Accurate Piriformis Injection

ºAlthough I have been happy with Rectal Coupled Piriformis Injections, Ultrasound Guided injections are becomeing more popular. Combined with Botulinum, the results can last 6 months or more.

The Piriformis syndrome, I contend, is a common complaint in resistant back pain situations – with or without radicuopathy.

The standard injection technique:

• patient sidelying with buttock off the edge of table and knees drawn up
• Put finger in rectum (guys- have a female assistant present if subject a woman)
• palpate the Sciatic notch- piriformis runs through it – if it’s not tender, abandon procedure as it’s not piriformis but gluteal bursitis higher up.

• I have done perhaps 60 injections, and over the years have found it is easier to give the injection if the needle is inserted closer to rectum than in Pace’s original article:
  Pace JB, Nagle D:
  Piriform syndrome. West J Med 124:
  435-439, Jun 1976  free article here

• You can feel the needle traversing the tissues and it gives a better feeling of how far you are in while you are holding the tender piriformis spot rectally
• I use a 22 gauge spinal needle as you cannot control a 25 gauge.
• I put local in the entry zone
• When you put the spinal needle in, if you cannot get it to go in, grab the needle with an alcohol swab and push it in.
• When you get close you can see how far off you are and redirect. On hitting the piriformis, sometimes the patient will jump or say you have hit a sore spot.
• I inject some local and steroid in the spot and then redirect to other areas that are tender – often more medially.  I am not convinced a one spot shot injections works as well.
• I have had questions about “what if you perforate the rectum?” – reality check: To have prostatic biopsies, the rectum is perforated 10-12 times. If you are concerned, put on Cipro Xr 1000mg od or Levaquin 500 mg od starting before injection and carried on a few days. I will start it if there is blood on my rectal glove – something that has only happened twice.
• I am careful having the patient get up in case there is sciatic nerve anesthesia, but have never had that happen.

The Ultrasound technique is fairly simple – when you Ultrasound above the sciatic notch, all there is to see, is the gluteus max – when you get lower, you can see a pear shaped muscle  which moves when you take the knee bent leg back and forth in rotation.

If you put a needle down at the end on the US probe just in mid line (just a few mm lie-way) – then you might see the spinal needle going down to target. Which target?

IASP Poster Presentation Number: PH 353, Montreal 2010
ACCURACY OF ULTRASOUND GUIDED INFILTRATION INTO THE PIRIFORMIS MUSCLE VERIFIED BY MAGNETIC RESONANCE IMAGING
J. A. Blunk1, M. Nowotny1, J. Scharf2, J. Benrath1, 1Anaesthesiology, Klinikum Mannheim, Mannheim, Germany, 2Neuroradiology, Klinikum Mannheim, Mannheim, Germany

• In discussion with this group, the sweat spot seems to be below the posterior inferior iliac spine in the sciatic fossa. They go through measure to avoid sciatic nerve. – As far as I am concerned, If one is really concerned one could alligator clip a pointer plus stimulator or acupuncture machine probe to spinal needle and stimulate as you get close.

Another group has narrowed it down to the lower end of the SI joint – which is about 1/2 – 1 inch out from the medial border of the Posterior Inferior Iliac Spine:

IASP Presentation Number: PH 407, Montreal 2010
A NEW TECHNIQUE FOR FLUOROSCOPIC GUIDED PIRIFORMIS INJECTION: A CASE REPORT OF SUCCESSFUL RELIEF OF PIRIFORMIS SYNDROME IN THE BOSTON VA HEALTHCARE SYSTEM
S. Cheema¹, L. Andima¹, E. Michna², ¹Anesthesia and Critical Care, VA Boston Hlth.care System, Boston, MA, USA, ²Brigham and Women’s Hosp., Boston, MA, USA

They would put the needle down ON the PIIS – SI spot location to judge depth, then angle 45 degrees inferior to go to piriformis – same depth -of course they used fluoroscopy.

They had 2 cases – used 4 ml 0.25% bupivicaine and 40 mg tiramcinolone. One case got 80% relief for 8 weeks. They other bilateral case got 100% relief for 8 weeks – sounds good but still a stop-gap measure that physio will have to work on.

Good news and bad news – Steroid piriformis injection may only last several weeks in which case it is only used to help with vigorous massage – discussed here:

How Should One Investigate Chronic Back Pain and What about the Back Muscles?

A recent US injection course I attended suggested Botox 50 u (although operator often uses a full bottle 100 u because rest will go to waste) can result in 6 month or more relief.

Other bad news is that I am not convince spot just by trochanter can be taken out by more medial injection – If it is present – it may need special injection and I believe it is probably a true tendonitis given that addition of steroid to just plain local has an additional effect… However I inject 40 gm Kenalog into medial piriformis and steroid effects seem to be very forgiving – close might be close enough.

Others have ideas about injections? I believe the lower lumbar spine, perhaps thoracolumbar spine, Quadratus lumborum, and sacroiliac all all players in this condition. Another concern would be the back and unilateral buttock pain that goes with ankylosing spondylitis and other sacroiliits..

Any comments on procedure or results?