PET and MRI detection of early and progressive neurodegeneration in spinocerebellar ataxia type 36.
BACKGROUND
The spinocerebellar ataxias (SCAs) form a clinically, genetically, and pathological heterogeneous group of autosomal-dominant degenerative diseases. In particular, SCA36 is characterized by a late-onset, slowly progressive cerebellar syndrome typically associated with sensorineural hearing loss. This study was aimed at analyzing the neurodegenerative process underlying SCA36 through fluorodeoxyglucose positron emission tomography (FDG-PET) and MRI scans.


METHODS
Twenty SCA36 patients underwent a study consisting of FDG-PET and MRI scans. Clinical motor evaluation was performed through the Scale for the Assessment and Rating of Ataxia (SARA). FDG-PET was carried out using a voxel-by-voxel and region-of-interest analysis. MRI evaluation was based on visual inspection and volumetric analysis.


RESULTS
SARA ranged from 0 to 24.5 (4 patients asymptomatic, 3 with unspecific symptoms, and 13 with cerebellar signs). FDG-PET revealed hypometabolism in the asymptomatic stage in the vermis and right cerebellar hemisphere. In the ataxic stage, hypometabolism spread to both cerebellar hemispheres and the brain stem. MRI was normal in asymptomatic and preataxic individuals and showed superior cerebellar vermis atrophy early in the ataxic stage, diffuse cerebellar atrophy some years into the disease course, and a pattern of olivopontocerebellar atrophy in the oldest patients. There was no significant cerebellar atrophy in patients younger than 50 years.


CONCLUSIONS
We present the first FDG-PET study of SCA36 and one of the largest neuroimaging study of SCAs. Our results revealed neuronal dysfunctions in the vermis and right cerebellar hemisphere as soon as a decade before the onset of motor symptoms. In the ataxic stage, dysfunctions spread to both hemispheres and the brain stem. © 2016 International Parkinson and Movement Disorder Society.
['Aguiar|Pablo|P|', 'Pardo|Julio|J|', 'Arias|Manuel|M|', 'Quintáns|Beatriz|B|', 'Fernández-Prieto|Montse|M|', 'Martínez-Regueiro|Rocío|R|', 'Pumar|José-Manuel|JM|', 'Silva-Rodríguez|Jesús|J|', 'Ruibal|Álvaro|Á|', 'Sobrido|María-Jesús|MJ|', 'Cortés|Julia|J|']
D000328:Adult D000368:Aged D001933:Brain Stem D065814:Cerebellar Vermis D002531:Cerebellum D018450:Disease Progression D005260:Female D006801:Humans D008279:Magnetic Resonance Imaging D008297:Male D008875:Middle Aged D009687:Nuclear Proteins D049268:Positron-Emission Tomography D012720:Severity of Illness Index D020754:Spinocerebellar Ataxias
PET MRI neurodegeneration ataxia preataxic stage