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| LETTER TO EDITOR |
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| Year : 2013 | Volume
: 61
| Issue : 4 | Page : 453-454 |
Ventral herniation of the dorsal spinal cord: A rare cause of myelopathy
Prasad Krishnan1, Rajaraman Kartikueyan1, Debashish Chowdhury2, Manash Saha3
1 Department of Neurosurgery, National Neurosciences Centre, Peerless Hospital Complex, IInd Floor, 360, Panchasayar, Kolkata - 700 094, India
2 Department of Neurology, National Neurosciences Centre, Peerless Hospital Complex, IInd Floor, 360, Panchasayar, Kolkata - 700 094, India
3 Department of Radiology, National Neurosciences Centre, Peerless Hospital Complex, IInd Floor, 360, Panchasayar, Kolkata - 700 094, India
| Date of Submission | 22-Jul-2013 |
| Date of Decision | 22-Jul-2013 |
| Date of Acceptance | 27-Jul-2013 |
| Date of Web Publication | 4-Sep-2013 |
Correspondence Address:
Prasad Krishnan
Department of Neurosurgery, National Neurosciences Centre, Peerless Hospital Complex, IInd Floor, 360, Panchasayar, Kolkata - 700 094
India
 Source of Support: None, Conflict of Interest: None  | Check |
DOI: 10.4103/0028-3886.117610
How to cite this article:
Krishnan P, Kartikueyan R, Chowdhury D, Saha M. Ventral herniation of the dorsal spinal cord: A rare cause of myelopathy. Neurol India 2013;61:453-4 |
Sir,
Ventral herniation of the dorsal spinal cord is a rare cause of myelopathy. It is frequently misdiagnosed as an intradural arachnoid cyst. We report one such case.
A 50-year-old female presented with slowly progressive difficulty in walking over 3 years. Other history included constipation and difficulty in passing urine with urgency and frequency for the past one year. On examination, she had spastic ataxic gait. Deep tendon reflexes were exaggerated in the lower limbs with bilateral up going plantars. Magnetic resonance imaging (MRI) of dorsal spine showed focal atrophy and ventral migration of the cord abutting the T6-T7 disc space. There was no posterior compression and cerebrospinal fluid (CSF) flow artifacts seen at this level on T2-weighted sequences [Figure 1]. T1 and T2 axial imaging showed ventrally displaced cord with hypointense CSF flow artifacts on T2-wighted sequences [Figure 2]. The patient underwent laminectomy and repair of an anteriorly placed dural defect with fascial graft and fibrin glue after reduction of the cord into the intradural space by gentle manipulation. Intraoperatively, the dentate ligament was cut and one dorsal spinal root was sacrificed to gain access to the anterior part of the cord. Postoperatively her gait showed improvement. | Figure 1: T1 and T2 weighted sagittal MR images showing focal atrophy and ventral sharp angulation of the spinal cord abutting the D6‑D7 disc space. There is no posterior compression and CSF flow artifacts were seen at this level on T2 sequences ruling out an arachnoid cyst
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 | Figure 2: T2 and T1 weighted axial MR images showing ventrally displaced cord (more to the right) with hypointense CSF flow artifacts on T2 sequences
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Ventral herniation of the dorsal spinal cord was first reported by Wortzman in 1974. [1],[2],[3] It is an extremely rare cause of myelopathy [1],[3],[4] and more common in women. [1],[2],[3] Most patients are reported to present as a Brown-Sequard syndrome [1] probably as the dural defect and hence cord herniation is usually to one side of the midline. Due to increase in posterior subarachnoid space on imaging, often a misdiagnosis of an intraspinal arachnoid cyst is made. [3],[5] Brugieres et al.[1] emphasized that the "sharp angulation" on the posterior aspect of the cord at the site of hernia is more consonant with scarring and tethering rather than posterior compression by an arachnoid cyst. This has been compared with a Greek letter "alpha" by van den Hauwe et al.[2] and with the letter "C" by Shin et al. [3] Though phase contrast MRI would be helpful in unmasking the presence of an arachnoid cyst, [1],[2] the CSF flow artifacts found on T2 sequences in our patient belied the presence of such a cyst through which pulsatile CSF flow would not occur.
Of particular note is that the hernia has always been reported to occur between T2 and T10 levels. [1] The root cause appears to be the presence of a defect in the anterior spinal dura. Various theories have been put forward to explain the defect - congenital, [3],[4] posttraumatic, [2],[3] erosion by disc herniation/osteophyte, [2] herniation into a preexisting ventral meningocele/arachnoid cyst, [3] duplication of the dura mater, [3] focal inflammation, [3],[5] etc., Whatever be the cause, CSF pulsation forces the spinal cord to first plug the defect [2],[4] and later pass through it resulting, along with adhesion formation, [4] in a situation akin to an "irreducible" abdominal hernia. Subsequent spinal cord ischemia leads to myelopathy. [3],[4] Surgical closure of the defect after gentle reduction of the herniated cord into the subarachnoid space is the treatment of choice for these patients. [4] Various techniques have been described including primary repair of the margins of the defect to closure using an artificial dural patch. Some authors have emphasized enlarging the dural defect [3],[5] rather than attempting an inward manipulation of the cord to prevent future strangulation as well as traction-induced cord injury. In our case we felt approximation of the margins would be risky and hence used fascia lata patch and fibrin glue to seal the defect. Postoperative worsening has been reported in several cases. [1],[3] It must be emphasized that functioning neural tissue may be present in the herniated cord [1] and no attempt must be made to sacrifice the prolapsed tissue as in an encephalocele. Also cord retraction must be kept to a minimum.
| » References | |  |
| 1. | Brugieres P, Malapert D, Adle-Biassette H, Fuerxer F, Djindjian M, Gaston A. Idiopathic spinal cord herniation: Value of MR phase-contrast imaging. AJNR Am J Neuroradiol 1999;20:935-9. 
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| 2. | Van den Hauwe L, Van Goethem JW, Goedseels K, Merlevede K, Degryse H, Parizel PM. Thoracic spinal cord herniation and arachnoid cyst. JBR-BTR 2006;89:150-1.
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| 3. | Shin JH, Krishnaney AA. Idiopathic ventral spinal cord Herniation: A rare presentation of tethered cord. Neurosurg Focus 2010;29:E10.
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| 4. | Dix JE, Griffitt W, Yates C, Johnson B. Spontaneous thoracic spinal cord herniation through an anterior dural defect. AJNR Am J Neuroradiol 1998;19:1345-8.
[PUBMED] |
| 5. | Najjar MW, Baeesa SS, Lingawi SS. Idiopathic spinal cord herniation: A new theory of pathogenesis. Surg Neurol 2004;62:161-70.
[PUBMED] |
[Figure 1], [Figure 2]
| This article has been cited by | | 1 |
The Pathogenesis of Ventral Idiopathic Herniation of the Spinal Cord: A Hypothesis Based on the Review of the Literature |
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| Ronald H. M. A. Bartels,Han Brunner,Allard Hosman,Nens van Alfen,J. André Grotenhuis | | Frontiers in Neurology. 2017; 8 | | [Pubmed] | [DOI] | |
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