A 70-year-old man comes to the physician with muscle rigidity that impairs his daily activities. He was diagnosed with Parkinson disease 5 years ago and takes levodopa/carbidopa. His initial response to the medication allowed him to continue all of his usual activities. Recently, the patient has been experiencing episodes of sudden restricted mobility lasting several hours, and sometimes he "freezes" altogether. These episodes alternate with symptom-free periods in which he is mobile and feels well. The patient desires relief as he believes he can still "do so much" with his life. During discussion of this patient's fluctuating mobility, which of the following should the physician emphasize?

Question

A 70-year-old man comes to the physician with muscle rigidity that impairs his daily activities.  He was diagnosed with Parkinson disease 5 years ago and takes levodopa/carbidopa.  His initial response to the medication allowed him to continue all of his usual activities.  Recently, the patient has been experiencing episodes of sudden restricted mobility lasting several hours, and sometimes he "freezes" altogether.  These episodes alternate with symptom-free periods in which he is mobile and feels well.  The patient desires relief as he believes he can still "do so much" with his life.  During discussion of this patient's fluctuating mobility, which of the following should the physician emphasize?

Quizplus · Accepted Answer

11ec160b_3c17_1676_9249_01a37fae119f_MD0001_00 Long-term treatment of Parkinson disease (PD) with levodopa can be complicated by periodic fluctuations in motor function: patients have good mobility during "on" periods and increased bradykinesia/rigidity during "off" periods ("on-off" phenomenon). Oftentimes, these fluctuations appear to correlate with serum drug levels (eg, reduced mobility 4 hours after the last dose). As PD progresses, the therapeutic window for levodopa narrows, possibly due to natural or levodopa-induced nigrostriatal degeneration. As a result, small changes in serum drug levels can result in motor fluctuations (eg, mild elevations may result in dyskinesia, whereas slight reductions may result in bradykinesia/rigidity). In advanced PD, motor fluctuations can occur independently of medication dosing and may become unpredictable. (Choice A) Drug holidays have not been shown to be effective in preventing motor fluctuations in PD. Also, stopping levodopa abruptly is not recommended as it could cause a condition similar to neuroleptic malignant syndrome. (Choices C and D) Progressive nigrostriatal neurodegeneration, not enhanced drug metabolism, is thought to be responsible for motor fluctuations in PD. As such, motor fluctuations are not typically temporary or self-limiting and usually require long-term medical management. (Choice E) Discontinuation of carbidopa (a decarboxylase inhibitor) is inappropriate as carbidopa reduces the peripheral conversion of levodopa to dopamine and consequently minimizes systemic side effects (eg, nausea/vomiting). Educational objective: Long-term treatment of Parkinson disease with levodopa can be complicated by periodic and sometimes unpredictable fluctuations in motor function. This "on-off" phenomenon is thought to be a consequence of progressive nigrostriatal neurodegeneration leading to a decreased therapeutic window for levodopa. __________ References: Treatment of motor symptoms in advanced Parkinson's disease: a practical approach. (http://www.ncbi.nlm.nih.gov/pubmed/21645577)

A 70-Year-Old Man Comes to the Physician with Muscle Rigidity