I wanted to brush up on my knowledge here, so I checked out the BMJ Learning module on Parkinson’s diagnosis, which led me to this BMJ article. I also had to look for more details on some of the points, which led me to this one.
There are, broadly speaking, three types of tremor; rest, postural, and intention. (It gets more complicated, but that seems to be good enough for my purposes.) Postural tremor is tremor which occurs when maintaining a position against gravity; carrying cups is a classic situation in which it gets noticed.
Rest and intention tremors are much as I remember from medical school:
Rest tremor: Parkinson’s disease. Typical pill-rolling rest tremor, normally asymmetrical for the first few years, possibly with associated bradykinesia and/or rigidity; in practice, those signs can show up as quiet voice, decreased facial expression, shuffling gait.
Intention tremor: Characterised by ‘overshooting movements of increasing amplitude when approaching a goal‘. Typically due to cerebellar disorders.
Other causes of tremor seem mostly to be postural, though this isn’t clear-cut as they can overlap with kinetic tremor, and drug-induced or thyroid-induced tremors don’t seem to have been categorised by type anyway. Basically, here are the other causes of tremor:
- Essential tremor. Postural or kinetic. Usually symmetrical. Relieved by alcohol. No other associated features. Can affect the head or the voice (only rarely the legs). Can be genetic; a family history of tremor is strongly suggestive of essential tremor (though lack of a family history doesn’t rule it out).
- Dystonic tremor; this is tremor affecting a dystonic body part. Look for dystonic posturing (e.g. hyperextension of the fingers when hands are outstretched).
- Physiological/enhanced physiological tremor. (Physiological we all have, obviously. Enhanced physiological tremor can be due to stress
- Drug induced – see below.
- Thyroid-induced. Most articles on tremor advise doing routine TFTs to rule this out, but one letter in response to the BMJ article above pointed out that anyone with thyrotoxicosis bad enough to cause a tremor would also have other symptoms or signs, which strikes me as eminently sensible.
Medications that can cause tremor
- SSRIs or tricyclics
- Anticonvulsants (don’t know which types this applies to)
- Lithium (note that a fine tremor is a common SE of therapeutic levels; a coarse tremor indicates toxic levels).
- Withdrawal from alcohol, opiates, or benzos
Medications for essential tremor
This article had a batting order, which was useful. Propranolol or primidone are first-line, and if neither works separately then they can be used together. Gabapentin, topiramate, or lorazepam are second or third-line.
Botulinum injections can also be used in extreme cases. So, to my interest, can clozapine.
I recall once e-mailing a neurologist for advice on treating a tremor, and receiving the advice that there were a lot of things that could be tried, but most of them just weren’t going to be that effective.