eMedicine Specialties > Neurology > Movement and Neurodegenerative Diseases

Writer's Cramp

Jonathan B Strober, MD, Director, Pediatric Muscular Dystrophy Association Clinic; Associate Clinical Professor, Departments of Pediatrics and Neurology, Division of Child Neurology, University of California at San Francisco

Updated: Jan 19, 2010

Introduction

Background

Writer's cramp is a form of task-specific focal dystonia. Dystonia is an involuntary, sustained muscle contraction causing twisting movements and abnormal postures; focal dystonia means only one body part is affected. Writer's cramp is the most common dystonia occurring in the setting of repetitive movement disorders. A focal dystonia can sometimes be the first manifestation of a generalized dystonia.

Pathophysiology

Normally, an antagonist muscle relaxes when an agonist muscle is contracted. Patients with dystonia have simultaneous contraction of both groups of muscles. Spinal reciprocal inhibition, a process that inhibits the antagonist muscles when the agonist muscles are active, is reduced in patients with writer's cramp. This is most probably due to aberrant descending commands.

Abnormalities in the basal ganglia lead to abnormalities of sensory processing and motor output. The normal increase in cerebral blood flow in the supplementary motor area is reduced in response to vibration and abnormal somatosensory evoked potentials. These provide evidence for the abnormal sensory processing in patients with dystonia. Increased motor cortex excitability along with decreased cortical inhibition causes abnormal motor output.

Frequency

United States

One study estimated the prevalence to be 69 cases per 100,000 population; this is thought to be an underestimation because a high percentage of patients never seek medical assistance.

International

Again, because of the small percentage of affected patients seeking medical attention, accurate prevalence estimates are not available.

Sex

Prevalence is slightly higher in men; the male-to-female ratio is 1.3:1.

Age

Typically, patients present in the third to fifth decades, and women usually present earlier than men.

Clinical

History

• Incoordination, cramping, and aching of the hand with task-specific movements are usually the initial complaints.
• The hand assumes a semiflexed position of the fingers with possible hyperextension of the fingers and hyperflexion or extension of the wrist with supination or pronation.
• The symptoms become exaggerated with attempts to perform a specific task, such as writing. In some cases, the hand may dart across the page with a sudden jerk.
• A related condition is primary writing tremor. Affected individuals exhibit a prominent large-amplitude tremor only with writing.

Physical

• Neurologic examination findings are usually normal.
• Subtle findings include mild dystonic postures developing either spontaneously or with movement and reduced arm swing.
• One third of patients have a tremor in the affected arm or hand while writing or when the extremity is outstretched. Observation of the limb during writing is an important part of the examination; the assumption of dystonic postures should be demonstrable. Patients affected with primary writing tremor, a variant of writer's cramp, may exhibit a large-amplitude tremor only during writing. In contrast to essential tremor, action or sustentation tremors are not seen with other tasks such as holding a full cup of liquid or coordination testing. Dystonic posturing is usually not seen with this condition.

Causes

• Writer's cramp frequently affects persons who write a great deal or perform other repetitive hand movements such as typing.
• Approximately 5% of patients have a positive family history of a similar condition.
• Five to ten percent report an accident or injury to the hand or arm immediately preceding the onset of symptoms.
• Several possible, but rare, associations have been reported, including C6 ruptured disk, lithium use, basal ganglia or cortical tumors, arteriovenous malformations (AVMs), and stroke. However, most cases are idiopathic.

Differential Diagnoses

Dopamine-Responsive Dystonia
Multiple Sclerosis
Parkinson Disease
Wilson Disease

Other Problems to Be Considered

Primary writing tremor
Postural tremor
Idiopathic torsion dystonia

Workup

Imaging Studies

• MRI - If a structural lesion is suspected

Procedures

• Electromyography/nerve conduction studies
  • To evaluate for nerve injury, if trauma is the suspected cause
  • Confirm diagnosis by showing simultaneous contraction of agonist and antagonist muscles

Treatment

Medical Care

• Approximately 5% of patients have spontaneous remission, most probably in the first 5 years. However, the majority of these patients have relapses.
• Treatment is generally disappointing.
• Transcutaneous electrical nerve stimulation (TENS) delivered to the forearm flexor muscles for a 2-week period has been found to improve symptoms for up to 3 weeks after treatment.^{[1 ]}
• Behavioral changes may help.
• Biofeedback, hypnotherapy, and relaxation therapy have been tried.
• Thalamotomy and thalamic deep brain stimulation for severe cases has been reported to be successful.^{[2 ]}

Activity

• Altering the grip of the pen and/or increasing the diameter of the pen used is the first step in treatment.
• Patients can use a writing device or other means of transcription, such as typing or dictation.

Medication

Several classes of drugs have been used in patients with writer's cramp. Anticholinergics have had conflicting results. Beta-blockers have helped the tremor in a few patients. Botulinum toxin injections seem to have the best results.

Anticholinergic

Blocking cholinergic innervation of the basal ganglia is hypothesized to increase the dopaminergic effect, thereby reducing dystonia.

Trihexyphenidyl (Artane)

Substituted piperidine that inhibits parasympathetic system. Available as 2 mg tab or 2 mg/5 cc elixir.

Dosing

Adult

Start with 1 mg PO qd, then increase by 2 mg at intervals of 3-5 d up to 6-15 mg/d divided tid

Pediatric

Administer as in adults

Interactions

Amantadine may increase anticholinergic adverse effects, which disappear when dose reduced; when taken with haloperidol, may decrease haloperidol serum concentration, resulting in worsening of schizophrenic symptoms; may reduce pharmacologic/therapeutic actions of phenothiazines

Contraindications

Documented hypersensitivity; glaucoma; peptic ulcer; pyloric or duodenal obstruction; stenosing prostatic hypertrophy or bladder neck obstructions; achalasia; toxic megacolon

Precautions

Pregnancy

C - Safety for use during pregnancy has not been established.

Precautions

Dose adjustment may be required in geriatric patients; caution in patients with tachycardia, cardiac hypotension, prostatic hypertrophy, arrhythmias, hypertension, or any tendency toward urinary retention, liver or kidney disorders, or obstructive disease of GI or GU tract; if dry mouth severe and impairs swallowing or speaking, or if loss of appetite and weight occurs, reduce dosage or discontinue medication temporarily

Beta-adrenergic blockers

These agents help reduce the tremor.

Propranolol (Inderal, Betachron E-R)

Class II antiarrhythmic, nonselective, beta-adrenergic, receptor blocker with membrane-stabilizing activity that decreases automaticity of contractions. Available as 10 mg, 20 mg, 40 mg, and 80 mg tablets and 60 mg, 80 mg, 120 mg, and 160 mg long-acting tablets (Inderal LA)

Dosing

Adult

40 mg PO bid initially; increase as tolerated; not to exceed 240-320 mg/d divided bid/tid

Pediatric

2-4 mg/kg PO divided bid; increase as tolerated; not to exceed 16 mg/kg/d

Interactions

Aluminum salts, barbiturates, NSAIDs, penicillins, calcium salts, cholestyramine, and rifampin may decrease effects; calcium channel blockers, cimetidine, loop diuretics, and MAOIs may increase toxicity; may increase toxicity of hydralazine, haloperidol, benzodiazepines, and phenothiazines

Contraindications

Documented hypersensitivity; uncompensated congestive heart failure; bradycardia; cardiogenic shock; AV conduction abnormalities

Precautions

Pregnancy

C - Safety for use during pregnancy has not been established.

Precautions

May decrease signs of acute hypoglycemia and hyperthyroidism; abrupt withdrawal may exacerbate symptoms of hyperthyroidism, including thyroid storm; withdraw drug slowly and monitor closely

Neurotoxins

Neurotoxin complex blocks neuromuscular conduction by binding to receptor sites on motor nerve terminals, entering the nerve terminals, and inhibiting the release of acetylcholine. When injected intramuscularly, it produces a localized chemical denervation muscle paralysis.

Botulinum toxin type A (BOTOX®)

Local intramuscular injections weaken overactive muscles, reducing dystonic symptoms.

Dosing

Adult

Injections usually given under EMG guidance and should be administered by physicians experienced in giving the injections

Pediatric

Not established

Interactions

Aminoglycosides or drugs that interfere with neuromuscular transmission may potentiate effects

Contraindications

Documented hypersensitivity

Precautions

Pregnancy

C - Safety for use during pregnancy has not been established.

Precautions

Do not exceed recommended dosages and frequencies of administration; presence of antibodies to botulinum toxin type A may reduce effects of therapy; not known if toxin excreted in breast milk

Follow-up

Prognosis

• The prognosis is good.

Patient Education

• Patients should reduce the task-specific activities that precipitate the condition.

Miscellaneous

Medicolegal Pitfalls

• Do not consider patients with writer's cramp and other action dystonias as having a psychiatric disorder. This could deprive the patient of evaluation by a movement disorder specialist and hence the benefit of adequate treatment. Patients with writer's cramp do not have a higher incidence of psychiatric disorder than the general population.

References

1. Tinazzi M, Farina S, Bhatia K, Fiaschi A, Moretto G, Bertolasi L, et al. TENS for the treatment of writer's cramp dystonia: a randomized, placebo-controlled study. Neurology. Jun 14 2005;64(11):1946-8. [Medline].

2. Goto S, Shimazu H, Matsuzaki K, Tamura T, Murase N, Nagahiro S, et al. Thalamic Vo-complex vs pallidal deep brain stimulation for focal hand dystonia. Neurology. Apr 15 2008;70(16 Pt 2):1500-1. [Medline].

3. Baur B, Schenk T, Furholzer W, Scheuerecker J, Marquardt C, Kerkhoff G, et al. Modified pen grip in the treatment of Writer's Cramp. Hum Mov Sci. Oct 2006;25(4-5):464-73. [Medline].

4. Chen R, Hallett M. Focal dystonia and repetitive motion disorders. Clin Orthop. Jun 1998;(351):102-6. [Medline].

5. Chen RS, Tsai CH, Lu CS. Reciprocal inhibition in writer's cramp. Mov Disord. Sep 1995;10(5):556-61. [Medline].

6. Cohen LG, Hallett M. Hand cramps: clinical features and electromyographic patterns in a focal dystonia. Neurology. Jul 1988;38(7):1005-12. [Medline].

7. Epidemiologic Study of Dystonia in Europe (ESDE) Collaborative Group. Sex-related influences on the frequency and age of onset of primary dystonia. Neurology. Nov 10 1999;53(8):1871-3. [Medline].

8. [Best Evidence] Kruisdijk JJ, Koelman JH, Ongerboer de Visser BW, de Haan RJ, Speelman JD. Botulinum toxin for writer's cramp: a randomised, placebo-controlled trial and 1-year follow-up. J Neurol Neurosurg Psychiatry. Mar 2007;78(3):264-70. [Medline].

9. Marsden CD, Sheehy MP. Writer's cramp. Trends Neurosci. Apr 1990;13(4):148-53. [Medline].

10. Rhoad RC, Stern PJ. Writer's cramp--a focal dystonia: etiology, diagnosis, and treatment. J Hand Surg Am. May 1993;18(3):541-4. [Medline].

11. Schmidt A, Jabusch HC, Altenmuller E, et al. Dominantly transmitted focal dystonia in families of patients with musician's cramp. Neurology. Aug 22 2006;67(4):691-3. [Medline].

Keywords

focal hand dystonia, graphospasm, musician's cramp, writer's cramp, focal dystonia, dystonic conditions, repetitive movements, spinal reciprocal inhibition

Contributor Information and Disclosures

Author

Jonathan B Strober, MD, Director, Pediatric Muscular Dystrophy Association Clinic; Associate Clinical Professor, Departments of Pediatrics and Neurology, Division of Child Neurology, University of California at San Francisco
Jonathan B Strober, MD is a member of the following medical societies: American Academy of Neurology, American Academy of Pediatrics, Child Neurology Society, and Society for Pediatric Research
Disclosure: Nothing to disclose.

Medical Editor

Stephen T Gancher, MD, Adjunct Associate Professor, Department of Neurology, Oregon Health Sciences University
Stephen T Gancher, MD is a member of the following medical societies: American Academy of Neurology, American Neurological Association, and Movement Disorders Society
Disclosure: Nothing to disclose.

Pharmacy Editor

Francisco Talavera, PharmD, PhD, Senior Pharmacy Editor, eMedicine
Disclosure: eMedicine Salary Employment

Managing Editor

Nestor Galvez-Jimenez, MD, MSc, MHA, Chairman, Department of Neurology, Program Director, Movement Disorders, Department of Neurology, Division of Medicine, Cleveland Clinic Florida
Nestor Galvez-Jimenez, MD, MSc, MHA is a member of the following medical societies: American Academy of Neurology, American College of Physicians, and Movement Disorders Society
Disclosure: Nothing to disclose.

Chief Editor

Selim R Benbadis, MD, Professor, Director of Comprehensive Epilepsy Program, Departments of Neurology and Neurosurgery, University of South Florida School of Medicine, Tampa General Hospital
Selim R Benbadis, MD is a member of the following medical societies: American Academy of Neurology, American Academy of Sleep Medicine, American Clinical Neurophysiology Society, American Epilepsy Society, and American Medical Association
Disclosure: Nothing to disclose.

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