Novel Surgical Approach to Superior Oblique Myokymia
Hersh Varma, MD; Mary Lou McGregor, MD
Nationwide Children’s Hospital
Columbus, Ohio, United States
Introduction: Superior oblique myokymia (SOM) is a rare eye movement disorder that produces debilitating oscillopsia and diplopia. Various medical and surgical techniques have been reported to attempt to alleviate oscillopsia including superior oblique (SO) tenectomy with inferior oblique (IO) myectomy, SO nasal tendon displacement, and intracranial neurovascular decompression.[1-3] These techniques have inherent risks of iatrogenic vertical strabismus or carry high risk for morbidity. We report a novel surgical approach that alleviates oscillopsia and avoids creating vertical strabismus.
Methods: A 40 year-old female presented with a 2-year history of diplopia and oscillopsia refractory to medications. Examination revealed 2 X(T) and 4-6 LH(T). Slit lamp examination revealed torsional microtremor of the left eye. Patient underwent left superior oblique tenectomy with insertion of 10mm silicone retinal band.
Results: Patient had resolution of oscillopsia at first postoperative visit. Exam revealed stable comitant 2 XT and 6 LHT which were managed with prisms. At 8 years post-op, patient remained free of oscillopsia with 4 LHT and free of diplopia with prisms.
Discussion: Trochlear nucleus dysfunction, localized irritation, aberrant peripheral and microvascular compression of trochlear nerve are proposed etiologies of SOM. The common pathway involves myotonic excitation of the muscle. Our technique introduces a silicone segment that may buffer excitatory impulses and dampen myokymia while retaining primary function of the muscle.
Conclusion: Superior oblique myectomy with spacer may be an effective technique for alleviating SOM without inducing vertical strabismus.
References: 1. Agarwal S, Kushner BJ. Results of extraocular muscle surgery for superior oblique myokymia. J AAPOS. 2009 Oct;13(5):472-6; 2. Kosmorsky GS, Ellis BD, Fogt N, Leigh RJ. The treatment of superior oblique myokymia utilizing the Harada-Ito procedure. J Neuroophthalmol. 1995 Sep;15(3):142-6; 3. Samii M, Rosahl SK, Carvalho GA, Krzizok T. Microvascular decompression for superior oblique myokymia: first experience. Case report. J Neurosurg. 1998 Dec;89(6):1020-4