Conjoined lumbar nerve roots: A potential cause of lumbosciatica and an incidental finding—A three-case report

Congenital anomalies of the lumbar nerve roots are uncommon within the broader spectrum of congenital vertebromedullary malformations. They are typically identified in adulthood. Often underrecognized, they may lead to inadvertent nerve injury during surgery. These anomalies can be discovered incidentally or during lumbosciatica imaging investigation. In our region, CT scan is the only available cross-sectional imaging modality. Although it has lower resolution than MRI, it enabled the detection of this anomaly in three patients. In one case, the anomaly was revealed by lumbosciatica, whereas in the other two cases, it was an incidental finding. In this article, we highlight the key imaging features necessary for accurate recognition of this underreported anomaly. Its prevalence is likely underestimated in preoperative imaging. It should be systematically considered among the differential diagnoses of enlarged nerve roots to ensure it is not overlooked. Its presence should be explicitly reported in the preoperative assessment, as failure to recognize the anomaly may result in nerve injury during surgery. Classification systems for lumbar nerve root anomalies have evolved substantially over the past decades. Among the various classification systems proposed, that of Neidre and MacNab (NM), subsequently amended on two occasions, remains one of the most widely used. More recently, Nikolenko et al. proposed a unifying classification system aimed at reconciling and integrating the various existing approaches to spinal nerve root anomalies.