Dystonia consists of sustained or repetitive involuntary muscle contraction, frecquently causing twisting movements with abnormal postures.Focal dystonias are the most common forms .Limb dystonias can be present in either arms and are often brought out by task specific activities such as hand writing ( writer’s cramp), playing a musical instrument (musician’s cramp).
Botulinum toxin can be of great benefit for patients with focal dystonia, particularly if involvement is limited to small muscle groups. Supportive treatments such as physical therapy are important and should be a part of the treatment for dystonia patients.
Dystonia is defined as a motor disorder characterized clinically by involuntary and sustained muscle contractions that, following a distribution to a limb, a segment of a limb or the whole body, causes abnormal attitudes which reproduce identically in the same patient. (8, 10)
Voluntary muscle contraction is abnormal, because instead of being a three-phase contraction, only the contraction of agonist and antagonist takes place.
In addition, there are anomalous synergies compromising gestural accuracy, causing abnormal attitudes, such as the writer’s cramp. (10)
The study of elementary motor reactions shows that dystonia complies with mono- and bi-synaptic reflexes, while it amends polysynaptic reflexes, especially in the skin, which give exaggerated answers.
For example, applying vibrations on the tendons of the forearm muscles involved in the writer’s cramp, they reproduced the dystonic attitude.
The most common forms of focal dystonia are:
- Oromandibular dystonia
- Spasmodic dystonia
- Cervical dystonia
- Focal hand dystonia (also known as musician’s or writer’s cramp)
The causes of focal dystonia are not yet specified, but genetic and autoimmune factors or repeated traumas are involved. (10, 11)
Personally, I had treated two cases of focal dystonia:
The first case was S.R. aged 15 years, who had the writer’s cramp, installed progressively for about six months, occurring after 6-7 pages of rapid writing, manifesting itself through a painful contracture of the hand and forearm muscles. The hand remained tense on the pen and the patient could not write anymore, not even a single letter. Therefore, it was the spasmodic form of focal dystonia (as opposed to the paralytic form or the one with tremor).
The following movements were affected: flexion – extension of fingers I, II, III and the adduction of the wrist that allows hand to progress from left to right during writing.
No history of other neurological problems, or trauma. There were no cases in the family.
- Tendon reflexes normal.
- Shortening reaction (inverse myotatic reflex) amplified, preventing the action of antagonistic muscles.
- Sometimes, the patient has parasitic extension movements of the other fingers.
- No shoulder asymmetry or abnormal curvature of the spine in the sagittal plane.
- In walking, the arm swing motion is lower in the right arm compared to the left one.
- Pronation and passive supination of the right forearm encounters a little resistance at the end of the movement.
- During dystonic manifestations, the patient changes the grip of the pen from pollex- index to pollex-digitus medius to continue to write.
- The emergence of dystonia was favoured by anxiety (thesis, examination).
- The patient learned to write with the left hand, but to no avail.
- EMG examination of the forearm muscles confirmed the co-contraction of agonists and antagonists muscles involved in writing as well as a diffusion of this activity of other muscles that are usually inactive.
- At the end of the movement, abnormal contraction of the agonists was observed.
A decrease in the late phase of the presynaptic inhibition has also been noted (4,7,11)
The neurologist recommended therapy with Baclofen and Tetrazepam without obvious results.
- Attention was given to proximal segments of the upper limb and of the spine, so that the patient might become aware of the abnormal attitude and interrupt the program of non-physiological postures.
- The “constraint” method was tried, meaning the immobilization with a splint of the finger which compensate the dystonic ones (IV, V) and then running repetitive exercises with the dystonic fingers in coordination with another free finger. (3)
- Stretching of dystonic muscles.
- Exercises with the muscles that were antagonist to the dystonic ones, stimulating their corresponding areas on the skin. (10)
B. Infiltration with botulinum toxin (Dysport)
- We proceeded to infiltrations with botulinum toxin in the motor points of the deep flexor muscle of fingers, short flexor pollicis, and adductor pollicis.
- On two occasions, we have infiltrated the brachial triceps, too due to an extension of the forearm that appeared simultaneously with the cramp.
- Infiltrations were done 3 times over an interval of 15 days in doses of 20, 25, and 30 units/kg of body weight. We did not receive the tracking of motor points following the EMG, but used the information from specialized atlases. (4,10,12)
As botulinum toxin prevents writing through diffusion to other muscles than the ones that have been infiltrated, the treatment was carried out during the summer holiday. After about three weeks, the student resumed writing with the right hand. The cramp appeared on page 7, which represented a progress. After 3 months, we repeated the cycle of 3 infiltrations, concomitant with stretching and constraint exercises. Cramp never appeared when introducing a break after writing 4-5 pages quickly (except for a stressful moment produced by an examination) .In addition, we recommended the thickening of the pen with a rubber sleeve to increase the volume of the grip. Currently, the patient is a student at the university and enjoys the fact that she uses the computer now; she had cramps only 2 more times since treatment.
The second case was Z.P., a 17 years old violinist, student at the school of music, with cramps in left upper limb, in the last two fingers of the hand with which he held the instrument and pressed the strings.
The symptoms started after a period of intense activity for the preparation of a contest. Ther discomfort appeared insidiously, starting with fatigue of the hand and forearm (previously non-existent) after prolonged practice, then stiffness of last fingers and an inability to handle the violin strings followed.
Of course, fear that the dystonia will occur again resulted in worsening this condition in the sense of cramp frequency and duration.
There was no history of trauma.
Normal neurological examination, no impairment of deep sensitivity.
Normal brain MRI. (Sometimes a merger of the zones representing finger area, is quoted, which areas are not clearly delineated.)
EMG with surface electrodes recorded a global activity without changes. The patient did not accept implanted electrodes.
The clinical examination of the trunk and limbs revealed an underdeveloped proximal muscularity of the left upper limb compared to the distal zone, which represented an imbalance that might encourage dystonia – It was element that was to be considered in the rehabilitation program.
Correction of the vicious positions at the level of the muscle groups situated at a distance from those that come into contact with the musical instrument.
Discontinuation of non-physiological postures and physiological compliance with the movement. ( 1,3,5 )
The “constraint” system cited above was tried, without a positive result. (1)
Elongation of the dystonic muscles was performed.
There have been electro stimulations of antagonist muscles. (10)
B. Botulinum toxin infiltration raised many problems because a musician cannot interrupt his/her activity for long periods. However, we tried infiltrating 20 units/kg of body weight into the motor point of the deep flexor of the fingers. The problem was to interrupt the patient’s instrument practice for about two weeks; after that interval, the resumption was difficult.
In these cases, the treatment with Dysport is disheartening – there is a long-standing disability in using fingers IV and V.
The patient was able to perform normally after about a month from the infiltration and the cramp reappeared after 38 days. We could not continue the therapy because the patient emigrated.
We kept in touch for a while and found out that the patient tried even psychological assistance, which is indicated in such cases. He was also prescribed therapy with Baclofen and anticholinergics (Trihexyphenidyl), without encouraging results and apparently he gave up the violin, becoming a conductor.
In conclusion, the treatment of these cases of focal dystonia with botulinum toxin is difficult, especially in the case of musicians’ cramp, because it requires long periods of inactivity, and musicians have no compensation opportunities as in the case of the writer’s cramp. In instrumentalists, the most important role belongs to physiotherapy and psychotherapy, which are preferable to medication and Dysport.
These local dystonia forms should give food for thought, because it has been demonstrated that, sometimes, they may be the first signs of Parkinson’s disease, even with many years
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