Academic journal article Journal of Allied Health

Possible Adverse Effects of Repeated Botulinum Toxin A Injections to Decrease Post-Stroke Spasticity in Adults Undergoing Rehabilitation: A Review of the Literature

Academic journal article Journal of Allied Health

Possible Adverse Effects of Repeated Botulinum Toxin A Injections to Decrease Post-Stroke Spasticity in Adults Undergoing Rehabilitation: A Review of the Literature

Article excerpt

Botulinum toxin A (Botox A) is widely prescribed for the management of spasticity due to stroke, and many patients receive repeated injections because the paralyzing effect diminishes after 3 to 4 months. There are many studies that report local complications of Botox A at the injected site. However, little is known about non-local or systemic adverse events with repeated injections. The purpose of this research was to examine published data about adverse effects of repeated Botox A injections. MEDLINE, CINAHL, and PEDro databases were searched for articles that report adverse effects from Botox A injections for reduction of post-stroke spasticity in adults. Based on studies selected for review, the adverse effects from Botox A injections can be classified into local, systemic, and subclinical types. Systemic and subclinical adverse effects are not commonly reported and need further studies. Therapists and the rehabilitation team need to be aware of the potential of these risk factors that may affect the participation of patients undergoing rehabilitation, and therefore other alternatives to these injections may need to be considered. J Allied Health 2015; 44(3):140-144.

OF THE NEUROTOXINS, botulinum toxin type A (Botox A) serotype is one of the most potent muscle paralytic drugs used for the treatment of spasticity.1,2 It is indicated for many neurological disorders including multiple sclerosis, cerebral palsy, stroke, Parkinson's disease, traumatic brain injury, transverse myelitis, and dystonias.1-3 The mechanism of botulinum toxin A as a pharmacologic agent in the treatment of focal spasticity is well-studied. Once Botox A is injected at the targeted skeletal muscles, it inhibits the release of the neurotransmitter acetylcholine at the neuromuscular junction, arrests muscle contraction, and causes muscle paralysis.2,3 The paralyzing effect is seen within a few days and lasts for about 3 months. Because of its long duration of action and ease of administration through injection, the use of Botox A is widely accepted. In the last two decades, there has been a sharp increase in its usage and it is considered a first line of medical treatment for post-stroke spasticity.3,4 There are many studies written about the efficacy of Botox A to reduce poststroke spasticity. Gallichio found that most studies looked at the efficacy of Botox A injections in the upper extremity, with pain and muscle weakness as common side effects at the injected sites.4

Because the effect of Botox A is temporary, patients may receive repeat injections every 3 or 4 months to manage post-stroke spasticity of the extremities.3,5,6 In addition, there is a general consensus that post-stroke spasticity management involves a multidisciplinary approach, because a reduction in focal spasticity alone does not translate to improved overall function or quality of life.5,8 Thus, patients are referred for physical rehabilitation where therapeutic interventions like stretching, splinting, and electrical stimulation have been incorporated in conjunction with Botox A injections. 8-11 However, in 2012, Teasell et al. raised concerns about an increasing trend toward higher dose injections with multi-modal therapy without well-defined outcome measures of long-term functional improvement.11

With increased prevalence of these procedures, longterm side effects have been reported.1,3,5 Patients may develop resistance to repeat injections or develop a shorter duration response to same dosages, though it is not fully understood why some patients develop neutralizing antibodies against Botox A.1,2,4,5 Generalized fatigue, excessive weakness, flu-like symptoms, sudden dizziness, and botulism-like syndrome are some unexpected serious side effects linked to neurotoxin spread outside targeted muscles.6,11,12 These have been documented mainly through patient self-report, interviews, and case reports.

Despite increased use, there is a lack of research that reports possible adverse effects (AE) after repeated Botox A injections for post-stroke spasticity, and its clinical significance in rehabilitation is lacking. …

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