Scrub typhus associated with transient parkinsonism and myoclonus.

Parkinsonism with myoclonus is rarely associated with infectious disease in adults. We present a 55-year-old man experiencing acute onset bilateral limb tremor, rigidity, and myoclonus with small-stepped gait, and skin rash involving the trunk and limbs, after a fever. Serum was positive for anti-Orientia tsutsugamushi immunoglobulin M antibody. Brain MRI revealed no abnormalities. The fever improved with oral doxycycline, and the parkinsonism and myoclonus improved with amantadine and clonazepam. This is a rare case of parkinsonism with myolonus associated with scrub typhus infection.

Segmental myoclonus preceding herpes zoster radiculitis.

Segmental myoclonus arising in the spinal cord occurs with several viral infections, including herpes zoster radiculitis. Usually, abnormal movements follow the rash and require drug treatment to suppress. We report a patient with AIDS in whom arm and shoulder myoclonus preceded herpes zoster involving the same segments contralaterally on two occasions. Myoclonus remitted promptly with antiviral treatment. Unlike in other immunosuppressed patients, encephalitis did not occur after the second episode.

Induction of acute myoclonic encephalopathy in hamsters by subacute sclerosing panencephalitis virus.

Myoclonus is a characteristic neurological sign of subacute sclerosing panencephalitis (SSPE). Attempts were made to induce myoclonus in a large proportion of hamsters with a cell-associated strain of SSPE virus (the Biken strain) and thereby to establish an experimental model for study of the mechanism of development of this condition. When injected intracerebrally, Biken virus induced myoclonus within two to 14 days in 84% of the three- to nine-week-old hamsters tested. Electroencephalographic traces showed a periodic and synchronous discharge consisting of high-voltage slow waves and spikes that appeared coincidentally with myoclonus. Neurons in the cortex and thalamus of the affected animals had severely degenerated cytoplasm. Inflammatory changes, such as perivascular cuffing or infiltration of mononuclear cells, were not detected. Staining with immunoperoxidase revealed measles viral antigens in the cytoplasm and dendrites of the affected neurons. SSPE virus with the same properties as the parent virus was recovered from brain cells of sick animals by cocultivation with Vero cells.

Creutzfeldt-Jakob disease. Infection of infancy or childhood?

A 51-year-old man who died of Creutzfeldt-Jakob disease (CJD), had transient dyskinesias with intention myoclonus and exaggerated startle reaction in early life. This may suggest a link between myoclonic encephalopathy of infants and CJD, and an incubation period of more than 40 years of the transmissible agent of CJD.