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A 44-year-old man with a bilateral hand tremor suffered from a decline in concentration and abnormal vision for several months. He also complained of easily falling down because of muscle stiffness and cramps in his lower limbs. On admission, he demonstrated lower limb stiffness, muscle cramps, diplopia, hyperhidrosis, left upper limb ataxia and dysesthesia in all limbs. Laboratory examination showed a marked elevation in his serum creatine kinase level (26,890 U/l), and needle electromyography demonstrated myokymic discharges in the muscles of his lower extremities. Isaacs' syndrome was diagnosed based on a positive voltage-gated potassium channel antibody titer of 1,007 pM. Administration of an anticonvulsant (phenytoin, 200 mg/day) did not resolve his symptoms; however, high-dose intravenous methylprednisolone therapy (1 g/day for 3 days) resulted in marked clinical improvement. This case suggests that high-dose intravenous methylprednisolone therapy for Isaacs' syndrome might be as effective as other immunosuppressive therapies such as plasma exchange or intravenous immunoglobulin.

A 27-year-old woman noticed diplopia when gazing left and paresthesia of the left face and headache of the left side for 8 months. Abduction and supraduction of the left eye were moderately restricted. Hypoesthesia of the face innervated by the ophthalmic branch of the left trigeminal nerve was detected. Visual disturbance due to optic neuropathy developed 5 months later. MRI with gadolinium revealed a mass lesion extending from the left cavernous sinus to the orbital apex. Ocular neuromyotonia and corresponding diplopia were induced by sustained right gaze. Such episodes occurred almost every day on awaking in the morning. Prednisolone (60 mg/day) was given and the headache and visual disturbance ameliorated in two days. The diplopia disappeared in 4 days. The patient remains free from these symptoms after 6 months. This is the first report of ocular neuromyotonia associated with Tolosa-Hunt syndrome.

A 71-year-old man had recurrent spells of transient diplopia for about four years. Vertical diplopia were induced by downward gaze, mostly to the lower-left, and lasted for about ten seconds. During the spells, limitation in elevation of the left eye was observed. Other neurological examinations were normal except for a minor paresis of the left trochlear nerve revealed only by detailed neuroophthalmological examination. The patient was treated with carbamazepine 200 mg daily, which abolished the spells. He was diagnosed to have idiopathic ocular neuromyotonia of the left third or fourth nerve. Ocular neuromyotonia is a rare disturbance of ocular motility, characterized by paroxysmal monocular involuntary spasms of one or more extraocular muscles supplied by the third, fourth or sixth cranial nerves. Past studies showed that most patients had radiation therapy to the parasellar or sellar regions. Slight injury to the peripheral nerves such as one caused by radiation may have an important role in the development of ocular neuromyotonia. Furthermore, patients with ocular neuromyotonia often benefit from the use of carbamazepine, a membrane-stabilizing agent. We report a case of idiopathic ocular neuromyotonia without history of damage to the cranial nerves. It is the first report in Japan.