Non terminal myelocystocele of cervical region in a newborn

Clinical History

A term male baby was born to a 31 year-old mother who was not followed up during the pregnancy. Following birth, he was referred due to a mass detected on his posterior neck. The physical examination revealed a skin covered, soft mass, approximately with 40 mm diameter on posterior cervical region.

Imaging Findings

Magnetic resonance imaging (MRI) of the cervical spine revealed a meningomyelocele located at the level of C5-6 (Figure 1). On T2-weighted axial image, the meningomyelocele sac contained a cyst continuous with the hydrosiringomyelic spinal canal that was formed by the posterior column of the spinal cord (Figure 2). The neural placode was shown to attach to the internal surface of the meningomyelocele sac (Figure 3). The diagnosis was made as Rossi type 2 non-terminal myelocystocele. Under general anaesthesia, the patient underwent surgical untethering of the spinal cord, resection of the meningomyelocele sac, and reconstruction of dura. The diagnosis was also confirmed surgically. Postoperatively on the postnatal 12th day, the patient was neurologically intact and was discharged. At follow-up after 1 month, the patient had normal activity of the lower extremities and there was no evidence of neurogenic bladder or bowel.

Discussion

The myelocystocele is a rare form of closed spinal dysraphism that mainly locates in the sacral region and when located in the sacral region, named as 'terminal' myelocystocele [1]. However, the non-terminal myelocystocele is less frequently observed and is located along the spinal column at posterior midline outside the sacral region. The meningocele sac is skin covered. The neural elements extend into the sac through a small defect of the spinous process. Two forms of myelocystocele have been identified: Ross type 1, the neural tissue is attached to the posterior column of the spinal cord with a fibroneurovascular stalk, and extends into the sac (myelocystocele manqué). Rossi type 2, at the level of meningocele, the spinal canal has hydrosyringomyelia and posterior part of the spinal canal along with hydrosyringomyelic cavity extends into the sac (complete form) [2].
The non-terminal myelocystocele embriologically is thought to occur due to partial defect of primary neurulation. The terminal and non-terminal forms differ from each other also in terms of clinical presentation. The patients with the diagnosis of non-terminal myelocystocele often present with no neurological deficit, urinary or fecal incontinence while patients with terminal myecystocele may have neurogenic bladder, bowel and difficulty in moving lower extremities [3]. Chiari type 2 and diastematomyelia are the additional anomalies that may be detected in patients with non-terminal myelocystocele commonly compared to with terminal myelocystocele [4].
Since the lesion is skin covered, the maternal alpha fetoprotein level does not rise contrary to open spinal dysraphisms. Therefore, the cooperation of radiologist and obstetrician is essential to make the in utero accurate diagnosis and plan the delivery and postnatal treatment. The fetal MRI obtained following ultrasound gives valuable information to establish the diagnosis.
The treatment consists of surgical excision of the meningocele sac, untethering of the spinal column, and repairment of the dural defect.

Differential Diagnosis List

Final Diagnosis

Non-terminal myelocycstocele of cervical region

URL:	https://eurorad.org/case/13025
DOI:	10.1594/EURORAD/CASE.13025
ISSN:	1563-4086