The piriformis muscle is a small muscle that attaches at the sacrum, travels across the pelvis and attaches to the top of the femur. It is an external rotator of the hip and leg, which allows the leg and hip to move outward. The sciatic nerve is comprised of L4-S3 spinal nerves coming together at the sacral notch and traveling either through the piriformis muscle or behind it and down the back of the leg.
When the piriformis muscle becomes inflamed and irritated it can tighten, pinching or pressing upon the sciatic nerve and causing pain in the buttock and leg.
There are other conditions that can cause pain in the buttocks and lower extremities. Some of these include facet joint arthritis, herniated intervertebral disc, degenerative disc disease of the lumbar spine, etc. As such, it is advised to seek consultation from a healthcare provider who can properly diagnose the condition and determine proper treatment.
Seeking consultation and advice from a healthcare professional is the best way to start the diagnosis process. Your healthcare provider will undoubtedly perform a physical examination and may or may not do the following:
Piriformis injections can be diagnostic and therapeutic but in either case, the injection procedure is the same.
Diagnostic: The patient undergoes preoperative pain evaluation and consenting. An IV is started for potential sedation, pain, or rescue medications and then is placed in the prone position (face down) on the procedure table. The patient is prepped and draped in the usual sterile fashion and the injection site cleansed with a Betadine solution.
Under radiologic guidance (fluoroscopy or ultrasound imaging) the provider injects an anesthetic agent such as bupivacaine or lidocaine into the piriformis muscle. Just as the anesthetic agent administered by a dentist numbs the mouth so otherwise painful work can be done, the anesthetic agent numbs or anesthetizes the injection site and the piriformis muscle, providing relief of any trigger points or muscle pain. Pain evaluation is done again, postoperatively to determine the success or lack thereof of the procedure performed and to discuss further treatment options.
Therapeutic: The preoperative, intraoperative, and postoperative services are the same as a diagnostic injection but in a therapeutic injection a corticosteroid agent such as dexamethasone or DepoMedrol is injected as well as the anesthetic agent. The corticosteroid will provide additional relief of pain and inflammation for anywhere from a few days to several months and allow the patient to undergo physical therapy and stretching exercises that will give more permanent relief of pain.
Although sciatic pain causes the patient to seek medical care a piriformis injection is not considered a sciatic nerve injection.
The December 2011 CPT Assistant1 clarifies that sciatic nerve injection (64445) should not be used to report a piriformis injection as the work involved in a sciatic nerve injection is substantially more than that which is required in a piriformis injection. The pain is caused from the pinch or pressure on the sciatic nerve but the root of the cause is muscle spasms in the piriformis muscle that keeps it tight and places this pressure on the sciatic nerve that then becomes painful.
As the root of the problem is a tightening, spasm or trigger points within the piriformis muscle trigger point injections (20552) would be the best code to report. When performed under fluoroscopic guidance report 77002 and when performed under ultrasound 76942 would be reported.
Decision Health Article: "Trigger point coding consistency found among carrier LCDs"2 indicates that proper diagnosis code selection is important. Review the medical record carefully to identify the diagnosis for the injection. Some possibilities include: muscle spasm (728.85), myofascial pain (729.1), and enthesopathy (a disorder affecting the hip region where muscle tendons and ligaments connect to the bones (726.5), sciatic pain (724.3).
1 CPT Assistant, December 2011, Page 8
2 DecisionHealth Articles, Trigger point coding consistency found among carrier LCDs (http://www.findacode.com/decision-health/trigger-point-coding-consistency-carrier.html?hl=piriformis - Find-A-Code subscription to DecisionHealth Articles is required to view article)
Aimee Wilcox, MA, CST, CCS-P is a Certified Coding Guru (CCG) for Find-A-Code. For more information about ICD-10-CM, ICD-10-PCS, and medical coding and billing please visit FindACode.com where you will find the ICD-10 code sets and the current ICD-9-CM, CPT, and HCPCS code sets plus a wealth of additional information related to medical billing and coding.
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