Severe pneumocranium after gamma knife stereotactic radiosurgery for brain metastasis: A case report and literature review

Rationale:Gamma knife stereotactic radiosurgery (GKRS) is a recognized safe and effective treatment for brain metastasis; however, some complications can present significant clinical challenges. This case report highlights a rare occurrence of cerebrospinal fluid (CSF) leakage and pneumocranium following GKRS, emphasizing the need for awareness and prompt management of these complications.Patient concerns:A 35-year-old male with a history of malignant neoplasm of the lip in 2015 and perineural spread of malignancy into the left cavernous sinus was treated with GKRS in 2017. The patient was admitted emergently 39 days after discharge due to persistent headache and dizziness.Diagnoses:Brain computed tomography (CT) revealed diffuse bilateral pneumocranium alongside an observation of CSF leakage.Interventions:A surgical procedure involving a left frontal-temporal craniotomy was performed to excise a residual skull base tumor and repair the dura, guided by a navigator system. The conclusive pathological assessment revealed the presence of squamous cell carcinoma markers.Outcomes:The patient exhibited excellent tolerance to the entire procedure and experienced a prompt and uneventful recovery process. After surgery, the symptoms alleviated and CSF leak stopped. The follow-up image showed the pneumocranium resolved.Lessons:Pneumocranium due to early-stage post-GKRS is uncommon. The rapid tumor shrinkage and timing of brain metastasis spreading through the dura can lead to CSF leak and pneumocranium. We reviewed current treatment options and presented a successful craniotomy-based dura repair case.