Spina bifida occulta
While typically referring to asymptomatic posterior fusion defects, some authors use it as a broad term that encompasses closed spinal defects such as:
- dorsal dermal sinus
- spinal lipoma
- posterior neural arch defects, namely spinous and paraspinal clefts
Spinda bifida occulta is the commonest form of spina bifida and is estimated to affect between 10-20% of the population in most western countries.
As there is overlying skin covering the vertebral defect and no associated developmental abnormalities of the cord or nerve roots, there are no usually no accompanying neurological symptoms found.
Spina bifida occulta is a congenital defect which occurs in the neural tube when the bony plates that form the bony spine covering the spinal cord do not form completely resulting in a defect of the spinous process (spinous cleft) or laminae (paraspinal cleft) . This usually involves the lower lumbosacral spine.
Appears as a midline or para-midline bony defect at the posterior arch.
This is the test of choice to assess for suspected spina bifida and determine its extent.