[Limited dorsal myeloschisis: from antenatal screening to postnatal evolution. About a series of cases from the Grand Est, Bourgogne and Franche Comté].

Introduction: Limited dorsal myeloschisis (LDM) is a rare closed neural tube defect characterized by the presence of a fibroneural rod connecting the spinal cord to the skin, and a focal closed skin defect. Distinguishing between open and closed forms of dysraphism is a major challenge, given their variable prognosis. However, the diagnosis of LDM in the ante-natal period is difficult and the prognosis of children is little studied, although these data are vital in order to establish suitable prenatal advice and provide couples with the best possible support.

Material and methods: We conducted a retrospective multicenter observational study from May 2010 to March 2023 on 5 reference centers attached to a prenatal diagnosis center: the university hospital centers (CHU) of Besançon, Dijon, Nancy, Reims and Strasbourg.

Results: A total of 21 cases of LDM suspected on reference ultrasonography were included. The ultrasound criteria used were standardized and corresponded to those described in the literature. In 76% of cases, MRI was performed to complement the obstetrical ultrasound. Amniocentesis was performed in over 50% of cases, and was always normal. Of the 21 cases initially suspected prenatally, there were 17 live births: 9 confirmed cases of LDM (52.9%), and 8 invalidated cases (47.1%), corresponding to another diagnosis. Of the 9 confirmed cases of LDM, 8 were isolated forms, and 1 was associated with a poly malformative syndrome (VACTERL). On reference ultrasonography, there were no significant differences in criteria between confirmed and invalidated LDM, apart from the fibroneural stalk described sonographically in 2 cases, both confirmed postnatally. Concerning the spinal level, there was a difference in involvement, with a predominance of the lumbar level in confirmed cases of LDM, whereas a sacral level was preferred among infirm cases. MRI was carried out in 76% of cases, and confirmed the diagnosis of LDM in 71% of confirmed cases in the postnatal period. Of the 5 requests for medical termination of pregnancy (MTP), 3 were accepted, but 2 were refused by the CPDPN. These two cases corresponded to a confirmed postnatal isolated LDM and a lipomyelomeningocele, both with a favorable prognosis and evolution. Post-natal follow-up averaged 32 months. No notable neurological abnormalities were noted. In terms of bladder and bowel function, urinary tract infections and constipation were common but rare (n=3/6; 50%) and not severe. No significant psychomotor retardation was reported. The 8 cases of invalidated LDM all corresponded to closed dysraphism. No diagnosis was corrected to open dysraphism.

Conclusion: In contrast to myelomeningocele, our study confirms that limited dorsal myeloschisis (LDM) tends to have a good prognosis. However, given the risk of postnatal symptoms, particularly sphincter symptoms, management must be early and multidisciplinary. The place of MTP seems questionable. Prenatal counseling must be adapted in the light of these results, after multidisciplinary discussion, in order to communicate clear and appropriate information to future parents.