Therapeutic results in sixth nerve palsy

Abstract

Authors aim to assess through a retrospective study the efficiency of different therapeutic methods used in VIth nerve palsy. 60 patients with VIth nerve palsy, admitted and treated in Oftapro Clinic, were divided into two groups: a group with partial dysfunction (paresis) of sixth nerve and a group with the complete abolition of neuromuscular function (VIth nerve palsy). Initial examination included assessment of neuromuscular function, binocular vision and existence of medial rectus muscle contracture (ipsi-and contralateral) and contralateral lateral rectus inhibitory palsy. Neuromuscular dysfunction was graded from -8 (paralysis) to 0 (normal abduction). Therapeutic modalities ranged from conservative treatment (occlusion, prism correction), botulinum toxin chemodenervation and surgical treatment: medial rectus recession + lateral rectus resection, in cases of paresis, and transposition procedures (Hummelscheim and full tendon transfer) in cases of sixth nerve palsy. Functional therapeutic success was defined as absence of diplopia in primary position, with or without prism correction, and surgical success was considered obtaining orthoptic alignment in primary position or a small residual deviation (under 10 PD). 51 patients had unilateral dysfunction, and 9 patients had bilateral VI-th nerve dysfunction. 8 patients had associated fourth or seventh cranial nerves palsy. The most common etiology was traumatic, followed by tumor and vascular causes. There were 18 cases of spontaneous remission, partial or complete (4-8 months after the onset), and 6 cases enhanced by botulinum toxin chemodenervation. 17 paretic eyes underwent surgery, showing a very good outcome, with restoration of binocular single vision. The procedure of choice was recession of medial rectus muscle, combined with resection of lateral rectus muscle. All patients with sixth nerve palsy underwent surgery, except one old female patient, who refused surgery. Hummelscheim procedure was applied in 19 cases, and full tendon transfer in 6 cases. In 13 cases partial results were obtained, who needed further prismatic correction or reintervention. In 12 cases the outcome was very good, with restoration of binocular single vision, without prismatic correction. Therapeutic success in sixth nerve palsy depends on accurate assessment of neuromuscular dysfunction and appropriate choice of therapeutic modality for each case. Interdisciplinary collaboration is mandatory for correct etiologic diagnosis of sixth nerve palsy.