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Tremors have been reported in our cohort of chromosome 18 genetic conditions, in particular 18q-, 18p- and Ring 18. Tremors often have underlying genetic causes, with factors in one’s life – such as the use of certain medications, caffeine, stress – sometimes exacerbating pre-existing tremors. There are medications proven to be effective in improving tremors, mainly Propranolol and Primidone. Surgical options, such as deep brain stimulation, are also available in cases of disabling tremors that do not respond sufficiently to medications.
Tremors have been reported in ~9% of our cohort of 18q-, ~3% in 18p-, and 4% in Ring 18. The prevalence in 18q- appears higher than the general population prevalence of ~1-5%. In the general population, action-postural tremor (APT) is the most common type of tremor, with the other two types being resting tremor (RT) and intention tremor (IT). APT tremors are induced by the maintenance of certain postures (such as holding one’s arms out) and the performance of actions (such as using utensils to eat). By contrast, RT is observed at rest. RT is often the first symptom of Parkinson's disease. As for intention tremor (IT), this is typically caused by cerebellar dysfunction (such as from stroke, inflammation, genetic cause, etc.). Intention tremor classically gets activated only as the hand nears the target – for example, when touching one’s nose - which helps to distinguish it from APT. Unlike APT, intention tremor does not respond well or at all to medications. APT could be especially impairing to the person as it is brought out when performing actions. By contrast, RT temporarily goes away when one performs an action.
APT has many different causes. The most common cause is essential tremor, which is a genetic predisposition to APT. Other causes include certain medical conditions such as hyperthyroidism, certain medications, rare diseases such as Wilson’s disease, among other causes. Medications known to cause an APT include certain anti-seizure medications (for example Valproic Acid), certain heart medications, and some anti-depressants. APT is classically temporarily improved while drinking alcohol.
Several medications have been proven to reduce APT and therefore improve functional ability. Propranolol, a blood pressure medication of the beta blocker type, is now commonly used to reduce symptoms of neurological conditions including action tremors and migraines. Infrequent side effects of Propranolol include slowing of the heart rate, dropping of blood pressure, and potential exacerbation of asthma. However, these side effects are rarely encountered with the low dose that is used to treat APT. Another medication is primidone, which is an anti-seizure medication. If tolerated, Primidone works as well as propranolol. While other medications have been reported to possibly help with tremors, including Topiramate and Botulinum toxin, Propranolol and Primidone continue to be the medications with the highest efficacy. If medications are not effective, surgical treatments – such as deep brain stimulation of parts of the thalamus - have been shown to be effective for the treatment of severely disabling tremors.
Tremors are commonly reported in chromosome 18 conditions, particularly 18q-, 18p- and Ring 18. There are medications proven to reduce the functional impairments of action-postural tremors, with the leading ones being Propranolol and Primidone. Tremors that are medication-induced and intention tremors are also less likely to respond to anti-tremor medications. Surgical options such as deep brain stimulation of the thalamus have been proven to be effective in cases of disabling tremors that are inadequately controlled with medications.
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