Arachnoidal Diverticula of Sacral Extradural Meningeal Cyst: A Novel Definition and Case Series

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.

Multiple dimensions of radiographic reconstruction for the optimal operative strategy of sacral meningeal cysts

BACKGROUND AND PURPOSE

The contents and subtypes of sacral cysts are sophisticated in many cases. We applied multiple dimensional magnetic resonance imaging (MRI) reconstruction to preoperatively clarify the specific subtype of sacral meningeal cysts.

MATERIALS AND METHODS

We preoperatively used multimodal neural reconstruction MRI sequences to evaluate 76 patients with sacral cysts. The linear nerve roots were precisely traced based on sagittal or coronal images processed at various angles and levels which was conducive to the design of the operation strategy.

RESULTS

Cysts with nerve passage were detected in 47 cases (62%, 47/76), whereas cysts without nerve roots were detected in 24 cases (32%, 24/76). Five patients had mixed cysts with or without nerve roots. Intraoperative exploration results proved the high accuracy of image reconstruction; only one cyst without a nerve root was misdiagnosed prior to surgery.

CONCLUSION

MRI reconstruction based on the three-dimensional fast imaging employing steady-state acquisition T2 sequence precisely tracked the nerve roots of sacral cysts and guided the optimal strategy during surgery.