"Microendoscopic" versus "pure endoscopic" surgery for spinal intradural mass lesions: a comparative study and review.

BACKGROUND CONTEXT: Endoscopy is increasingly being used for minimal invasiveness and panoramic visualization, with unclear efficacy and safety among spinal intradural mass.

OBJECTIVE: The present study aims to compare microendoscopic and pure endoscopic surgery for spinal intradural lesions.

MATERIALS AND METHODS: Spinal intradural lesions operated using endoscopic or access ports were categorized into "microendoscopic" (predominant microscope use) or "pure endoscopic" (stand-alone endoscopy) surgery, and were studied with respect to clinico-radiological features, techniques, perioperative course, histopathology, clinical, and radiological outcome at minimum of 3 months.

RESULTS: Among 34 patients studied, the initial 15 had "microendoscopic" surgery, 16 had "pure-endoscopic" surgery, and 3 had "mixed" use. There were 18 nerve sheath tumors, 6 meningiomas, 6 cysts, 2 ependymomas, ranging in size from 1.5 to as large as 6.8 cm (21%≥4 cm), including 4 in craniovertebral junction (CVJ). Intermuscular or paraspinous approach was utilized, followed by small bony fenestration or interlaminar corridor. Even larger tumors could be excised using expandable ports or "sliding delivery" technique. Although visualization of sides and angles was better with endoscope, hemostasis and dural closure had steep learning curve, necessitating the use of microscope in the initial cases. Clinical improvement and radiological resolution could be achieved in all. There was no significant difference between the groups. The change in Nurick grade had significant correlation with only the dimension of lesion (p=.03) and preoperative grade (p=.05).

CONCLUSIONS: This is probably the first report of spinal endoscopy for intradural tumors in CVJ or as big as 7 cm. Endoscopy is effective and safe for even large tumors with better visualization of sides and angles, albeit with hemostasis and dural closure having initial learning curve. Wide heterogeneity of surgical terminologies in the literature on these procedures warrants consensus for uniform reporting.