AMA CPT Assistant April 2012 page 19
Coding Clarification
iriformis Muscle Injection Reporting
In the December 2011 issue of the CPT Assistant (page 8), instruction in the article stated that sciatic nerve injection code 64445, Injection, anesthetic agent; sciatic nerve, single, should not be used to report a piriformis muscle injection. However, from a CPT coding perspective, piriformis muscle injection(s) should be reported using CPT code 20552, Injection(s); single or multiple trigger point(s), 1 or 2 muscle(s). For further clarification, should fluoroscopic guidance be performed, this is additionally reported using code 77002, Fluoroscopic guidance for needle placement (eg, biopsy, aspiration, injection, localization device.
AMA CPT Assistant December 2011 page 8
Piriformis Muscle vs Sciatic Nerve
This article was updated in April 2012.
There is a significant difference in the work and procedure, as well as intent, between an injection of the piriformis muscle and the perineural injection of the sciatic nerve. The sciatic nerve injection code (64445) should not be used to report a piriformis injection. However, from a CPT coding perspective, piriformis muscle injection(s) should be reported using CPT code 20552, Injection(s); single or multiple trigger point(s), 1 or 2 muscle(s). For further clarification, should fluoroscopic guidance be performed, this is additionally reported using code 77002, Fluoroscopic guidance for needle placement (eg, biopsy, aspiration, injection, localization device.
A piriformis injection may be performed when piriformis syndrome is suspected. In this condition, the muscle is believed to impinge upon the sciatic nerve, which may pass close to or actually run through the muscle. Prolonged or repetitive use of the piriformis muscle, causing either hypertrophy or stretching, can potentially induce the impingement upon the nerve, which may cause pain in the buttock. Diagnostic testing to evaluate the piriformis syndrome usually includes pain on palpation; however, the presence of electromyographic abnormalities is variable. In some cases, magnetic resonance imaging (MRI) scanning may reveal the nerve running through the body of the muscle or abnormal increased signals in the proximal sciatic nerve. In the case of piriformis myofascial pain syndrome, it is suspected that muscle strain or injury may result in areas of sustained muscle spasm that produces trigger points and pain in the buttock.
Injection of the piriformis muscle with local anesthetic and/or steroid in this situation may relieve the pain but may also be diagnostic in nature. In many cases, injections in combination with physical therapy will produce longterm relief. In a small number of patients, further therapy (eg, surgical division of the muscle, injection with botulinum toxin) may be required to obtain definitive relief. Although fluoroscopy may be used to guide some injections, the muscle is best imaged on computed tomography (CT) scan. Currently, there is growing interest in the use of ultrasound to guide these injections, although its use may be challenging in adults. Use of a nerve stimulator to avoid injection into the nerve is recommended when injections are being performed at the midpoint of the muscle. A successful piriformis injection should not have any evidence of sciatic nerve block present.
The sciatic nerve injection, on the other hand, is a well-documented method intended to provide regional anesthesia or to alleviate acute or chronic pain of the leg and foot. It does not aid in the management of buttock pain. The injection of the nerve should be managed with anatomic landmarks, using guidance via fluoroscopy, ultrasound localization, and/or a nerve stimulator, as necessary, in order to place the medication as close to the sciatic nerve as possible but not within it. In some cases, patients may need light sedation to manage the placement of local anesthetic in the large muscles overlying the target structure, but the patient should be awake to report any manifestation of paresthesia that could indicate intraneural injection.
The successful injection around the sciatic nerve may alleviate leg or foot pain in the postoperative period. In the case of chronic pain, successful injection of the sciatic nerve may rule out the role of a neuraxial disease process or facilitate passive physical therapy. It may also direct the use of diagnostic and therapeutic maneuvers to the lower extremity and away from the spine.