Anali Rojas: A 28-Year-Old Yoga Instructor With Pain, Numbness, and a Foot Drop

Learning Objectives

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Learn the common causes of lower extremity pain and numbness.
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Develop an understanding of the unique anatomy of the common peroneal nerve.
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Develop an understanding of the causes of foot drop.
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Develop an understanding of the causes of common peroneal nerve entrapment.
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Develop an understanding of the differential diagnosis of common peroneal nerve entrapment.
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Learn the clinical presentation of common peroneal nerve entrapment.
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Learn how to perform a sensory and motor examination of the lower extremity.
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Learn how to use physical examination to identify common peroneal nerve entrapment.
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Develop an understanding of the treatment options for common peroneal nerve entrapment.

Anali Rojas

Anali Rojas is a 28-year-old yoga instructor with the chief complaint of, “The toe of my tennis shoe keeps catching on the carpeting.” Anali stated that over the past several weeks by the end of the day, she is experiencing a pins and needles sensation down the front of her leg and across the top of the foot. She went on to say that she has to be very mindful when she is walking because the toe of her tennis shoe keeps catching on the floor when she walks, especially when she is walking on carpeting. “Doctor, I really have to pay attention because a couple of times I have almost fallen.”

I asked Anali what made the pain worse and she said that the vajrasana yoga position was the worst. “I like to have my class assume this position before we start so we can focus, and honestly, if I stay in this position for any length of time, I just want to scream because of the pins and needles sensation in my left leg, which doesn’t do much for my focus. Doctor, the craziest thing is the pins and needles seem much worse at night, so getting to sleep is a serious challenge. I’ve also noticed that anything that puts pressure on the outside of my left knee or rubs on the skin increases the pins and needles. The skin down the front of my leg and on top of my left foot is really sensitive to touch.”

I asked Anali what made her symptoms better and she said Advil helped, but it was upsetting her stomach. She also noted that gently straightening the left knee and icing the outside of the knee felt good, but the pain came back as soon as she took off the ice. Anali denied any back pain or other constitutional or neurologic symptoms. I asked Anali about any antecedent trauma to the back or lower extremities or other neurologic symptoms and she said, “Not that I can remember.”

I asked Anali to show me where she felt the pins and needles sensation, and she ran her hand down the outside of her left leg and across the dorsum of her foot ( Fig. 14.1 ).

On physical examination, Anali was afebrile. Her respirations were 16 and her pulse was 64 and regular. Her blood pressure was 116/68. Anali’s head, eyes, ears, nose, throat (HEENT) exam was normal, as was her cardiopulmonary examination. Her thyroid was normal. Her abdominal examination revealed no abnormal mass or organomegaly. There was no costovertebral angle (CVA) tenderness. There was no peripheral edema. Her low back examination was within normal limits. Visual inspection of the left lateral knee revealed no obvious abnormality. There was decreased sensation in the distribution of the common peroneal nerve with a suggestion of allodynia. Range of motion of the hip and knee joints was normal. There was weakness of the foot dorsiflexors and foot everters on the left ( Fig. 14.2 ). The Lasegue straight leg test was negative bilaterally; however, the repetitive plantar flexion test was positive on the left, which is highly suggestive of common peroneal nerve entrapment ( Figs. 14.3 and 14.4 ). After a careful neurologic examination of the upper and lower extremities, I was unable to identify any evidence of peripheral or entrapment neuropathy, other than the sensory and motor deficits of the common peroneal nerve. The deep tendon reflexes throughout were normal. I asked Anali to walk down the hall, where I noted a marked steppage gait ( Fig. 14.5 ).

Key Clinical Points—What’s Important and What’s Not

The History

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Gradual onset of left-sided pins and needles sensation and allodynia in the distribution of the common peroneal nerve
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Weakness of the foot dorsiflexors and evertors on the left
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Toe catching on the carpeting when walking
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Vajrasana yoga position exacerbates symptoms
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No antecedent trauma to the back or lower extremities or other neurologic symptoms
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No fever or chills
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Sleep disturbance
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Unable to maintain the vajrasana yoga position

The Physical Examination

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Numbness and allodynia in the distribution of the common peroneal nerve
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Weakness of the foot dorsiflexors and evertors on the left
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Steppage gait to compensate for foot drop
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Positive repetitive plantar flexion test on the left
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Negative Lasegue test bilaterally
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Physiologic deep tendon reflexes
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No evidence of peripheral neuropathy or entrapment neuropathy except for compromise of the left common peroneal nerve
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The patient is afebrile
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No evidence of infection
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Pain on range of motion, especially active resisted flexion of the affected left knee
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An antalgic gait was present

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 tenderness to deep palpation of the lumbar paraspinous muscles
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No peripheral edema

What Tests Would You Like to Order?

The following tests were ordered:

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Plain radiographs of the left knee
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Ultrasound of the left knee
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Electromyography and nerve conduction velocity testing of the low back and bilateral lower extremity

Test Results

The plain radiographs of the left knee reveal no bony abnormality of the fibular head. Ultrasound examination of the left knee reveals displacement of the common peroneal nerve as it passes over the fibular head ( Fig. 14.6 ). Electromyography and nerve conduction velocity testing of the low back and left lower extremity reveal slowing of the conduction of the common peroneal nerve across the fibular head when compared with the right. Needle examination reveals denervation of the dorsiflexors and evertors of the foot.