Fact-sheet: Diastematomyelia
Updated on 03/12/2018 at 5:01 PM
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Definition
Rare spinal cord malformation characterized by a sagittal, more or less extensive, splitting of the spinal canal and its contents, resulting in a split cord appearance
Accounts for 4% of all closed dysraphisms
Possible association with: myelomeningocele, syringomyelia, tethered cord, or neurenteric cyst
Clinical features
- Cutaneous signs: hair tufts, lumbosacral mass, café-au-lait spots
- Orthopedic signs: scoliosis, foot deformity
- Neurologic signs: gait disturbance, amyotrophy and paresis of the lower limbs, sexual and sphincter dysfunction, flaccid paraplegia
Radiography
Vertebral malformations: spina bifida, scoliosis, butterfly vertebra, interpedicular widening, bony spur, and disk dysplasia
Ultrasound
Allows for antenatal diagnosis
- Widening of the spinal canal
- Two hemicords
- Abnormal spinal curvature
CT
- Spur: fibrous, osteofibrous, or bony (absent in 5 cases)
- Bony abnormalities: Widening of the spinal canal, spina bifida, vertebral segmentation anomalies
- Spinal cord abnormalities: two hemicords in all cases
MRI
Examination of choice.
Allows better assessment of intraspinal malformations and clarifies their relationship with canal anomalies.
MRI demonstrates:
- both spinal cord hemicords and assesses their size.
- the level of the cord division, whether single or multiple
- in the case of an ossified spur, it appears as T2 hyposignal between the two hemicords
- the presence of conus medullaris ectopia (¾ of cases)
- any associated malformations
Management
Isolated diastematomyelia: generally good prognosis.
Surgery may be indicated in the presence of neurological deficits, to prevent neurological complications related to growth and to subsequent correction of scoliosis.
Surgery consists of relieving the constraints on the spinal cord by resecting the bony spur, with release of a low-lying tethered cord if present.
Classification
Two types of diastematomyelia have equal prevalence:
- Type I: Two hemicords each covered by their own pial sheath with a common arachnoid and dural envelope, separated by simple fibrous adhesions. Rarely symptomatic.
- Type II: Double arachnoid and dural envelope. The two dural sacs are separated by a bony or cartilaginous spur, which inserts on the posterior aspect of the vertebral body, with variable orientation (sagittal or oblique). Often symptomatic, but the clinical presentation is not specific.