How many of Hollywood’s male and female actors are driven by vanity and career opportunities to appear young by using Botox (botulinum toxin) injections? Well, there’s no way to know – and anyway, what does it matter? But now let’s ask, how many people have Essential Tremor (ET), the most common movement disorder? Estimates are as high as 10% of the U.S. population. While ET can begin at any age, it most commonly begins after age 40, and is most prevalent in older adults. For those who can’t live normally due to tremors, finding a solution matters greatly.
ET is not life threatening, but it can have a serious impact on a person’s ability to lead a normal life if it becomes severe. Most ET patients manage to cope until it reaches that point, at which time they are likely to seek treatment. Therapies fall into three broad categories:
- Systematic therapy – The use of oral medications (generally primidone or propranolol) means that the drugs circulate throughout the body. These agents are reported to provide less than 100% control of tremors, with at least half of ET patients experiencing no relief. In addition, many patients find side effects to be unpleasant, especially as the dosage must be increased as tremors progress.
- Source therapy – Essential tremor originates in the brain. Interventions such as MRI-guided Focused Ultrasound MRgFUS) and Deep Brain Stimulation (DBS) are aimed at controlling tremors by interrupting them at their source in the brain.
- Local therapy – Stopping the muscle movements at the location of the tremor (e.g. for hand tremors, quieting the wrist or hand muscle oscillations by means of botulinum toxin injections into the muscles).
4 things to know about botulinum injections
Most people know botulinum toxin (BoNT) by its trade name, Botox. This drug is a neurotoxin, meaning it has a toxic effect (paralysis) on muscles and nerves. When used properly, it is safe. And, when the tremors are controlled, BoNT is appealing because there are no systemic side effects as there are with oral medicines. Here are four important things to keep in mind about the use of BoNT for ET:
- Dosage can vary – Clinical studies of BoNT for either ET or Parkinson’s disease tremors have tested doses of 50 or 100 units. For example, in one study of 10 ET patients, the participants’ tremors were tracked with motion sensors on each arm while performing certain tasks. According to the study authors, “Dosing patterns were determined using the movement disorder neurologist’s interpretation of muscles contributing to the kinematically (motion-related) analyzed upper limb tremor biomechanics.”1 Since each patient’s tremors are unique to him/her, it’s important that the doctor tailor the dose to the patient’s needs.
- Location of injections – Since BoNT works directly on the site where it is injected, the doctor must identify which muscle groups are associated with the tremors as they are occurring during different positions (postural) and activities (writing, drinking water, etc.). Electromyogram (EMG) guidance is frequently used to ascertain accurate injection placement, though some sources question whether this potentially painful procedure is necessary. Improper injection placement can result in no effect, or unwanted side effects.
- Lack of durability – BoNT injections offer various degrees of tremor control, but even when relatively successful, the results are temporary. Studies report a range of 10-16 weeks, at which time another round of injections must be administered.
- Side effects – BoNT is considered safe when used properly. The most common side effect reported is weakness. According to one review, “The side effects of BoNT are related in part to undesired diffusion of the drug from the muscle of interest to nearby muscles/structures.”2 Other side effects reported in clinical studies include dose-related “including finger weakness, pain at injection sites, hematoma formation, and paresthesias [prickly, skin-crawling, or burning sensation]…”3 The point is, doctors should discuss the risks of side effects with patients.
Controlling the tremor source using MRgFUS
Sperling Neurosurgery Associates offers source control of tremor with a treatment called MRI-guided Focused Ultrasound (MRgFUS). Increasingly recognized as a revolution in ET treatment, MRgFUS stops tremors by deadening the “relay station” in the part of the brain that forwards dysfunctional brain transmissions outward to the limbs and other areas. What makes it particularly special is that no incisions or holes drilled in the skull are needed during this outpatient treatment – AND results are immediate and durable!
For more information, contact Sperling Neurosurgery Associates.
1 Samotus O, Kumar N, Rizek P, Jog M. Botulinum Toxin Type A Injections as Monotherapy for Upper Limb Essential Tremor Using Kinematics. Can J Neurol Sci. 2017 Nov 21:1-12. doi: 10.1017/cjn.2017.260.
2 Zakin E, Simpson D. Botulinum Toxin in Management of Limb Tremor. Toxins (Basel). 2017 Nov 10;9(11).