- Department of Neurosurgery, Hamad General Hospital, Doha, Qatar,
- Department of Neurological Sciences, Weill Cornell Medicine, Doha, Qatar,
- Department of Clinical Academic Sciences, College of Medicine, Qatar University, Doha, Qatar.
Saleh Salah Safi, Department of Neurosurgery, Hamad General Hospital, Doha, Qatar.
DOI:10.25259/SNI_16_2022Copyright: © 2022 Surgical Neurology International This is an open-access article distributed under the terms of the Creative Commons Attribution-Non Commercial-Share Alike 4.0 License, which allows others to remix, transform, and build upon the work non-commercially, as long as the author is credited and the new creations are licensed under the identical terms.
How to cite this article: Saleh Salah Safi1, Abdulla Allyan1, Arshad Ali1,2,3, Ali Raza1,2. Diagnosis and management of thoracic intradural extra-arachnoidal disc herniation. 25-Feb-2022;13:73
How to cite this URL: Saleh Salah Safi1, Abdulla Allyan1, Arshad Ali1,2,3, Ali Raza1,2. Diagnosis and management of thoracic intradural extra-arachnoidal disc herniation. 25-Feb-2022;13:73. Available from: https://surgicalneurologyint.com/surgicalint-articles/11408/
Background: Intradural extra-arachnoidal disc herniations (IEDHs) are rare. Here, we reviewed the clinical features and magnetic resonance (MR) diagnostic features of IEDH.
Case Description: A 58-year-old male presented with mid-thoracic back pain radiating to the left leg associated with ipsilateral leg weakness. The thoracic MR documented T8-T9 focal spinal canal stenosis and a ventral disc herniation. Thoracic spine computed tomography scan confirmed the diseased level and did not show any calcification. The patient underwent a right-sided transpedicular extracavitary approach for disc excision. At surgery, IEDH was identified with soft cartilaginous consistency and was morcellated to remove in piece meal while preserving the integrity of the arachnoid layer.
Conclusion: IEDH poses a significant challenge for its diagnosis and management. A careful preoperative MR imaging review with a high index of clinical suspicion may ensure a good clinical outcome.
Keywords: Disc, Extra-arachnoidal, Herniation, Intradural, Spine, Thoracic
In intradural extra-arachnoid disc herniations (IEDHs), the discal tissue detaches the arachnoid layer from the dura mater and invades this potential space but does not reach the rootlets and the cerebrospinal fluid (CSF) space.[
A 58-year-old male patient presented with 1-week duration of mid-thoracic and left hip-thigh-knee pain. On examination, he had left-sided iliopsoas/quadriceps (2/5) and dorsiflexion/ extensor hallucis longus weakness (0/5) along with the left lower limb clonus and a bilateral Babinski response. The thoracic MR imaging (MRI) documented an anterior dural/epidural, central, and rounded ventral nodule of 3–4 mm at the T8-T9 level. The lesion was isointense on T1 and hypointense on T2 (i.e., on short-term inversion recovery) sequences. On axial sections, the lesion compressed the cord but was surrounded by a hyperintense signal consistent with CSF [
Magnetic resonance imaging of the thoracic spine with T2-weighted sagittal image (a). It is showing an anterior dural/epidural rounded nodule of 3–4 mm (blue arrow) of low signal intensity at the disc level between vertebra 8 and 9 with features of secondary compressive myelopathy. It includes attenuated caliber, central hyperintensity, and syringohydromyelia. It is isointense in T1 weighted (b) and hypointense in short-tau inversion recovery sequence (c).
The patient underwent a right-sided transpedicular extracavitary approach to the T8-T9 level. As no epidural lesion was encountered, a small dural incision revealed a pinkish-white extra-arachnoidal smooth disc fragment which was cartilaginous in nature that was readily delivered utilizing a dissector [
The pathogenesis of IDH is variously attributed to adhesions occurring between the posterior longitudinal ligament (PLL), disc annulus, and dural interface.[
MR diagnosis of thoracic disc herniation
MR diagnostic features for thoracic intradural discs typically demonstrated either a “hawk-beak sign” (i.e., sharp compressive lesion with a beak-like appearance to the dural sac/abrupt loss of PLL or “Y-sign” (i.e., one line of dural arachnoid layer splits into two lines due to disc herniation in the potential extra-arachnoidal intradural space).[
Different surgical approaches have been used to remove intradural extra-arachnoidal disc herniations.[
Postoperatively, the patient nearly fully recovered over the next 6 months. Other cases of thoracic disc excisions reported similar findings or no improvement and had long-standing irreversible postoperative neurological deficits.[
Thoracic intradural extra-arachnoidal disc herniations are rare and should optimally be diagnosed preoperatively utilizing both MR (i.e., optimizing soft tissue) and CT (identifying attendant ossification/calcification and confirming the correct level).
Institutional Review Board (IRB) permission obtained for the study.
There are no conflicts of interest.
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