Teaching Case

21-year-old female having history of swelling in lower back region since birth presented with lower back pain associated with radiculopathy since 3 months with no history of bowel/bladder incontinence. On clinical examination skin lined swelling was seen at lower back region. Detailed radiological examination was done.

• X-ray spine showed dextroscoliosis involving cervicothoracic spine with block vertebrae involving C7, D1 and D2 vertebrae and D9 and D10 vertebrae with D1 being hemivertebra.
• Spina bifida seen involving spinous processes of D10, D11, D12 and L1 vertebrae with a maximum defect of 8 mm in spinous process of D11.
• CT scan of whole spine confirmed X-ray findings.
• MRI showed division of spinal cord within single thecal sac into two hemicords extending from superior part of D10 to mid part of D11 vertebra associated with segment of hydrosyringomyelia extending from superior part of D8 to inferior part of D9 vertebra with no fibrous/bony septum, suggesting type II diastematomyelia.
• Posterior spinal defects were lined by skin and shows interspersed lipomatous tissue with neural placode-lipoma interface lying within spinal canal suggesting lipomyelocele with no evidence of abnormally low position of conus medullaris to suggest tethered cord.
  • Overlying para-spinal muscles displaced posteriorly. 

Diastematomyelia is a spinal dysraphism in which there is partial/complete sagittal clefting of one or more segments of the spinal cord, conus medullaris, and/or filum terminale dividing the spinal cord into two hemicords which contains one central canal, one dorsal horn that gives origin to the ipsilateral segmental dorsal nerve root, and one ventral horn that gives origin to the ipsilateral segmental ventral nerve root. The involved segments may be contiguous or anatomically distant from each other [1, 2].

Depending upon the presence or absence of a fibrous partition or bony spur interposed between the hemicords there are two types of Diastematomyelia. In type 1, the two hemi cords are located within individual dural tubes separated by an osseous, fibrous or cartilaginous septum. In type 2 having a single dural tube contains two hemi cords, sometimes with an intervening fibrous septum [1].

The severity of symptoms and signs varies greatly, ranging from cutaneous hairy patch and swelling at sacral region to gait disturbance with mild atrophy or weakness of one or both lower extremities, absent deep tendon reflexes, progressive paraparesis, and bladder or bowel dysfunction [3-5]. The diagnosis depends on presence or absence of bony spur and the associated features of spinal dysraphism such as spina bifida occulta, block vertebrae, widened interpediculate distance, hemivertebrae, and scoliosis which are commonly seen with type-I [6-8].

The open forms of spinal dysraphism, such as meningocele and myelomeningocele, can be identified on obstetric sonography. The occult forms, such as intracanalicular lipoma and a tethered cord can be identified through sonographic screening of neonates and infants [9]. In late childhood and adults, plain radiographs of spine can give good details about abnormalities of spinal cord and vertebral bodies and bony spur. Computed tomography can demonstrate bony spur and its extent and relationship with vertebral bodies and vertebral anomalies more accurately. MRI with its better soft tissue contrast, allows visualization of extent of split in the cord and shows associated anomalies such as lipoma and syrinx. So accurate diagnosis can be made. T1WI is good for demonstrating lipomyelocele and filum terminale tethering. T2WI can show evidence of hydrosyringomyelia.

Treatment options vary. Tethering of cord by bony spur should be relieved immediately after diagnosis, especially before growth spurt as most of patients are symptomatic during growth spurt, possibly due to traction by spur on spinal cord. Some studies prefer removal of spur when patient becomes symptomatic.