Acquired Synergistic Divergence: Contrary to Current Literature

Area of Science:

• Ophthalmology
• Neurology
• Genetics

Background:

• Synergistic divergence is a rare congenital ocular motility pattern associated with adduction palsy.
• Its mechanism is often compared to Duane's syndrome, with some literature suggesting it be classified as Duane's Type 4.
• Congenital synergistic divergence is well-documented, but acquired forms have not been previously reported.

Observation:

• An 18-year-old female presented with diplopia and outward turning of the left eye.
• Diagnosis revealed a third nerve palsy secondary to a cavernous sinus schwannoma.
• The patient underwent treatment including botulinum toxin injections and squint correction surgery.

Findings:

• Synergistic divergence was first observed seven months after squint correction surgery.
• The condition remained stable during subsequent assessments.
• The late onset in adulthood, after five years of monitoring, strongly suggests an acquired etiology rather than a congenital one.

Implications:

• This case report presents the first evidence of acquired synergistic divergence.
• It challenges the current literature by suggesting that synergistic divergence can manifest as an acquired condition.
• Clinicians should consider the possibility of acquired synergistic divergence, although it is likely exceedingly rare.