Clinical Videos:   Piriformis Muscle Videos

Myoguide™ Guided Piriformis Muscle Injection


The Piriformis exists deep in the lower back/pelvic area, in close proximity to the sacrum, sacroiliac joints and interior hip joints. Nerve supply to the Piriformis muscle is via the L5/S1/S2 spinal nerve roots which are known problem areas affected by many spinal conditions.

There are several symptoms associated with "Piriformis Syndrome" such as pain in the hip, pain in the center of the butt, or pain down the back of the leg: The first symptom suggesting Piriformis syndrome would be pain in and around the outer hip bone. The tightness of the muscle produces increased tension between the tendon and the bone which produces either direct discomfort and pain or an increased tension in the joint producing a bursitis. The second symptom suggesting Piriformis syndrome would be pain directly in the center of the buttocks. This pain can be elicited with direct compression over the belly of the buttocks area. The third symptom suggesting Piriformis syndrome would be a sciatic neuralgia, or pain from the buttocks down the back of the leg and sometimes into different portions of the lower leg.



Injection Procedure


The trigger point locations are normally found by physical examination and manual palpation. Piriformis is so deep that palpation is impossible. Diagnosis from physical examination and patient history determines the course of action. The injection site is determined by anatomy and familiarization with anatomical landmarks. The entry point for any injection is pre-determined before the needle EMG guided injection procedure is ready. This patient is lying on his side. The injection entry point is through his buttocks. It is quite difficult to find the optimal injection locations without Myoguide™, as there is a subtlety related to the depths where hyperactive muscle fibers reside. Myoguide™ allows the clinician to see and hear the EMG signal, providing confirmation that the needle is indeed in the best location. It is of benefit to be able to see the EMG signal, as it provides information about activity that EMG audio alone cannot. It is quite possible that ultrasound cannot be used for this particular injection due to tissue depth. This is especially true in the obese patient in this video demonstration. Abundant fatty tissue makes ultrasound imaging impossible. The video demonstrates the value of Myoguide™ in finding the injection site, as indicated by a significantly increased level of EMG activity. Once more, you will also notice that EMG is briefly heard when the muscle is initially penetrated by the needle, and again when the patient is asked to go through a movement known to activate Piriformis ("knee lift toward the ceiling"). In this demo video, he is asked to do this twice - once by the treating clinician, and once by the clinician instructor. In this case, a 4" needle was used. This length of needle is almost inadequate in this obese patient.


Myoguide™ and Ultrasound Guided Piriformis Muscle Injection



This video provides a view into a Piriformis injection procedure. There is a brief overview of landmarks used to find the injection site, clinically. There are lines drawn for illustration purposes. Clinicians don't generally need to draw on patients. The Sciatic nerve is highlighted as a spot to avoid. Ultrasound demonstrates what the Piriformis Muscle looks like, and it's position is verified by contraction and relaxation. Myoguide is an important tool for this procedure as you can see. EMG audio and raw EMG is a great indicator of where you are. There is also a good view of what the integrated EMG (iEMG) bar graph and EMG RMS indicator looks like on the Myoguide display screen. The deeper you progress with the needle, the more difficult it is to see on the ultrasound. Myoguide EMG guidance is an essential tool.

Myoguide illustrates the various muscles entered along the way to Piriformis. The anatomy tour in this video is an outstanding illustration of how well trained these Physical Medicine and Rehabilitation (Physiatrists) specialists are.



Benefits of Myoguide™
  • Myoguide™ provides a superior injection site targeting system with many useful features, such as, the ability to see and hear EMG signals, display real time analyzed EMG, and stimulation location capability.

  • Myoguide™ provides both quantitative and qualitative feedback necessary for clinicians to make decisions about treatment and treatment delivery. All these features are wrapped up in a small , battery operated, hand-held device.

  • Myoguide™ helps identify involved muscles through pre-injection, or pre-intervention evaluation. This can be done by either EMG evaluation, or stimulation location, and is particularly useful in cases where the site may be surrounded by essential nerves and blood vessels.

  • Pre-injection evaluation can lead to use of reduced drug dose and volume, thereby contributing to limiting drug diffusion into adjacent areas. This is especially pertinent in cases where drugs will be re-injected on follow up appointments, as the basal EMG activity level can be assessed before a dose decision is finalized.

Improve Efficacy

The need to increase accuracy when injecting neuromodulators has been highlighted by recent FDA reviews of the dangers of peripheral effects.

Use of Myoguide™ can lead to more accurate injection site targeting, allowing reduced concentrations and volumes of injected drugs.