Metastatic Tumor to the Spine: Compression and Instability

History

The patient is a 44-year-old woman with a prior history of left-sided nephrectomy for renal cell carcinoma. She presented 6 months later with acute mechanical back pain and intermittent urinary incontinence. She also complained of leg heaviness and difficulty with ambulation.

Examination

The patient was in mild distress. There was significant tenderness to palpation at the thoracolumbar junction. Motor exam was normal in the upper and lower extremities. Reflexes were symmetric and brisk. There was no clonus and no Babinski sign. Sensation was normal to pin prick throughout. Her gait was unstable, in part due to her back pain. Her Frankel score was E and her Karnofsky performance score was 80%.

Pre-Treatment Imaging

Metastatic work-up revealed significant pathology at the thoracolumbar junction, including pathological fracture at L1, and tumor involvement at the level above and within the canal causing severe compression on the conus (Figures 1a and 1b). The remainder of the metastatic work-up showed no other lesions.

Figure 1a: Sagittal T2-weighted MRI demonstrating pathological fracture at L1, tumor involvement above and into the canal causing severe compression of the conus.

Figure 1b: Axial T2-weighted MRI demonstrating pathological fracture at L1, tumor involvement above and into the canal causing severe compression of the conus.

Diagnosis

Pathological fracture of L1, with spinal cord compression, likely from metastatic renal cell carcinoma

Selected Treatment

Circumferential decompression and stabilization, followed by adjuvant therapy.

Given the patient's age, her high Karnofsky score, lack of visceral metastases, lack of diffuse systemic tumor burden, presence of a pathological fracture, presence of spinal cord compression (conus), and the relative radioresistence of renal cell carcinoma, the decision was made to proceed with circumferential decompression and stabilization.

After pre-operative emobolization, the patient first underwent posterior laminectomy and fixation, followed by second stage left-sided anterolateral corpectomy and fixation.

Post-Operative Imaging

Figure 2a: Post-operative AP upright x-rays demonstrating circumferential fixation.

Figure 2b: Post-operative lateral upright x-rays demonstrating circumferential fixation.

Figure 3: Post-operative 3D reconstructed CT image demonstrating circumferential fixation.

Outcome

Post-operatively, the patient's pain level immediately improved. She was ambulating with minimal assistance and her urinary retention had completely resolved. There were no immediate complications. She was transferred to inpatient rehabilitation after surgery, with post-operative adjuvant therapy planned as outpatient.

Case Discussion

Jeffrey S. Roh, MD

Director

Seattle Minimally Invasive Spine Center

Dr. Baaj is to be commended for his treatment and presentation of this unfortunate 44-year-old patient with metastatic renal cell carcinoma (mRCC). Typically, patients with mRCC tend to have a poor prognosis with average survival times ranging from 1-2 years following diagnosis. Sadly, the 5 year survival rate for patients diagnosed with mRCC is less than 10%, and approximately 40% of the patients with RCC ultimately succumb to death because of metastatic progression of the disease (Ramana J, BMC Research Notes, 2012).

In this patient with known L1 spinal metastases, high-grade stenosis of the conus, and urinary incontinence, surgical intervention is most definitely warranted. Although this patient appeared to have had a relatively high functional status prior to surgery, with a Karnofsky performance status scale rating of 80 (ie, normal activity with effort, some signs or symptoms of disease) and a Frankel Grade E, among the treatment choices provided, circumferential decompression and stabilization, followed by adjuvant therapy appears to be a very reasonable one.

Based on the imaging studies provided, a staged procedure involving:
(1) Stage I: T12 and L1 open laminectomies and instrumented posterior instrumentation spanning from T11-L3, and
(2) Stage II: L1 corpectomy and expandable cage placement via an open anterolateral approach appears to have been successfully accomplished.

Although it appears that the patient did relatively well, and the procedure itself was without significant complications, the only other approach-related consideration I would have entertained would have been to perform this procedure in a less invasive fashion. Based on the placement of the skin staples on the post-operative radiograph, the posterior skin incision alone appears to span from T8-L4. Apart from the scientifically-proven benefits of less invasive approaches on intra-operative blood loss and post-operative infection rates (Park Y, Spine, 2007; Smith J, Spine, 2011), an immunocompromised patient who would undoubtedly undergo post-operative adjuvant therapy (eg, radiation tx, chemo tx, immuno tx) could certainly benefit from an MIS approach.

My preferred approach would have been to perform the procedure in a similar staged fashion, but in a less invasive manner:
(1) Stage I: Bilateral T12 and L1 MIS hemilaminotomies and percutaneous T11-L3 instrumented posterior spinal fusions, and
(2) Stage II: L1 corpectomy and expandable cage placement via an MIS LLIF (Lateral Lumbar Interbody Fusion) technique.

Regardless of the approach or technique, however, Dr. Baaj deserves full credit and commendation for the thoughtful care and treatment of this patient with the unfortunate diagnosis of mRCC.