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Symptoms of Parkinson's Disease Related to Treatment

End-of-dose Failure and the On-off Phenomenon 

When symptomatic antiparkinson therapy is instituted (especially with the mainstay of treatment, levodop a), patients usually have a smooth response for a long time. After years of treatment, however, there may be a wearing - off of the beneficial effect of the medication before the next dose is taken; that is, the patient may respond and feel good ("on") for a period of time and then the effect of the medication wears off, causing the parkinsonian symptoms to return ("off"). This is a common situation in the PD patient, and end-of-dose failure may be corrected by shortening the interval between doses, or by adding additional medications. As these motor fluctuations progress, however, the interval between doses may be very short. In severe, advanced patients, there occasionally arises a complication of long-term therapy where the response to medication is unpredictable; this is termed the on-off phenomenon, in which the patient may cycle from on to off or back again during one dosage interval, or the medication may never kick in at all. The on-off phenomenon is very difficult to treat.


Usually seen as an overdosage or peak-dose phenomenon (when a dose of levodopa is at its highest point in its dosing interval, also called high-dopa dyskinesias), abnormal involuntary movements (dyskinesia s) with irregular, flowing, dance-like or jerky motions may occur in any or all parts of the body; these are called choreic or choreiform movements or simply chorea (from the Greek word for "dance". Less commonly, dyskinesias may occur as the dose is wearing off (which we call low-dopa dyskenisias). Dyskinesias may be choreic or dystonic in nature. Dystonia may also occur as high - dopa (usually above the neck) or low - dopa (usually in the lower part of the body) phenomena.

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Comments on The Topic
recrutcom (Jan 02, 2007 11:40:18 AM) [reply]
discussionhey everyone I am new here just thought I would send a shout out!!
Dizzopam (Dec 06, 2006 11:21:26 PM) [reply]
discussionA Worried Patient
A distraught patient phoned her doctor's office. "Is it true", the woman wanted to know, "that the medication you prescribed has to be taken for the rest of my life?"
"Yes, I'm afraid so." The doctor told her.
There was a moment of silence before the woman continued, "I'm wondering, then, just how serious my condition is. This prescription is marked 'NO REFILLS.'"

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