Minimally Invasive Resection of an Intradural Spinal Tumor

History

A 38-year-old female presents with low back pain with one-year history of pain radiating from the buttock into the left leg and lateral aspect of the foot.

Examination

The patient's neurological examination is notable for full strength, positive left straight leg raise, and mild S1 hypesthesia.

Prior Treatment

Physical therapy and epidural injections did not effectively resolve the patient's symptoms. There was mild improvement with gabapentin.

Preoperative Imaging

MR imaging demonstrates a small contrast-enhancing intradural lesion, left L5-S1, travelling within the S1 root sleeve.

Figure 1. Preoperative Axial T2

Figure 2. Preoperative Axial T2

Figure 3. Preoperative Axial T1 with Contrast

Diagnosis

Intradural spinal tumor

Selected Treatment

Given the patient's progressive symptoms and desire to establish a tissue diagnosis and likelihood for surgical cure, she elected for resection.

A left L5-S1 laminectomy, medial facectectomy and gross total intradural tumor resection via an expandable tubular retractor (6cm length, opened to 22mm diameter).

Intraoperative Imaging

Figure 4. Expanded nerve root sleeve from the intradural tumor

Figure 5

Figure 6. Schwannoma

Figure 7. Normal rootlet

Figure 8. Suture line from the dural repair

Figure 9. Fibrin glue

Postoperative

• Normal motor function bilateral lower extremities
• S1 numbness in the left leg; most dense in the foot
• Decreased left ankle reflex
• Significant improvement of preoperative leg and back pain
• No cerebrospinal fluid leak
• Pathology: Schwannoma

Outcome

At one-month postop, the patient's MR imaging showed diffuse epidural enhancement at the surgical site consistent with scar, and without residual tumor.

Figure 10: Postoperative Axial T2

Figure 11. Postoperative Axial T1 with Contrast

Authors' Discussion

Joshua M. Ammerman, MD

Neurosurgeon

Washington Neurosurgical Associates

• Spinal schwannomas are the most common intradural extramedullary spinal tumor.
• While stereotactic radiotheray is an option, the primary treatment modality is cure via gross total resection.
• The primary challenge for minimally invasive resection is adequate dural repair--bayonetted instruments, self-closing U-clips, tissue glue.

As compared to open techniques, minimally invasive procedures have been demonstrated to show:

• Equivalency in length of the procedure
• Length of stay
• Extent of resection
• ASIA score improvement
• Recurrence rate
• Superiority in blood loss

References
Raygor KP, Than KD, Chou D, et al. Comparison of minimally invasive transspinous and open approaches for thoracolumbar intradural-extramedullary spinal tumors. Neurosurg Focus. 2015;39(2):E12.

Nzokou A, Weil AG, Shedid D. Minimally invasive removal of thoracic and lumbar spinal tumors using a nonexpandable tubular retractor. J Neurosurg Spine. 2013;19(6):708-715.

Park P, Leveque JC, La Marca F, et al. Dural closure using the U-clip in minimally invasive spinal tumor resection. J Spinal Disord Tech. 2010;23(7):486-489.

Case Discussion

Harel Deutsch, MD

Associate Professor

Rush University

The case involved a 38-year-old woman with back pain and left leg pain who was otherwise neurologically intact. Her MRI showed a left S1 nerve root tumor with enhancement of the tumor on a post gadolinium MRI.

The most likely diagnosis was a schwannoma, although a neurofibroma is also a possibility. Surgery allows for establishment of the pathology. The discussion mentions possible stereotactic radiotherapy to treat this tumor. I don't think treating a benign, easily resected tumor in a young patient with radiation would be reasonable.

Certainly in older patients or patients who are minimally symptomatic, observation of this tumor would be reasonable. The surgery was done through a tubular retractor with excellent results. Surgery through an open approach would have yielded similar results.