Cerebral blood flow changes in general paresis following penicillin treatment: a longitudinal single photon emission computed tomography study.

Three cases of general paresis were successfully treated with high-dose penicillin. In all cases, cerebrospinal fluid cell counts decreased to normal and mental status improved rapidly. Cerebrospinal fluid protein concentrations decreased and IQ scores and overall levels of functioning improved gradually over 1 year. Regional cerebral blood flow (CBF) changes were analyzed longitudinally for 1 year using single photon emission computed tomography (SPECT). Autoradiography method and region of interest (ROI) analyses were used for quantitative CBF assessment and 3D stereotactic surface projections (3D-SSP) analyses were used for qualitative CBF pattern assessment. 3D-SSP could not reveal remarkable CBF pattern changes through the courses. The ROI analyses showed remarkable CBF decreases in all brain regions 1 month after the treatment, which recovered to normal levels 1 year after the treatment. These results suggest that remarkable decreases of quantitative CBF counts reflect the disappearance of encephalitis, while their gradual recovery reflects the gradual improvement of cerebral functional activity. As Treponema pallidum infection affects whole brain and CBF changes globally, quantitative CBF assessment may be more efficient than qualitative CBF pattern analyses for the purpose of understanding the pathophysiology of general paresis.