Evaluation of the effect of thyrotropin releasing hormone (TRH) on regional cerebral blood flow in spinocerebellar degeneration using 3DSRT

Thyrotropin releasing hormone (TRH) therapy improves cerebellar ataxia in patients with spinocerebellar degeneration (SCD). We investigated the effect of TRH on regional cerebral blood flow (rCBF) using the fully automated region of interest (ROI) technique, 3DSRT. Ten patients with SCD received TRH intravenously (2 mg/day) for 14 days and underwent brain perfusion single photon emission computed tomography before and after therapy. Clinical efficacy was assessed using the International Cooperative Ataxia Rating Scale (ICARS). The rCBF in each ROI was measured using the noninvasive Patlak plot method and calculated using 3DSRT. TRH significantly improved the ICARS scores and increased rCBF in the callosomarginal segment and cerebellum. Cerebellar rCBF increased in 4 of 5 patients with improved ICARS scores and in 3 of 5 patients without improved ICARS scores after TRH therapy. The correlation between the change in cerebellar rCBF and the improved ICARS score, however, was not significant. These findings indicate that TRH therapy may increase cerebellar rCBF in some patients with cerebellar forms of SCD and that 3DSRT may be useful for evaluating the efficacy of TRH for increasing CBF. The beneficial effects of TRH may be due to increased cerebellar rCBF or the increased rCBF may be a secondary effect of TRH therapy.