BRAIN MRI, LUMBAR CSF MONOAMINE CONCENTRATIONS, AND CLINICAL DESCRIPTORS OF PATIENTS WITH SPINOCEREBELLAR ATAXIA MUTATIONS

Objectives-To serially assess changes in lumbar CSF biogenic amines, r adiographic characteristics, and neurological signs in 34 patients wit h dominantly inherited ataxia. Methods-Mutational analysis was used to identify genetic subgroups. Annual assessment of lumbar CSF monoamine metabolites using a gas chromatographic/mass spectrometric method and morphometric measurements of the cerebellum, pens, and the cervical s pinal cord on MRI were analysed for each patient and compared with nor mal controls. Results-Patients with CAG trinucleotide repeat expansion s on chromosome 6p (mutSCA1) and chromosome 14q (mutSCA3) had only abo ut one half the normal concentrations of lumbar CSF homovanillic acid (HVA) whereas, 5-hydroxyindoleacetic acid (5-HIAA) concentrations were similar to those in age matched normal subjects. The HVA and 5-HIAA c oncentrations in clinically similar patients without mutSCA1 or mutSCA 3 were normal. One year after the first study, HVA concentrations were reduced by a mean of 22% regardless of the patient's SCA mutation. Ab normalities on MRT were consistent with a spinopontine atrophy in pati ents with mutSCA3, spinopontocerebellar atrophy in patients with mutSC A1, and ''pure'' cerebellar atrophy in patients without these mutation s. Conclusions-Quantitative MRT measurements were not useful in monito ring progression of disease but lumbar CSF HVA concentrations and tota l scores on a revised version of the ataxia clinical rating scale seem ed to progress in parallel.