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Background: The aims of the present study were: i) to measure levels of the dopamine metabolite homovanillic acid (HVA), the serotonin metabolite 5-hydroxindoleacetic acid (5HIAA) and precursor tryptophan, as well as the noradrenaline metabolite 3-methoxy-4-hydroxyphenylethylene glycol (MHPG) and thiamine in the cerebrospinal fluid (CSF) of patients with Friedreich's ataxia (FA), olivopontocerebellar atrophy (OPCA), and the autosomal recessive spastic ataxia of Charlevoix-Saguenay (ARSAC), as compared with sex- and age-matched control subjects., Patients and Methods: CSF amine related compound levels and thiamine results were compared in 40 FA, 44 OPCA and nine ARSAC patients with those of 94 sex- and age-matched subjects. Neuroimaging (CT scans and single photon emission computed tomographies i.e. SPECT) were carried out in all patients and controls. Genetic studies were conducted on OPCA patients. CSF amine related compounds were measured by high performance liquid chromatography, whereas CSF thiamine levels were measured by a microbiological method., Results: FA patients had significantly lower CSF HVA, 5HIAA and thiamine values than control patients and a trend for lower MHPG levels. In OPCA patients, CSF HVA, MHPG and thiamine values were markedly lower whereas CSF 5HIAA values showed only a trend towards lower levels; in ARSAC patients only thiamine and HVA CSF values were lower than those in control subjects., Conclusion: After presenting the relationships between neurochemical findings on one side, the degree of ataxia, the degree of cerebellar atrophy and the SPECT findings on the other, the authors concluded that replacement and neuroprotective clinical trials in these patients would have to include two or three drugs because the neurotransmitter deficiencies are multiple.

Actual therapeutic assays in spinocerebellar ataxias, i.e. in Friedreich's ataxia (FA) and olivopontocerebellar atrophy (OPCA) are discussed in relation to (i) the serotoninergic theory; (ii) the excitotoxic action of glutamate; and (iii) cerebrospinal fluid thiamine deficiency in ataxic patients. Data from the literature show that neurochemical deficiencies arising from cerebellar damage in both FA and OPCA patients are multiple. Assays of replacement and neuroprotective therapeutics with a single drug have produced controversial data or mildly effective results. Consequently, it is hypothesized that a drug cocktail, i.e. L-5-hydroxytryptophan, thiamine and amantadine hydrochloride, would be more beneficial. This cocktail proved to be useful in open studies, improving respiratory disorders in FA patients. More powerful inhibitors of N-methyl-D aspartate receptor channels should be tried initially in animal experiments.

Blood thiamine levels in ataxia patients were studied. No significant differences were found between 30 patients with Friedreich's ataxia and 29 patients with olivopontocerebellar atrophy (OPCA) compared with control subjects. Both OPCA and Friedreich's ataxia patients presented significantly lower cerebrospinal fluid thiamine levels than their controls (p less than 0.001 and p less than 0.04 respectively). These results, discussed in terms of the high degree of cerebellar atrophy on CT scans in OPCA v Friedreich's ataxia patients, seem to correlate with cerebellar thiamine turnover and content.