Effects of repetitive transcranial magnetic stimulation on cerebral glucose metabolism

Objective To investigate the mechanisms underlying the effect of repetitive transcranial magnetic stimulation (rTMS) on post-stroke hemiplegia, we assessed alterations in cerebral glucose metabolism. Methods Five post-stroke hemiplegic patients (three targeted for upper limb impairment and two targeted for lower limb impairment) aged 62.6 +/- 6.1 years (mean +/- standard deviation) with a duration since stroke onset of 3.5 +/- 3.8 years participated in this preliminary study. Cerebral glucose metabolism was measured twice-before and after rTMS with intensive rehabilitation-using positron emission tomography with [18F]fluorodeoxyglucose. The Asymmetry Index (AI) was calculated to assess laterality of metabolism between the lesional and contralesional motor areas. The alteration rates of AI (%Delta AI) were compared between participants in whom rTMS was effective and ineffective. Results Two of the three upper-limb-targeted patients and one of the two lower-limb-targeted patients showed motor function improvements following rTMS treatment. All three patients who responded to rTMS had improved laterality of cerebral glucose metabolism in motor areas, commonly in the precentral gyrus, with an %Delta AI of approximately 10%. In contrast, the two patients who did not respond to rTMS had no improvements in laterality. Conclusions These results suggest for the first time that improved glucose metabolism is associated with improved motor function after a combination of rTMS and intensive rehabilitation.

Automated summary

This preliminary study investigated the effect of rTMS on post-stroke hemiplegia by assessing alterations in cerebral glucose metabolism. Responding patients showed improved laterality of cerebral glucose metabolism in motor areas, while non-responding patients did not show improvements in laterality. These findings suggest a correlation between improved glucose metabolism and motor function after rTMS treatment paired with intensive rehabilitation.