Reversed Calcaneal Spur
Joseph Junewick, MD FACR
over 7 years ago
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Heather Borders, MD
|Diagnostic Category: Developmental or Congenital
|Created: over 6 years ago
|Updated: over 6 years ago
5 year old with prior history of repaired myelomeningocele in China. New onset of paresthesias in the lower extremities.
Two hemicords in the lumbar region with one dural tube and a fibrous spur. Also present, but not shown were L3 butterfly vertebrae and non segmentation of L2-4. Terminal epidermoid cyst, tethered cord and a hemicord syrinx.
Diastematomyelia likely develops due to splitting of the notochord, possibly due to an obstacle between the endoderm and ectoderm encountered during migration. Commonly this is associated with vertebral anomalies such as hemivertebrae or butterfly vertebrae.
The cleft is most commonly lumbar. Lumbar is generally associated with tethering and may be more symptomatic. The two hemicords usually reunite below the level of diastematomyelia.
There are two types: Type I with two separate dural and arachnoid tubes and type II with one tube surrounding the hemicords.
Type I may have a bony, fibrous or cartilaginous spur. The type II usually does not have a bony spur, but there may be a bone protrusion at the site of origin of the fibrous or cartilaginous spur.
The spur may be missed and needs to be looked for carefully. The spur is usually at the caudal end and divides the cord into two fairly equal halves.
Patients with type II diastematomyelia may be less symptomatic unless there is associated hydromyelia or tethering.
Up to 85% of patients have associated spinal anomalies. Findings include tethering, myelocele/myelomeningocele, lipoma, dermal sinus, dermoid or epidermoid, or meningocele manque.
The meningocele manque is very subtle. There is a small band of tissue from the hemicord to the dura mimicking a nerve root. This can be a cause of persistent tethering.
The diastematomyelia is also associated with klippel feil anomaly; unsegmented vertebrae in the cervical region. The patient in this case also has cervical segmentation anomalies.
Barkovich: Pediatric neuroimaging; pp. 745-752.