(OSD) are well known to most neurosurgical practitioners: the patch of hair, the subcutaneous lipoma, the dermal sinus tract, the lumbosacral dimple, and more exotic signs, such as the caudal appendage and the so-called “cigarette burn” lesion. These stigmata are a matter of neurosurgical lore, but they have received very little rigorous analysis as tests indicative of the presence of underlyin...
