Compressive and entrapment neuropathies are common disorders often caused by mechanical or dynamic compression of a segment of nerve. These nerve abnormalities often occur as the nerve passes adjacent to osseous prominences, through fibro-osseous tunnels or openings in fibrous or muscular tissues.

The clinical diagnosis of nerve injury requires a detailed level of nerve anatomy, innervation patterns and an accurate neurological examination. Electromyography, motor and sensory nerve conduction and velocity studies can be utilized for the diagnosis of nerve injury in select cases, although false negative rates have been reported in as many as 30% of cases. MR imaging, with its excellent soft tissue contrast and multiplanar imaging capabilities, is the diagnostic imaging method of choice for compressive or entrapment neuropathies. It allows visualization of the nerve at the level of clinical abnormality, as well as identification of the compressive lesion. Moreover, MR imaging can also be utilized to assess the end-organ (muscle innervated) for resultant changes from nerve compression.

The purpose of the discussion will be to review the MR imaging findings of a variety of classic compressive neuropathies.