Electrodiagnosis of radiculopathies

Area of Science:

• Neurology
• Neurophysiology
• Diagnostic Imaging

Background:

• Electrophysiology complements structural imaging like myelography for a comprehensive diagnosis.
• Electromyography (EMG) is a safe, non-invasive test that should precede invasive procedures such as myelography and CT scans.
• Radiculopathies require accurate diagnostic methods to determine the extent of nerve involvement.

Purpose of the Study:

• To highlight the utility of electrophysiology, particularly needle EMG, in evaluating radiculopathies.
• To emphasize EMG's role in differentiating weakness causes and identifying axonal damage.
• To discuss the complementary nature of electrophysiologic tests and their interpretation in clinical practice.

Main Methods:

• Needle electromyography (EMG) for assessing denervation and motor unit recruitment.
• Evaluation of paraspinal muscles for early signs of axonal interruption.
• Analysis of conventional conduction studies, F-wave, H-reflex, and somatosensory evoked potentials.
• Consideration of amplitude and dispersion in addition to latency for diagnostic yield.

Main Results:

• Needle EMG is the most effective electrophysiologic test for radiculopathies, detecting denervation indicative of axonal damage.
• Abnormalities in paraspinal EMG provide evidence of spinal root lesions.
• Motor unit recruitment abnormalities help distinguish true weakness from other causes in early stages.
• Sensory nerve action potential abnormalities suggest specific conditions like ganglionopathy or double crush syndrome.

Conclusions:

• Electromyography (EMG) is a vital, complementary tool for diagnosing radiculopathies, offering functional insights alongside structural imaging.
• Early detection of denervation through needle EMG is critical for prognosis and treatment planning.
• While conventional studies may be normal, advanced electrophysiologic techniques can aid in confirming root lesions.