Surgical Treatment of a Rare Presentation of Bertolotti's Syndrome from Castellvi Type IV Lumbosacral Transitional Vertebra: Case Report and Review of the Literature

Background Advancements in radiological imaging and diagnostic criteria enable doctors to more accurately identify lumbosacral transitional vertebrae (LSTV) and their association with back and L5 distribution leg pain. It is considered the most common congenital anomaly of the lumbosacral spine with an incidence between 4 and 35%, (3) although many practitioners describe 10 to 12% overall incidence. LSTVs include sacralization of the L5 vertebral body and lumbarization of the S1 segment while demonstrating varying morphology, ranging from broadened transverse processes to complete fusion. (5) The most common types of LSTV that present with symptomatic Bertolotti's syndrome are the Castellvi type I and type II; type III and type IV variants rarely present with symptoms referable with confirmatory and provocative testing to the transitional vertebra itself, and therefore there is limited experience and no case reports of treatment toward this particular entity. Case Description We illustrated a case of a 37 years old female in which a computed tomography scan demonstrated type III LSTV on the left and a type I anomaly on the right. The patient presented with right-sided leg pain and left-sided sacroiliac (SI) region low back pain, worse with rotation and standing, for several years, and had been on daily narcotic pain medications for more than 2 years. The patient had temporary relief of her leg pain with a transverse/ALA injection on the right, but no improvement in her back pain, whereas a left-sided injection into the region around the type III interface on the left did transiently alleviate her SI pain without improvement in her leg pain. We proposed that this particular anomaly induced mechanical back pain on the left side by flexion of the bone bridge (a form of stress-fracture, with associated sclerotic changes in the interface in the transverse/ALA junction) with associated irritation of the right L5 nerve from the type I anomaly on the right in conjunction with her typical radiating leg pain on the right. A patent, but somewhat hypoplastic L5/S1 disk space was also present. Nonsegmental pedicle screw instrumentation with low-profile screws was implanted on the right side with fusion induced using allograft and off label use of infuse rh-BMP2 bone graft substitute, and the patient was discharged the same day. The patient noted immediate improvement in her preoperative symptoms, and by 2 weeks after her surgery noted complete resolution of the preoperative symptoms, and required no narcotic medications to control her incisional pain. Conclusion Patients who present with symptoms consistent with Bertolotti's syndrome, even if they have a type III or type IV LSTV, should be considered for surgical treatment of their LSTV. These patients can respond well, even if symptoms have been present for years. Given the prevalence of these anatomic variants in the general population (10–12% in most series), Bertolotti's syndrome should be considered in the differential diagnosis of any patient with a presentation of L5 radiculopathy and/or back pain.