Brain single-photon emission computed tomography and magnetic resonance imaging in Machado-Joseph disease

Background: Machado-Joseph disease (MJD) is one of the most frequently encountered spinocerebellar ataxias. However, few reports on brain single-photon emission computed tomographic (SPECT) imaging (BSI) with hexylmethylpropylene amineoxine labled with technetium Tc99m and magnetic resonance imaging (MRI) have been performed for the evaluation of patients with MJD. Objectives: To investigate possible abnormalities with BSI and MRI in patients with MJD and to correlate these findings with the duration of symptoms; cerebellar, extrapyramidal, and pyramidal syndromes; and the molecular characteristics of the MJD mutation. Patients and Methods: Twelve patients (8 males and 4 females [mean age, 39 years]) with genetically proven MJD were studied. The patients underwent BST and MRI on the same day. Brain SPECT imaging was performed after an intravenous injection of Tc-99m-hexylniethylpropylene amineoxine. The transaxial, coronal, and sagittal BSIs obtained were submitted to visual and semiquantitative analyses. Magnetic resonance imaging was obtained in a 2-T system with coronal, sagittal, transaxial, and 3-dimensional (volumetric) acquisitions. The volumes of the cerebellar hemispheres and vermis were calculated. Control groups for BSI (22 female and 20 male subjects [mean age, 33 years]) and MRI (13 female and 4 male subjects [mean age, 32.2 years]) were included for comparison. Results: Correlation was observed between the perfusion abnormalities identified by visual analysis in the BSI with the structural abnormalities observed on MRI in the parietal lobes and vermis. Brain SPECT imaging identified (by visual analysis) more perfusion abnormalities in the inferior portion of the frontal lobes, mesial and lateral portions of the temporal lobes, basal ganglia, and cerebellar hemispheres. Magnetic resonance imaging identified more abnormalities in the pons and superior portions of the frontal lobes. Olivary atrophy was identified by MRI. Semiquantitative analysis showed a statistically significant difference of perfusion in the inferior and superior portions of the frontal lobes, lateral portion of the temporal lobes, parietal lobes, left basal ganglia, cerebellar hemispheres, and vermis when compared with the control group. A significant difference was noted between the vermis and cerebellar volumes on MRI when compared with the control group. A significant relationship was observed between the perfusion of the left parietal lobe (P=.05) and extrapyramidal syndrome. There was a tendency toward an inverse relationship between the duration of symptoms and the perfusion of the cerebellar hemispheres (rho=-0.37; P=.24) and volume of the vermis (rho=-0.30; P=34); between the length of the expanded (CAG)(n) repeat and the perfusion of the left parietal lobe (rho=-0.32; P =36), vermis (rho=-0.28; P =.43), and pons (rho=-0.28; P=.42). A direct association was observed between the length of the expanded (CAG), repeat and the perfusion of the lateral portion of the right temporal lobe (rho =0.67; P=.03). Conclusions: Brain SPECT imaging and MRI were capable of identifying subclinical abnormalities in individuals with MJD. These findings may be helpful for a better understanding of the pathophysiology of this disease.