Minimally Invasive Far Lateral Transforaminal Approach (MI-FLT) to Ventrally Located Intradural Lesions of the Thoracic Spine without Instability: Case Series and Technical Note

• Ventral located intradural lesions of thoracic spine pose surgical challenges • MI-FLT enables safe resection of ventral located intradural thoracic lesions • No postoperative signs of clinical or radiological spinal instability were observed • MI-FLT demands advanced 3D anatomy knowledge and surgical skill Accessing the ventral thoracic spinal canal poses a significant challenge due to complex anatomy. Ideal approaches for ventrally located intradural lesions must ensure sufficient exposure while minimizing spinal cord manipulation. Traditional techniques often require resection of stabilizing structures, increasing the risk of spinal instability. With advances in minimally invasive surgery, there is growing interest in anatomical preservation without compromising surgical outcomes. Here, we present a minimally invasive posterolateral approach using foraminal enlargement to access and remove ventrally located intradural lesions. Three patients underwent this approach: two for ventral thoracic meningiomas (Th1–2, Th6) and one for a hemorrhagic cavernoma (Th9–10). In the prone position, a paramedian incision was made 6-10 cm from the midline. After blunt muscle dissection and, if necessary, partial rib resection the intervertebral foramen was exposed. Foraminal enlargement was accomplished by meticulously drilling the articular processes and part of the adjacent pedicles, providing direct access to the ventral spinal canal. Mean operative time was 211 minutes, with minimal blood loss and no complications. Complete resection was confirmed postoperatively. Patients that underwent surgery for spinal meningioma showed early neurological improvement. Patients were discharged by days 3–6 without bracing. At 17-month follow-up, no recurrences or instability were noted. The Minimally Invasive Transforaminal Approach (MI-FLT), achieved through a selective foraminal enlargement, provided a safe lateral access to ventral intradural lesions while preserving spinal stability. The approach minimizes tissue disruption but requires high-level surgical expertise in minimally invasive techniques.