Spinal Adhesive Arachnoiditis Mimicking a Spinal Tumor: A Case Report.

Spinal adhesive arachnoiditis (SAA) is a rare condition of the meningeal layers of the spinal cord and nerve roots, which can lead to disability. Our patient was a 44-year-old female with a history of cervical spine surgery, followed by external lumbar drain insertion for cerebrospinal fluid (CSF) diversion three years ago. She presented with gradually worsening back pain and bilateral leg weakness. Initial evaluation and MRI of the lumbosacral spine suggested the presence of a spinal tumor. She underwent lumbar spine surgery. But no tumor was identified intra-op; instead, dense arachnoid adhesions encasing the nerve roots were identified, for which partial adhesiolysis was done. Surprisingly, the retained proximal catheter of the lumbar drain was found embedded within adhesions encasing the nerve roots. How it was left in place and missed during the previous drain removal remains unknown and is not documented in the prior treatment records. Though MRI is the most sensitive and specific diagnostic imaging, SAA can mimic an intradural tumor. Despite current knowledge of the nature of adhesive arachnoiditis, as well as advances in treatment and intensive rehabilitation, there are still no established guidelines for prophylaxis, and neurological improvement remains rare. This case report highlights the possible pathophysiology, causes of SAA, and treatment options available for this rare condition.