J Korean Neurosurg Soc.  2020 May;63(3):342-345. 10.3340/jkns.2020.0094.

Enlargement of Extraspinal Cysts in Spinal Dysraphism : A Reason for Early Untethering

• Kim KH
• Wang KC
• Lee JY

• KMID: 2501721
• DOI: http://doi.org/10.3340/jkns.2020.0094

Abstract

Some types of spinal dysraphism can be accompanied by extraspinal cysts, including myelomeningocele, myelocystocele, myelocele, meningocele, limited dorsal myeloschisis, lipomyelomeningocele, and terminal myelocystocele. Each disease is classified according to the developmental mechanism, embryologic process, site of occurrence, or internal structure of the extraspinal cyst. In most cystic spinal dysraphisms except meningocele, part of the spinal cord is attached to the cyst dome. Most open spinal dysraphisms pose a risk of infection and require urgent surgical intervention, but when the cyst is accompanied by closed spinal dysraphism, the timing of surgery may vary. However, if the extraspinal cyst grows, it aggravates tethering by pulling the tip of the cord, which is attached to the dome of the cyst. This causes neurological deficits, so urgent surgery is required to release the tethered cord.

Keyword

Extraspinal cyst; Spinal dysraphism; Untethering; Intraoperative neurophysiologic monitoring; Tethered cord

Figure

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  Fig. 1. Meningocele without any neural structure inside the sac.

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  Fig. 2. A : Saccular type of limited dorsal myeloschisis. B : Note the stalk to dome (yellow arrow).

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  Fig. 3. ‘True’ lipomyelomeningocele shows the herniated spinal cord with fat tissue and cerebrospinal fluid in the dural sac through the fascial defect. A : T2-weighted imaging. B : T1-weighted imaging.

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  Fig. 4. Terminal myelocystocele. Note the low-lying syringomyelic spinal cord (yellow arrow). A : Sagittal section. B : Axial section.

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  Fig. 5. A : A gross photo of the patient shows a cystic mass in the back. B : An operative photo shows the cystic mass herniated through the fascial defect (right - cephalad side of the patient). C : Tracings of motor evoked potentials (MEPs) demonstrate changes in MEPs during the operation. The baseline MEPs were recorded at the start of surgery (left upper). Decreases in MEPs in both lower extremities were noticed. Only the right-side tracings are shown in this figure (from top to bottom : vastus medialis, anterior tibialis, gastrocnemius, abductor hallucis, adductor pollicis brevis). Please note that there was no change in the control MEPs in the upper extremity from abductor pollicis brevis (yellow arrow) (right upper). After aspiration of cerebrospinal fluid, the signal appeared again immediately (left lower) and was fully recovered after 20 minutes (right lower). Adopted from Kim et al. [2], with permission from Springer Nature.

Reference

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