Neurology -- Correspondence for Qerama et al., 67 (2) 241-245

Correspondence published:

A double-blind, controlled study of botulinum toxin A in chronic myofascial pain: Bruce A. Richards MD (28 September 2006)

Reply from the Authors: Erisela Qerama, MD, PhD, Anders Fuglsang-Frederiksen , Helge Kasch, Flemming W. Bach , Troels S. Jensen (28 September 2006)

A double-blind, controlled study of botulinum toxin A in chronic myofascial pain 28 September 2006

Bruce A. Richards MD,
Private Practice
1100 NW 8th Ave, #C, Gainesville FL, 32601
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Re: A double-blind, controlled study of botulinum toxin A in chronic myofascial pain

macdr{at}bellsouth.net Bruce A. Richards MD

I read with interest the article by Qerama et al on botulinum toxin A and myofacial pain syndrome. [1] As a neurologist, I have been treating patients for 15 years with Btx (botulinum toxin A), many of whom fulfill the inclusionary criteria for this study (ie. chronic shoulder and arm pain of greater than six months duration).
Given the somewhat complex nature of the innervation and musculature of the shoulder and upper extremity, I wonder why a single trigger point located in the infraspinatus muscle was chosen. Furthermore, why there would be any expectation that a single injection of botulinum toxin would be of any benefit in this group of patients. For these reasons, it was not surprising that there were not favorable outcomes in this small study. It should also be noted that the concentrations of Btx used were four times what is recommended (200U/ml in this study vs. the standard concentration of 50U/ml).
Treatment of this problem with Btx can be done successfully. The principle muscles involved in almost all patients with chronic shoulder and arm pain are the middle scalene and levator scapula muscles, based on my clinical experience. I typically dose these at 15-25 U for the middle scalene, and 50-75 U for the levator scapula.
Furthermore, it is my opinion that the pain in this group of patients is not principally of trigger point origin, but rather originates from pressure on the brachial plexus. My rate of success is greater than 80% if patients with cervical disk or foramenal stenosis are excluded.
Reference
1. Qerama E, Fuglsang-Frederiksen A, Kasch H, Bach FW, Jensen TS. A double-blind, controlled study of botulinum toxin A in chronic myofascial pain Neurology 2006; 67: 241-245.
Disclosure: I provide preceptorship training for Allergan for beginning and advanced injectors of Btx for Neurology and Physical and Rehabilitation Medicine practitioners. I also provide lecture services for companies that are supported by Allergan, and provide occasional consultative services to Allergan. I have no financial interests in Allergan.

Reply from the Authors 28 September 2006

Erisela Qerama, MD, PhD,
Danish Pain Research Center
Building 1 A, 1st floor, Parterre, Noerrebrogade 44, DK-8000 Aarhus, Demnark,
Anders Fuglsang-Frederiksen , Helge Kasch, Flemming W. Bach , Troels S. Jensen
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Re: Reply from the Authors

erisela{at}akhphd.au.dk Erisela Qerama, MD, PhD, et al.

Thank you for the opportunity to respond to the letter from Dr. Richards. The entry criterion for our study was shoulder and arm pain associated with active trigger points in the infraspinatus muscles and not general shoulder and arm pain as the author of the correspondence implies. This was done to ensure a distinct assessment of the trigger point despite the variability of the underlying disease conditions.
Moreover, we excluded patients with trigger points in the ipsilateral trapezius, supraspinatus and teres muscles. The trigger point chosen for injection was the most painful and our primary outcomes were not only spontaneous shoulder pain but also the evoked pain (pain evoked by pressure applied on the injected trigger points) as a direct measure of the effect on the trigger point. Neither the primary nor the secondary outcome measures were affected by the toxin, supporting our conclusion.
In addition, the infraspinatus muscle is a small muscle and the dose used in this study did have a distinct effect on the motor function. However, from our study we cannot exclude that injection of botulinum toxin at several sites might have had an effect on the pain. On the other hand, choosing only one spot for measurements made the statistical evaluation stronger. The dose used in earlier studies of pain conditions has varied between 25 U and 100 U /site. [2,3,4] We injected 50 units (administered in a volume of 0.25 ml) at the most painful trigger point through one insertion and in five directions at four sites (1-2 mm apart) per direction. [5] This dose was sufficient to significantly influence the motor function of the entire muscle. We believe that the lack of effect on pain cannot be due to an insufficient dose as the dose was adequate for the purpose of the study.
We acknowledge the author's personal experiences with botulinum toxin in treating painful musculoskeletal conditions apparently with a high success rate. Our report is the result of a controlled clinical trial and the reader will have to make his/her evaluation from the presented evidence.
References
2. Cheshire WP, Abashian SW, Mann JD. Botulinum toxin in the treatment of myofascial pain syndrome. Pain 1994;59:65-69.
3.Foster L, Clapp L, Erickson M et al. Botulinum toxin A and chronic low back pain: a randomized, double-blind study. Neurology 2001;56:1290-1293.
4. Freund B, Schwartz M, Symington JM. Botulinum toxin: new treatment for temporomandibular disorders. Br J Oral Maxillofac Surg 2000;38:466-471.
5. Qerama E, Fuglsang-Frederiksen A et al Effects of evoked pain on the electromyogram and compound muscle action potential of the brachial biceps muscle. Muscle and Nerve 2005 Jan;31:25-33.
Disclosure: The authors report no conflicts of interest.