Bertolotti syndrome is caused by a lumbosacral transitional vertebra, a congenital variation of the most caudal lumbar vertebra, characterized by an enlarged transverse process that articulates or fuses with the sacrum, ilium, or both. This syndrome accounts for 4.6 to 7% of cases of low back pain in adults and for more than 11% of patients with low back pain who are under 30 years old. The primary effect of lumbosacral transitional vertebra is reduced and asymmetrical motion between the transitional vertebra and the sacrum, resulting in early arthritic changes at pseudoarticulation; the secondary effect is the progressively compensatory modifications in the biomechanics of the mobile vertebral segments superior to the transitional vertebra related to restriction in rotation and bending motion at the lumbosacral articulation. Bertolotti syndrome should be considered in the differential diagnosis of low back pain. Clinical findings include low back pain in the midline or paramedian area that is reproduced with palpation along the base of the lumbosacral spine and near the posterosuperior iliac spine and aggravated by forward flexion, excessive extension, or lateralization of the back to the same side of the mega-apophysis. A plain x-ray is diagnostic; the extension-flexion lumbosacral radiographs in anteroposterior, lateral, and oblique views demonstrate lumbosacral transitional vertebra, with an enlarged unilateral or bilateral transverse process of the most distal lumbar vertebra, abnormally articulating with the ala of the sacrum and degenerative changes of the pseudarthrosis. Other imaging studies, such as computed tomography and magnetic resonance imaging of the lumbosacral spine and selective radiculography of the spinal nerve, could provide additional detailed anatomic information. Major differential diagnoses of Bertolotti syndrome include sacroiliac joint pain, myofascial pain, lumbar facet pain, lumbar disk herniation, compression fracture, and Baastrup disease/interspinous bursitis. These conditions are not mutually exclusive and, in fact, often coexist. A course of conservative management, including activity modification, medication management with nonsteroidal antiinflammatory drugs, muscle relaxants, and rehabilitative physical therapy, should be offered initially. Due to the multifactorial etiology of low back pain in patients with Bertolotti syndrome, procedures such as diagnostic intrapseudoarticular block for arthritis, medial branch block for facet arthropathy, diskography for diskogenic pain, and selective nerve roots block for radiculopathy can potentially help identify the primary and secondary origins of the pain. Surgical treatment of Bertolotti syndrome was only slightly better than conservative treatment and should only be used in very selective patients with disk pathology. To achieve long-term improvement by any of these therapeutic options, a continuing physical rehabilitation program is often needed.
Key words: Bertolotti syndrome, intrapseudoarticular block, transitional lumbosacral vertebra, transverse process
Congenital anomalies of the lumbosacral spine
