Cortico-Cortical Modulation Induced by 1-Hz Repetitive Transcranial Magnetic Stimulation of the Temporal Cortex

BACKGROUND AND PURPOSE: Repetitive transcranial magnetic stimulation (rTMS) has potential as a noninvasive neuromodulation treatment method for various neuropsychiatric disorders, and repeated sessions of rTMS are more likely to enhance the therapeutic efficacy. This study investigated neurophysiologic and spatiodynamic changes induced by repeated 1-Hz rTMS of the temporal cortex using transcranial magnetic stimulation (TMS) indices and fluorodeoxyglucose positron emission tomography (FDG-PET). METHODS: Twenty-seven healthy subjects underwent daily 1-Hz active or sham rTMS of the right temporal cortex for 5 consecutive days. TMS indices of motor cortical excitability were measured in both hemispheres daily before and after each rTMS session, and 2 weeks after the last stimulation. FDG-PET was performed at baseline and after the 5 days of rTMS sessions. RESULTS: All subjects tolerated all of the sessions well, with only three of them (11.1%) reporting mild transient side effects (i.e., headache, tinnitus, or local irritation). One-Hz rTMS decreased motor evoked potential amplitudes and delayed cortical silent periods in the stimulated hemisphere. Statistical parametric mapping of FDG-PET data revealed a focal reduction of glucose metabolism in the stimulated temporal area and an increase in the bilateral precentral, ipsilateral superior and middle frontal, prefrontal and cingulate gyri. CONCLUSIONS: Repeated rTMS sessions for 5 consecutive days were tolerated in all subjects, with only occasional minor side effects. Focal 1-Hz rTMS of the temporal cortex induces cortico-cortical modulation with widespread functional changes in brain neural networks via long-range neural connections.

A Case with Viral Encephalitis presenting a Dissociations in the Retrograde Amnesia

We describe a case of anterograde and retrograde amnesia resulting from probable herpes simplex encephalitis. In retrograde amnesia, dissociations not only between episodic and semantic memories, but also between semantic memories for personal and public things were observed. We postulated, using FDG-PET, that the former was caused by mesial temporal lesions, based on `multiple trace theory', and the latter, by bilateral lateral temporal lesions, which were probably related to the retrieval of semantic memory, especially for public things.

A Case of Systemic Lupus Erythematosus Presenting with Chorea: Evidence for Striatal Hypermetabolism

Chorea is an uncommon clinical manifestation of Sytemic lupus erythematosus (SLE). Its pathogenic mechanism has not been clearly clarified. We report a 54-year-old woman with SLE who presented with generalized chorea as an initial manifestation. Fluorine-18-fluorodeoxyglucose (FDG) PET revealed increased metabolism in the bilateral putamen. Intravenous and oral administration of steroid markedly improved chorea. Hypermetabolism of the bilateral putamen diminished on follow-up FDG-PET after the disappearance of chorea. This study suggests that chorea in SLE is associated with striatal hypermetabolism.