Abstract
Intradural disc herniation (IDH) is usually diagnosed during surgery when a herniated mass is found to have penetrated the ventral dura. We experienced a case of IDH that entered the dura from the lateral side with no penetrating hole. A 61-year-old man presented to our institution with left leg pain of two months' duration. Plain x-ray imaging showed degeneration of the lumbar spine, and a magnetic resonance imaging (MRI) scan revealed a suspected tumor at the L3-L4 level. Two weeks later, the patient suffered from acute cauda equina syndrome. A gadolinium-enhanced MRI showed an enlarged lesion with no enhancement visible, and emergency surgery was performed. The lesion originated from the left side of the dura. Despite the white debris suggesting a herniated disc, no penetrating hole was found in the dura. Pathologically, the lesion was found to be an intervertebral disc and was diagnosed as an intradural lumbar disc herniation. The patient’s neurological symptoms improved, but he did not recover his left ankle dorsiflexion. In a degenerated lumbar spine, IDH may not always originate from the ventral dura and may not be accompanied by a penetrating hole.
Highlights
Intradural disc herniation (IDH) is a rare condition that is difficult to diagnose on preoperative magnetic resonance imaging (MRI)
The etiology of IDH is unknown, but previous studies have postulated that adhesions of the ventral dura and posterior longitudinal ligament (PLL) promote disc herniation into the dural sac [3,5,6]
Rather than the adhesion between the PLL and the ventral dura, there may have been an adhesion between the yellow ligament and the lateral dura, and this may have been the location of the herniated disc penetration
Summary
Intradural disc herniation (IDH) is a rare condition that is difficult to diagnose on preoperative magnetic resonance imaging (MRI). It is usually confirmed at the time of surgery when a herniated mass is found to have entered the ventral dura. We report a case of an intradural prolapse of a herniated disc from the lateral side, rather than the ventral dura, with no apparent penetration hole. (a) T2-weighted sagittal images showed enlargement of the lesion but no discontinuity of the posterior longitudinal ligament (arrow). (c) The lesion was found to originate from the inner left wall of the dura (arrow), but no penetrating hole was apparent.
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