Treatment of nonoccupational limb and trunk dystonia with botulinum toxin

Classification of Dystonia

Dystonia is a hyperkinetic movement disorder characterized by abnormal movement or posture caused by excessive muscle contraction. Because of its wide clinical spectrum, dystonia is often underdiagnosed or misdiagnosed. In clinical practice, dystonia could often present in association with other movement disorders. An accurate physical examination is essential to describe the correct phenomenology. To help clinicians reaching the proper diagnosis, several classifications of dystonia have been proposed. The current classification consists of axis I, clinical characteristics, and axis II, etiology. Through the application of this classification system, movement disorder specialists could attempt to correctly characterize dystonia and guide patients to the most effective treatment. The aim of this article is to describe the phenomenological spectrum of dystonia, the last approved dystonia classification, and new emerging knowledge.

Botulinum toxin treatment of lateral axial dystonia in parkinsonism

Lateral axial dystonia (LAD) has been described in patients with Parkinson's disease (PD), but treatment might be more controversial than treatment of LAD in other neurological conditions. Our study was designed as a blinded cross-over with botulinum toxin (BTX) and placebo in order to investigate the efficacy of BTX in PD LAD. Nine patients with LAD who failed to experience benefit from oral medications were randomly assigned to 2 groups, 4 patients received BTX and 5 placebo as a first treatment, and were switched-over to BTX or placebo in the following treatment session, performed 3 months after the first session. Each patient was evaluated at baseline, 2 and 4 weeks after injection and after 3 months follow-up with the Trunk Dystonia Disability Scale (TDDS), a Visual Analogue Scale (VAS) and a goniometric measurement of the lateral displacement. Patients were videotaped at each visit. None of the patients of the placebo group experienced benefit from treatment. BTX treatment was effective in 6 patients. One patient reported subjective benefit, with improvement of VAS score and mild improvement of TDDS score, but with no improvement of flexion degree. Two patients did not report any benefit. Four patients opted to continue to receive BTX treatment for 2 years after the cross-over study. Our study shows that BTX could be considered a possible treatment for LAD in parkinsonism.

Botulinum toxin: Clinical use

Since its development for the use of blepharospasm and strabismus more than 2.5 decades ago, botulinum neurotoxin (BoNT) has become a versatile drug in various fields of medicine. It is the standard of care in different disorders such as cervical dystonia, hemifacial spasm, focal spasticity, hyperhidrosis, ophthalmological and otolaryngeal disorders. It has also found widespread use in cosmetic applications. Many other indications are currently under investigation, including gastroenterologic and urologic indications, analgesic management and migraine. This paper is an extensive review of the spectrum of BoNT clinical applications.

The current use of botulinum toxin

Botulinum toxin is the most potent neurotoxin known, and has been in clinical use since the late 1970s. The toxin inhibits the release of acetylcholine from nerve terminals by inhibiting transport of the synaptic vesicles, thus causing functional denervation lasting up to 6 months. Our understanding of the mechanism of action of the toxin and the spectrum of diseases treatable with this agent continues to increase. Efficacy has been demonstrated in hemifacial spasm, dystonia, spasticity, hyperhidrosis and other conditions. Alternative serotypes are used in some centres, generally after the development of immunoresistance to the standard toxin (serotype A), and are likely to be in routine use in the near future. This paper reviews the history, pharmacology and current uses of botulinum toxin.

Treatment of childhood myoclonus with botulinum toxin type A

Because of inadequate response to or intolerable side effects of oral medication, nine patients with segmental, generalized, and focal myoclonus were treated with intramuscular botulinum toxin type A. All patients were evaluated with neuroimaging, routine and limb-monitored electroencephalography, electromyography, evoked potentials and appropriate biochemical studies. Patients were aged 2 to 22 years, with duration of myoclonus from 1 month to 10 years. Multiple medication trials included antiepileptic drugs, benzodiazepines, tryptophan, L-dopa/carbidopa, baclofen, and dantrolene. Patients were injected with botulinum toxin in their affected area with electromyographic guidance to affected muscles with different doses (8 to 20 units/kg), except two patients who were injected with 32 and 45 units/kg, respectively, at 4- to 8-month intervals. One patient did not complete botulinum toxin treatment because of subjective weakness, although there were virtually no side effects reported in patients completing therapy. Patients reported a dramatic reduction in painful myoclonus. In addition, patients exhibited improved functional skills, as demonstrated by markedly improved use of affected extremities and improvements in ambulation. One patient, who was nonambulatory prior to treatment, was able to walk afterward. Long-term benefits could be related to higher dosage used or negative feedback effect.