Cervical saccular limited dorsal myeloschisis, so-called "cervical myelomeningocele": long-term follow-up of a single-center series and systematic review
Authors: Maroufi Seyed Farzad , Dabbagh Ohadi Mohammad Amin , Hosseinnejad Iman , Tayebi Meybodi Keyvan , Takzare Alireza , Ashjaei Bahar , Nejat Farideh , Habibi Zohreh 
Published: October 2023

OBJECTIVE
Cervical saccular limited dorsal myeloschisis (LDM), previously so-called "cervical myelomeningocele," is a rare spinal dysraphism. Although the pathogenesis of true myelomeningocele is primary neurulation failure, LDM results from a delayed abnormality during the final stages of neurulation. The aim of the study was to evaluate the outcome of these patients and to assess the correlation of outcomes with the level and type of lesion. Also, pooled data from the literature on similar lesions were systematically reviewed.

METHODS
A retrospective study was conducted at Children’s Medical Center (CMC), Tehran, Iran. Information of patients who underwent surgery between 2004 and 2020 (i.e., the recent series) was extracted and combined with data from a previously published series from the same center that were obtained between 2000 and 2003 (CMC series). The literature was reviewed for all published cases, to be combined with the CMC series for further analyses.

RESULTS
Twenty-two patients were included in the recent series. Combined with 16 previously published cases, 38 patients with a mean ± SD age at surgery of 11.75 ± 28.64 months were included in the CMC series. The rates of neurological deficit, hydrocephalus, and Chiari malformation type II in the CMC series were 26.32%, 39.47%, and 28.95%, respectively. The lesions were at the upper levels in 17 (44.7%) and lower cervical levels in 21 (55.3%) patients, with 31 cases (81.58%) diagnosed with stalk-type lesions and 7 cases (18.42%) with myelocystocele-type lesions. At final follow-up, 31 patients (81.57%) achieved sphincter continence, and all 36 accessible patients were ambulated, consisting of 28 (73.68%) independent and 8 (21.05%) dependent ambulation patients. The rates of Chiari malformation type II and hydrocephalus were insignificantly higher in patients with upper-level lesions, but those of neurological deficit, ambulation, and sphincter continence were not associated with level. The rates of hydrocephalus (p < 0.01), Chiari type II malformation (p < 0.01), and neurological deficit (p = 0.04) were significantly higher in the myelocystocele group. In the systematic review, 24.77% of patients had neurological deficit. Binary logistic regression showed that older age at surgery (p = 0.03) and associated spinal anomalies (p = 0.04) were significant predictors of deficits. Chiari type II malformation was significantly (p < 0.001) and hydrocephalus was marginally (p = 0.06) more common in patients with myelocystocele-type lesions. The rate of Chiari malformation type II was higher in patients with upper-level lesions (p = 0.02).

CONCLUSIONS
Patients with cervical saccular LDM had better outcome compared with those patients with true myelomeningocele in more distal areas. According to the current series, most patients obtained ambulation and voiding continence, regardless of the level or type of lesion. Hydrocephalus, Chiari type II malformation, and neurological deficit were more common in patients with myelocystocele-type lesions.