Limited Dorsal Myeloschisis and Congenital Dermal Sinus: Comparison of Clinical and MR Imaging Features.

BACKGROUND AND PURPOSE: While limited dorsal myeloschisis is a distinctive form of spinal dysraphism, it may be confused with congenital dermal sinus. The aim of this study was to describe clinical and MR imaging findings of limited dorsal myeloschisis that can distinguish it from congenital dermal sinus. MATERIALS AND METHODS: We retrospectively reviewed the clinical and MR imaging findings of 12 patients with limited dorsal myeloschisis and 10 patients with congenital dermal sinus. Skin abnormalities, neurologic deficits, and infectious complication were evaluated on the basis of clinical information. We evaluated the following MR imaging features: visibility of the tract along the intrathecal course, attachment site of the tract, level of the conus medullaris, shape of the spinal cord, and presence of intradural lesions such as dermoid/epidermoid tumors. RESULTS: A crater covered with pale epithelium was the most common skin lesion in limited dorsal myeloschisis (10/12, 83%). Infectious complications were common in congenital dermal sinus (6/10, 60%), whereas none were found in limited dorsal myeloschisis (P = .003). The following MR imaging findings were significantly different between the 2 groups (P < .05): 1) higher visibility of the intrathecal tract in limited dorsal myeloschisis (10/12, 83%) versus in congenital dermal sinus (1/10, 10%), 2) the tract attached to the cord in limited dorsal myeloschisis (12/12, 100%) versus various tract attachments in congenital dermal sinus, 3) dorsal tenting of the cord in limited dorsal myeloschisis (10/12, 83%) versus in congenital dermal sinus (1/10, 10%), and 4) the presence of dermoid/epidermoid tumors in congenital dermal sinus (6/10, 60%) versus none in limited dorsal myeloschisis. CONCLUSIONS: Limited dorsal myeloschisis has distinct MR imaging features: a visible intrathecal tract with dorsal tenting of the cord at the tract-cord union. Limited dorsal myeloschisis was not associated with infection and dermoid/epidermoid tumors.