Combining Peripheral-Surgical (Tenotomy) with either Central-Pharmacological (Memantine) or other Peripheral-Surgical (Anderson) Therapies to Damp Acquired Pendular or Downbeat Nystagmus and Oscillopsia

摘要

We report the results of our studies of the effects of tenotomy on two different types of acquired nystagmus, pendular (APN) and downbeat (DBN). Eye movements of two subjects, Case 1 with APN and Case 2 with DBN were recorded using infrared reflection, magnetic search coil, or high-speed digital video. The eXpanded Nystagmus Acuity Function (NAFX) quantified tenotomy-induced foveation changes in the nystagmus. Horizontal rectus muscle tenotomies of both eyes were combined with recessions to correct exotropia (Case 1) and to move the null region downward (Case 2); memantine was given following surgery (Case 1). Search-coils were used to record ocular motility before and after surgery and after memantine in Case 1; high-speed digital video was used in Case 2. Following surgery, APN decreased by ～50%, NAFX increased by 34%, and Snellen visual acuity increased 100% to 0.25. Saccades were unaffected. Memantine further damped the APN 69%, increased the NAFX by 9%, and increased visual acuity 60% to 0.4. The cumulative effects were: APN reduced by 82%; NAFX increased by 46%; acuity increased by 220%; and oscillopsia reduced by 75%. Following surgery, DBN decreased by 46%, NAFX increased by 17% in primary position over the previous peak at 10° upgaze, and visual acuity increased by 25% to 1.0+. Four-muscle surgery (including tenotomy and reattachment) reduced APN, DBN, and oscillopsia and improved NAFX and visual acuity; memantine provided additional improvement in APN. Their synergistic effect suggests a dual-mode (surgery + drug) therapy for maximal effectiveness in APN.