Sacral terminal filar cyst: a distinct variant of spinal meningeal cyst and midterm clinical outcome following combination resection surgery

Utility of routine mid-trimester fetal ultrasound scan in detecting filar cysts and follow-up outcomes

PURPOSE

To assess the value of routine mid-trimester fetal ultrasound scans in detecting FCs, as well as the related ultrasound and clinical follow-up outcomes.

METHODS

A retrospective analysis was conducted on 1064 fetuses who underwent standardized ultrasound screening during the mid-trimester. During the examination, high-frequency ultrasound was used to examine the fetal spine. Different frequency ultrasound probes were used to compare and analyze the detection rates of FCs. We conducted follow-up ultrasound observations on all FCs and conducted long-term follow-up observations in terms of the motor function of the children after birth.

RESULTS

Among 1064 fetuses detected by ultrasound, a total of 910 fetuses were completely evaluated using high-frequency and low-frequency ultrasound, and 24 FCs were found. In all 24 cases of FCs, 7 cases were detected using low-frequency ultrasound, while high-frequency ultrasound detected all cases. There was a significant difference in the detection rates between the two groups (χ2 = 26.323, P = 0.000). Of all the 24 FCs, 21 cysts disappeared spontaneously (87.5%); one fetus was induced for abortion due to a concurrent cleft lip; after multiple ultrasound examinations, it was found that the cyst persisted in one fetus; one case was not followed up by ultrasound. There was no statistically significant difference in the start of sitting and crawling time between the control group and the FCs group.

CONCLUSION

Routine mid-trimester fetal ultrasound scan detect FCs, particularly when high-frequency ultrasound probes were routinely applied. Most FCs detected by prenatal ultrasound spontaneously disappear and have no impact on the motor function of the fetus after birth (with the conus medullaris located at or above the L3 level). The shortest time interval from the detection to the disappearance of the cyst was 11 days.

Accurate diagnosis and treatment of sacral meningeal cysts without spinal nerve root fibres: identifying leakage orificium using high-resolution spherical arbitrary-dimensional reconstructing magnetic resonance imaging

Objective

This study aimed to develop an arbitrary-dimensional nerve root reconstruction magnetic resonance imaging (ANRR-MRI) technique for identifying the leakage orificium of sacral meningeal cysts (SMCs) without spinal nerve root fibres (SNRFs).

Methods

This prospective study enrolled 40 consecutive patients with SMCs without SNRFs between March 2021 and March 2022. Magnetic resonance neural reconstruction sequences were performed for preoperative evaluation. The cyst and the cyst-dura intersection planes were initially identified based on the original thin-slice axial T2-weighted images. Sagittal and coronal images were then reconstructed by setting each intersecting plane as the centre. Then, three-dimensional reconstruction was performed, focusing on the suspected leakage point of the cyst. Based on the identified leakage location and size of the SMC, individual surgical plans were formulated.

Results

This cohort included 30 females and 10 males, with an average age of 42.6 ± 12.2 years (range, 17-66 years). The leakage orificium was located at the rostral pole of the cyst in 23 patients, at the body region of the cyst in 12 patients, and at the caudal pole in 5 patients. The maximum diameter of the cysts ranged from 2 cm to 11 cm (average, 5.2 ± 1.9 cm). The leakage orificium was clearly identified in all patients and was ligated microscopically through a 4 cm minimally invasive incision. Postoperative imaging showed that the cysts had disappeared.

Conclusion

ANRR-MRI is an accurate and efficient approach for identifying leakage orificium, facilitating the precise diagnosis and surgical treatment of SMCs without SNRFs.