Brown Syndrome - Causes, Diagnosis, and Treatment

Introduction:

About six muscles attach to the eye to aid its movements (up, down, sideways, and rotation). Any defective muscle attachment leads to improper eye movements. This article reviews a rare eye disorder known as Brown’s syndrome, which Dr. Harold W. Brown first described in 1949. Several studies show that women are more commonly affected than men, and the disorder affects both eyes in 10 % of cases.

What Is Brown Syndrome?

The extraocular muscle is called the superior oblique muscle, and its tendons (connective tissue) attach to the eye to aid in downward and outward movements and inward rotation of the eyeball. Brown syndrome is characterized by abnormalities of the superior oblique muscle and its tendon that lead to difficulty in moving the eyes upward. It is usually present at birth or may develop later in life.

What Are the Causes of Brown Syndrome?

Brown’s syndrome mainly occurs due to abnormalities in the superior oblique muscle tendon.

According to the cause, it is classified as follows:

1) Congenital Brown Syndrome - The superior oblique muscle and its tendon may be short or tight, which leads to improper muscle attachment and, thus, defective eye movements. Few children are born with these defects.

2) Acquired Brown Syndrome - Certain factors like trauma, inflammation, or the below-mentioned disorders may induce Brown’s syndrome.

• Dysthyroid disease is an autoimmune disorder where the immune cells attack one or more extraocular muscles and weaken them.

• Juvenile rheumatoid arthritis causes swelling and stiffness in the joints of children below 16 years of age.

• Sjogren syndrome is an autoimmune disorder characterized by dry mouth and eyes.

3) Due to Eye Disorders -

• Orbital floor fracture.

• Neoplasm.

• Sinusitis: Inflammation of the air-filled cavities called a sinus.

4) Other Causes -

• Sinus surgery: In rare cases, surgery to repair the sinus may lead to eye pain and reduced eye movements.

• Glaucoma implant: Brown syndrome after the placement of a glaucoma implant is uncommon but may occur. A glaucoma implant is a small device placed in the eye to drain excess fluids and reduce elevated eye pressure.

How Does an Eye With Brown Syndrome Appear?

The main characteristic signs and symptoms are listed down:

• Limited eyeball movements to the center and downwards.

• Restricted or lack of upward eye movements (elevation).

• The affected eye looks down, while the other eye is directed towards a different position.

• Strabismus (crossed eyes).

• Ptosis (droopy eyelid).

• Abnormal head posture - The affected child may hold their chin up and tilt their head.

• Double vision.

• Hypotropia - The affected eye points down when both eyes are open.

• Pain in eye movements.

• A click sound is detected during an eye movement.

How Is Brown Syndrome Graded?

Based on the severity of symptoms, Brown syndrome is graded as follows:

• Mild - Limited upward and inward eye movement; Absence of hypotropia.

• Moderate - Restricted eye movement towards up; the affected eye faces down while moving the eyeball to the center.

• Severe - The features mentioned above are more prominent in the severe stage.

How to Diagnose Brown Syndrome?

• Clinical Examination - The ophthalmologist examines the affected eye and looks for the classic signs of Brown syndrome. The limited or lack of upward and inward movements of the eye are observed during the examination.

• Forced Duction Test - The test determines the function of extraocular muscles, their restricted movement, etc. The examiner topically anesthetizes the area to be evaluated and observes the stretching of the superior oblique muscle when the eyeball is moved upward and inward. It greatly helps in diagnosing Brown syndrome.

• Radiological Imaging - Various imaging modalities also assess in identifying any trauma, injury, or other disorders affecting the superior oblique muscle.

What Is the Differential Diagnosis?

Certain eye disorders may resemble Brown syndrome, and it needs to be differentiated while diagnosing.

It includes:

• Duane Syndrome is a congenital disorder that leads to the eye's restricted inward and outward movements. Usually, it affects one eye, and the patient may also present with a small eye and cornea (outer layer of the eye).

• Inferior Oblique Palsy - The inferior oblique eye muscle assists in moving the eyes upwards and outwards. Any injury to the muscle or the nerve supplying it weakens the muscle and thus causes limited eye movements.

• Congenital Fibrosis Syndrome is a nervous disorder that affects the extraocular eye muscles. Thus, the upwards and sideways movement of the eye is greatly restricted.

Is Brown Syndrome Treatable?

The acquired form of Brown disease shows good improvement with treatment than the congenital type. It includes:

• Eye Exercise - The doctor may suggest some exercises that improve eye movement. Studies have proven good results in patients after daily eye exercises.

• Steroid Therapy - Oral or topical administration of corticosteroids also aids in reducing the symptoms of underlying inflammatory diseases (rheumatoid arthritis).

• Steroid-Sparing Immunosuppressants - Certain individuals may show resistance to steroid therapy; in such cases, drugs like Adalimumab help relieve symptoms.

• Tenotomy - The surgeon cuts through the tendon to relieve the shortened or tightened superior oblique tendon. It greatly assists in improving eye movements. The surgery is performed with utmost care to prevent severe damage to the superior oblique muscle, or it may lead to a complete lack of its action.

• Silicone Expander - In 1991, Wright described the effectiveness of using a silicone expander. The procedure involves placing a silicone-made band between the cut ends of the tendon to increase its length and thus improve eye movements.

Conclusion:

Brown syndrome is a rare condition, and its early diagnosis is essential in providing conservative treatment. Several supportive cares are available to relieve the patient's symptoms. In addition, surgery is considered for individuals who do not show any improvement with medications. However, the physician should educate the patient about the complications after surgery. After conservative treatment, the prognosis is reasonable in patients with the acquired Brown syndrome.