SYMPTOMS: Pain deep in the buttock with referred pain down the leg
and sometimes into the foot. Sitting worsens the pain as often does
counterclockwise rotation of the right leg or clockwise rotation of the
left leg. The pain is on one side. Often these patients walk with the
foot turned out in order to avoid pain. Sacroiliac joint disease can
activate the piriformis muscle, thereby secondarily producing pain from
the buttock to the foot.
ONSET: Often after a fall or direct blow to the buttocks. Trauma to the
piriformis (direct fall on the buttocks, twisting internal rotation injury of
the hip, etc) can lead to a deep aching pain in the low buttocks, which
can be transmitted down the sciatic nerve to the foot.
ANATOMY: The piriformis muscle connects the lateral sacrum to the
greater trochanter of the femur. As shown on the right, the muscle
overlies the sciatic nerve. There are some patients with anatomic
variants of the relationship between the sciatic nerve and the muscle in
which the muscle is spit by the nerve.
DIAGNOSIS:
Diagnosis is made by performing a piriformis block using fluoroscopy
and piriformis myography (right photo) to confirm needle placement.
TREATMENT:
Once a local anesthetic block has confirmed the syndrome, treatment
consists of stretching exercises, Botox injections into the muscle using
electromyelographic guidance, intermittent local anesthetic injections,
or piriformis release surgery. The latter is reported to have a
reasonable success rate, but is reserved for only the most severe
refractory cases.
