Acute Acquired Brown Syndrome:

38-year-old Male with Ethmoidal Sinus Mucocele

Acute Acquired Brown Syndrome:

38-year-old Male with Ethmoidal Sinus Mucocele

Chief Complaint: 38-year-old male presented with binocular vertical diplopia

History of Present Illness (History of Present Illness): The patient noted the sudden onset of vertical binocular diplopia which he noticed was greatest in left gaze and was relieved with a chin-up position. There was no history of trauma or any medical illness.

Medical History and Past Ocular History: Unremarkable

Family and Social History: Non-contributory

Ocular Exam:

• General: Well-appearing male patient in no acute distress
• Visual Acuity: OD-- 20/20; OS-- 20/20
• Intra-ocular pressure: Within normal limits, OU
• Motility: Under-elevation in adduction of the right eye mimicking Brown Syndrome (see Figure 1). A right hypotropia of 2 prism diopters (2 PD) in primary gaze increasing to 4 PD in left and upgaze
• External exam, eyelids, adnexa, and anterior ocular examination:
  • Right: A soft compressible tender mass measuring 2x2 cm on the superonasal aspect of the right upper lid extending from the trochlea to the medial canthal tendon was noted. Normal anterior ocular exam.
  • Left eye: Normal
• Pupils:
  • Equally reactive, OU
  • No relative afferent pupillary defect (- RAPD)
• Dilated fundus exam (DFE):
  • OU-- Normal macula, vitreous, and peripheral retina

Figure 1: Versions in the nine cardinal gazes at the time of presentation. Note the under-elevation in adduction of the right eye, which is worse in attempted gaze to the patient's upper left.

Course: The patient's symptoms and motility examination are consistent with restriction of motility involving the right superior oblique. This is in the same anatomical location where a soft, tender mass was noted. Magnetic resonance imaging (MRI) with contrast (see Figure 2) revealed an expansile, nonenhancing 3-4 cm mass of the right ethmoidal sinus with an intraorbital and extraconal extension consistent with a mucocele. The mass appeared to be pressing on the globe causing effacement of the right medial rectus and superior oblique tendon with anterolateral displacement of the trochlea.

Figure 2: Axial section of T1 contrast MRI showing right-sided ethmoidal mass consistent with a mucocele.

Course:

The cause of vertical binocular diplopia in this patient was a ethmoidal sinus mucocele pressing on the globe resulting in effacement of the superior oblique tendon with anterolateral displacement of the trochlea thus causing a limitation to elevation in adduction classically known as Brown Syndrome. Following endoscopic removal of the mass the patient was relieved of diplopia and ugze ability in adduction was improved, but moderately limited. The histopathology of the lesion was consistent with a mucocele.

Discussion:

Brown Syndrome was first characterized in 1950 by Harold Whaley Brown as a restrictive limitation to elevation in adduction. On the basis of surgical findings Brown implicated a shortened superior oblique (SO) tendon sheath as the cause of the syndrome. Most subsequent reports have alternatively proposed an abnormality in the trochlear-SO tendon complex as the etiology of restriction to elevation in adduction.

Various etiologies of acquired Brown Syndrome have been described including frontal sinus surgery (Rosenbaum et al, 1985), blepheroplasty (Levine et al, 1975), chronic sinusitis, trauma, inflammatory (Hermann, 1978), systemic lupus erythematosis (Whitefield et al, 1995), and restrictive fibrous bands. High-resolution MRI demonstrated varied abnormalities in both congenital and acquired Brown syndrome such as traumatic or iatrogenic scarring, avulsion of the trochlea, cyst in the superior oblique tendon, inferior displacement of the lateral rectus pulley and fibrous restrictive bands extending from the trochlea to the globe (Bhola et al, 2005).

According to the anatomic abnormalities noted by MRI, four distinct mechanisms of Brown syndrome have been identified: trochlear damage, superior oblique (SO) tendon abnormalities, abnormalities of rectus extra ocular muscle pulleys, and congenital abnormalities of superior oblique muscle (Bhola et al, 2005). MRI can delineate the pathological anatomical abnormalities causing Brown syndrome thereby individualizing surgical management without reliance on extensive exploratory surgery.

Diagnosis: Acquired Brown Syndrome secondary to Ethmoidal Mucocele

Differential Diagnosis of diplopia and elevation deficit:

• Brown syndrome
• Elevation deficit in adduction
• Inferior oblique palsy
• Primary superior oblique overaction
• Double elevator palsy