Extra-spinal sciatica and sciatica mimics: a scoping review.

Not all sciatica-like manifestations are of lumbar spine origin. Some of them are caused at points along the extra-spinal course of the sciatic nerve, making diagnosis difficult for the treating physician and delaying adequate treatment. While evaluating a patient with sciatica, straightforward diagnostic conclusions are impossible without first excluding sciatica mimics. Examples of benign extra-spinal sciatica are: piriformis syndrome, walletosis, quadratus lumborum myofascial pain syndrome, cluneal nerve disorder, and osteitis condensans ilii. In some cases, extra-spinal sciatica may have a catastrophic course when the sciatic nerve is involved in cyclical sciatica, or the piriformis muscle in piriformis pyomyositis. In addition to cases of sciatica with clear spinal or extra-spinal origin, some cases can be a product of both origins; the same could be true for pseudo-sciatica or sciatica mimics, we simply don't know how prevalent extra-spinal sciatica is among total sciatica cases. As treatment regimens differ for spinal, extra-spinal sciatica, and sciatica-mimics, their precise diagnosis will help physicians to make a targeted treatment plan. As published works regarding extra-spinal sciatica and sciatica mimics include only a few case reports and case series, and systematic reviews addressing them are hardly feasible at this stage, a scoping review in the field can be an eye-opener for the scientific community to do larger-scale prospective research.