Juniper Publishers- Pathogenesis of Duane’s Retraction Syndrome

JUNIPER PUBLISHERS- JOJ Ophthalmology

Aetiology

The most accepted theories until now are: Agenesis or partial development of the 6^th cranial nerve nucleus in the brain stem and Branches from the 3^rd nerve are redirected to innervate the lateral rectus. So lateral rectus has both Subnormal or no innervations from the 6^th cranial nerve and anomalous innervations from the 3^rd nerve. According to the amount of anomalous innervations going to the lateral rectus; different presentations and patterns of Duane’s syndrome results (Figure1).

Duane Type 1

No innervations from the 6^th nerve. Mild anomalous innervations from the 3^rd nerve so the clinical picture is that limited abduction and mild narrowing of the palpebral fissure in adduction (Figure 2).

Duane Type 2

Normal innervations from the 6th nerve. Moderate anomalous innervations from the 3rd nerve so the clinical picture includes normal abduction and limited adduction together with narrowing of the palpebral fissure in adduction (Figure 3).

Duane’s Type 3

No innervations from the 6^th nerve. Nerve fibers to the medial rectus is divided 50/50 between medial rectus and lateral rectus so; the clinical picture is that limited abduction (no innervations from the 6^th), limited adduction due to equal contraction of both medial and lateral recti on adduction (Figure 4).

Duane’s Type 4

No innervations from the 6^th nerve. Most of the fibers of the medial rectus go to the lateral rectus so that with attempted adduction, abduction occur (simultaneous divergence) (Figure 5).

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