Learning Objectives
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Learn the common causes of lower extremity pain.
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Develop an understanding of the anatomy of the sciatic nerve.
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Develop an understanding of the unique relationship of the sciatic nerve to the piriformis muscle.
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Develop an understanding of the causes of piriformis syndrome.
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Develop an understanding of the differential diagnosis of lower extremity pain and numbness.
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Learn the clinical presentation of piriformis syndrome.
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Learn the dermatomes of the lower extremity.
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Learn how to use physical examination to identify piriformis syndrome.
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Develop an understanding of the treatment options for piriformis syndrome.
Ashley Stubbs
Ashley Stubbs is a 32-year-old chief of security for a tech firm with the chief complaint of, “Ever since I fell on the ice, I’ve had a pain in my butt that goes down the back of my right leg.” Ashley stated that a couple of months ago, as he was walking back from the corner bodega, he slipped on an icy patch and fell hard onto his right buttock. He said that he lay there for a few moments and then carefully got to his feet. He felt around and didn’t think he broke anything so he carefully made his way home. By the time he got home, his butt was really hurting. He looked in the mirror and saw that a large bruise was beginning to form. He took a couple of aspirin and got out the heating pad. The next morning, he felt like he had been hit by a car, and in addition to the bruise, he now had a large, tender lump in the center of his right buttock. It really hurt, but he toughed through it. Over the next couple of weeks, the bruise got better, as did the lump, but the pain actually got worse and at times the top of his foot felt like it was asleep. “Doctor, I consider myself a pretty tough guy. You know, I was in the Special Forces, but this is literally kicking my ass. Fortunately, most of my day is in the office, but I don’t know what I would do if I had to be back out in the field. Sitting is bad enough, but I seriously can’t run, and going up stairs is a bitch. I can’t believe I fell on the ice—so stupid!”
I asked Ashley if he had experienced any pain, numbness, or weakness in his left leg and he just shook his head and replied, “Doc, the pain is all on the right—the side that I fell on. You know, over the last couple of weeks, I feel like my right leg is getting weaker. Maybe it’s just the fact that I am off my exercise routine, but I have really started having trouble walking up the stairs.” “Do both legs feel weak?” I asked. He said “No, just the right.” I asked Ashley what he had tried to make it better and he said that he felt like the heating pad and sleeping on his left side with a pillow between his legs helped a little, but he was having trouble sitting for long periods of time and felt the need to get up every 10 to 15 minutes to avoid the pain getting too strong. “Also, a Tylenol PM with a beer chaser seemed to help some, at least with sleep.”
I asked Ashley to show me where the pain was and he pointed to his right buttock and then traced his hand down his posterior thigh all the way to the posterior calf. “Once in a while, if I sit too long, like when I’m in a meeting with the boss, the pain can go all the way down to my foot. I’ve got to tell you, that’s no fun.” I asked Ashley about any fever, chills, or other constitutional symptoms such as weight loss, night sweats, etc., and he shook his head no. He denied any musculoskeletal or systemic symptoms.
On physical examination, Ashley was afebrile. His respirations were 18, his pulse was 74 and regular, and his blood pressure was 124/76. Ashley’s head, eyes, ears, nose, throat (HEENT) exam was normal, as was his thyroid exam. Auscultation of his carotids revealed no bruits, and the pulses in all four extremities were normal. He had a regular rhythm without abnormal beats. His cardiac exam was otherwise unremarkable. His abdominal examination revealed no abnormal mass or organomegaly. There was no peripheral edema. His low back examination was unremarkable, although flexion of the lumbar spine caused some pain in the right buttock. There was no costovertebral angle (CVA) tenderness. Visual inspection of the right buttock and lower extremity was unremarkable. There was no rubor or color and no evidence of ecchymosis. Palpation of the sciatic notch caused Ashley to say, “You’re right on it, Doc. That’s it.” I performed the piriformis test as well as the heel contralateral knee test, which were both markedly positive ( Figs. 12.1 and 12.2 ).
A careful neurologic examination of both lower extremities revealed a mildly decreased sensation in the distribution of the right sciatic nerve and marked weakness of the right gluteal muscles ( Fig. 12.3 ). Deep tendon reflexes were physiologic throughout. There was a positive Tinel sign over the right sciatic nerve.
Key Clinical Points—What’s Important and What’s Not
The History
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A history of the onset of severe right buttock, posterior thigh, posterior calf, and foot pain immediately following a fall on the ice
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Right foot feels like it is falling asleep
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The right leg feels weak
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Difficulty walking up stairs
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Pain made worse with sitting and walking
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No symptoms in the left lower extremity
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No fever or chills
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History of recent trauma
The Physical Examination
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The patient is afebrile
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Marked weakness of the gluteal muscles on the right
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Numbness in the distribution of the sciatic nerve on the right (see Fig. 12.3 )
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Tenderness over sciatic notch
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Positive piriformis test (see Fig. 12.1 )
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Positive heel contralateral knee test (see Fig. 12.2 )
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Positive Tinel sign over the sciatic nerve on the right
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No motor deficit in the left lower extremity
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Deep tendon reflexes within normal limits
Other Findings of Note
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Normal HEENT examination
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Normal cardiovascular examination
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Normal pulmonary examination
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Normal abdominal examination
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No peripheral edema
What Tests Would You Like to Order?
The following tests were ordered:
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Ultrasound of the right sciatic nerve at the level of the piriformis muscle
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Magnetic resonance imaging (MRI) of the pelvis with special attention to the right sciatic nerve
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Electromyography (EMG) and nerve conduction velocity testing of the right sciatic nerve
Test Results
Ultrasound examination of the sciatic nerve at the level of the sciatic triangle reveals no obvious tumor or mass compressing the sciatic nerve. MRI of the pelvis, EMG, and nerve conduction velocity testing revealed normal needle examination of the muscles above the piriformis muscle and abnormal below the piriformis muscles.
Clinical Correlation—Putting It All Together
What is the diagnosis?
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Piriformis syndrome secondary to acute trauma to the right buttock
The Science Behind the Diagnosis
Anatomy
The sciatic nerve provides innervation to the distal lower extremity and foot with the exception of the medial aspect of the calf and foot, which are subserved by the saphenous nerve. The largest nerve in the body, the sciatic nerve is derived from the L4, L5, and S1–S3 nerve roots ( Fig. 12.4 ). The roots fuse in front of the anterior surface of the lateral sacrum on the anterior surface of the piriformis muscle ( Fig. 12.5 ). The nerve travels inferiorly and leaves the pelvis just below the piriformis muscle via the sciatic notch ( Figs. 12.6 and 12.7 ). Just beneath the nerve at this point is the obturator internus muscle. The sciatic nerve lies anterior to the gluteus maximus muscle; at this muscle’s lower border, the sciatic nerve lies halfway between the greater trochanter and the ischial tuberosity. The sciatic nerve courses downward past the lesser trochanter to lie posterior and medial to the femur. In the midthigh, the nerve gives off branches to the hamstring muscles and the adductor magnus muscle. In most patients, the nerve divides to form the tibial and common peroneal nerves in the upper portion of the popliteal fossa, although in some patients these nerves can remain separate through their entire course. The tibial nerve continues downward to provide innervation to the distal lower extremity, whereas the common peroneal nerve travels laterally to innervate a portion of the knee joint and, via its lateral cutaneous branch, provides sensory innervation to the back and lateral side of the upper calf.
Related posts:
Bob Hamilton: A 42-Year-Old Male With Numbness in the Lateral Thigh
Carol Kane: A 23-Year-Old Female With Buttock and Posterior Hip Pain
Jimmie Kaline: A 27-Year-Old Male With a Snapping Hip
Avi Rudin: A 68-Year-Old Male With Anterior Thigh and Medial Calf Pain and Difficulty Walking Up Stairs
Buddy Johnson: A 32-Year-Old Male With Tailbone Pain Following a Fall off a Ladder
Meredith Grace: A 32-Year-Old Female With Right Ill-Defined Low Back and Buttock Pain
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