Graded Spinal Cord Injuries Produced in Rabbits with Non-Invasive Microwave Hyperthermia

ABSTRACTThe use of non-invasive microwave energy to produce spinal cord injuries with intraspinal hyperthermia was studied in experimental animals. Lesions were produced with external beam microwave irradiation at 915 MHz in rabbits, using intraspinal temperature levels from 40 to 43 degrees C., and periods of heating ranging from 15 to 60 minutes. The parameters which determined thermal dose were the degree of temperature elevation in the spinal cord relative to the body core and the duration of that elevation. Thermal doseresponse relationships were established by monitoring intraspinal temperatures during heating using an epidural thermistor probe at T8. Animals were examined 48 hours after lesion production and assigned a neurological grade. Injuries were grouped clinically according to their degree of relative functional severity as minimal, mild, moderate, or severe. Evaluation of spinal cord integrity was carried out by recording cortical somatosensory evoked responses (SER) following sciatic nerve...