Neuromyotonia with polyneuropathy, prominent psychoorganic syndrome, insomnia, and suicidal behavior without antibodies: a case report

INTRODUCTION Peripheral nerve hyperexcitability disorders are characterized by constant muscle fiber activity. Acquired neuromyotonia manifests clinically in cramps, fasciculations, and stiffness. In Morvan's syndrome the signs of peripheral nerve hyperexcitability are accompanied by autonomic symptoms, sensory abnormalities, and brain disorders. CASE PRESENTATION A 70-year-old Caucasian man developed, in the course of 3 months, polyneuropathy with unpleasant dysesthesia of lower extremities and gradually increasing fasciculations, muscle stiffness and fatigue. Subsequently, he developed a prominent insomnia with increasing psychological changes and then he attempted a suicide. Electromyography confirmed a sensory-motor polyneuropathy of a demyelinating type. The findings included fasciculations as well as myokymia, doublets and multiplets, high frequency discharges, and afterdischarges, following motor nerve stimulation. No auto-antibodies were found either in his blood or cerebrospinal fluid. Magnetic resonance imaging of his brain showed small, unspecific, probably postischemic changes. A diagnosis of Morvan's syndrome was confirmed; immunoglobulin (2g/kg body weight) was applied intravenously, and, subsequently, carbamazepine 2 × 200 mg, venlafaxine 150 mg, and mirtazapine each night were prescribed. His sleep improved, suicidal tendencies stopped, less fasciculations occurred, and muscle hypertonia also improved. Hyperexcitation also partially remitted including the electromyography finding. CONCLUSIONS We described here the case of a patient with Morvan's syndrome; his case is rare because of severe psychical changes with a suicide attempt, short admission to a psychiatric ward, prominent electromyographic changes, and because antibodies were not detected. After therapy with immunoglobulins followed by corticosteroids with sodium channel blocker, his motor, autonomic, psychical signs and symptoms, and electromyography changes substantially improved.