Comparison of somatosensory evoked potentials with striatal glucose consumption measured by positron emission tomography in the early diagnosis of Huntington's disease.

Both somatosensory evoked potentials (SEP) and striatal glucose consumption (rCMRGlc) measured by positron emission tomography (PET) have been reported to be abnormal early in the course of Huntington's disease (HD). To compare their diagnostic value, SEP and rCMRGlc were measured in a group of 18 first degree off-spring of HD families: 6 had manifest HD with chorea and the remaining 12 individuals were chorea-free subjects at risk for HD. In five patients with manifest disease, both SEP and striatal rCMRGlc were significantly abnormal, defined in SEP as having either a bilaterally absent frontal N30 amplitude or a reduction of the parietal N20/P25 amplitude below 1 microV on at least one side; in PET as exhibiting a reduction of the cerebellar ratio (CR) of both caudate and lentiform rCMRGlc below the 99% confidence limits of these variables determined in 20 normal volunteers. The remaining patient with manifest HD had questionably abnormal SEP and significantly reduced indices of striatal rCMRGlc. The five persons at risk for HD who had normal SEP also had normal striatal rCMRGlc; those three at-risk patients with abnormal SEP also had a reduction of the CR of both caudate and lentiform rCMRGlc. Of the remaining four individuals at risk for HD who had questionably abnormal SEP, three had CR values of striatal rCMRGlc in the normal range and one a reduction of the CR of lentiform rCMRGlc. In at-risk patients, the SEP diagnosis correlated significantly with caudate (r = -0.8; p < 0.002) and lentiform (r = -0.76; p < 0.005) rCMRGlc. These data indicate a parallel deterioration of SEP and striatal rCMRGlc early in the course of HD even before the development of chorea.