Background Botulinum toxin type A (BTA) (Botox) received Food and Drug Administration (FDA) approval for therapeutic treatment of strabismus and blepharospasm in 1989, cervical dystonia in 2000, and cosmetic treatment of glabellar wrinkles (Botox Cosmetic) in 2002. In 2002 alone there were approximately 1.1 to 1.6 million patients using cosmetic BTA. Our objective was to review adverse event (AE) reporting to the FDA after BTA administration. Methods We reviewed all (therapeutic and cosmetic use) serious (per FDA regulations) AEs reported to the FDA for the 13.5 years since licensure of the product (December 1989-May 2003) and nonserious AEs reported from December 2001 to November 2002. AEs are reported to the FDA through the MedWatch system. Results We reviewed 1437 AE reports; 406 followed therapeutic use of BTA (217 serious and 189 nonserious) and 1031 followed cosmetic use (36 serious and 995 nonserious). Reported AEs occurred predominantly in female patients, with a median age of 50 years. In the year December 2001 to November 2002, when both serious and nonserious reports were evaluated, the proportion of reports classified as serious was 33-fold higher for therapeutic than for cosmetic cases. The 217 serious AEs reported in therapeutic cases involved a wide spectrum of events and included all 28 reported deaths. Among cosmetic users, no deaths were reported and, of the 36 serious AEs, 30 were included as possible complications in the FDA-approved label. The remaining 6 serious AEs did not display a pattern suggesting a common causal relationship to BTA. Among the 995 cosmetic cases reported to have nonserious AEs, most commonly noted were lack of effect (623, 63%), injection site reaction (190, 19%), and ptosis (111, 11%). Conclusions Serious AEs were more likely to be reported for therapeutic than for cosmetic use, which may be related to higher doses, complicated underlying diseases, or both. Among cosmetic cases, few serious AEs were reported, and these were predominantly events that were previously recognized in clinical trials of BTA for the labeled use. This study is limited primarily by the incomplete nature of AE reporting by clinicians. Numerous departures from FDA-approved recommendations for drug dose, dilution, handling, site of injection, and storage were noted in these AE reports.

Botulinum toxin type A injections: adverse events reported to the US Food and Drug Administration in therapeutic and cosmetic cases.

Piriformis syndrome (PS) is an uncommon cause of sciatica that involves buttock pain referred to the leg. Diagnosis is often difficult, and it is one of exclusion due to few validated and standardized diagnostic tests. Treatment for PS has historically focused on stretching and physical therapy modalities, with refractory patients also receiving anesthetic and corticosteroid injections into the piriformis muscle origin, belly, muscle sheath, or sciatic nerve sheath. Recently, the use of botulinum toxin (BTX) to treat PS has gained popularity. Its use is aimed at relieving sciatic nerve compression and inherent muscle pain from a tight piriformis. BTX is being used increasingly for myofascial pain syndromes, and some studies have demonstrated superior efficacy to corticosteroid injection. The success of BTX in treating PS supports the prevailing pathoanatomic etiology of the condition and suggests a promising future for BTX in the treatment of other myofascial pain syndromes.

Piriformis syndrome, diagnosis and treatment.

Botulinum toxins: mechanisms of action, antinociception and clinical applications.

http://headacheclinics.co.uk/wp-content/uploads/2010/07/Botulinum-toxin-A-for-myofascial-trigger-point-injection.pdf

Botulinum toxin A for myofascial trigger point injection: a qualitative systematic review.

Purpose
In this narrative review, we aim to provide the pathophysiology and diagnostic criteria of the piriformis syndrome (PS), an underdiagnosed cause of buttock and leg pain that can be difficult to treat. Based on existing evidence, frequencies of clinical features are estimated in patients reported to have PS. In view of the increasing popularity of ultrasound for intervention, the ultrasound-guided technique in the treatment of PS is described in detail.

/pdf/brief-review-piriformis-syndrome-etiology-diagnosis-and-12q3eesm6g.pdf

Brief review: Piriformis syndrome: etiology, diagnosis, and management

Objective This study was undertaken to test the hypothesis that intramuscular botulinum toxin type A decreases chronic pain attributed to piriformis muscle syndrome to a greater extent than a similar injection with vehicle (saline) alone. Design This double-blind, single group, crossover study was performed at an outpatient university clinic. Nine women with chronic buttock, hip, and lower limb pain without evidence of lumbar disk herniation or nerve root impingement on imaging studies participated in the study. The analgesic efficacy of a fluoroscopic/electromyographically guided unilateral intramuscular piriformis injection with 100 units botulinum toxin type A was compared with a similar injection of vehicle alone. Visual analog pain scales (VASs) were used to measure pain intensity, distress, spasm, and interference with activities. Results No differences in mean VASs were detected between groups at baseline or after injection with vehicle. However, decreases were observed between baseline and post-botulinum toxin type A injection mean VASs, but only in one of four categories (interference with activities). VASs from every time point (days) were also compared with the average baseline VASs. After injection with vehicle, decreases were detected, but only in one of the four categories (distress). In comparison, after injection with botulinum toxin type A, decreases were observed under all VAS categories. Conclusions VAS data suggest that intramuscular piriformis injection with 100 units of botulinum toxin type A can reduce pain to a greater extent than similar injections with vehicle alone.

Robert R Conway

Papers

Botulinum toxin type A use in piriformis muscle syndrome: a pilot study.