Abstract
Objectives: Epidural phenol neurolysis for severe cancer pain has been linked to complications such as paraplegia and urinary incontinence. Given the ease of administration of epidural injections, proof of the safety and efficacy of epidural phenol injection would increase the popularity of this procedure for cancer pain relief. This study was conducted to evaluate the analgesic effects and histopathological changes in the spinal nervous system of rabbits after epidural administration of phenol.
Materials and methods: Under pentobarbital anesthesia, percutaneous epidural catheterization at the level of the L6–L7 lumbar interspace was conducted in 16 rabbits. After epidurography using 0.3 ml of iopamidol, 0.3 ml of 7% phenol in saline was injected through the catheter into the epidural space of 15 rabbits, and 0.3 ml saline was epidurally injected in one rabbit serving as control. Motor function and analgesia were investigated on days 1 and 14. On day 14, the spinal cords were resected and processed for histopathological study.
Results: The analgesic area extended over 4.9 ± 1.2 spinal segments (mean ± SD) on day 14. Motor weakness was seen in 5 of 15 rabbits on day 14. Histopathological examination revealed spinal cord and root damage in all phenol-injected rabbits.
Discussion: Damage to the spinal cord and anterior roots were seen in all phenol-injected rabbits, suggesting that epidural phenol neurolysis ought to be used in only those areas where the resultant motor weakness can be ignored.