Piriformis Syndrome: What’s Actually Causing the Nerve Irritation?

Last week, we looked at sciatica through a mechanical lens, exploring how lumbopelvic positioning may influence the environment surrounding an irritated nerve root. This week, we’re following the sciatic nerve farther down.

With piriformis syndrome, the irritation occurs in the deep gluteal region, where the sciatic nerve passes in close relationship to the piriformis muscle. When the piriformis becomes chronically shortened and contributes to irritation or compression of the sciatic nerve, symptoms such as pain, burning, tingling, numbness, or other symptoms may travel from the hip into the leg.

Mechanically, this gives us a more direct problem to address than we had with sciatica. If a chronically shortened piriformis is contributing to nerve irritation, reducing the tension it is maintaining becomes our first objective. But reducing that tension is only part of the solution. To create a more lasting change, we also need to address the muscular imbalance associated with that shortened position.

How Piriformis Tension Can Affect the Sciatic Nerve

The piriformis is a small, deep muscle that extends from the sacrum to the greater trochanter of the femur. Its location places it in close proximity to the sciatic nerve as the nerve exits the pelvis and travels down the back of the leg. Typically, the sciatic nerve passes beneath the piriformis, although anatomical variations exist, and portions of the nerve may sometimes pass through the muscle rather than entirely beneath it.

Because these structures occupy such close quarters, excessive piriformis tension can influence the mechanical environment surrounding the sciatic nerve. When a chronically shortened piriformis contributes to compression or irritation of the nerve, symptoms may develop in the deep gluteal region and extend along the nerve’s pathway into the leg.

This is where the distinction between piriformis syndrome and the sciatica we discussed last week becomes important. Although both can produce similar symptoms, the location of the irritation is different. With lumbar radiculopathy, the problem originates near a spinal nerve root. With piriformis syndrome, the sciatic nerve is affected farther along its pathway through the deep gluteal region.

The Muscular Tug-of-War

In Is a Tight Muscle Really a Weak Muscle?, we explored muscular balance using the analogy of a tug-of-war. Muscles rarely function in isolation. They work together and in opposition to produce movement and control joint position. When one side becomes chronically shortened and maintains excessive tension, we can think of that muscle as winning the tug-of-war.

If the piriformis is winning that tug-of-war, simply getting it to relax temporarily doesn’t necessarily restore balance. We also want to strengthen the opposing musculature so it can better counter the actions of the piriformis. This gives us two related objectives: reduce excessive piriformis tension and strengthen the opposing side of the muscular relationship.

Fortunately, we can begin working on both at the same time.

Using Reciprocal Inhibition to Reduce Piriformis Tension

One way we can reduce tension in the piriformis is through reciprocal inhibition. Reciprocal inhibition describes the relationship between muscles that perform opposite actions: as one contracts to create a movement, the opposing muscle relaxes enough to allow that movement to happen.

Think about bending your elbow. Your biceps contracts to bend your arm while your triceps relaxes enough to allow it. If both muscles contracted equally at the same time, they would work against each other instead of creating smooth movement.

We can use this same relationship with the piriformis. By actively contracting the muscles that perform its opposing actions, we can reduce activity in the piriformis while simultaneously loading the other side of the muscular relationship. Reciprocal inhibition helps the piriformis loosen its grip on the tug-of-war, while resistance begins giving the opposing side more strength to pull back.

Putting Reciprocal Inhibition Into Practice

If we’re using reciprocal inhibition intentionally, we want more than simply moving the hip in the opposite direction. We want the opposing muscles to actively contract, with an emphasis on producing a strong contraction as they move toward their shortened position.

When the hip is relatively close to neutral, the piriformis helps externally rotate the femur, making internal rotation a logical place to start. Using resistance, actively move the hip into internal rotation and finish with a controlled contraction near the end of the available range. The resistance should be challenging enough that the internal rotators have to work, but not so heavy that other movements begin compensating for the rotation. After holding the contraction briefly, relax and repeat for several repetitions.

The piriformis, however, does more than externally rotate the hip. With the hip extended, it also contributes to abduction, while in hip flexion it contributes to transverse abduction. This means internal rotation alone may not address every function through which the piriformis is maintaining tension. Depending on hip position, we can apply the same principle by actively performing adduction or transverse adduction against resistance, allowing us to target the opposing musculature while reducing activity in the piriformis.

This is where reassessment becomes useful. Rather than asking whether reciprocal inhibition worked, we can ask whether we adequately addressed the functions through which the piriformis was maintaining tension. If significant tension remains after targeting external rotation, its other actions may give us the next muscular relationships to address.

Reducing Tension Is Only the Beginning

Reciprocal inhibition can immediately reduce piriformis activity, but the long-term objective is bigger than getting one muscle to relax. We want to improve the muscular balance that allowed the piriformis to remain chronically shortened in the first place.

Think back to the tug-of-war. Reciprocal inhibition helps the piriformis loosen its grip, while strengthening the opposing musculature gives the other side more ability to counter its pull. Over time, the goal is to improve that relationship so we aren’t repeatedly chasing the same tight muscle.

When excessive piriformis tension is contributing to sciatic nerve irritation, this gives us both an immediate and a long-term strategy: reduce the tension through reciprocal inhibition, then continue strengthening the opposing musculature to help restore balance between the two sides.

The Bigger Picture

Throughout this series, we’ve looked at two conditions that can produce remarkably similar symptoms while involving irritation at very different points along the same nerve. That distinction matters because knowing what hurts and where it hurts is only the beginning. To address the problem effectively, we need to understand what is happening mechanically at the source of the irritation.

With sciatica, that meant looking at the lumbopelvic mechanics surrounding an irritated nerve root. With piriformis syndrome, it meant following the sciatic nerve into the deep gluteal region and looking at the muscular relationships surrounding it. Same nerve. Similar symptoms. Different mechanical problems.

Ultimately, symptoms can point us toward the irritated nerve, but understanding the mechanics helps us determine where the irritation is coming from and what to do about it.

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📖 Read this next: Sciatica: What’s Actually Causing the Nerve Irritation?

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