Pediatric Spinal Dysraphisms 

Meningocele: 
- Protrusion of meninges filled with CSF, NO spinal cord tissue within
- Associated with hydrocephalus

Myelomeningocele: 
- Associated with hydrocephalus, chiari II (almost all), syrinx, lipomas, dermoid/epithelioid cysts, ventral and vertebral anomalies, diastematomyelia ("split cord" malformations)
- Kids who have myelo and chiari II who have hydrocephalus and fail their shunts tend to present with mild symptoms, and then clinically deteriorate very rapidly into coma and death. Perhaps the presence of the chiari II makes for less space in the posterior fossa and thus less room for progression of symptoms before acute decompensation.
- Chiari II associated with learning disability / decreased cognitive functioning, although the vast majority will be within the range of normal intelligence
- 70% will have bowel or bladder incontinence.
- Tx: prophylactic antibiotics until closure of neural tube defect to prevent infection, neurosurgical closure within 72 hours of life -- approximate edges of neural placode to create a tube.

A side note on hydrocephalus and shunt failure: its not a question of absolutes but relatives; ventriculomegaly does not have to be present, its more a function of deviation from baseline. Kids with shunts in typically have slit or very small ventricles, so a shunted kid who presents with "normal" ventricles who previously had slit ventricles may be in acute shunt failure. Likewise a kid with a relatively moderate headache who never has headaches and has had progressively worsening pain is concerning, even if the pain is not bad on an absolute scale.

Both brainstem compression or acute hydrocephalus (from shunt failure) can occur in these kids, and they can present with similar symptoms -- make sure to r/o hydrocephalus before doing a suboccipital decompression, because that in the setting of hydro can cause hernation.