The useful of botulinum toxin Type-A in the treatment of chronic sixth ocular nerve palsy

Objective: to analyze the efficacy of Botulinum toxin Type-A (BTA) injection in the differential diagnosis between paresis vs paralysis.

Methods: 21 patients (12 F; 9 M), mean age 38,1+/-18, with acquired VI nerve palsy (mean 41.7^Δ ET near and 45^Δ ET distance), have been treated with BTA injection into the ipsilateral medial rectus muscle, 6 months after onset. At 6 months follow up, paresis and paralysis were differentiated and the correct surgical strategy was planned.

Results: At 6 months follow up, 19% of patients recovered the lateral rectus muscle functionality (mean 4^Δ ET near, 2^Δ ET distance) avoiding the surgical treatment; 23.8% manifested paresis (mean 30.5^Δ ET near, 32^Δ ET distance) and 57.1% paralysis (mean 40.3^Δ ET near, 42.8^Δ ET distance). These patients underwent surgery and at 1 year follow up the mean residual angle deviation was respectively: 2.4^Δ ET and 1^Δ ET.

Conclusions: Botulinum Toxin Type-A injection is an invaluable tool in the differential diagnosis between paresis vs paralysis of the VIth nerve, allowing the correct surgical choice.