The catheter should pass more than 32 mm. Atresia may be confirmed by CT scan. Treated initially with a McGovern's nipple followed by surgical correction. This is an extracranial herniation of the meninges and brain through a cranial defect, histologically identical to a nasal glioma. There is a high incidence of other CNS anomalies.
Treatment includes a staged surgical closure of the intracranial communication and bony defect.