Subdural Collection Above the Surgical Site After Endoscopic Surgery: A Case Report.

Endoscopic decompression continues to expand its therapeutic scope in alleviating chronic back pain. Endoscopic decompressions are minimally invasive and have rare complications. This case details a unique occurrence of a subdural collection following an interlaminar endoscopic laminotomy, facetectomy, lateral recess, and left L5 decompression. The subdural collection manifested above the operative site, despite the absence of dural puncture during the intervention. Subsequent to the procedure, the patient reported significant pain relief and presented for a follow-up appointment, disclosing new symptoms which included new weakness in his hamstrings and burning pain in his bilateral feet. A repeat MRI revealed a subdural collection, the etiology of which remains unclear given the intact dura during the surgical procedure. The MRI showed no new herniation and had objective improvement where his decompression took place. While previous cases have documented subdural collections primarily in association with dural puncture, this instance is distinctive in that regard. An intriguing aspect specific to endoscopic procedures is the potential for injury related to irrigation pressure. This scenario raises the hypothesis of a hematoma formation within the subdural space, possibly due to trauma to bridging vessels between the dura and arachnoid membrane. Alternatively, an unexpected increase in intra-abdominal or thoracic pressure may have led to elevated spinal vessel pressure, particularly affecting radiculomedullary veins traversing both the subdural and subarachnoid spaces. Further investigation and clinical monitoring are warranted to elucidate the precise mechanism underlying this subdural collection and its implications for postoperative management.