Medication Summary
Beta-adrenergic blockers (principally propranolol) and primidone are the first-line treatment for essential tremor. Each provides good benefit in 50-75% of cases and neither has been demonstrated to be unequivocally superior to the other. Adverse effects are more prominent early in treatment with primidone but are more prominent later in treatment with propranolol. Starting with propranolol is preferable in younger individuals, and primidone is started first in older patients.
Patients are usually started on one of these medications. The drug is introduced at a low dose that is increased slowly until complete response, tolerance, or usual maximum dose is attained. If some benefit is achieved but is incomplete, the other medication may be introduced and increased in an effort to achieve maximum benefit. Treatment with both drugs has been shown to be effective in patients who have had an insufficient response to one. Patients should not expect complete resolution of symptoms.
More evidence exists to support effectiveness in upper extremity tremor than in head or lower extremity tremor. A decrease in tremor amplitude rather than in frequency is the usual response, although some evidence indicates that primidone may decrease tremor frequency as well.
For patients who do not achieve an adequate response with primidone and propranolol, the authors try topiramate. Clozapine, an atypical neuroleptic, has been shown to be effective in a randomized, double-blind, crossover study of patients who had definite or probable essential tremor and poor response to propranolol or primidone. Thirteen of 15 patients demonstrated greater than 50% improvement of upper extremity tremor with 12.5 mg of clozapine.
Beta-Blockers, Nonselective
Class Summary
The mechanism of action in the reduction of essential tremor is not known. The action is hypothesized to be mediated primarily by peripheral beta2 adrenoreceptors, but some evidence indicates that beta1-receptor antagonists such as metoprolol also have some efficacy. Peripheral beta2 adrenoreceptors are located in the extrafusal muscle fibers and on the intrafusal fibers of the muscle spindles.
Propranolol hydrochloride (Inderal, InnoPran XL)
Propranolol, 1 of 2 medications of choice for essential tremor, has been shown to be effective in double-blind, placebo-controlled trials. It is a nonselective beta-adrenergic blocker with negative inotropic, chronotropic, and dromotropic properties. Propranolol is lipophilic with central nervous system (CNS) effects. Its mechanism of action is probably related to peripheral beta2 antagonism. The drug's long-acting formulation has efficacy similar to that of the standard formulation and may allow fewer daily doses.
In general, beta1-receptor antagonists are more effective than placebo but are not as effective as beta2-receptor antagonists. Metoprolol, a relatively selective beta1-receptor antagonist, may be useful in patients with asthma and other pulmonary conditions.
Anticonvulsants, Other
Class Summary
Primidone and, to a lesser extent, phenobarbital have demonstrated tremor-suppressing effects. Their mechanism of action is unknown, but it presumably involves the CNS.
Primidone (Mysoline)
Primidone is metabolized to phenobarbital and PEMA. It has tremor-suppressing activity independent of plasma concentrations of phenobarbital and is thought to be superior to phenobarbital. PEMA is not tremorolytic. Primidone is believed to have an independent mechanism for its effect on tremor.
It is strongly recommended that treatment with primidone be initiated with low doses because adverse effects at initiation of treatment are common. Start with one quarter or one half of a 50-mg tablet at bedtime and increase the dose slowly every week. Alternatively, introduce primidone using a 250 mg/5 mL suspension. Start with 1 drop at bedtime and increase the dose by 1 drop each night for 20 nights. Then convert the patient to a 50-mg tablet and increase the dose slowly every week.
For patients who initially respond to primidone but later develop a tolerance to it, increasing the dose to as high as 1000 mg/day in an effort to regain benefit is advisable.
Topiramate (Topamax)
Topiramate's mechanism of action is unknown, but the blockage of voltage-dependent sodium channels and the augmentation of GABA are thought to play a role. Topiramate is not extensively metabolized and is excreted unchanged in the urine.
Antipsychotics, 2nd Generation
Class Summary
In a randomized, double-blind, crossover study of 15 patients who had definite or probable essential tremor and poor response to propranolol or primidone, 13 showed greater than 50% improvement of upper extremity tremor with 12.5 mg of clozapine.
Clozapine (Clozaril, FazaClo)
Clozapine's mechanism of effect in essential tremor is unknown. The long-term effects of clozapine in essential tremor have not been studied. The drug may be tried before resorting to surgery when other methods have failed. Clozapine is weakly antidopaminergic, antiadrenergic (alpha1 and alpha2 receptors), anticholinergic, antihistaminergic (H1, H3), and antiserotonergic (5-HT1c, 5-HT2, 5-HT3).
Antidepressants, Other
Class Summary
In a case series report, 4 patients (3 with Parkinson disease and 1 with essential tremor) who responded initially to propranolol had improvement of tremor with mirtazapine.
Mirtazapine (Remeron, Remeron SolTab)
Mirtazapine is a potent 5-HT2, 5-HT3, and H1 antagonist. It is a moderate peripheral alpha1-adrenergic antagonist and a moderate antagonist of muscarinic receptors. The drug's half-life is 20-40 hours.
Walter AR, Bower JH, Ahlskog JE et al. Increased risk of essential tremor in first-degree relative of patients with Parkinson's disease. Mov Disord. Aug 15 2007;22(11).
Louis ED, Vonsattel JP. The emerging neuropathology of essential tremor. Mov Disord. Jan 30 2008;23(2):174-82. [Medline].
Shill HA, Adler CH, Sabbagh MN, et al. Pathologic findings in prospectively ascertained essential tremor subjects. Neurology. Apr 15 2008;70(16 Pt 2):1452-5. [Medline].
Louis ED, Zheng W, Mao X, Shungu DC. Blood harmane is correlated with cerebellar metabolism in essential tremor: a pilot study. Neurology. Aug 7 2007;69(6):515-20. [Medline].
Louis ED, Honig LS, Vonsattel JP, Maraganore DM, Borden S, Moskowitz CB. Essential tremor associated with focal nonnigral Lewy bodies: a clinicopathologic study. Arch Neurol. Jun 2005;62(6):1004-7. [Medline].
Louis ED, Vonsattel JP, Honig LS, Ross GW, Lyons KE, Pahwa R. Neuropathologic findings in essential tremor. Neurology. Jun 13 2006;66(11):1756-9. [Medline].
Shin DH, Han BS, Kim HS, Lee PH. Diffusion tensor imaging in patients with essential tremor. AJNR Am J Neuroradiol. Jan 2008;29(1):151-3. [Medline].
Bermejo-Pareja F, Louis ED, Benito-Leon J. Risk of incident dementia in essential tremor: a population-based study. Mov Disord. Aug 15 2007;22(11):1573-80. [Medline].
Benito-Leon J, Louis ED, Bermejo-Pareja F. Elderly-onset essential tremor is associated with dementia. Neurology. May 23 2006;66(10):1500-5. [Medline].
Klebe S, Stolze H, Grensing K, Volkmann J, Wenzelburger R, Deuschl G. Influence of alcohol on gait in patients with essential tremor. Neurology. Jul 12 2005;65(1):96-101. [Medline].
Daniels C, Peller M, Wolff S, et al. Voxel-based morphometry shows no decreases in cerebellar gray matter volume in essential tremor. Neurology. Oct 24 2006;67(8):1452-6. [Medline].
Ross GW, Dickson D, Cersosimo M. Pathological investigation of essential tremor. Neurology. Apr 2004;62(7) S5:A537-A538.
Ma S, Davis TL, Blair MA, et al. Familial essential tremor with apparent autosomal dominant inheritance: should we also consider other inheritance modes?. Mov Disord. Sep 2006;21(9):1368-74. [Medline].
Deng H, Le W, Jankovic J. Genetics of essential tremor. Brain. Jun 2007;130:1456-64. [Medline].
Shatunov A, Sambuughin N, Jankovic J, et al. Genomewide scans in North American families reveal genetic linkage of essential tremor to a region on chromosome 6p23. Brain. Sep 2006;129:2318-31. [Medline].
Higgins JJ, Lombardi RQ, Pucilowska J, Jankovic J, Tan EK, Rooney JP. A variant in the HS1-BP3 gene is associated with familial essential tremor. Neurology. Feb 8 2005;64(3):417-21. [Medline].
Dogu O, Sevim S, Camdeviren H, et al. Prevalence of essential tremor: door-to-door neurologic exams in Mersin Province, Turkey. Neurology. Dec 23 2003;61(12):1804-6. [Medline].
Louis ED, Barnes LF, Ford B, Pullman SL, Yu Q. Ethnic differences in essential tremor. Arch Neurol. May 2000;57(5):723-7. [Medline].
Tan EK, Lum SY, Prakash KM. Clinical features of childhood onset essential tremor. Eur J Neurol. Dec 2006;13(12):1302-5. [Medline].
Louis ED, Dogu O. Does age of onset in essential tremor have a bimodal distribution? Data from a tertiary referral setting and a population-based study. Neuroepidemiology. 2007;29(3-4):208-12. [Medline].
Louis ED, Ottman R. Study of possible factors associated with age of onset in essential tremor. Mov Disord. Nov 2006;21(11):1980-6. [Medline].
Louis ED, Benito-Leon J, Ottman R, Bermejo-Pareja F. A population-based study of mortality in essential tremor. Neurology. Nov 20 2007;69(21):1982-9. [Medline].
Rajput A, Robinson CA, Rajput AH. Essential tremor course and disability: A clinicopathologic study of 20 cases. Neurology. Mar 23 2004;62(6):932-6. [Medline].
[Best Evidence] Thawani SP, Schupf N, Louis ED. Essential tremor is associated with dementia: prospective population-based study in New York. Neurology. Aug 25 2009;73(8):621-5. [Medline].
Chatterjee A, Jurewicz EC, Applegate LM, Louis ED. Personality in essential tremor: further evidence of non-motor manifestations of the disease. J Neurol Neurosurg Psychiatry. Jul 2004;75(7):958-61. [Medline].
Miller KM, Okun MS, Fernandez HF, Jacobson CE 4th, Rodriguez RL, Bowers D. Depression symptoms in movement disorders: comparing Parkinson's disease, dystonia, and essential tremor. Mov Disord. Apr 15 2007;22(5):666-72. [Medline].
Benito-Leon J, Louis ED, Bermejo-Pareja F. Reported hearing impairment in essential tremor: a population-based case-control study. Neuroepidemiology. 2007;29(3-4):213-7. [Medline].
Ondo W, Jankovic J, Schwartz K, Almaguer M, Simpson RK. Unilateral thalamic deep brain stimulation for refractory essential tremor and Parkinson's disease tremor. Neurology. Oct 1998;51(4):1063-9. [Medline].
Stolze H, Petersen G, Raethjen J, Wenzelburger R, Deuschl G. The gait disorder of advanced essential tremor. Brain. Nov 2001;124:2278-86. [Medline].
Deeb J. Gannon K. Shah M, et al. Comparison of datscan imaging and smell testing in essential tremor and Parkinson disease. Jr Neurol, Neurosurg. & Psych. Sept 2007;78(9):1018-1019.
Findley LJ, Shah M. Muhammed N, et al. Olfactory tests distinguish essential from parkinsonian tremor. Evidence of enhanced detection and age resistance in familial essential tremor. J Neurol Neurosurg Psych. Jan 2006;77(1):140.
Doep F. Plotkin M, Siegel L. Brain parenchyma sonography and 123I-FP-CIT SPECT in Parkinson's disease and essential tremor. Mov. Disord. Dec 7 1007;23(3):(405-410).
Stockner H, Sojer M, K KS, et al. Midbrain sonography in patients with essential tremor. Mov Disord. Feb 15 2007;22(3):414-7. [Medline].
Luo WF, Zhang YC, Sheng YJ, Fang JC, Liu CF. Transcranial sonography on Parkinson's disease and essential tremor in a Chinese population. Neurol Sci. Dec 11 2011;[Medline].
Fytagoridis A, Sandvik U, Aström M, Bergenheim T, Blomstedt P. Long term follow-up of deep brain stimulation of the caudal zona incerta for essential tremor. J Neurol Neurosurg Psychiatry. Dec 28 2011;[Medline].
Benabid AL, Pollak P, Gao D, et al. Chronic electrical stimulation of the ventralis intermedius nucleus of the thalamus as a treatment of movement disorders. J Neurosurg. Feb 1996;84(2):203-14. [Medline].
O'Brien MD, Upton AR, Toseland PA. Benign familial tremor treated with primidone. Br Med J (Clin Res Ed). Jan 17 1981;282(6259):178-80. [Medline]. [Full Text].
Goldman MS, Ahlskog JE, Kelly PJ. The symptomatic and functional outcome of stereotactic thalamotomy for medically intractable essential tremor. J Neurosurg. Jun 1992;76(6):924-8. [Medline].
Kondziolka D, Ong JG, Lee JY, Moore RY, Flickinger JC, Lunsford LD. Gamma Knife thalamotomy for essential tremor. J Neurosurg. Jan 2008;108(1):111-7. [Medline].
Pahwa R, Lyons KL, Wilkinson SB, et al. Bilateral thalamic stimulation for the treatment of essential tremor. Neurology. Oct 22 1999;53(7):1447-50. [Medline].
Schuurman PR, Bosch DA, Bossuyt PM, et al. A comparison of continuous thalamic stimulation and thalamotomy for suppression of severe tremor. N Engl J Med. Feb 17 2000;342(7):461-8. [Medline].
Taha JM, Janszen MA, Favre J. Thalamic deep brain stimulation for the treatment of head, voice, and bilateral limb tremor. J Neurosurg. Jul 1999;91(1):68-72. [Medline].
Tasker RR. Deep brain stimulation is preferable to thalamotomy for tremor suppression. Surg Neurol. Feb 1998;49(2):145-53; discussion 153-4. [Medline].

