PURPOSE: To report the long-term outcome of full-tendon vertical rectus muscle transposition combined with chemodenervation of the ipsilateral medial rectus muscle for acquired chronic sixth (abducens) nerve palsy.
METHODS: A retrospective study of all patients treated for severe abduction deficit with transposition plus botulinum toxin over the course of 11 years. Minimum follow-up was 12 months. Main outcome measures were the surgical result and its stability.
RESULTS: A total of 22 patients were included. Mean age at the time of surgery was 41.7 ± 19.1 years (range, 4.5-69). The etiologies for the palsy were head trauma (11), tumor (10), and idiopathic (1). Mean follow-up time was 44.2 ± 37.4 months (range, 12-123). The average distance deviation was 38.1(Δ) ± 11.6(Δ) preoperatively, 4.0(Δ) ± 16.1(Δ) 3 months after the operation (p = 0.0004), and 7.9(Δ) ± 8.8(Δ) at 12 months (p = 0.0003), with no subsequent change. At the final examination, on average 44.2 months after the operation, 13 patients (59%) were within 10(Δ) of alignment, 2 (1%) were overcorrected, and 7 (32%) had vertical deviations. The majority of patients (73%) had no double vision in the primary position. No patient developed anterior segment ischemia.
CONCLUSIONS: Vertical rectus muscle transposition combined with intraoperative botulinum toxin injection into the ipsilateral medial rectus muscle improved alignment in patients with complete chronic sixth nerve palsy. While the effects of treatment may have diminished slightly during the first year after surgery, they remained stable thereafter.