Risk Evaluation of Thermal Injury to the Cervical Spine during Intradiscal Laser Application in Vitro

Objective: We aimed to investigate temperature distribution during laser and its possible thermal damage to the neurovascular structures. Background Data: Percutaneous laser disc decompression (PLDD) is now being performed as a minimally invasive intradiscal technique for the operative therapy of non-sequestered herniated cervical discs. As yet, no experimental basic research has been reported with regard to temperature rise and distribution in the cervical region during laser radiation. Materials and Methods: An in vitro laser procedure was performed on human cervical intervertebral discs under standardized conditions. A thermo-camera was used to monitor in real-time the zones sensitive to temperature increase. Results: Average intervertebral disc volume was 2000 mm³. With a total enegy conduction of 600 Joules, a temperature increase of around 30°C was shown with an initial temperature of 28°C at the posterior longitudinal ligament lying immediately in front of the myelon. The defect volume was less than 1% of the total intervertebral disc volume. Conclusion: If, during laser application, the total amount of conducted energy is too high, with an unfavorable position of the fibers in the intervertebral space, there is a risk of thermal damage to the spinal cord and nerve roots.