A promising new technology for Parkinson’s disease
2005; Lippincott Williams & Wilkins; Volume: 65; Issue: 2_suppl_1 Linguagem: Inglês
10.1212/wnl.65.2_suppl_1.s6
ISSN1526-632X
Autores Tópico(s)Neuroscience and Neural Engineering
ResumoIt is remarkable that, over 35 years after its introduction, levodopa remains the single most effective drug for treating the symptoms of Parkinson’s disease (PD). Because of its progressive nature, virtually all individuals with PD eventually require levodopa and virtually all individuals with PD respond to it. However, it is not a perfect drug. Initially, the response to levodopa can be dramatic. The term “honeymoon period” is often used to describe that period of time immediately after institution of levodopa therapy because patients derive prolonged benefit from individual doses of the drug. They can miss a dose, or even several doses, and not experience any discernible deterioration in motor function.1,2 This presumably is possible because sufficient nigrostriatal dopaminergic neurons still survive early in the clinical course of PD to convert the administered levodopa to dopamine (DA) and then to release, reuptake, and recycle it, thus approximating the normal synaptic milieu, which is characterized by sustained, tonic firing of dopaminergic neurons with periodic superimposed phasic bursts of activity triggered by sensory stimuli.3–5 With the passage of time, however, and continued loss of dopaminergic neurons, this “long-duration” effect of levodopa gradually fades. What then emerges is the “short-duration” response, in which clinical benefit becomes much more dependent on the plasma levodopa levels generated by individual doses of the medication which presumably, in turn, mirror the levels of levodopa and DA within the brain itself. This time-limited benefit from individual levodopa doses may lead to the appearance of a pattern of motor fluctuations in which benefit from a dose of levodopa becomes less prolonged and more unpredictable. The number of individuals with levodopa-treated PD who experience motor fluctuations grows relentlessly with the duration of treatment. Motor fluctuations are evident in approximately 30% of levodopa-treated PD patients by 3 years, in over …
Referência(s)