Complex Spinal Dysraphism Complicated by Intramedullary Dermoid

Spinal dysraphism presents in myriad ways. Meningomyeloceles presenting with Split cord malformations are termed as complex dysraphisms.  We encountered a child with myelomeningocele and a split cord with intramedullary lesion making it a more complex dysraphism. J Nepal Paediatr Soc 2015;35(3):277-279


Introduction
O ver the past decades, there has been a signifi cant decrease in Spinal dysraphism in developed countries.However, in an underdeveloped country like Nepal it s ll con nues to be a major pediatric neurosurgical problem.Spinal dysraphism presents in various ways ranging from occult to large dorsal lesions.
It is not uncommon to fi nd dysraphism associated with mul ple orthopedic abnormali es.The dysraphic spine commonly has tethered spinal cord with variable syrinx.We came across a child who presented with a large mass in the back with normal neurological fi ndings.On MRI scan we found meningomyelocele with a split cord and an intramedullary lesion.She was managed accordingly.

The Case
A six year female child presented to us with a swelling in low back since birth.No similar complaints were there in siblings.She had normal neurology.On examina on; she had a cys c skin covered swelling in the upper lumbar region.She had no neurological defi cits and no deformi es.MRI revealed a meningocele communica ng with the intradural space at D12 and addi onally split cord and an intramedullary lesion at D9-D11 ( Excision of the meningocele together with removal of the bony spur was done.The intramedullary dermoid was excised and the dural sacs were converted into a single sac (Fig3).The child developed mild post opera ve weakness in her le foot which improved with physiotherapy.

Discussion
The unifi ed theory of embryogenesis proposes that all variant types of SCMs (Split cord malforma ons) have a common embryogene c mechanism.Basic to this mechanism is the forma on of adhesions between ecto-and endoderm, leading to an accessory neurenteric canal around which condenses an endomesenchymal tract that bisects the developing notochord and causes forma on of two hemineural plates 1 .
If the dividing septum is bony, it is termed as type I split (formerly Diastematomyelia) and if it is a fi brous septum, it is termed as Type II split (formerly diplomyelia) Meningomyeloceles are due to failure of fusion of the neural tube during 3 rd to 4 th week (day 21 to 27) of gesta on.The dermoid cysts are developmental in origin and arise from the nests of embryonic ectoderm which get buried or trapped under the lines of fusion of the ectodermal folds in the developing embryo.Combina on of all these type of embryological errors together are not very common.Dorsal cord is the most common site for SCM in 38.8% pa ents, followed by lumbar region in 28.6%, dorsolumbar in 22.4% lumbosacral in 4.1% and cervicodorsal region in 6.1% cases 2 .In 28.6% pa ents SCM is found at 2 to 3 level higher than the associated MMC sac, whereas in 12.2% children SCM and MMC are encountered at the same level 2 .
The presence of combina on of spilt cord and meningomyelocele has been coined as complex spina bifi da 3 .In a series of 106 pa ents with split cord 16 had meningomelocele(15%) 3 .Borkar et al reported 6 MMC in their series of 53(11%) split cord malforma ons 4 .Similarly, Ansari et al reported 10% associa on between split cord and MMC 5 .

Conclusion
Complex spinal dysraphism should always be suspected in a pa ent with meningomyeloceles.Microsurgical management with de-tethering and forma on of a water ght single dural tube is the goal of surgery.

Fig 2 :Fig 3 :
Fig 1a Fig 1b Fig 1c Fig 1a: Sagi al T1W MRI images showing intramedullary lesion with meningomyelocele and low lying tethered cord Fig 1b: Coronal image showing intramedullary lesion with split cord below it Fig 1c: Axial image depic ng the double cord forming an owl eye appearance