Imaging of Entrapped Peripheral Nerves

The peripheral nerves can be affected by different diseases, and these diseases can be broadly categorized, according to etiology, as either entrapment or nonentrapment neuropathies. Entrapment syndrome is a neuropathy due to a structural abnormality that results in compression, displacement, or traction of the nerve (. Miller & Reinus, 2010). The main diagnostic work-up includes clinical history, physical examination, and electrodiagnostic testing. Magnetic resonance imaging (MRI) can also play a crucial role by providing further information about the exact anatomic location of the pathology, as well as the alternative findings. MRI can show both the nerve involvement (e.g., change in caliber, increased signal, and enhancement) and the abnormalities of the associated innervated muscles (e.g., increased signal and denervation edema in early stages and atrophy with fatty replacement in more severe and chronic cases). The purpose of the chapter is to briefly review the imaging of the common entrapment syndromes in the upper and lower extremities.