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Syndromes,
Injuries and Diseases |
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The piriformis syndrome is a condition
in which the piriformis muscle irritates the sciatic nerve,
causing pain in the buttocks and referring pain along
the course of the sciatic nerve. This referred pain, called
"sciatica", often goes down the back of the
thigh and/or into the lower back. Patients generally complain
of pain deep in the buttocks, which is made worse by sitting,
climbing stairs, or performing squats. The piriformis
muscle assists in abducting and laterally rotating the
thigh. In other words, while balancing on the left foot,
move the right leg directly sideways away from the body
and rotate the right leg so that the toes point towards
the ceiling. This is the action of the right piriformis
muscle.
Stretching the muscle often duplicates the pain. To do
the piriformis stretch, lie on your back, and flex the
right hip and knee. Now, while grasping the right knee
with your left hand, pull the knee towards your left shoulder.
This adducts and flexes the hip. In this position, grasp
just above the right ankle with the right hand, and rotate
the ankle outwards. This applies internal rotation to
the hip and completes the stretch. Another way to do this
stretch is to stand on your left foot and place the right
foot on a chair, such that the right knee and hip are
flexed at about 90 degrees. Now, using the right hand,
press the right knee across towards the left side of the
body while keeping the ball of the right foot on the same
spot on the chair.
Anatomically, the piriformis muscle lies deep to the gluteal
muscles. It originates from the sacral spine and attaches
to the greater trochanter of the femur, which is the big,
bony "bump" on the outside top of the thigh.
The sciatic nerve usually passes underneath the piriformis
muscle, but in approximately 15% of the population, it
travels through the muscle. It is thought that acute or
chronic injury causes swelling of the muscle and irritates
the sciatic nerve, resulting in sciatica. Patients with
an aberrant course of the nerve through the muscle are
particularly predisposed to this condition.
The piriformis syndrome is diagnosed primarily on the
basis of symptoms and on the physical exam. There are
no tests that accurately confirm the diagnosis, but X-rays,
MRI, and nerve conduction tests may be necessary to exclude
other diseases. Some of the other causes of sciatica include
disease in the lumbar spine (e.g. disc herniation), chronic
hamstring tendinitis, and fibrous adhesions of other muscles
around the sciatic nerve.
Once properly diagnosed, treatment is undertaken in a
stepwise approach. Initially, progressive piriformis stretching
is employed, starting with 5 seconds of sustained stretch
and gradually working up to 60 seconds. This is repeated
several times throughout the day. It is important that
any abnormal biomechanical problems, such as overpronation
of the foot or other coexisting conditions, are treated.
This stretching can be combined with physical therapy
modalities such as ultrasound. If these fail, then injections
of a corticosteroid into the piriformis muscle may be
tried. Finally, surgical exploration may be undertaken
as a last resort. |
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