Imaging of peripheral nerve causes of chronic buttock pain and sciatica

Chronic buttock pain is a common and debilitating symptom, which severely impacts daily activities, sleep, and may affect athletic performance. Lumbar spine, posterior hip, or hamstring pathology are usually considered as the primary diagnoses; however, pelvic neural pathology may be a significant cause of chronic buttock pain, particularly if there are prolonged (>6 months) buttock and/or radicular symptoms. The subgluteal space is the site of most pelvic causes of neural-mediated buttock pain, primarily relating to entrapment neuropathy of the sciatic nerve (deep gluteal syndrome), although other nerves within the subgluteal space including the gluteal nerves, pudendal nerve, and posterior cutaneous nerve of thigh may also be involved. Additionally, cluneal nerve entrapment at the iliac crest may result in "pseudo-sciatica". Anatomical variants of the pelvic girdle muscles and functional factors, including muscle spasm and pelvic instability, may contribute to development of deep gluteal syndrome, along with neural senescence. Imaging findings primarily relate to the presence of sciatic neuritis and peri-sciatic pathology, including neural compression and peri-neural adhesions or fibrosis. This imaging review describes the causes, magnetic resonance imaging and ultrasound imaging findings and imaging-guided treatment of pelvic neural causes of chronic buttock pain and sciatica.