Abstract ID: A30
Abstract Title: CT-guided injections of Botulinum toxin into the subscapularis muscle in children
Poster Type: Either
ABSTRACT BODY
Introduction:
Interventional pain management has dramatically expanded over the last decade. The use of image-guided pain procedures (e.g., ultrasound and CT-guided regional anesthesia and fluoroscopy guided blocks) has influenced the safety, efficacy, and precision of pain diagnosis and management. Botulinum toxin A (BTA) has been shown to alleviate pain and improve motor function in prior clinical studies. (1) Computed Tomography (CT) was used as a tool to visualize the subscapularis muscle during a procedure to inject BTA in order to enhance the accuracy of the injection directly into the belly of the muscle.
Methods:
The purpose of this study was to evaluate whether the accuracy of injecting BTA into the belly of the subscapularis muscle was enhanced by using CT guidance. After IRB approval, a retrospective chart review identified seventeen subjects with brachial plexus injuries primarily to C5 and C6 who underwent CT-guided BTA injections into the subscapularis muscle. CT scans were evaluated by the radiologist for muscle atrophy, ultimate needle position, and the availability of a safe (open) window for comparable needle placement without CT guidance. An open window was defined as the area a needle might take to blindly enter the subscapularis muscle, minimizing the risk of pneumothorax and maximizing the likelihood of injection into the muscle belly.
Results:
Of the seventeen patients (mean age = 1.8 ± 1.6 yrs; mean weight = 12.2 ± 4.75 kg), only one had an open window. Ten (58.8%) subjects did not have an open window, while six (35.4%) were evaluated to have the open window just at the lateral edge of the muscle. Additionally, eleven patients (64.7%) had atrophy of the subscapularis muscle. Using Fisher’s exact test and grouping the subjects into <10 kg and >10 kg, a statistically significant difference (p=0.0276) was noted for muscle atrophy.
Discussion:
This study demonstrated the importance of CT-guidance for precise BTA injection into the belly of the subscapularis. Because only 1 subject had an open window, and the majority had an atrophied muscle, we feel blinded injection would be extremely difficult and increase the incidence of complications such as a pneumothorax. CT guidance allowed for needle repositioning so the BTA dose could be injected directly into the belly of the muscle. Our injection volumes were typically less than 1 cc (BTA stock solution was diluted to a dose ranging from 30 to 100 units of BTA). Because of this small volume, precise needle placement was critical. This study did not permit evaluation of whether or not direct injection is more efficacious than injections into the lateral edge of the subscapularis. We speculate that direct injection may result in both a more localized and more concentrated effect.
Reference:
(1) Fanucci, et al. CT-guided injection of botulinic toxin for percutaneous therapy of piriformis muscle syndrome with preliminary MRI results about denervative process. Eur. Radiol. (2001) 11: 2543-2548.
ATTACHED FILES
A30_Table 1 for ASRA 04.doc
Reg Anesth Pain Med 2004; 29(2):A30