Managing a Large Intradural Spinal Arachnoid Cyst: An Anesthesiologist’s Perspective

Dear Editor, Spinal arachnoid cysts are rare spinal lesions with an incidence of approximately 1%–2%. Intradural arachnoid cysts form only 10% of these lesions.1,2 They are mostly congenital but can also develop due to traumatic and inflammatory etiologies, such as neuraxial blocks.3 We report the case of a 12-year-old girl presenting with low back pain, neurogenic bladder, and recurrent urinary tract infections. She was on intermittent self-catheterization and oral mirabegron therapy. There was no history of previous surgeries involving neuraxial anesthesia. Magnetic resonance imaging of the spine showed a dorsal intradural arachnoid cyst extending from the D2 to D10 level Figure 1. The patient underwent D3, D5, and D9 skip laminectomy with cyst fenestration under general anesthesia with intraoperative neuromonitoring (IONM) guidance.Figure 1: T2-weighted sagittal magnetic resonance imaging of the dorsal spine showing focal dilatation of the intradural space posteriorly from D2 to D10 levels (red arrows), suggestive of dorsal intradural arachnoid cyst. The dorsal spinal cord is displaced anteriorly and mildly compressed in the middorsal region by the lesion (yellow arrows)Our goal was a balanced anesthetic technique that ensures adequate depth and good analgesia without interfering with IONM. In the operating room, standard monitors and bispectral index (BIS) electrodes were attached, and intravenous (IV) access was secured. Midazolam 1 mg was intravenously administered for anxiolysis. Anesthesia was induced with remifentanil 0.5–1 µg/kg IV over 1 minute and propofol 2–3 mg/kg IV. Endotracheal intubation was facilitated with atracurium 0.5 mg/kg IV. Anesthesia was maintained using total intravenous anesthesia (TIVA) with propofol, dexmedetomidine, and remifentanil. Propofol was administered via target-controlled infusion (TCI) targeting a predicted plasma concentration (Cp) of 3–4 µg/mL (Kataria model). Dexmedetomidine was administered at a loading dose of 1 µg/kg over 10 min, followed by an infusion of 0.5 µg/kg/h, and remifentanil was infused at 0.25–0.5 µg/kg/h. Infusions were titrated to maintain a BIS between 50 and 60. Erector spinae plane block provides good analgesia, aborts the neuroendocrine stress response, and ensures stable hemodynamics without interfering with IONM.4 Under ultrasound guidance, 5 mL of 0.25% bupivacaine was deposited below the erector spinae muscle D3, D5, and D9 levels bilaterally. After completion of the laminectomy, cyst fenestration, and dural closure, a global depression in IONM signals was observed. Immediate measures included administration of 100% oxygen, reduction in anesthetic depth, cessation of controlled hypotension, and replacement of blood loss. Methylprednisolone was administered as a 30 mg/kg bolus IV over 60 min, followed by an infusion of 5.4 mg/kg/h. These maneuvers resulted in the restoration of IONM signals to baseline levels. One hour before extubation, morphine 0.1 mg/kg IV and paracetamol 15 mg/kg IV were administered, and dexmedetomidine and remifentanil infusions were discontinued. The patient was extubated smoothly, and the postoperative course was uneventful. In conclusion, this case highlights the successful anesthetic management of a rare case of a large intradural spinal arachnoid cyst. TIVA with TCI offers analgesia, hemodynamic stability, and smooth emergence, and minimizes blood loss without interfering with IONM. Combined with BIS, this minimizes the risk of awareness during IONM, while ensuring patient immobility. Awareness of the anesthesiologist regarding factors affecting neurophysiological monitoring is essential for optimal outcomes. Acknowledgments Artificial intelligence tool ChatGPT was used exclusively for grammar checking and language refinement, and the authors remain fully responsible for the content. No AI tool was used to generate scientific content or to interpret data. Financial support and sponsorship Nil. Conflicts of interest There are no conflicts of interest. Author contributions Concepts: SR. Design: SR. Definition of intellectual content: SR. Literature search: SR. Manuscript preparation: SR. Manuscript editing: KS. Manuscript review: KS. Guarantor: SR.