An intracranial hematoma is a rare, yet significant, complication following spinal surgery. The authors describe two cases with acute intracranial hematoma formation after excision of a cervical subdural schwannoma. One was a 14-year-old girl who developed bilateral intracranial extradural hematomas immediately following excision of the C4 subdural schwannoma. The other was a 59-year-old woman who had an acute cerebellar hematoma after removal of the C2-C5 subdural schwannoma. During the surgeries of both cases, spinal dura was partially removed together with the tumor and the dural sac could not be repaired, resulting in large amounts of intraoperative CSF loss and persistent postoperative CSF leakage. Both patients failed to regain consciousness from anesthesia after surgery, and a cranial CT scan identified large intracranial hematomas. Urgent hematoma evacuation was ultimately performed to save the patients. Based on the authors' experience and literature review, a conclusion was drawn that considerable CSF leakage and a sharp decrease of CSF pressure are common features during the excision of a spinal subdural tumor, which may lead to acute intracranial hematomas. Continual postoperative monitoring in patients with this condition should be of a very high priority. A CT or MRI should be immediately investigated to exclude intracranial hematomas for any patient with delayed emergence from anesthesia following spinal surgery. Hematoma evacuation is indispensable once an intracranial hematoma is identified in the patient who fails to regain consciousness from anesthesia post surgery. Furthermore, the possible pathophysiological mechanisms responsible for the formation of an intracranial hematoma after spinal procedures, particularly after manipulations of a cervical subdural tumor, are discussed.