Keyhole approaches to intradural pathologies

OBJECTIVE Spinal tumors account for 2%-4% of all tumors of the central nervous system and can be intramedullary, intradural extramedullary, or extradural. In the past, wide approaches were used to obtain safe access to these tumors, as complete resection is the goal in treating most tumor entities. To reduce surgical complications due to large skin incisions and destabilizing laminectomies, minimally invasive approaches were established. In this study, the authors share their experience with mini-open approaches to intradural tumor pathologies. METHODS The authors retrospectively reviewed cases involving patients with intramedullary and intradural extramedullary lesions treated between 2009 and 2016. They present their surgical mini-open approach to the spinal cord as well as unique characteristics, key steps, and postsurgical complications for specific tumor subgroups (meningioma, neuroma, and intramedullary tumors). RESULTS A total of 245 intradural tumors were surgically treated during the study period. Of these lesions, 151 were intradural extramedullary meningiomas (n = 79) or neuromas (n = 72). Nine (12.5%) of the neuromas were dumbbell neuromas. Ninety-four tumors were intramedullary. The mean age of the patients was 51.4 years, and 53.9% were female. The mean duration of follow-up was 46.0 months. All meningiomas and neuromas could be resected using a mini-open keyhole approach, but only 5.3% of the intramedullary lesions could be accessed using this technique. Of the 94 patients with intramedullary tumors, 76.6% required a laminotomy, 7.4% required a hemilaminectomy, and 10.6% required a 2-level laminectomy. Only 2 of the patients with intramedullary tumors needed stabilization for progressive cervical kyphosis during follow-up. None of the other patients developed spinal instability after undergoing surgery via the mini-open (keyhole/interlaminar) approach. There were significantly more surgery-associated complications in the large exposure group than in the patients treated with the mini-open approach (19.1% vs 9.6%, p < 0.01). CONCLUSIONS Intradural extramedullary and in selected cases intramedullary pathologies may safely be resected using a mini-open interlaminar approach. Avoiding laminectomy, laminotomy, and even hemilaminectomy preserves spinal stability and significantly reduces comorbidities, while still allowing for complete resection of these tumors.