension of the bursa-like structure may cause acquired Brown’s syndrome, which could result in an acquired Brown’s syndrome, with or without a click
Shortened superior oblique tendon : A relatively short or inelastic tendon would result in a positive FDT but cannot be proved unless the posterior tendon is explored.
Inelastic Tendon: Short or inelastic tendon can cause the syndrome.
Nodule/Swelling: Nodules or swelling on the tendon may prevent free passage through the trochlea. If the swelling could be forced through the trochlea, a click could be felt or even heard and elevation in adduction improved.
A number of disease processes can cause an inflammatory response and result in swelling on the tendon which include rheumatoid arthritis, scleritis and systemic lupus erythematosus. Some patients with Brown’s syndrome respond to retrotrochlear injection of local steroids, supporting the view that an inflammatory process is responsible. Trauma affecting the trochlea usually results in restriction of elevation and depression.
Other Possible Causes:
Fibrous attachments, abnormal superior oblique insertion, and paradoxical innervation of the inferior oblique and the superior oblique (Amisinnervation of a non- or underinnervated superior oblique muscle by fibres intended for the inferior oblique would restrict elevation in adduction and widen the palpebral fissure by co-contraction of the two muscles).
browns Symptoms
Limitation of elevation in adduction (Hess chart)
Down-drift of affected eye on contralateral version, possibly with palpebral fissure widening in adduction.
Overaction of the contralateral superior rectus muscle.
A- or V-pattern of deviation.
An AHP, comprising head up, head tilt to the affected side and a head turn to the contralateral side. The head posture is confined to head up if the syndrome is bilateral and symmetrical. Many patients with Brown’s syndrome can maintain comfortable BSV without an AHP.
Discomfort and possible pain on attempted elevation in adduction.
If a click is suspected, it can best be detected by placing a finger over the trochlea and asking the patient to look up and in. If a click occurs the examiner can feel the sudden movement of the tendon through the trochlea. It is advisable to repeat this procedure on the other side, placing a finger over the opposite trochlea. A bilateral click can sometimes be felt in patients whose symptoms are related only to one side
browns Diagnostics:
Positive FDT. Differentiates Brown’s syndrome from inferior oblique palsy
Absence of cyclotropia in primary and down-gaze
browns diff dx
Isolated inferior oblique palsy: Very rare, possibly seen after orbital trauma or in association with myasthenia gravis.
Double elevator palsy: Can be distinguished from Brown’s syndrome by its limitation of up-gaze on both adduction and abduction, along with the presence of ptosis. Also, Bell’s phenomenon may be intact, indicating no mechanical restriction of elevation.
Orbital blow-out fracture: Typically results in limitation of elevation, which is usually greatest in abduction and associated with retraction of the globe on attempted up-gaze. Rarely elevation may be maximally restricted in adduction, making differentiation from Brown’s syndrome difficult. May also present with enophthalmos and infraorbital nerve anesthesia.
Congenital fibrosis of the extraocular muscle syndrome: Fibrosis of the inferior rectus leads to limitation of up-gaze, especially in abduction. Bilateral cases often display convergent retraction movement.
Adherence syndrome: Can occur due to complications from inferior oblique muscle surgery, such as rupture of the tendon’s capsule, hemorrhage, and anterior orbital fat prolapse. Results in the development of inflammatory adhesions, causing mechanical restriction of elevation, which is greatest in abduction.
Glaucoma drainage surgery: External drainage devices used in complex glaucoma treatment may cause a restriction of ocular movement similar to Brown’s syndrome.
Graves’ orbitopathy: Oblique muscle involvement in Graves’ orbitopathy is likely underreported (exophthalmos ect)
browns mx non surgical
Natural History:
Spontaneous Improvement: Improvement in symptoms may occur
over time.
Management
Nonsurgical Treatment:
Observation: Most patients maintain BSV and may not require treatment.
Features that suggest the deviation is poorly compensated include: loss of AHP; a slow recovery to BSV after dissociation, best seen when using the cover test; loss of BSV; a manifest deviation
Children should be kept under observation. The parents should be told that the syndrome may improve with time but, if it does not, up-gaze will be used less as the child grows in height and the anomaly will become less noticeable
Retrotrochlear Steroid Injection (late-onset): Short-term improvement; either to reduce an inflammatory reaction or to prevent the development of fibrous tissue secondary to trauma- indicated in patients who would otherwise require surgery.
See a few times then discharge if everything stable.
browns sx indications
Surgery for severe cases with marked head posture or decompensation.
Exploration of the posterior tendon should not be attempted as it could lead to serious fibrosis and would limit the passage of the tendon through the trochlea in both directions. Scan?
browns sx
Superior Oblique Tendon Expander: Wright described using a silicon spacer for graded superior oblique weakening.
Superior Oblique Tenectomy: Division of the anterior tendon on the nasal side of the superior rectus muscle to improve elevation in adduction, whether the underlying defect was a shortened tendon or a lesion preventing free passage of the tendon through the trochlea. Superior oblique palsy with secondary inferior oblique overaction is common after the procedure for Brown’s syndrome; superior oblique palsy can be managed by an ipsilateral inferior oblique weakening at the same time as the tenotomy.
Other Procedures:
Contralateral superior rectus recession, which would probably be used only if earlier surgery had been insufficient or if the patient preferred to fixate with the affected eye, making the overaction more obvious.
Correcting manifest horizontal strabismus.
Taking down the superior oblique tendon tuck that has resulted in a marked iatrogenic Brown’s syndrome in a primary superior oblique palsy
Controlling the gap between the cut ends with an adjustable suture
Postoperative Management
browns
Positive FDT After Surgery: Possible causes include anomalous orbital structures and dynamic instability of the lateral rectus muscle pulley.
The response to superior oblique tenotomy or tendon spacer may be delayed by days or in some cases several weeks. During the postoperative period, all patients should be instructed to carry out ductional exercises, occluding the nonoperated eye and forcing the operated eye to look in the field of elevation in adduction
Trapped Superior Oblique Tendon
Aetiology: Mainly caused by trauma in the trochlear region.
Symptoms:
Limitation of elevation and depression of gaze, hypotropia on up-gaze, hypertropia on down-gaze.
Vertical and torsional diplopia.
Cyclotropia in the primary position.
Head posture involving a head turn to the sound side.
Management
Nonsurgical Treatment
Observation: Patient may achieve useful BSV with an AHP and may not require treatment.
Local Steroid Injection: May reduce fibrosis.
Surgical Treatment
Removal of Scar Tissue: Surgery for freeing the tendon from scar tissue may exacerbate the problem.
Superior Oblique Tenectomy: Tenectomy with or without a tendon spacer may be beneficial
IO vs browns
IO forced dictions negative (B = positive)
A pattern IO, Browns - v
downshoot in browns in add
