[Metastatic epidural spinal compression: prognostic factors and results of radiotherapy]

A novel dynamic model for experimental spinal cord compression

Object. The goal of this study was to develop a novel dynamic model for experimental spinal cord compression that closely approximates neoplastic epidural compression of the spinal cord in humans.

Methods. In 30 New Zealand white rabbits, the thoracic spine was exposed via a posterior approach. On each side of one vertebral lamina a small hole was drilled caudal to the articular process. A silicone band was passed through these holes, forming a loop. The spinal dura mater was exposed via an interlaminar approach. The loop was brought into contact with the dura mater and fixed in its position encircling 270° of the circumference of the spinal cord. Thereafter, the loop was gradually tightened at set times by pulling at the ends of the band and fixing them again in their new position. The spinal cord was thus increasingly compressed in a circular and dynamic manner.

Neurological deficits of various degrees were created in all animals in the compression group, and the compressive effect of the loop was reliably demonstrated on MR imaging. After decompression of the spinal cord, the neurological deficits were reversible in the majority of animals, and MR imaging revealed either no signal changes or only circumscribed ones within the cord. In contrast, MR images obtained in animals that did not recover revealed the occurrence of extensive chronic myelopathy.

Conclusions. This novel model features reproducibility of paresis and neurological recovery. It is a dynamic model simulating circular tumor growth and is characterized by its easy, straightforward, and cost-saving applicability.

Clinical results of retreatment of vertebral bone metastases by stereotactic conformal radiotherapy and intensity-modulated radiotherapy

PURPOSE

Reirradiation of spinal tumors is limited by the tolerance of the spinal cord. We evaluated local control, pain relief, neurologic improvement, side effects, and survival rates after fractionated conformal radiotherapy (FCRT) and intensity-modulated RT (IMRT) of recurrent spinal metastases.

METHODS AND MATERIALS

Eighteen patients with 19 radiologic manifestations were retreated for recurrent spinal metastases using FCRT (n = 5) or IMRT (n = 14). All patients had previously undergone conventional RT (median dose 38 Gy). The indication for reirradiation was tumor progression associated with pain (n = 16) or neurologic symptoms (n = 12). The median time to recurrence was 17.7 months. The median total dose for reirradiation was 39.6 Gy.

RESULTS

The overall local control rate was 94.7% after a median follow-up of 12.3 months. Of 16 patients with pain, 13 experienced significant relief after reirradiation. Neurologic improvement was obtained in 5 of 12 patients. Tumor size remained unchanged in 84.2%. A partial response was seen in 2 of 19 patients. One patient had local tumor progression 9.5 months after reirradiation. Six patients received chemotherapy after reirradiation because of progressive distant metastases. Twelve patients died 10.5 months median after reirradiation. No clinically significant late toxicity was seen after FCRT or IMRT.

CONCLUSION

These data demonstrate that FCRT and IMRT are effective and safe in recurrent spinal tumors and can be offered to patients to achieve local control, as well as pain relief.