Iliolumbar syndrome as a common cause of low back pain: diagnosis and prognosis.

Most cases of low back pain fall into the category of nonspecific low back pain in which no specific pathology can be detected by x-ray, laboratory tests, or biopsy. In the authors' experience about 50% of the patients falling into this group have a clinical picture characterized by symptoms and signs localized at one iliac crest. The symptoms can be abolished temporarily by infiltration of the posterior iliac crest with lidocaine. Because of the location of the findings and the unknown etiology the term iliolumbar syndrome is suggested. Distinguishing the iliolumbar syndrome from the root irritation syndrome may avoid unnecessary surgery. Chronic iliolumbar syndrome is a frequent cause of permanent low back disability, a fact not commonly recognized.