Anesthesia Coding Alert

Question: Do piriformis blocks fall under 64450* (Injection, anesthetic agent; other peripheral nerve or branch)? What is the diagnosis code for piriformis syndrome?

California Subscriber

Answer: The piriformis is a pear-shaped muscle that runs right next to the sciatic nerve. If the muscle becomes inflamed, it can press against the sciatic nerve. The resulting condition is called piriformis syndrome (355.0), which ICD-9-CM defines as an acquired disorder of the sciatic nerve that causes motor and sensory dysfunction in the back, buttocks and leg.

Two coding scenarios involve piriformis blocks. Most coders recommend using 64450 because there is no specific code for piriformis muscle injections. Other coders use 64445* (Injection, anesthetic agent; sciatic nerve) with modifier -52 (Reduced services).

According to the 2002 Physician Fee Schedule, there is not a great difference in the relative value units (RVUs) for the two procedure codes. 64450 has a facility RVU of 1.68 and a nonfacility RVU of 3.14, while 64445 has a facility RVU of 1.98 and a nonfacility RVU of 3.16.