First case of mechanical compression by methylprednisolone crystals following transforaminal lumbar nerve root block for left sciatic pain leading to hyperesthesia and progressive weakness: A case report

Introduction: Lumbosacral nerve root blocks and epidural corticosteroid injections are commonly used for short-term pain relief among patients with degenerative spinal disc disease. Serious complications following these injections are rare, and there are only a few published papers on this subject. It is important that spine surgeons are aware of the potential complications, and the possible factors that contribute to such complications. Presentation of case: 32-year-old Lebanese female presented with progressive weakness and hyperesthesia following a transforaminal lumbar nerve root corticosteroid particulate injection. The case was managed by surgical lumbar decompression. Discussion: Neurological complications following transforaminal/selective nerve root block are the most feared of all possible associated complications with epidurals blocks. It has been hypothesized that such a complication is mainly due to a spinal cord infarct from corticosteroid crystal. However, there are no previous reports that such progressive weakness and hyperesthesia could be due to the mechanical compression caused by corticosteroid particulate crystals themselves as confirmed in the current case. Conclusions: Progressive weakness and hyperesthesia following nerve root block could be due to the effect of the corticosteroid particles used in the injectate. Such complications could be simply avoided by the use of more dilutional volume of the local anaesthetic agent and/or using a non-particulate corticosteroid in order to avoid the adherence of the corticosteroid crystals to the nerve root sheath. This is the first case of post-nerve root block neurological complications due to mechanical compression caused by corticosteroid particulate crystals.