FOCAL DYSTONIA OF THE HAND

Marcos Sanmartin

 

 

Definitions: The dystonias are movement disorders in which sustained muscle contractions cause twisting and abnormal postures. Movement disorders are clinically divided in hypokinesia and hyperkinesia states. Dystonia is one of the hyperkinetic states, among tremors, chorea, choreoathetosis, ballism, tics, akathisia, myoclonus, and hemifacial spasms. All movement disorders stem from disturbance of basal ganglia or their connections.

Reciprocal inhibition is a process by which activation of a muscle suppresses activity in its antagonist. Deficient reciprocal inhibition, which could result in cocontraction of antagonist muscle, has been demonstrated in patients with writer’s cramp (Chen et al., 1995), as well as other types of dystonia.

 

 

I. Presentation:

 

a.       Presenting complaints and epidemiology:

 

In focal hand dystonia, abnormal movements are initiated by an attempt to carry out a specific motor skill within a particular context, which it is not explained by diminished practice efforts and it cannot be circumvented by any masking strategy.

Focal dystonia is more common than generalized dystonia. Its prevalence rate was 24 per million per year. Musicians are affected in a proportion of 1/500, much more than in other professions requiring skilled hand movements, as watchmakers, dentists and surgeons (NUTT et al, 1988). Tubiana (2003) reported 165 cases of focal dystonia in 1320 musicians between 1992 and 1999.

Occurs mostly in men Bartolome et al. (2003) between the ages of 20 to 50 years. Onset is generally gradually progressive. Rarely, there is a precipitating factor, such as a relative death and a major or minor traumatic event. Sometimes there is a painful episode or a trauma (Wilson et al., 1993). Regardless of the pain, not uncommonly, the patient keeps working. Eventually the pain resolves, but the problem persists. History of ulnar neuropathy predisposing dystonia of the ring and small finger has been reported (Charness et al., 1996). Focal dystonia is also associated to obsessive-compulsive disorders (Cavallaro et al., 2002).

Some patients exhibit a sensory trick, in which touching a specific body parts relieves dystonic symptoms. It is also interesting the so-called mirror image effect, for when the patient simulates the playing of the instrument with his unaffected hand, dystonic movements and cramp will appear in the resting hand.

 

 

Writer’s cramp: Patients can present in three ways: simple, dystonic and progressive. In the dystonic form, the muscles spasms affect not only writing, but also other manual tasks. In the progressive form, patients present with the simple form and progress to the dystonic form. Most initially are unable to describe the problem in detail. They describe deterioration in neatness or speed of writing or just clumsiness. A minority of patients describes the initial symptoms as a cramp, while others complain of aching in the hand on writing. Several reports that the hand freeze on attempting to write, or that there is difficulty in moving the pen across the page. Others reports the hand ignore ruled lines or involuntarily jerk through the paper or off the page. Few patients complain of real curling or flexion spasms of the fingers. Instead, cramp is secondary to muscular effort in keeping the pen in the hand and in a straight line. Often the problem becomes more apparent when patients are being observed in conditions of pressure (Sheehy and Marsden, 1982).

 

Musicians: Symptoms frequently start with holding the instrument but become exaggerated when playing begins. Adverse biomechanics, particularly inflexibility of the hand, constitute an important predisposing factor (Leijnse, 1997).

Musicians are almost always very talented and ambitious people. They also tend to be somewhat fanatic in their work habits. During the period when the problem begins, they are usually in a particular hurry or working unusually hard. In some musicians, the burst of activity comes because a critical point in their career has been reached, and intense technical work has been undertaken to break through to a higher level. Occasionally, a musician starts a program with the goal of overcome a particular problem that has a long history and is definitely stubborn. The problem can start after changing to a new instrument, when loss of finger control can start abruptly. When the new instrument is abandoned, the musician finds out he can no longer play the old instrument either (Wilson et al., 1993).

The side affected depends more on the instrument than the dominant hand. In pianists, the right hand and ulnar digits more often are involved. In violinists and viola players, the left side is the most frequently involved. In wind instrumentalists, the hand supporting the instrument and doing the fingering at the same time is the most affected. Rarely, wind players also present orofacial dystonia. Percussionist may present foot dystonia. (Tubiana, 2003).

The disobedient fingers most often implicated are the two ulnar digits. It seems that these two fingers are not designed for the prolonged, rapid, highly complex movements demanded in musical performance (Leijnse et al., 1992).

 

b.      Physical Exam

 

i.                     Inspection

 

The pen commonly is held very tightly, with an exaggeration of the normal semiflexed posture of thumb, index and other fingers, and with hyperextension of the distal interphalangeal joint of the index finger. Occasionally, the hand suddenly stops and the paper is perforated, or it might dart across the page with a sudden jerk. The script produced is usually abnormal (figure 1). Some patients are able to produce legible words at expenses of bizarre postures, but most examples of writing are completely unsuccessful. Tremor is a common finding in all forms of writer’s cramp but it is usually not severe (Sheehy and Marsden, 1982) (Video 1).

      Examination of the musician while playing reveals non-physiologic posture and gestures in most of the patients (Tubiana, 2003) (figure 2). Sometimes it is possible to identify involuntary dysfunction such as flexion, curling in one or two fingers, or involuntary extension of the “sticking fingers” (figure 3). They may be difficult to detect, even with slow motion video (Tubiana, 2003)

The remainder of physical examination is often normal, but subtle findings can be noted in some patients: dystonic postures of the affected limb when the patients sit or walk, or loss of arm swing of the affected side during the gait (Sheehy and Marsden, 1982).

 

 

ii.                   Palpation

 

Sheehy and Marsden (1982) reported minimal unilateral increase in muscle tone in some patients. There are no other abnormal findings.

 

iii.                  Quantification

 

The Fahn-Marsden scale was designed to quantify generalized or focal dystonia and it is presented in table X (www.mdvu.org/pdf/bfm_scale.pdf).

 

iv.                 Special examination

 

No special examinations are described for focal dystonia other than inspect the patient performing his task.

 

 

v.                   Investigations

 

1. Labs:

Electromyography studies show prolonged duration of muscle bursts with superimposed shorter, repeated bursts of activity. The pattern is of complete lack of selectivity for individual muscles with overflow of contraction to muscles not normally activated by the task being performed (Berardelli et al., 1998).

Electromyography is also useful as a guide to botulinum toxin injections.

 

 

2. X-rays:

 

Radiographs are not useful in the assessment of focal dystonia, as well as other image modalities. Occasionally, in an appropriate setting, magnetic resonance image can be useful to rule out a cerebrovascular disease.

 

 

 

 

c.       Classification

 

Tubiana et al. (2003) established in 1993 a classification of severity of focal dystonia in musicians (table 1). They used it to monitor the evolution of treatment.

 

 

 

 

Text Box: Table 1 – Classification of Tubiana et al. (2003) for focal dystonia in musicians. Stage 1 Plays several notes but stops because of blockage or lack of facility Stage 2 Plays short sequences without rapidity and with unsteady fingering Stage 3 Plays easy pieces but is unable to perform more technically challenging pieces Stage 4 Plays almost normally but difficult passages are avoided for fear or motor problems Stage 5 Returns to concert performances

 

 

d.      Differential diagnosis:

 

Diagnosis is mainly based on history and physical examination. It is important to watch the patient performing their tasks, i.e., musicians playing their instruments and writers writing. Occasionally, when the symptoms are mild, the diagnosis can be extremely difficult to make.

Trigger fingers are important differential diagnosis. Careful history and physical examination are sufficient to differentiate these two conditions. Abruptness of the triggering and tenderness over A1 pulley area are characteristics of trigger finger.

 

 

 

 

III - Treatment:

 

            Current therapeutic options for dystonia include botulinum toxin injections, oral medication, chemodenervation, peripheral nerve or muscle surgery, and brain neurosurgical procedures. Oral medications are most useful in generalized, hemi-, segmental and severe cervical dystonia.

Writer’s cramp is often well controlled with botulinum toxin injections. Efficacy of clinical treatment is more pronounced in the spastic form (Shavlovskaia et al., 2002).

 Focal dystonia in musicians is difficult to treat, but physical therapy and sensory retraining can yield good results.

           

 

a.       Conservative:

 

i.                     Drugs and doses

 

Botulinum toxin type A has been used for the treatment of writer’s cramp with good results (Marion et al., 2003). However, its application demands careful and precise technique. The selection of the muscle should be based on careful physical examination while the patient writes in order to trigger the dystonic movements. The injection should be carried out under EMG guidance with a hollow recording needle and the botulinum toxin is injected through the same needle. Small volume injections into multiple sites are preferred to a single large injection. Dose per muscle varies from 2.5-25 units. Initially, only few muscles are injected. The dose per muscle and number of muscles injected are optimized (based on response) for subsequent injections (Iyer, personal communication).

            The response rate in musician’s cramp seems to be lower, which may be because of musician’s high demand for perfect performance so that anything less than a complete response is considered unsatisfactory (Cole et al., 1991). Therefore, it is only indicated in musician’s cramp in severe localized contractures as adjuvant to rehabilitation treatment.

Regarding oral medications, there are a number of therapeutic agents with clear beneficial effects to writer’s cramp, including anticholinergics, clonazepam and benzodiazepines.

Oral administration of high dosage of anticholinergic drugs is firstly recommended for the treatment of dystonia. Effective cases usually do not show obvious side effects (Kachi, 2001). Doses recommended of biperiden are 2 mg per oral two or three times a day and titration to 16 mg a day.

Diazepam is another choice, which does not bring adverse effects as well in successful cases. However, it is rarely adequate when used as sole agent. Doses are 10mg per oral two or three times a day.

In cases with myoclonus and/or tremor, clonazepam can be useful for improvement of phasic symptoms (Kachi, 2001). Doses are 0.25 mg per oral twice a day, increasing to 0.125 to 0.25 mg every three days up to a dose of 4 mg/day.

 

ii.                   Splints

Some patients find that finger-splinting device made individually according to their symptoms help improve their ability to write or to play a musical instrument (Chen and Hallet, 1998). Priori et al. (2001) reported that limb immobilization for four weeks and a half is a simple and effective treatment for this condition.

 

iii.                  Rehabilitation

 

Cooling of hand and forearm muscles by immersion in 15 degrees Celsius water for 5 minutes improves temporarily the writing performance of patients with writer’s cramp (Pohl et al., 2002).

Tubiana and Chamagne reported published their results of a multidisciplinary approach to focal dystonia in musicians in 1993. In all their dystonic patients, they have found the existence of vicious postures of the upper limb, extending to the shoulder girdle and the spine, and, when playing, movements that do not respect normal physiology. Because of their orthopedic outlook, these defects have been corrected empirically since 1965. This therapeutic program aims make the patient aware of his poor posture, deprogram non-physiological postures and teach new movements that respect normal physiology. Re-education was not restricted to the upper limb and included the whole body and lasted for 1 year. The results of this treatment depended on the severity of the dystonia, delay between onset of symptoms and beginning of the treatment, age, and the morphological and psychological state of the musician. Their results are staged according to their own classification, as described above.

 

 

b.      Surgical

 

Sterotatic neurosurgery to treat dystonia was used as early as the 1950’s. Overall lack of uniformity in technique, target and patient selection led to a wide and undesirable range of outcomes and the procedures were largely abandoned. Recent stereotactic advances have led to a revival in neurosurgical approaches to treating dystonia. Surgical targets for dystonia are largely the thalamus and globus pallidus internus.

In order to treat patients with refractory conservative treatment for focal hand dystonia, Taira et al (2003) performed stereotactic thalamotomy in eight patients, including a guitarist, a comic artist and a barber. The target was chosen at the junction of anterior and posterior ventrooralis nuclei. All patients showed immediate postoperative disappearance of dystonic symptoms. The effect was sustained during the follow up period, which ranged from 3 to 29 months, except in one case. One patient showed partial recurrence of the symptom and underwent second thalamotomy 5 months after the initial surgery with satisfactory results.

Pallidal stimulation has been favored recently as an alternative to pallidotomy. Deep Brain Stimulation (DBS) of globus pallidus internus is gaining acceptance for patients with dystonia since its introduction to treat chronic pain. DBS entails the implantation of electrodes in the same brain targets. Activation of electrodes suppresses neuronal firing. The electrodes are controlled by a stimulation implanted under the skin and they can be turned on or off at will.

 

 

 

            V – Web sites and URLs:

 

Dystonia – medical research foundation:

www.dystonia-foundation.org/defined/writers.asp - 35k - Jan 29, 2004

 

 

Writer’s cramps news:

users.boardnation.com/~rliberty/index.php?board=3 - 23k

 

 

 

 

 

           

 

The Fahn-Marsden (BFM) Scale: Movement Scale

 

Region             Provoking factor         Severity           Weight factor  Product

Eyes                            0-4                  X                      0-4                  0.5       0-8

Mouth                          0-4                  X                      0-4                  0.5       0-8

Speech-Swallow          0-4                  X                      0-4                  1.0       0-16

Neck                            0-4                  X                      0-4                  0.5       0-8

R arm                          0-4                  X                      0-4                  1.0       0-16

L arm                           0-4                  X                      0-4                  1.0       0-16

Trunk                           0-4                  X                      0-4                  1.0       0-16

R leg                            0-4                  X                      0-4                  1.0       0-16

L leg                            0-4                  X                      0-4                  1.0       0-16

Sum:

Maximum=120

I. Provoking Factor

 

A. General

0. No dystonia at rest or with action

1. Dystonia only with particular action

2. Dystonia with many actions

3. Dystonia on action of distant part of body or intermittently at rest

4. Dystonia present at rest

 

B. Speech and swallowing

0. Occasional, either or both

1. Frequent either

2. Frequent one and occasional other

3. Frequent both

 

 

II. Severity Factors

 

Eyes

0. No dystonia

1. Slight. Occasional blinking

2. Mild. Frequent blinking without prolonged spasms of eye closure

3. Moderate. Prolonged spasms of eyelid closure, but eyes open most of the time

4. Severe. Prolonged spasms of eyelid closure, with eyes closed at least 30% of the time

 

Mouth

0. No dystonia present

1. Slight. Occasional grimacing or other mouth movements (e.g., jaw opened or clenched; tongue movement

2. Mild. Movement present less than 50% of the time

3. Moderate dystonic movements or contractions present most of the time

4. Severe dystonic movements or contractions present most of the time

 

Speech and swallowing

0. Normal

1. Slightly involved; speech easily understood or occasional choking

2. Some difficulty in understanding speech or frequent choking

3. Marked difficulty in understanding speech or inability to swallow firm foods

4. Complete or almost complete anarthria, or marked difficulty swallowing soft foods and liquids

 

Neck

0. No dystonia present

1. Slight. Occasional pulling

2. Obvious torticollis, but mild

3. Moderate pulling

4. Extreme pulling

 

Arm

0. No dystonia present

1. Slight dystonia. Clinically insignificant

2. Mild. Obvious dystonia, but not disabling

3. Moderate. Able to grasp, with some manual function

4. Severe. No useful grasp

 

Trunk

0. No dystonia present

1. Slight bending; clinically insignificant

2. Definite bending, but not interfering with standing or walking

3. Moderate bending; interfering with standing or walking

4. Extreme bending of trunk preventing standing or walking

 

Leg

0. No dystonia present

1. Slight dystonia, but not causing impairment; clinically insignificant

2. Mild dystonia. Walks briskly and unaided

3. Moderate dystonia. Severely impairs walking or requires assistance

4. Severe. Unable to stand or walk on involved leg

 

 

 

Figure 1: Two-minutes writing test, crawing of a spiral and writing of one line of eeeeeeeeeeee (patient had to interrupt four times) of a 38-year-old man with simple writer’s cramp. (From Jedynak et al, 2001)

 
 
 

 

 

 

 

 

 

 


Figure 2: Non-physiologic gestures found in most musicians with focal dystonia.
 

 
 

 

 

 

 

 

 



Figure 3: Dystonic movements found in musicians.

 
 
 

 

 

 

 

 

 

 

 

 

 

 

 

 
 

 

 

 
 



Video 1: Findings in writer’s cramp.

 

..\KLEINERT\interesting\caimbra do escrivao.avi
 
 

 

 

 

 

 


REFERENCES:

  1. Bartolome FM, Fanjul S, Cantarero S, Hernandez J, Garcia Ruiz PJ. [Primary focal dystonia: descriptive study of 205 patients]. Neurologia.18(2):59-65, 2003.
  2. Berardelli A, Rothwell JC, Hallet M et al.: The pathophysiology of primary dystonia. Brain 121, 1195-212, 1998.
  3. Cavallaro R, Galardi G, Cavallini MC, Henin M, Amodio S, Bellodi L, Comi G. Obsessive compulsive disorder among idiopathic focal dystonia patients: an epidemiological and family study. Biol Psychiatry, 15;52(4):356-61, 2002.
  4. Charness ME, Ross MH, Shefner JM. Ulnar neuropathy and dystonic flexion of the fourth and fifth digits: clinical correlation in musicians. Muscle Nerve. Apr;19(4):431-7, 1996.
  5. Chen R and Hallet, M. Focal dystonia and repetitive motion disorders. Clin Orthop Rel Res 351: 102-106, 1998.
  6. Chen R, Tsai CH, Lu CS. Reciprocal inhibition in writer’s cramp. Mov Disord 10 (5), 556-61, 1995.
  7. Cole RA, Cohen LG, Hallett M. Treatment of musician’s cramp with botulinum toxin. Med Probl Perform Art 6: 137-143, 1991.
  8. Kachi T. Medical treatment of dystonia. Rinsho Shinkeigaku 41: 1181-2, 2001.
  9. Karp BI, Goldstein S, Hallet M. Dystonia In …,.
  10. Leijnse JN, Bonte JE, Landsmeer JM, Kalker JJ, Van der Meulen JC, Snijders CJ. Biomechanics of the finger with anatomical restrictions--the significance for the exercising hand of the musician. J Biomech 25(11): 1253-64, 1992.
  11. Leijnse, JN: Anatomical factors predisposing to focal dystonia in the musician's hand--principles, theoretical examples, clinical significance. J Biomech. Jul;30(7):659-69, 1997.
  12. Marion MH, Afors K, Sheehy MP. Problems of treating writer's cramp with botulinum toxin injections: results from 10 years of experience. Rev Neurol (Paris). 159: 923-7, 2003.
  13. Nutt JG, Muenter MD, Aronson A, Kurland LT, Melton LJ 3rd. Epidemiology of focal and generalized dystonia in Rochester, Minnesota. Mov Disord.;3(3):188-94, 1988.
  14. Pohl C, Happe J, Klockgether T. Cooling improves the writing performance of patients with writer’s cramp. Mov Disord 17(6): 1341-4, 2002.
  15. Priori A, Pesenti A, Cappellari A, Scarlato G, Barbieri S. Limb immobilization for the treatment of focal occupational dystonia. Neurology. Aug 14; 57(3): 405-9, 2001.
  16. Shavlosvskaia OA, Orlova OR, Golubev VL, Vein AM. Clinical and physiologica analysis and treatment of writer’s cramp. Zh Nevrol Psikhiatr Im S S Korsakova 102: 35-41, 2002.
  17. Sheehy MP; Marsden CD. Writers’cramp – a focal dystonia. Brain 105, 461-480, 1982.
  18. Taira T, Harashima S, Hori T. Neurosurgical treatment for writer's cramp. Acta Neurochir Suppl 87: 129-31, 2003.
  19. Tubiana R, Chamagne P: Les affections profesionnelles du membre supérieur chez les
  20. Tubiana R. Musician’s focal dystonia. Hand Clin 19: 303-308, 2003.
  21. Wilson F, Wagner C, Volker H. Biomechaical abnormalities in musicians with occupational cramp/focal dystonia. J Hand Ther 6(4): 298-307, 1993.