Analysis of the Surgical Technique and Outcome of the Thoracic and Lumbar Intradural Spinal Tumor Excision Using Minimally Invasive Tubular Retractor System.

Background: Conventionally, intradural spinal tumor excision requires longer skin incision, bilateral subperiosteal muscle stripping, and total laminectomy, thereby decreasing the stability of the spine and increasing the morbidity. Minimally invasive surgery (MIS) for intradural spinal tumor excision preserves the posterior supporting structures of the spine in the midline and on the contralateral side and decreases morbidity and achieves the resection of the tumor.

Aims: The aim is to analyze the surgical technique and outcome of the thoracic and lumbar intradural spinal tumor excision using minimally invasive tubular retractor system.

Patients and Methods: A retrospective study was conducted in patients admitted with thoracic and lumbar intradural spinal tumors who had undergone tumor excision using minimally invasive tubular retractor system and satisfied the inclusion and exclusion criteria. Intradural tumors involving one or two vertebral levels were included in the study. Intramedullary spinal tumor, intradural tumor extending into intervertebral foramen, and intradural tumor involving more than two vertebral levels were excluded from the study. The study included the data of the 13 patients, who were operated between January 2017 and October 2018. The age and sex of the patients were noted. Gadolinium-enhanced magnetic resonance imaging scan and X-ray of the spine were taken in all the patients. The pre- and postoperative data analyzed include pain using visual analog scale (VAS), power using Medical Research Council (MRC) grading, myelopathy using Nurick's grade, sensory changes, and bowel and bladder symptoms. The steps involved in the surgical technique, extent of resection, intraoperative blood loss, duration of surgery, postoperative complications, duration of stay after the surgery, and postoperative X-ray were analyzed.

Results: Out of 13 patients, one case of dorsally placed meningioma was converted to open laminectomy and excision due to nonvisualization of the spinal cord and increased bleeding from the tumor. Hence, data of the remaining 12 patients were analyzed. The histopathology of these cases was meningioma (6), schwannoma (5), and neurenteric cyst (1). There were 5 men and 7 women with age group of 27-70 years (mean: 48 years). There were 8 thoracic and 4 lumbar tumors. The duration of symptoms was 2 days to 72 months (mean: 35 months). Eight cases were predominantly occupying on the right side and 4 cases on the left side within the spinal canal. The skin incision length was 25 mm to 35 mm (mean: 28 mm). We used tubular retractors with diameter ranging from 22 mm to 30 mm (mean: 24 mm). Expandable retractors were used in 9 cases (75%) and nonexpandable in 3 cases (25%). Tubular retractor of company Jayon (India) was used in 5 cases and PITKAR (India) in 7 cases. We have not found any significant difference in the usage of both the systems. The tumor size (craniocaudal) was ranging from 9.5 mm to 38 mm (mean: 19 mm). Intraoperative blood loss was 75-200 ml (mean: 115 ml). Gross total resection was achieved in 8 cases and near-total resection in 4 cases. Dura was sutured primarily in all the cases. The dural closure was done with continuous sutures in 6 (50%) cases and interrupted in 6 (50%) cases. Polypropylene suture was used in 10 cases and polyglactin suture in 2 cases of dural closure. The authors found it easy to suture the dura using 7-0 polypropylene. Fibrin sealant was used in 9 (75%) cases. The duration of the surgery was ranging from 160 min to 390 min (mean: 260 min). Cerebrospinal fluid leak and pseudomeningocele were noted in one case. One patient developed suture site infection. VAS for pain, sensory symptoms, Nurick's grade for myelopathy, and MRC grading for power were improved in all the affected patients. Out of two patients with constipation, one patient improved and the other developed incontinence, which was recovered on follow-up after 2 weeks. Out of the 4 patients with urinary symptoms, 3 were improved. Another patient of preoperative normal micturition developed urinary retention due to exacerbation of benign prostatic hypertrophy. Postoperative X-ray showed preserved spinous process and facet joints in all cases. The duration of the hospital stay was ranging from 2 days to 11 days (mean: 6 days).

Conclusion: Anteriorly or laterally placed intradural spinal tumors confined to the spinal canal can be excised safely and effectively using tubular retractor system, with adding the advantages of the MIS surgery. When in doubt, always convert the MIS to open surgery to avoid injury to vital structures.