Polyradiculoneuritis following botulinum toxin therapy

Botulinum toxins in neurological disease

Botulinum toxins are among the most potent neurotoxins known to humans. In the past 25 years, botulinum toxin has emerged as both a potential weapon of bioterrorism and as a powerful therapeutic agent, with growing applications in neurological and non-neurological disease. Botulinum toxin is unique in its ability to target peripheral cholinergic neurons, preventing the release of acetylcholine through the enzymatic cleavage of proteins involved in membrane fusion, without prominent central nervous system effects. There are seven serotypes of the toxin, each with a specific activity at the molecular level. Currently, serotypes A (in two preparations) and B are available for clinical use, and have been shown to be safe and effective for the treatment of dystonia, spasticity, and other disorders in which muscle overactivity gives rise to symptoms. This review focuses on the pharmacology, electrophysiology, immunology, and application of botulinum toxin in selected neurological disorders.

Polyradiculoneuritis after botulinum toxin therapy for cervical dystonia

A 40-year-old man with cervical dystonia developed an acute inflammatory demyelinating polyradiculoneuritis after botulinum toxin type A treatment. Some cases of idiopathic brachial plexopathy and polyradiculoneuritis have been reported to date. Although a causal relationship is not firmly established, the clinical temporal profile suggests a pathogenic relationship. In patients with cervical dystonia, further use of type A botulinum toxin should be considered contraindicated, and the use of another type of botulinum toxin should be taken into consideration.

Botulinum-A toxin in the treatment of craniocervical muscle spasms: short- and long-term, local and systemic effects

Botulinum toxin has become the initial treatment of choice for the management of essential blepharospasm, hemifacial spasm and other craniocervical dystonias. Numerous studies have confirmed a 90% to 95% response rate. Although a number of common side effects have been reported, the occurrence and incidence of rare local complications remains poorly understood. More importantly, the acute and chronic distant effects of botulinum toxin have not been clearly elucidated. A better understanding of such effects is essential if clinicians are to appropriately advise patients on the use of this therapeutic modality. This article is based on the Duke University experience in the management of over 500 patients with craniocervical spasm disorders, combined with a review of the published literature. These disorders include essential blepharospasm, oromandibular dystonia, hemifacial spasm, and torticollis. The incidence of side effects following more than 6000 treatments with botulinum toxin is presented. Pertinent research relating to the causes of these complications is also reviewed. The most common complications of treatment with botulinum toxin are related to acute local effects resulting from chemodenervation. The most important clinical effect in this group is weakening of the levator muscle resulting in ptosis, and the corneal consequences of lagophthalmos. The latter includes exposure keratitis, dry eyes, blurred vision, and hypersecretion epiphora. Less common local effects include facial numbness, diplopia, and ectropion. Some distant effects are being observed with increasing frequency. These include pruritus, dysphagia, nausea, and a flu-like syndrome. Most significant, however, are the rare reports of generalized weakness and the documentation of EMG abnormalities distant to the site of toxin injection. This has been seen with injections for both blepharospasm and torticollis. Until further studies on the long-term distant complications of botulinum toxin are available, it is recommended that patients receive as few life-time doses of toxin as possible, consistent with adequate management of their spasms. The practice of reinjecting patients routinely every three months, or at the first return of mild spasms should be discouraged.

Neuroleptic induced blepharospasm and its treatment with botulinum toxin type A

Three cases of neuroleptic induced blepharospasm successfully treated by botulinum toxin type A are reported.

Botulinum toxin in the treatment of myofascial pain syndrome

Six patients with chronic myofascial pain syndrome involving cervical paraspinal and shoulder girdle muscles received trigger point injections of botulinum toxin type A (Botox) or saline in a randomized, double-blind, placebo-controlled study. Four patients experienced reduction in pain of at least 30% following Botox, but not saline, injections, as measured by visual analog scales, verbal descriptors for pain intensity and unpleasantness, palpable muscle firmness, and pressure pain thresholds. Results were statistically significant. Botox, which inhibits muscle contraction by blocking the release of acetylcholine from peripheral nerves, appears to be an effective treatment for focal myofascial pain disorders.

Botulinum toxin therapy for neurologic disorders

In the last 20 years, the therapeutic uses of botulinum toxin, a potent neurotoxin, have been investigated. The agent produces chemical denervation of muscle, thereby causing atrophy and weakness. Studies have shown that injection of this agent is an effective therapy for focal dystonias, particularly blepharospasm, hemifacial spasm, and torticollis. Investigation continues into the role of botulinum toxin in the treatment of anismus, detrusor-sphincter dyssynergia, writers' cramp, and other disorders in which focal weakening of selected muscles could be useful.