Intradural disc herniation has been consistently reported in the literature [1-3
]. Although the pathogenesis of intradural disc herniation is not certain yet, still Blikra [1,4,5
] found the relationship between the ventral dura and the posterior longitudinal ligament (PLL) in form of dense adhesion throughout the lumbar spine. He concluded that non-separable adhesion between these structure could be the pathological basis of the intradural disc herniation [1,4-6
]. Another study on cadavers demonstrated the presence of dural ligaments fixing the dura and nerve roots at their exit from the main dural sac to the posterior longitudinal ligament and vertebral body periosteum proximal to the intervertebral disc [7
It has been studied that adhesions formed between ventral dura and PLL can be due to trauma, surgery, inflammation, osteophytes, disc protrusion fixed the dural sac or may be congenital [6,8
]. Chronic herniated disc is another possible cause of adhesion which could be the reason in our patient. Chronic inflammation on herniated disc can cause adhesion and thinning of the dura, which eventually ruptures the dura thus herniation of disc in dural sac [8
]. Disc herniation through both the anterior and posterior dural sac has also been observed [9
]. Intradural disc can rupture the posterior dural sac depending on the size of nucleus pulposus [9
]. Bigger size disc and chronic disc pathology explains herniation of disc across anterior and posterior dura sac in our case.
Gadolinium-enhanced MRI is the best modality for the precise diagnosis of intradural disc herniation [7,10
]. Rim enhancement [7
] and loss of continuity of PLL and sharp beak like appearance on T2-weighted images [10
] are helpful radiological prediction for diagnosing intradural disc herniation.
Treatment of intradural disc is excision of disc and primary closure of defect. In most of the reports, ventral dural defect were closed primarily. Han et al. [8
] closed ventral dural defect using dura-allograft. We closed ventral dural defect primarily and duroplasty using posterior layer of thoracolumbar fascia of the back for dorsal dural defect. Additionally, pedicle screw instrumentation and posterolateral bony fusion can be considered if wide laminectomy and facetectomy is in the plan of management [8
We conclude that dorsal herniation of the cauda equina rootlet can be the sequlae of intradural disc. Autologus posterior layer of thoracolumbar fascia can be use for duroplasty of the defect.