Limited dorsal myeloschisis associated with dermoid elements

Limited dorsal myeloschisis (LDM) originates from undisjointed neural and cutaneous ectoderms during primary neurulation. Its hallmark is a fibroneural stalk causing tethering on the dorsal spinal cord rostral to the conus. Its treatment is a relatively straightforward resection of the LDM stalk from the spinal cord. On reviewing our series of 75 cases of LDMs, we found that the majority of LDM stalks have only a glioneuronal core within a fibrous stroma, but a small number have been found to have elements of dermoid cyst or a complete dermal sinus tract either contiguous with the fibroneural stalk or incorporated within its glial matrix, not surprising considering the original continuum of cutaneous and neural ectoderm in LDMs’ embryogenesis. The dermoid element can be microscopic and escape casual observation, but could grow to large intradural dermoid cysts if part of the dermoid invested LDM stalk is left inside the dura. We present our series of LDMs associated with dermoid elements and recommend excising the entire length of the intradural LDM stalk from its dural entry point to its merge point with the spinal cord during the initial treatment to avoid secondary deterioration and additional surgery.