Bioseal Dural Sealing Study BIOS-14-001

Inclusion Criteria: * Preoperative 1. Patient undergoing elective craniotomy/craniectomy for pathological processes (such as benign and malignant tumors, vascular malformation) in the posterior fossa or in the supratentorial region. 2. Age ≥ 18 years. 3. Patients who are able and willing to comply with the procedures required by the protocol. 4. Signed and dated written informed consent from the subject or from his/her legal representative prior to any study-specific procedures. * Intraoperative 1. Patient undergoing elective craniotomy/craniectomy for pathological processes (such as benign and malignant tumors, vascular malformation) in the posterior fossa or in the supratentorial region and who are demonstrated to have persistent CSF leakage following suture closure of the dural incision. CSF leakage will be evaluated during a period of Valsalva of 10-20 cm of H20 for 5-10 seconds. If a spontaneous leak is apparent immediately after dural closure, no Valsalva will be performed. 2. Surgical wound classification Class I. Penetration of mastoid air cells during partial mastoidectomy is permitted. 3. The cuff of native dura along the craniotomy edge is ≥10 mm wide, to facilitate suturing and to allow for sufficient surface area for adherence of the investigational product. Exclusion Criteria: * Preoperative 1. Subjects with a dura lesion from a recent surgery that still has the potential for CSF leakage. 2. The previous craniotomy/ craniectomy within 6 months or radiation therapy within 2 years before this surgery. 3. Chemotherapy or radiation therapy scheduled within 7 days following surgery. 4. Subjects with severely altered renal (serum creatinine \>2 mg/dL) and/or hepatic function \[ALT, AST \> 5 x upper limit of norm (ULN)\]. 5. Severe Anemia (Hemoglobin \<60 g/L) or Hypoproteinemia (Total protein \<60 g/L or 6g% ) . 6. Non-compliant or insufficient treatment of diabetes mellitus \[glycosylated hemoglobin (HbA1c) \> 7.5%\]. 7. Conditions compromising the immune system; existence of autoimmune disease. 8. Evidence of a potential infection: fever \>38℃, WBC \<3500/uL or \>13000/uL, positive urine culture, positive blood culture, positive chest X-ray, evidence of infection along the planned surgical path. 9. Known hypersensitivity to the porcine fibrin sealant product. 10. Female subjects of childbearing potential with a positive urine or serum pregnancy test within 7 days prior to surgery. 11. Female subjects who are breastfeeding or intend to become pregnant during the clinical study period. 12. Participation in another clinical trial with exposure to another investigational drug or device within 30 days prior to enrolment. * Intraoperative 1. Native dura cuff during craniotomy/craniectomy that cannot be completely repaired. 2. Use of implants made of synthetic materials coming into direct contact with dura (e.g., PTFE patches, shunts, ventricular and subdural drains). 3. Occlusive hydrocephalus caused by posterior fossa pathology or partial blockage of CSF pathways during surgical procedure. 4. Existing CSF drains on the surgical path. 5. Use of other fibrin sealants for hemostasis. 6. Placement of Gliadel Wafers or similar products. 7. Persistently increased brain surface tension that may lead to an incomplete repair requiring. 8. Intersecting durotomy scars in the surgical path from a previous operation that cannot be completely removed by the planned dura resection. 9. Two or more separate dura defects during surgery. 10. Others in addition to above exclusion criteria, the subject, in the opinion of the investigator, would not be suitable for participation in the study.