Reduced brain perfusion and neurocranial shape abnormalities of the temporal regions in patients with Klinefelter syndrome.

OBJECTIVES: In patients with Klinefelter syndrome dissocial behaviour, learning difficulties and low intelligence are common. Thus, the aim of our study was to perform brain perfusion studies and cranial cephalometry in 27 cases of Klinefelter syndrome and compare the results with those in a group of 26 healthy subjects.

METHODS: Single photon emission tomography (SPECT) was performed after injection of 20 mCi 99mTc-HMPAO and the data from transaxial slices were analyzed for 46 regions of interest in the cerebellar, thalamic, ventricular and parietal planes. Right/ left ratios were calculated and differences above 10 per cent were considered abnormal. Skull radiographs in frontal and lateral view were taken and measurements of the cerebral part were made.

RESULTS: SPECT imaging in 27 Klinefelter patients revealed 82 hypoperfusion foci, most frequently in temporal regions, less frequently in temporoparietal and frontal regions, whereas only 11 hypoperfusion foci in 6 of the 26 control subjects were found. Skull radiography revealed the following abnormalities : flattening of the temporal regions, reduced width of the vault, shortening of the anterior cranial fossa and definitely reduced angle of the cranial base; all these anomalies differed significantly from those in the skulls of the control subjects.

CONCLUSIONS: The high coincidence of the location on the temporal regions of brain perfusion defects and the neurocranial shape anomalies indicate that an extra X chromosome in Klinefelter patients has detrimental effects on the temporal lobe development and function.