Limited Dorsal Myeloschisis

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flowchart TD
    A["Incomplete disjunction<br>between cutaneous and<br>neural ectoderms"] --> C["Formation of<br>fibroneural stalk without<br>epithelial lining<br>from skin to dorsal<br>spinal cord"]
    B["Incomplete fusion<br>of the neural<br>folds at the midline"] --> C

• A persistent cutaneo-neuroectodermal tract maintains a physical link between the cutaneous margin of the limited skin defect and the dorsal midline spinal cord.
• Ensheathed by a dural extension from the thecal sac as dura forms around the cord, is present in every LDM and is an internal hallmark.
• The cord is often tented up and tethered by this stalk.
• The initially unfused midline integument is subsequently closed by a bridging layer of squamous epithelium that is not full-thickness skin.
• This midline “non-skin” coverage is the external hallmark of an LDM

• The defining external or cutaneous signature always involves a focal area not of normal full-thickness skin, in two forms (midline crater or pit on a flat surface OR on the dome of a saccular swelling)
• Most flat craters are small and discrete, but the occasional saccular bulge can be obtrusive.

• The defining internal structure is always a neatly circumscribed stalk connecting the base of the skin lesion to a ‘‘limited’’ locus on the dorsal midline of the underlying spinal cord.
• At least part of the connection contains central nervous system tissue, qualifying it as a fibroneural or fibrovasculoneural stalk, depending on the accompanying elements.

• The connecting stalk is always ensheathed in a slender dural fistula extending from the site of the stalk’s attachment on the dorsal spinal cord to the base of the skin lesion and sometimes beyond.