Superior Oblique Myokymia

Uniocular paroxysms of small-amplitude, high-frequency rotary nystagmus.

• Unknown.
• May be regeneration of damage to trochlear nerve as it has been described in two patients who had superior oblique palsy. Arch Ophth Link
• If there are other neurological symptoms there could be a tumor compressing the midbrain.

• Intermittent bursts of torsional and/or vertical diplopia or “shimmering” vision.
• Episodes last several seconds to several minutes
• Fatigue and stress may exacerbate

• Rapid small-amplitude torsional eye movement, may only be seen at the slit lamp
• Normal eye movements in absence of symptoms

None unless other neurologic signs then consider neuroimaging

None if the patient is not bothered

• topical betaxolol (Betoptic 0.5%, Betoptic S 0.25%) BID- one report of success
• carbamazepine (tegretol) 100 mg BID or TID to start and move to up to 200 mg TID as needed
  • potential side effects including leucopenia, acute renal failure, thromboembolism, and arrhythmias
  • blood counts (CBC, including platelets and reticulocytes), serum iron, liver function and renal function (urinalysis an BUN) needed to be monitored regularly
• gabapentin 100mg QD or BID can titrate up to 300mg PO BID
• propranolol 80 mg long acting
• phenytoin (dilantin) 100mg PO TID
• propranolol plus valproic acid
• Medical treatment is often disappointing and fraught with side effects

• Tenectomy of Superior Oblique- a large portion needs to be removed
• Combine above with prophylactic inferior oblique weakening
• Some require a second surgery to treat residual diplopia with recession of contralateral inferior rectus with a nasal shift and possibly a nasal shift of both inferior rectus muscles if there is excyclotorsion