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CASE REPORTS
Year : 2006  |  Volume : 1  |  Issue : 3  |  Page : 19-21
 

Pure diplomyelia of the cervical cord associated with tight filum terminale causing tethered cord syndrome


Department of Neurosurgery, Sanjay Gandhi Postgraduate Institute of Medical Sciences, Lucknow

Correspondence Address:
S Behari
Department of Neurosurgery, Sanjay Gandhi Post Graduate Institute of Medical Sciences, Lucknow - 226 014.

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How to cite this article:
Wani A A, Sahu R N, Jaiswal A K, Sharma M, Behari S. Pure diplomyelia of the cervical cord associated with tight filum terminale causing tethered cord syndrome. J Pediatr Neurosci 2006;1, Suppl S1:19-21

How to cite this URL:
Wani A A, Sahu R N, Jaiswal A K, Sharma M, Behari S. Pure diplomyelia of the cervical cord associated with tight filum terminale causing tethered cord syndrome. J Pediatr Neurosci [serial online] 2006 [cited 2020 Oct 26];1, Suppl S1:19-21. Available from: https://www.pediatricneurosciences.com/text.asp?2006/1/1/19/17044


The presence of a double spinal cord residing in a single dural sheath is called diplomyelia. In most of the cases, there is a presence of a fibrous band or septum between the two hemicords and pure diplomyelia without septum is a rare entity. Our case was unique due to the presence of cervical diplomyelia without any intervening bony or fibrous septum and hence not qualifying to as Pang's type I or II split cord malformation (SCM). The neurological deterioration was probably due to the presence of tethered cord due to an associated tight filum terminale.


  Case report Top


A five-year-old male child presented with a history of difficulty in walking with frequent falls for last 3 months. His examination revealed mild weakness in right ankle dorsiflexion and plantar flexion with sensory loss of 30-40% in right L5-S1 distribution. His MRI and intrathecal contrast CT scan [Figures 1]A and B, [Figure - 2]A and B revealed the presence of focal duplication of the cervical cord within a single dural sac without any intervening bony or fibrous septum at C6-7 level with associated tethered cord at L5 level. At surgery, a C6-7 laminectomy was done. On opening the dura, the two cords were seen lying in a common dural sheath without any intervening septum [Figure - 3] and [Figure - 4]. Through a separate incision, a L4-5 laminectomy was performed to expose the tight filum terminale. Detethering of the filum caused the cord to ascend a little [Figure - 5]. Postoperatively, the patient had no further deterioration in his neurological status.


  Discussion Top


The SCM is an anomaly in which the spinal cord is clefted over a portion of its length to form a double neural tube. The two hemicords may both be contained within their own separate dural sheaths (SCM I) or they may each be contained within a single dural sheath (SCM II). The SCM may occur in association with open neural tube defects or more commonly as occult malformations developing either in isolation or in conjunction with other associated anomalies. According to the traditional concept, Hertwig first used the term diastematomyelia (from the Greek diastema , meaning cleft, and melos , meaning medulla) to describe malformations in which the spinal cord is split into two hemicords, each containing only a single set of dorsal and ventral nerve roots. In contrast Herren and Edwards introduced the term diplomyelia to describe a complete duplication of the spinal cord, with each side containing two sets of ventral and dorsal nerve roots.[1],[2],[3]

These malformations were further divided according to the composition of their dural coverings or by the presence or absence of the tethering midline structures. According to this classification, each of the hemicords in diastematomyelia lies within its own dural sheath, whereas both of the duplicated spinal cords in diplomyelia lie within a single dural sheath. Thus the wide spread belief is that diastematomyelia involves a splitting of the spinal cords into two half-cords lying within two separate dural sheaths and separated by an osseous or fibro-cartilaginous tethering spur. In contrast, diplomyelia is thought to involve a true spinal cord duplication within a common dural tube, with interposed mesenchymal tissue leading to development of fibrous septum.[1],[2] However, distematomyelia and diplomyelia have been used interchangeably in different series.[2],[3],[4],[5],[6],[7] Pang et al. provided a new classification and an embryogenic theory.[8],[9] They suggested that these confusing and misleading terms should be abandoned and proposed an alternative classification which comprised all double cord malformations. They also proposed the unified theory, which explains the embryogenic mechanisms of all patients of SCMs. In type I SCM, the meninx primitiva cells become admixed with the endomesenchymal tract and are situated in midline between the two hemicords forming an osseo-cartilaginous spur. In type II SCM, the menix primitiva cells are not involved in the endomesenchymal tract and enclose only the surface of each hemicord to form a single dural sac that surrounds both hemicords. The mesenchyme from the endomesenchymal tract forms a thin fibrous septum in the space between the hemicords. The presence of paramedian roots is due to involvement of neural crest cells in the early phases of endomesenchymal tract formation.[8] When SCM is associated with myelomeningocele, this dysraphic state is called complex spina bifida.[10] Nevertheless, the occurrence of diplomyelia (or type II SCM) is rare.[9],[11],[12],[13],[14],[15] All the 18 cases of type II SCM quoted by Pang et al[9] had a fibrous median septum found during surgery. Our case was unique due to the presence of pure diplomyelia without any intervening bony or fibrous septum and hence not qualifying to Pang's type I or II SCM. The absence of fibrous septum or osseocartlaginous spur may be due to the complete regression of the endomesenchymal tract after the duplication had occurred. There was no cord tethering at the level of the diplomyelia. However, the tight filum terminale was responsible for the development of the progressive neurological symptoms.



 
  References Top

1.Cohen, Sledge CB. Diastematomyelia. An embryological interpretation with report of a case. Am J Dis Child 1960;100:127-33.  Back to cited text no. 1    
2.Herren RY, Endwards JE. Diplomyelia(duplication of the spinal cord). Arch Pathol 1940;30:1203-14.  Back to cited text no. 2    
3.Naidich TP, Harwood-Nash DC. Diastematomyelia: hemicords and meningeal sheaths; Single and double arachnoid and dural tubes. Am J Neuroradiol 1983;4:633-6.  Back to cited text no. 3  [PUBMED]  
4.Bruce A, Donal S, Pirie JH. A second case of partial doubling of the spinal cord. Rev Neurol Psychiatr 1906;4:6-19.  Back to cited text no. 4    
5.Humpharys RP, Hendrick EB, Hoffman HJ. Diastematomyelia; in weis MH (ed): Clin Neurosurg Baltimore Williams and Wilkins: 1982. p. 436-56.  Back to cited text no. 5    
6.Louw JA, Roos MF. Diastematomyelia without a median septum in congenital scoliosis. A report of 2 cases. S Afr Med J 1987;72:433-4.  Back to cited text no. 6  [PUBMED]  
7.Pickels W. Duplication of the spinal cords (diplomyelia). J Neurosurg 1949;6:324-31.  Back to cited text no. 7    
8.Pang D, Dias MS, Ahab-Barmada M. Split cord malformation, I: Aunified theory of embryogenesis for double spinal cord malformations. Neurosurgery 1992;31:451-80.  Back to cited text no. 8  [PUBMED]  
9.Pang D. Split cord malformation II: Clinical syndrome Neurosurgery 1992;31:481-500.  Back to cited text no. 9  [PUBMED]  
10.Kumar R, Bansal KK, Chhabra DK. Occurrence of split cord malformation in myelomeningocele: complex spina bifida. Pediatr Neurosurg 2002;36;119-27.  Back to cited text no. 10    
11.James CC, Lassman LP. Diastematomyelia. A critical surgery of 24 cases submitted to laminectomy. Arch Dis Child 1964;39:125-30.  Back to cited text no. 11  [PUBMED]  
12.Jindal A, Mahapatra AK. Split cord malformations - a clinical study of 48 cases. Indian Pediatr 2000;37:603-7.  Back to cited text no. 12  [PUBMED]  [FULLTEXT]
13.Hori A. Dimyelia, diastematomyelia and diplomyelia. Clin Neuropathol 1988;7:314.  Back to cited text no. 13  [PUBMED]  
14.Li L, Will DW, Sanda A. Diplomyelia: report of an autopsied case. Arch Pathol 1968;85;416-8.  Back to cited text no. 14    
15.Wolf A, Bradford D, Lonstein J, Ogilvie J, Erickson D. The adult diplomyelia syndrome. Spine 1987;12:233-7.  Back to cited text no. 15  [PUBMED]  


Figures

[Figure - 1], [Figure - 2], [Figure - 3], [Figure - 4], [Figure - 5]



 

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