Patients frequently come to see me for evaluation of their tremor. Invariably the history is that the tremor was first brought to their attention by a close friend or a family member. The patient is worried that he/she has Parkinson’s disease and hence seek a neurologist’ s attention. Rarely are they bothered by the tremor per-se. By that I mean the tremor is usually not disabling and does not impair their quality of life at least initially. So do all tremors represent Parkinson’s disease? Are there any benign tremors? Which tremors warrant medical attention? These are some of the issues I plan to dwell on in this blog post. I hope some of my readers shall find the information useful.
So what exactly is a tremor. Well neurologically a tremor is characterized by rhythmic oscillatory and involuntary movement across a joint. I used the work involuntary because tremors at times can be voluntary. Voluntary tremor is usually psychogenic (meaning it has a psychological basis to it). We shall not discuss psychogenic/voluntary tremors in this post though. Suffice to say that a doctor shall be able to identify psychogenic tremor based on the history and examination findings alone.
So what do I look for when a patient with tremor comes to me seeking an explanation. Well the age of the patient is the first clue to the etiology of the tremor. Idiopathic Parkinson’s disease usually starts off in the sixth to seventh decade of life. Familial Parkinson’s disease can start at a younger age but usually the tremor is not so prominent nor is it the initial manifestation. There can be many causes of tremor in the “young”. Various medical conditions some more common such as hyperthyroidism, hepatic and renal diseases and some more exotic such as Wilson’s disease (due to a problem with copper metabolism in the body)come to mind. At times the answer is more innocuous and the tremor is either due to stress or excessive intake of coffee and other caffeine containing drinks. In that case all that is needed is reassurance. One other disease that needs to be kept in mind is multiple sclerosis though usually more findings are documented in exam (meaning that the tremor is not see in isolation). One should never forget to ask patients about the use of prescription, over the counter and illicit drugs. Many drugs such as sodium valproate (commonly used to treat seizures and at times bipolar disorder), bronchodilators (drugs used to treat asthma, reactive airway disease and chronic obstructive airway disease) cause a coarse postural and kinetic tremor as a side-effect. Once the drug is stopped the tremor abates.
Another common entity frequently confused with Parkinson’s disease is what is called essential tremor or also sometimes referred to as benign essential tremor. Patients who have essential tremor are usually in the same age group as patients with idiopathic Parkinson’s disease and hence the confusion and concern arises. Essential tremor has the following characteristics: it is usually a postural tremor (meaning that the tremor is most prominent when the hands are kept out and maintained at a posture such as having them stretched out in front of you. Remember the classical tremor of Parkinson’s disease is a resting tremor. Meaning the tremor is most prominent when the hands are at rest like for example resting on the patient’s lap and the patient’s attention is diverted). Essential tremor is a faster and finer tremor as compared to the tremor of Parkinson’s disease which is a slower (2-5 Hz) and of higher amplitude. A point to note here is that tremors are frequently classified based on their frequency, amplitude and position (rest Vs postural Vs kinetic). Patients who have essential tremor frequently in addition to the hand tremor also may have a head tremor (the head shakes either from side to side [no-no tremor] or up and down [yes-yes tremor]). They may also have a tremor in their speech (voice tremor). On further questioning some of them may admit to having the tremor run in their family (meaning their father and grandfather also had a similar tremor). They may have also noted that when they drink alcohol the tremor becomes less prominent. Infact some patients start drinking excessively for this very reason! Essential tremor usually progresses very very slowly (if at all) and may never become problematic and disabling in the patient’s lifetime. Hence it does not need to be treated unless it is socially disabling (“Doctor Sethi I cannot drink a glass of wine without spilling it over my dress!” “Dr Sethi I am so embrassed when my hands shake in a business meeting!”). Essential tremor is not accompanied by the other signs and symptoms which accompany Parkinson’s disease such as gait problems, freezing, stiffness, rigidity and mask like facies.
So not all tremors represent Parkinson’s disease. A quick visit to your “local” neurologist shall give you an answer to what kind of tremor you have.