A physical therapist is evaluating a 38-year-old patient who reports an electric shock-like sensation radiating down the spine and into both arms when flexing the neck. The therapist suspects a positive Lhermitte's sign. Which of the following conditions is MOST likely associated with this clinical finding?

1. Thoracic outlet syndrome

2. Multiple sclerosis

3. Cervical radiculopathy

4. Cervical paraspinal spasm

Transcript

Welcome back to the Scorebuilders' Question and Answer Podcast! This podcast provides members of the Scorebuilders' team with the opportunity to explore challenging multiple-choice examination questions with students actively preparing for the licensing examination.

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A physical therapist is evaluating a 38-year-old patient who reports an electric shock-like sensation radiating down the spine and into both arms when flexing the neck. The therapist suspects a positive Lhermitte's sign. Which of the following conditions is MOST likely associated with this clinical finding?

1. Thoracic outlet syndrome

2. Multiple sclerosis

3. Cervical radiculopathy

4. Cervical paraspinal spasm

Lhermitte's Sign

Lhermitte's sign is a neurological test that involves flexing the patient's neck and observing for the reproduction of an electric shock-like sensation that radiates down the spine and sometimes into the extremities. This sign is named after French neurologist Jean Lhermitte and is considered a significant clinical finding that can help narrow down potential diagnoses.

This question is asking you to identify which condition is most commonly associated with a positive Lhermitte's sign. To answer this correctly, we need to understand both the pathophysiology of Lhermitte's sign and the characteristic features of each condition listed.

The key to Lhermitte's sign is that it involves the spinal cord itself - not just peripheral nerves or muscles. When the neck is flexed, it stretches the spinal cord slightly. If there's any pathology affecting the cord, particularly involving demyelination, this stretching can trigger that distinctive electric shock sensation.

Let's explore each of the options:

Option 1 - Thoracic outlet syndrome

Thoracic outlet syndrome involves compression of the neurovascular structures (brachial plexus, subclavian artery, or subclavian vein) as they pass through the thoracic outlet. This typically causes symptoms like numbness, tingling, or pain in one arm, especially with overhead activities. But here's the thing - thoracic outlet syndrome affects peripheral nerves after they've exited the spinal cord. It doesn't involve the spinal cord itself. So while it can cause neurological symptoms in the arm, it wouldn't produce that characteristic electric shock sensation down the spine with neck flexion.

Option 2 - Multiple sclerosis

Multiple sclerosis (MS) is an autoimmune condition that causes demyelination of nerve fibers in the central nervous system, including the spinal cord. This demyelination disrupts normal nerve conduction. When a patient with MS flexes their neck, the slight stretching of the already compromised spinal cord can trigger abnormal nerve firing, resulting in that classic electric shock sensation. 

Option 3 - Cervical radiculopathy

Cervical radiculopathy occurs when a nerve root in the cervical spine is compressed or irritated, often due to a herniated disc or bone spur. This typically causes pain, numbness, or weakness that follows a specific dermatomal pattern in one arm. But here's the key difference - radiculopathy affects individual nerve roots, not the spinal cord itself. While neck movements might aggravate symptoms, the bilateral, down-the-spine electric shock sensation is not characteristic of radiculopathy. Radiculopathy symptoms tend to be unilateral and follow specific dermatomes.

Option 4 - Cervical paraspinal spasm

Cervical paraspinal muscle spasms are exactly what they sound like - spasms in the muscles alongside the cervical spine. These can cause neck pain and stiffness, and might limit range of motion. However, muscle spasms don't directly involve neural tissue at all. They're a muscular issue, not a neurological one. While they might make neck flexion painful, they wouldn't cause that distinctive electric shock sensation down the spine.

So which condition is most likely to produce a positive Lhermitte's sign? The one that directly affects the spinal cord itself, which is multiple sclerosis.

The correct answer is Option 2.

Let's explore the all student data:
8% of students selected Option 1 - Thoracic outlet syndrome
47% of students selected Option 2 - Multiple sclerosis - the correct response
40% of students selected Option 3 - Cervical radiculopathy
5% of students selected Option 4 - Cervical paraspinal spasm

System Classification
This question is a Neuromuscular and Nervous Systems question which represents approximately 24% of all exam items.

Content Outline Classification
This question is a Physical Therapy Examination question which represents approximately 24% of all exam items.

Level Classification
This question is a Level 2 question since the question requires students to integrate numerous pieces of information or to apply knowledge in a given clinical scenario. Remediation of Level 2 questions occurs by increasing flexibility with academic content and by carefully analyzing decision making processes when answering applied examination questions.  

Thanks for joining us on the Scorebuilders Q&A podcast! See you next week!