The essentials of Essential Tremor
Although it was previously known as benign essential tremor, we now know this disorder of movement is anything but benign. When your patient comes in to see you because they have lost weight from inability to feed him or herself, or they are so stressed by the social stigma of the hand or head movements, or even if they have associated cognitive deficits that often accompany the disease, you will realize how bad essential tremor (ET) can get. Check out this week’s episode on BrainWaves for more information:
Clinically, ET is a high frequency, medium amplitude kinetic tremor that may symmetrically involve the upper extremities, but on closer look there is often a subtle asymmetry—on the order of about a 30% difference between sides. It can emerge at any phase in adult life, and typically will remain stable for many years, sometimes followed by a delayed progression. Most commonly, it involves the upper extremities (usually the hands and fingers), followed by the face, then the remainder of the body. Although ET is similar to postural tremor in that you can see it with a limb suspended in space, half of the time the tremor will worsen with movement (intentional component). It always revolves around the same axis, and you can appreciate that by having the patient draw an Archimedes spiral (left). Here you can see this patient’s tremor oscillated from the top right to the bottom left as the spiral was drawn. Also helpful is inertial loading (e.g., giving the patient a weighted object to hold), which will not change the frequency of ET or other tremors of central origin. So this is often used as a diagnostic aid (to exclude psychogenic tremors), but it can be therapeutically useful. For instance, inertial loading will improve the amplitude of the tremor, allowing patients to make use of heavy utensils during meals. I’ve even had a patient come to me saying she has had to buy heavier utensils because she found them easier to feed herself with. Or you can ask your patient to shell out the $$$ by dropping $200 on a Liftware spoon (below). These things really do work. And they really are that expensive.
Besides the tremor, there are other associated features with ET that are worth mentioning here, which is what makes this episode important to neurology trainees. In fact, tremor was thought to be the only neurologic symptom of ET until 2001. Other notable symptoms include:
- An ataxic gait (usually mild)
- Vocal tremor (which can be socially stigmatizing)
- Cognitive impairment (attention, memory and language most often affected)
- Hearing impairment
- Sleep disturbances
The treatment of choice in ET is propranolol, a non-selective beta-adrenergic antagonist. Experts recommend starting propranolol at 20mg three times daily and uptitrating to a total of 200 or 300mg daily. Primidone has also earned a level A recommendation from the AAN. If propranolol or primidone cannot be used, topiramate, gabapentin, nimodipine, botulinum toxin, clozapine, and other medications of the benzodiazepine class may be considered. Deep brain stimulation has also curried favor among movement disorder specialists in recent years, with the standard target being the ventrolateral nucleus of the thalamus (aka the ventral intermediate nucleus [VIM]), and a second target being the radiation prelemniscalis—a small subnucleus whose name I had honestly never even heard of and most surgeons never really target these days. This surgical option has dramatically improved the symptoms in a great many patients–at least 50% improvement according to some older data–albeit with not insignificant neurosurgical risk (1% nationwide risk of peri-operative death).
I hope you find this week’s episode helpful. The bottom line here is, once you’ve made the diagnosis of ET, don’t just shake it off. Do something for your patients.
Deuschl G, Raethjen J, Hellriegel H and Elble R. Treatment of patients with essential tremor. The Lancet Neurology. 2011;10:148-61.
Louis ED. Diagnosis and Management of Tremor. Continuum (Minneap Minn). 2016;22:1143-58.
Sandvik U, Koskinen LO, Lundquist A and Blomstedt P. Thalamic and subthalamic deep brain stimulation for essential tremor: where is the optimal target? Neurosurgery. 2012;70:840-5; discussion 845-6.
Zesiewicz TA, Elble R, Louis ED, Hauser RA, Sullivan KL, Dewey RB, Jr., Ondo WG, Gronseth GS, Weiner WJ and Quality Standards Subcommittee of the American Academy of N. Practice parameter: therapies for essential tremor: report of the Quality Standards Subcommittee of the American Academy of Neurology. Neurology. 2005;64:2008-20.