Essential Tremor

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Contents 1 Epidemiology 2 Pathology 3 Genetics 4 Clinical-manifestations 5 Laboratory 6 Radiology 7 Complications 8 Differential-diagnosis 9 Management 10 More General Terms 11 Internet Database 12 References

Epidemiology

• 0.3-5.6% of the general population

• most common movement disorder

• men & women equally affected
• prevalence increases with age
• mean age at onset 35-45 years
• virtually always presents by age 70 years

Pathology

• abnormally functioning central oscillator located in the Guillain Mollaret triangle near the brain stem
• involves the inferior olivary nucleus
• cerebellar- brainstem- thalamic- cortical circuits probably involved

Genetics

• type 1 is autosomal dominant
• susceptibility loci

• FET1 gene at 3q13 identified in 75 members of 16 Icelandic families
• locus 2p25-22 identified in 15 members of 4 generations & 3 other families
• DRD3 gene

• 70% of patients have a family history of essential tremor

Clinical-manifestations

• low or moderate amplitude, fast (6-12 Hz) tremor
• most evident during active use of affected muscles
• generally symmetrical

• asymmetric tremor predicts more rapid progression of tremor [6]

• may involve:

• head & neck
• extremities
• voice

• movement is flexion- extension
• aggravated by emotions, hunger, fatigue & temperature extremes
• functional impairment may be significant

Laboratory

• comprehensive chemistry panel

• serum electrolytes
• serum urea nitrogen ( BUN)
• serum creatinine
• liver function tests

• thyroid function tests
• serum ceruloplasmin (for Wilson disease)

Radiology

• CT & MRI of the head are normal
• MRI helps exclude structural & inflammatory lesions (including multiple sclerosis) & Wilson disease
• MRI should be performed if the tremor has acute onset or stepwise progression

Complications

• may be associated with increased mortality for unclear reason(s) [7]

Differential-diagnosis

• distinguished from tremor of Parkinson's disease by absence of: rigidity, bradykinesia, postural instability, resting tremor

Management

• avoidance of caffeine & other stimulants
• alcohol in small amounts
• beta blockers

• propranolol considered effective agent [8]

• start 20 mg PO TID
• titrate to effect
• response rate 50-67% [8]

• other beta blockers probably effective [8]

• naldolol, atenolol, sotalol

• non cardiac beta-2 adrenergic receptors may be involved or a central effect is possible [3]

• primidone ( Primaclone, Mysoline) considered effective agent [8]

• start 50 mg QHS
• gradually increase to 250-300 mg/day in divided doses
• response rate 50-67% [8]

• gabapentin ( Neurontin) 400 mg TID

• comparable to propranolol 40 mg TID [4]
• probably effective [8]

• topiramate ( Topamax) probably effective [8]
• alprazolam ( Xanax) may be useful [4,8]
• mirtazapine ( Remeron) may be useful [4]
• botulinum toxin ( Botox)
• stereotactic thalamotomy/ thalamic stimulation should be considered for more severe tremors not responsive to medical management

More General Terms

• tremor

Internet Database

OMIM: 190300

References

1. Saunders Manual of Medical Practice, Rakel (ed), WB Saunders, Philadelphia, 1996, pg 1015-16
2. Medical Knowledge Self Assessment Program (MKSAP) 11, 14, 15, American College of Physicians, Philadelphia 1998, 2006, 2009
3. Physician's Desk Reference (PDR) 56th ed, 2002
4. Gironell A et al A randomized placebo-controlled comparative trial of gabapentin and propranolol in essential tremor. Arch of Neurol 56:475, 1999 PMID: &dopt=Abstract
   - Harrison's Online, 2002
5. Zesiewicz TA et al, CME Practice Parameter: Therapies for essential tremor Report of the Quality Standards Subcommittee of the American Academy of Neurology Neurology 2005;64:2008-2020 <PubMed> PMID: [1] <Internet> [2]
6. Putzke JD, Whaley NR, Baba Y, Wszolek ZK, Uitti RJ. Essential tremor: predictors of disease progression in a clinical cohort. J Neurol Neurosurg Psychiatry. 2006 Nov;77(11):1235-7. PMID: [3]
7. Louis ED et al, A population-based study of mortality in essential tremor. Neurology 2007, 69:1982 PMID: [4]
8. Zesiewicz TA et al Evidence-based guideline update: Treatment of essential tremor Report of the Quality Standards Subcommittee of the American Academy of Neurology Neurology, October 19, 2011 <PubMed> PMID: [5] <Internet> [6]
   - Evidence-based guideline update: Treatment of essential tremor Data Supplement [7]
9. Prescriber's Letter 19(3): 2012 Drug Treatment for Essential Tremor Detail-Document#: [8] (subscription needed) [9]
10. National Guideline Clearinghouse Evidence-based guideline update: treatment of essential tremor. Report of the Quality Standards Subcommittee of the American Academy of Neurology. ngc-guideline: [10]

essential tremor