Monozygotic twins discordant for chronic fatigue syndrome: Regional cerebral blood flow SPECT

PURPOSE: To evaluate the relationship between regional cerebral blood flow (rCBF) and chronic fatigue syndrome (CFS) in monozygotic twins discordant f or CFS. MATERIALS AND METHODS: The authors conducted a co-twin control study of 22 monozygotic twins in which one twin met criteria for CFS and the other was unhealthy. Twins underwent a structured psychiatric interview and resting t echnetium 99m- hexamethyl-propyleneamine oxime single photon emission compu ted tomography of the brain. They also rated their mental status before the procedure. Scans were interpreted independently by two physicians blinded to illness status and then at a blinded consensus reading. Imaging fusion s oftware with automated three-dimensional matching of rCBF images was used t o coregister and quantify results. Outcomes were the number and distributio n of abnormalities at both reader consensus and automated quantification. M ean rCBF levels were compared by using random effects regression models to account for the effects of twin matching and, potential confounding factors . RESULTS: The twins with and those without CFS were similar in mean number o f virtually detected abnormalities and in mean differences quantified by us ing image registration software. These results were unaltered with adjustme nts for fitness level, depression, and mood before imaging. CONCLUSION: The study results did not provide evidence of a distinctive pat tern of resting rCBF abnormalities associated with CFS. The described metho d highlights the importance of selecting well-matched control subjects.