OcuLearning › Strabismus

Strabismus Syndromes

ROUTINE — Strabismus

Symptoms

abnormal eye position: usually noted by parents in early infancy or childhood
compensatory head posture: face turns, chin tilts, or head tilts to maintain single vision
absence of diplopia: children usually suppress the deviating eye, avoiding double vision
stable/non-progressive: unlike tumors or neuro diseases, these are typically birth-onset and static
face turn in duane type i: child turns face TOWARD the affected eye to align the eyes in primary gaze

Clinical Findings

Duane retraction syndrome (DURS)

pathognomonic sign: globe retraction and narrowing of the palpebral fissure on attempted adduction
type i (80%): limited abduction (looks like a VI palsy), esotropic in primary gaze
type ii: limited adduction; exotropic in primary gaze
type iii: limited both abduction and adduction
leash effect: dramatic upshoots or downshoots of the eye during adduction

Brown syndrome (SO tendon sheath syndrome)

restricted elevation in adduction: the eye cannot look up and in, but elevation is NORMAL in abduction
v-pattern: often shows a V-pattern exotropia in upgaze

Möbius syndrome

mask-like facies: bilateral CN VII palsy (cannot smile or close eyes tightly)
horizontal gaze palsy: bilateral CN VI palsy (eyes fixed in or limited horizontally)

Other syndromes

marcus gunn jaw-winking: ptosis that improves/elevates when the child opens their mouth or chews
cfeom: bilateral ptosis with eyes fixed in a downward ("chin-up") gaze

Etiology

Congenital cranial dysinnervation disorders (CCDDs)

duane: failure of the CN VI nucleus; the lateral rectus is aberrantly innervated by branches of CN III
brown: mechanical restriction—the superior oblique tendon is too short or caught in the trochlea
möbius: developmental failure of the brainstem nuclei (CN VI and VII)
marcus gunn: "miswiring" between the CN V (jaw muscles) and the CN III (levator muscle)

Red Flags

adult-onset: new "syndrome-like" features in an adult are NEVER congenital; rule out tumor or MG
positive forced duction: indicates a physical/mechanical restriction (like Brown or Entrapment)
negative forced duction: indicates an innervational/paretic problem (like Duane or Nerve Palsy)
progressive worsening: congenital syndromes should be stable; change warrants neuroimaging

Investigations

Motility testing

9 cardinal positions: document exactly where the "block" or "retraction" occurs
versions vs. ductions: check if the limitation is the same in both eyes or just one

The "gold standard"

forced duction test: physically moving the eye with forceps (usually under anesthesia) to find a "tug"

Refraction

cycloplegic refraction: must rule out accommodative esotropia (high hyperopia)

Treatment

Surgical rules

duane syndrome: medial rectus recession to fix face turn; NEVER resect the lateral rectus (worsens retraction)
brown syndrome: superior oblique tenotomy or expander if the primary gaze is affected

Ptosis & winking

marcus gunn: levator excision and frontalis sling if the "wink" is cosmetically severe
cfeom: frontalis suspension to lift the lids and muscle recessions to center the eyes

Clinical Pearl

The unifying feature of strabismus syndromes is CONGENITAL, NON-PROGRESSIVE aberrant innervation or mechanical restriction. Duane is the most common (~80% type I, limited abduction). The pathognomonic Duane sign is globe retraction + palpebral fissure narrowing on adduction. Brown syndrome has a POSITIVE forced duction (mechanical); Duane has a NEGATIVE forced duction (innervational). NEVER resect the lateral rectus in Duane — it worsens retraction.

Differential Diagnosis

• abducens (vi) nerve palsy (no retraction on adduction; usually trauma or viral-onset)
• thyroid eye disease (restrictive, usually older patients)
• orbital blowout fracture (history of trauma, entrapment on forced ductions)
• myasthenia gravis (variable, tired lids, fluctuating diplopia)