Unusual subcutaneous air collection and lipoid meningitis as a complication of fat migration after retrolabyrinthyine vestibular schwannoma resection: Case report and review of the literature

Background Autologous fat grafting is considered a simple, safe technique for reconstructing and optimizing dural closure in skull base surgeries rarely associated with complications. It showed successful results after skull base vestibular schwannoma and meningiomas resection. This article reports a rare case of postoperative lipoid meningitis and surgical site subcutaneous air collection following subarachnoid fat migration from an autologous fat graft after retrolabyrinthine vestibular schwannoma resection. Case description: A 63-year-old woman who underwent resection of a right vestibular schwannoma via a right retrolabyrinthine pre-sigmoid approach. Intraoperatively, a free fat graft was harvested from the right buttock to close the craniotomy defect. One month later, she returned to the emergency department with intermittent headaches, low-grade fever, neck stiffness, and general malaise. No signs of cerebrospinal fluid leakage were noted on examination. Based on laboratory investigations and imaging, she was admitted under suspicion of bacterial meningitis and treated with antibiotics accordingly. However, no organisms were observed in the culture and staining tests. Ultimately, multiple locules of fat were observed throughout the brain, leading to a final diagnosis of lipoid meningitis, in addition to the presence of unexplained, unusual subcutaneous air collection in the surgical cavity. Conclusion This case report demonstrates rare complications following subarachnoid fat migration from an autologous fat graft after retrolabyrinthine vestibular schwannoma resection. Similarly, it illustrates the clinical presentation and appropriate treatments for lipoid meningitis, informing physicians of the need to distinguish bacterial meningitis from lipoid meningitis.