Уважаемый Сергей Александрович, писчий спазм (Writer"s crampi) это не синдром, а разновидность фокальной дистонии. Точные причины неизвестны, но предполагается, что заболевание связано с дисфункцией базальных ганглиев и повышением активности нейронов в премоторных областях коры. Встречаются, но реже, такие причины писчего спазма, как грыжа C6 диска, использование лития, опухоли в области базальных ганглиев и шейного отдела спинного мозга, артериовенозная мальформация, инсульт. Тогда писчий спазм будет симптомом. Но чаще все же встречается идиопатический писчий спазм. Тем не менее дифдиагностика необходима. В лечении идиопатического писчего спазма сейчас наиболее эффективным методом лечения считается применение инъекций ботулотоксина ( Ботокс, Диспорт) в мышцы предплечья и кисти под контролем электромиографии.
J Med Assoc Thai. 1991 May;74(5):239-47. Related Articles, Links
Writer's cramp: the experience with botulinum toxin injections in 25 patients.
Poungvarin N.
Department of Medicine, Faculty of Medicine, Siriraj Hospital, Mahidol University, Bangkok, Thailand.
Twenty-five writer's cramp patients have been attending the Movement Disorder Clinic at the Division of Neurology, Department of Medicine, Faculty of Medicine, Siriraj Hospital, Mahidol University, Bangkok during three years period (between January 1988 - January 1991). There were 17 male subjects and the male to female sex ratio was 2.125:1. The mean age of the patient was 36.80 (SD 10.21) years with the range of 18-60 years. The mean duration of illness of all patients was 5.88 (SD 7.14) years with the range of 1 to 30 years. Eighteen patients (72.0%) were classified as simple writer's cramp and seven patients (28.0%) were dystonic writer's cramp. The mean age of the patients of both groups was not different while the duration of illness in the dystonic group was statistically significantly longer than the simple group, i.e. 12.0 (SD 12.1) versus 3.9 (SD 3.1) years. Fourteen patients (56%) had associated pain during writing and 6 patients (24%) had hand tremor. All patients were right handed and had a history of various pharmacological treatments without any consistent benefit. They included muscle relaxants, tranquillisers, antiepileptic drugs, and betablockers. Fourteen patients from 17 available history records (82.4%) had been spending at least 4-10 hours writing each day. Twenty-one patients (84%) had botulinum toxin injections, 40-80 international mouse units were given in 2-4 divided doses over the overactive forearm muscles observed during writing without the electromyographic glidance. There was no loss to the follow-up. Fourteen of the 21 subjects (66.7%) showed definite improvement in hand writing, 4 patients (19.0%) improved minimally and 3 patients (14.3%) revealed no improvement. Arm pain in all 12 patients associated during writing was abolished after the injections. There were complications in 7 patients (33.3%) presented as transient finger drop (5 patients, 23.8%) and easily fatigued arm (2 patients, 9.5%). These preliminary results confirm that botulinum toxin injections is a successful treatment for many patients with writer's cramp without performing complex electromyographic recordings while the patients are writing. The constraints of this treatment are its high cost (i.e. 1 vial of 100 units costs 300 US dollars) and its benefit lasts for only 4-6 months.
Wien Klin Wochenschr. 2001;113 Suppl 4:6-10. Related Articles, Links
[Treatment of focal dystonia with botulinum toxin A]
[Article in German]
Sojer M, Wissel J, Muller J, Poewe W.
Universitatsklinik fur Neurologie, Innsbruck, Osterreich.
Local injections with Botulinum toxin A (BtxA) are safe and effective in the treatment of focal dystonia. In cervical dystonia and blepharospasm, BtxA injections have become the treatment of choice. However, good results have also been reported with oromandibular dystonia, spasmodic dysphonia and writer's cramp. In cervical dystonia, muscles for injection are selected by clinical presentation or in complex forms with EMG guidance. Several studies have shown that 500 units Dysport are safe and effective in the treatment of cervical dystonia. In blepharospasm, injections are performed in the periorbital part of the orbicularis oculi muscle with good results for 12-14 weeks. The most frequently employed starting dose is 120 units Dysport per eye, divided in three periorbital injection sites. In case of levator inhibition, the pretarsal part of the orbicularis oculi muscle should be injected in a lower dose. EMG guidance is not necessary. By contrast, BtxA treatment of spasmodic dysphonia and writer's cramp require EMG-guided injections in order to avoid side-effects. Dose recommendations for the various types of dystonia are given in the text. In up to 5% of patients with dystonia, the development of neutralising antibodies is reported following repetitive injections with BtxA. Patients with antibodies had a shorter interval between injections, more "boosters", a higher dose per 3-month interval, and a higher total dose injected. In case of neutralizing antibodies against the A toxin, the treatment with Botulinum toxin B (Neurobloc) is a possible alternative.
А также есть опыт применения транскраниальной магнитной стимуляции:
Subthreshold low-frequency repetitive transcranial magnetic stimulation over the premotor cortex modulates writer's cramp.
Murase N, Rothwell JC, Kaji R, Urushihara R, Nakamura K, Murayama N, Igasaki T, Sakata-Igasaki M, Mima T, Ikeda A, Shibasaki H.
Department of Neurology, Tokushima University School of Medicine, Tokushima, Japan.
Writer's cramp, or focal hand dystonia, is characterized by involuntary coactivation of antagonist or unnecessary muscles while writing or performing other tasks. Although the mechanism underlying this muscle overactivation is unknown, recent studies of changes in cerebral blood flow during writing have demonstrated a reduction in the activation of the primary motor cortex (MC) and hyperactivity of parts of the frontal non-primary motor areas. Therefore, any measures that decrease the activities of non-primary motor areas such as the premotor cortex (PMC) and the supplementary motor area (SMA) might improve dystonic symptoms. To explore this possibility, we studied nine patients with writer's cramp and seven age-matched control subjects, using subthreshold low-frequency (0.2 Hz) repetitive transcranial magnetic stimulation (rTMS), which exerts an inhibitory action on the cortex. Previous studies have demonstrated shortened cortical silent periods in dystonia, suggesting deficient cortical inhibition in the MC. We compared the silent periods and computer-assisted ratings of handwriting before and after rTMS applied to the MC, SMA or PMC. We also used the sham coil for control runs. Stimulation of the PMC but not the MC significantly improved the rating of handwriting (mean tracking error from the target, P = 0.004; pen pressure, P = 0.01) and prolonged the silent period (P = 0.02) in the patient group. rTMS over the other sites or using a sham coil in the patient group or trials in the control group revealed no physiological or clinical changes. This increased susceptibility of the PMC in dystonia suggests that the lack of inhibition in the MC is secondary to the hyperactivity of PMC neurons. Inhibition of the PMC using rTMS could provide a therapeutic measure of writer's cramp.
