Stereotactic percutaneous cryoablation technique for spinal tumor lesion: pilot study

Abstract

INTRODUCTION: Percutaneous cryoablation is a method of minimally invasive treatment of patients with metastatic bone lesions, which is also used for lesions of the vertebrae. The spine is one of the most difficult anatomical areas for ablation due to the risk of mechanical and thermal damage to the spinal cord and adjacent structures. OBJECTIVE: Consideration of methodological aspects of performing minimally invasive percutaneous cryoablation in metastatic lesions of the vertebrae, clarification and systematization of puncture stereotaxic approaches. MATERIALS AND METHODS: The cryoablation procedure was performed in 10 patients. The sizes of metastatic lesions varied from 8 to 45 mm (34.6±9.7 mm). Positioning of cryoprobes was performed in sequential mode using the «free hand» method or using a robotic navigation attachment to a CT scanner. The process of installing cryoprobes and ablation was monitored using a multislice computed tomograph. Number and diameter of cryoprobes determined taking into account the characteristics of the lesion; in one procedure used from 1 to 3 cryoprobes. The PCA procedure included two cooling cycles to a temperature of –190 four °C with an exposure of 10 and 7 minutes, with automatic temperature maintenance at the set parameters and continuous temperature monitoring between cycles. After the end of ablation, active and passive thawing modes were used. Dimensions ice ball was assessed at periodic CT scans with an interval of 2–3 minutes. RESULTS: Two patients without previous pain syndrome using costovertebral and transforaminal approaches after the procedure developed a pain syndrome of 4–5 points on a digital analogue scale, which required medical analgesic correction using, among other things, narcotic analgesics. In a patient in the case of transforaminal access, the pain syndrome completely resolved within 7 days; in the second case, the pain decreased to 2 points, but persisted for 3 weeks. In 4 patients with previous pain syndrome after PCA, its decrease to 0–2 points was noted. These changes in 2 patients persisted throughout the entire observation period (more than 6 months), in 2 patients the effect was observed for 1 and 3 months; the resumption of pain was due to the local progression of the tumor process. In general, local tumor control was achieved in 7 patients (follow-up period 6–14 months). In 3 patients, according to the control CT scan, continued growth of metastases was established, while in all these clinical cases, the size of the foci before PCA exceeded 4 cm. DISCUSSION: In PCA of the vertebrae, a wide range of puncture approaches can be used: transpedicular, costovertebral, transforaminal, posterolateral, and posterior. The choice of the optimal variant depends on the spine and the features of localization, shape, size and structure of the lesion. CONCLUSION: When performing PCA of metastatic foci in the thoracic and lumbar spine, most of the known puncture approaches can be used. In case of marginal destruction of the vertebral body, posterolateral (in the thoracic region) and posterior (in the lumbar region) puncture approaches can be used, in which the cryoprobe is installed paravertebral, without direct perforation of the bone.