Musculoskeletal mimics of lumbosacral radiculopathy

Abstract

Electrodiagnostic evaluations are commonly requested for patients with suspected radiculopathy. Understanding lower extremity musculoskeletal conditions is essential for electrodiagnostic medicine specialists, as musculoskeletal disorders often mimic or coexist with radiculopathy. This review delineates radicular pain from other types originating from the lumbosacral spine and describes musculoskeletal conditions frequently mimicking radiculopathy, such as those that cause radiating pain and sensorimotor dysfunction. In clinical evaluation, a history of pain radiating along a specific dermatomal territory with associated sensory disturbance suggests radiculopathy. Physical examination findings consistent with radiculopathy include myotomal weakness, depressed or absent muscle stretch reflexes, focal atrophy along a discrete nerve root territory, and potentially positive dural tension maneuvers like the straight leg raise. However, electrodiagnostic medicine specialists must be knowledgeable of musculoskeletal mimics, which may manifest as incomplete radiation within or beyond a dermatomal territory, non-radiating pain, tenderness, and give-way weakness, in the context of a normal neurological examination. A systematic approach to musculoskeletal examination is vital, and this review focuses on high-yield physical examination maneuvers and diagnostic investigations to differentiate between musculoskeletal conditions and radiculopathy. This approach ensures accurate diagnoses, promotes resource stewardship, enhances patient satisfaction, and optimizes care delivery. Musculoskeletal conditions resembling L1 to S4 radiculopathy are reviewed, emphasizing their distinctive features in history, physical examination, and diagnostic investigation. Among the more than 30 musculoskeletal disorders reviewed are hip and knee osteoarthritis, lumbar facet syndrome, myofascial pain syndrome, greater trochanteric pain syndrome, and plantar fasciitis.

Keywords: back pain with radiation; differential diagnosis; musculoskeletal diseases; nerve root compression; radiculopathy.

FIGURE 1

Lower extremity dermatomes.

FIGURE 2

Selected anatomical landmarks for palpation tenderness on physical examination. Palpation of the above landmarks can be useful for identifying potential generators of patients' pain. The presence of pain on palpation at these landmarks as part of a comprehensive history and physical examination may suggest the patient has a painful musculoskeletal condition; this does not exclude concurrent radiculopathy.

FIGURE 3

Patterns of referred pain from lumbosacral interspinous ligaments. Referred pain from conditions affecting the low back may be mistaken for radiculopathy. For instance, pain generated by lumbosacral interspinous ligaments frequently presents in the patterns outlined above, and therefore can mimic lumbosacral radiculopathy. Source: Adapted with permission from Kellgren.