CSF studies on the relationship between dopamine and 5-hydroxytryptamine in Parkinsonism and other movement disorders

In Parkinson's disease, the concentration of homovanillic acid (HVA) was reduced in lumbar CSF from patients with idiopathic Parkinsonism (n = 54, P less than 0.05) and post-encephalitic Parkinsonism (n = 19, P less than 0.01). The reduction in the concentrations of 5-hydroxyindolylacetic acid (5-HIAA) was not significant, and there was no alteration in the levels of 4-hydroxy-3-methoxyphenylethylene glycol (MHPG). Treatment with L-dopa increased the concentration of HVA in the CSF (P less than 0.05) but had no effect on the levels of 5-HIAA and MHPG. Carbidopa given in combinations with L-dopa produced similar CSF concentrations of dopa as did L-dopa alone but caused less than half the rise in HVA. Fourteen patients who became functionally independent on treatment with L-dopa had higher 5-HIAA levels than 23 patients who showed no such improvement (P less than 0.001), suggesting that intact 5-hydroxyltryptamine neurones may be important in the therapeutic response to L-dopa. In a variety of movement disorders, the levels of HVA, 5-HIAA, and MHPG were not significantly different from age-matched controls. Treatment with tetrabenazine did not significantly alter the metabolite levels in patients in whom it produced either improvement, or side effects.