As someone with Parkinson’s disease, I am accustomed to people mistaking dyskinesia for tremor. It is very common for people to confuse one with the other. After all, both are a form of shaking. However, dyskinesia is a side effect of drug therapy for Parkinson’s, while tremor is the most common symptom of the disease. I want to highlight the differences to enhance the reader’s understanding of Parkinson’s disease and its manifestations. It helps us if you know what you are seeing.
Parkinson’s disease is a slowly progressive neurodegenerative illness characterized by: tremor, stiffness (rigidity), slowness of movement (bradykinesia) and difficulty with balance (postural instability). The symptoms appear when there is not enough dopamine in the brain. Dopamine is a naturally-occurring chemical (neurotransmitter) that allows nerve cells to transmit messages between each other and then to muscles to allow normal movement to take place. In Parkinson’s disease, for reasons not yet understood, many of these cells have died. The remaining cells cannot produce enough dopamine.
Levodopa, also called L-dopa, is the most common and effective drug used to treat Parkinson’s disease. It replaces dopamine in the brain. It is most effective against rigidity and slowness. It produces less benefit for tremor.
Dyskinesia is a distortion or impairment of voluntary movement. The person is unable to control muscle movement. It often occurs as a side effect of long-term therapy with levodopa. Dyskinetic movements look like smooth tics — sometimes like an uncoordinated dance. They include writhing and twisting movements. Levodopa-induced dyskinesia is evident in people with Parkinson’s disease who have been on levodopa for prolonged periods of time.
Dyskinesia only occurs when the person’s levodopa is at optimum levels (peak-dose dyskinesia) or during the so-called “on” phase of levodopa therapy. It dissipates as levodopa levels in the brain drop.
Tremor is also an involuntary movement. But it is characterized by a rhythmic shaking or vibrating movement. A resting tremor is found in a majority of persons with Parkinson’s disease. It normally starts in one hand and is most prominent when the hand is resting and relaxed. Over time it often travels to the opposite hand or to the leg on the same side of the body. Tremor does not respond well to levodopa therapy.
Does the Distinction Matter?
The tendency is for casual observers to equate limited involuntary movements with the disease being less present. It is normally the opposite. In my case, I experience dyskinesia every day; I rarely have a tremor. But dyskinesia is the most obvious outward sign of the disease since most of my symptoms (rigidity, slowed movement and poor balance as well as non-motor symptoms) are invisible to the untrained eye. In other words, lack of movement is not the same as feeling well. Anecdotally, when I see a friend with Parkinson’s go still, it is rarely a good thing. It is why we call it being “off”. I suppose the danger is in assuming “wellness” when the better course is to ask or ignore our condition altogether. There is no harm in saying nothing.
Shake It Up for Parkinson’s
*Don’t miss a special evening with rock legend Tom Cochrane in support of the Morton & Gloria Shulman Movement Disorders Centre at the Toronto Western Hospital. Set in the fabulous Capital Event Theatre, the event will include an open bar, great food, a silent auction and amazing entertainment.