Spinal Arachnoid Cysts and Their Intraoperative Differentiation From Spinal Cord Herniation: A Single-Center Cohort...

Spinal arachnoid cysts (SAC) are benign but space-occupying outpouchings of the arachnoid membrane. Symptoms at presentation in adults often include back pain and spinal cord compression symptoms. MRI is key for diagnosis, complemented by cervicothoracic junction myelography. On MRI, misdiagnosis of ventral myelon herniation (VMH) may be falsely made. To facilitate intraoperative diagnosis, here we suggest the application of ultrasound for surgical planning and real-time confirmation.

We performed a single-center retrospective analysis on patients treated surgically for suspected VMH, ventral myelon adhesion (VMA), or intradural SAC from 2007 to 2024. Primary diagnosis was made on MRI. Neurological status was assessed pre- and postoperatively by the modified McCormick scale, and surgical approaches were documented. Intraoperative ultrasound imaging was used in 2 illustrative cases.

Among 42 patients, initial MR imaging suggested VMH/VMA in 10 patients and SAC in 32 patients. 36 cases were ultimately intraoperatively confirmed to be SAC. In 16 patients, additional inspection of the ventral dura was performed, and surgery was significantly longer (P = .0168; 154 minutes vs 114 minutes). Most pathologies were thoracic (81%), and surgical approaches varied. Neurological improvement was observed in 16.2%% and deterioration in 8.1%; neurological status was unchanged in 75.7%. Intraoperative ultrasound effectively aided diagnosis and surgical guidance in 2 cases, which are illustrated.

SAC are rare lesions causing spinal cord compression, often misdiagnosed as VMH or VMA. Our study promotes intraoperative ultrasound as a handy tool for precise surgical planning and accurate diagnosis. It enables precise cyst localization and thus improving outcomes by reducing the extent of procedures. As a consequence of surgical manipulation of the myelon, potentially by the ventral dura inspection, some patients may experience neurological decline. These findings highlight the potential of intraoperative ultrasound in enhancing surgical strategy for SAC and suspected VMH/VMA.