A Rare Foramen at the Base of the Transverse Process of the Fourth Lumbar Vertebra

A 58-year-old male presented with paraplegia of the lower limbs due to a burst fracture of the first lumbar vertebra following a road traffic accident. During routine imaging studies for the evaluation of a fracture, a foramen was found at the fourth lumbar vertebra. This foramen was located at the junction of the pars articularis, pedicle, and base of the transverse process on the left side of the fourth lumbar vertebra. The dimensions of the upper and lower openings of the foramen are 3.3 cm and 3.6 cm, respectively. The contents of this foramen were identified as a tributary draining directly into the inferior vena cava. Therefore, the insertion of a pedicle screw in this region is an absolute contraindication due to the risk of significant bleeding. Most foramina are typically found in the lumbosacral region; this is the first documented instance of a similar foramen in the fourth lumbar vertebra. The knowledge of this foramen is important for spine surgeries. There is no evidence in the existing literature that has demonstrated the contents of this novel foramen by imaging, as most research has been based on osteology collections, with one case report based on a cadaver study.