Cervical radiculopathy occurs when a nerve root near the cervical spine becomes compressed or irritated where it exits the spinal column. This condition typically results in pain, numbness, or weakness that radiates from the neck down into the shoulder, arm, or hand, following the path of the affected nerve. Because these symptoms can mimic several other conditions, accurately diagnosing a pinched nerve requires a methodical, multi-step approach that combines a detailed physical assessment with advanced technological studies.
Initial Clinical Evaluation
The diagnostic process begins with a comprehensive initial visit, where the physician gathers a detailed patient history regarding the onset and nature of the symptoms. The patient is asked about the exact location of the radiating pain, whether it is sharp or burning, and which activities or neck positions tend to worsen or relieve the discomfort. Understanding the trajectory of the pain is important because symptoms often follow a specific dermatomal pattern, which is the sensory distribution map of a particular nerve root.
Following the history, a meticulous neurological physical examination is performed to localize the affected nerve root. This examination includes an assessment of the neck’s range of motion, noting any guarded movements or pain elicited during rotation or extension. The physician tests deep tendon reflexes (DTRs), such as the biceps, brachioradialis, and triceps, looking for asymmetry or diminished responses that can pinpoint nerve involvement at the C5, C6, or C7 levels.
A thorough motor strength assessment is conducted by manually testing specific muscle groups corresponding to different cervical nerve roots, known as myotomes, to detect subtle weakness. The diagnostic utility of the examination is further enhanced by specific manual tests, such as Spurling’s maneuver, which involves extending and side-bending the patient’s neck while applying gentle downward pressure. A positive result, indicated by the reproduction of the radiating arm pain, strongly suggests nerve root compression.
Structural Imaging Modalities
Once the clinical evaluation suggests a specific nerve root is compromised, structural imaging is often employed to visualize the physical cause of the compression. These modalities provide a static picture of the bony and soft tissue anatomy of the cervical spine. Plain film X-rays are typically the first imaging study performed, primarily to assess bone alignment, identify any instability, and detect signs of degenerative changes.
X-rays can reveal conditions like cervical spondylosis, characterized by bony growths (osteophytes or bone spurs) that can narrow the space where nerves exit the spine. While X-rays provide excellent bone detail, they cannot visualize the soft tissues that frequently cause nerve compression, such as intervertebral discs. This limitation often necessitates the use of Magnetic Resonance Imaging (MRI), which is generally considered the definitive structural test for radiculopathy.
MRI uses powerful magnetic fields and radio waves to generate high-resolution images of soft tissues, visualizing the spinal cord, nerve roots, and intervertebral discs. This study can clearly demonstrate a herniated disc that is bulging or rupturing into the spinal canal or neural foramen. When an MRI is contraindicated, such as in patients with certain types of metallic implants, a Computed Tomography (CT) scan may be used as an alternative. A CT scan excels at showing detailed bone structure and can be performed with an injected contrast dye, known as a CT myelogram, to highlight the spinal cord and nerve roots for better visualization of any structural narrowing.
Electrophysiological Confirmation
When the clinical presentation is complex or the imaging findings are inconclusive, electrophysiological testing provides a functional assessment of the nerve’s health and activity. These tests confirm the diagnosis, determine the severity of nerve damage, and rule out other conditions that mimic radicular pain, such as peripheral nerve entrapments. The process involves two primary components: Nerve Conduction Studies (NCS) and Electromyography (EMG).
Nerve Conduction Studies measure how quickly and efficiently electrical signals travel along the peripheral nerves in the arms. In most cases of cervical radiculopathy, the sensory nerve action potentials remain normal because the nerve root compression occurs proximal to the dorsal root ganglion (the location of the sensory nerve cell body). This specific pattern of normal sensory studies alongside abnormal motor findings is a characteristic marker that distinguishes a nerve root problem from a peripheral nerve injury like carpal tunnel syndrome.
Electromyography involves inserting a fine needle electrode into muscles supplied by the suspected nerve root to record electrical activity. This test assesses the health of the nerve-muscle unit, looking for signs of denervation, which indicates chronic nerve irritation or damage. Abnormal spontaneous electrical activity, such as fibrillation potentials or positive sharp waves, can be detected in the affected muscles, but these changes typically take two to three weeks to develop after the initial injury. The needle EMG is particularly useful for localizing the exact nerve root level by identifying abnormalities in muscles innervated by that specific root, including the small paraspinal muscles in the neck.