Clinical presentations of the most severe NTDs are the obvious cranial defect in anencephaly and open spinal defects of the thoracic and/or lumbar spine with open spinal NTDs, both with exposure of neural tissue. NTDs with an intact skin cover may show an obvious mass (eg, an occipital encephalocele) or be more subtle. Subtle findings include bulging of the skin cover over the occipital or spinal defect, small openings sometimes missed on initial examination, dimples, or hair patches. See Section I for definitions and description of the different NTDs.