This 69-year-old woman suddenly developed nausea and headache followed on the next day by bouts of vomiting and gradual mild consciousness disturbance. At the time of admission to our hospital, she had mild consciousness disturbance (Glasgow Coma Scale [GCS] = 14) and her drowsiness increased (GCS = 13). She also had right dominant limb ataxia. She had undergone mitral valve replacement with a mechanical valve earlier and was on anticoagulation therapy. She also suffered from diabetes mellitus, rheumatoid arthritis, had an old vertebral compression fracture, old pulmonary tuberculosis, and an old brain infarct from cardiogenic embolism. There was no history of trauma. As laboratory data showed hypercoagulation (prothrombin time-international normalized ratio: 6.0), we reversed her status by administering Vitamin K. Computed tomography (CT) revealed a low- to high-density area in the subdural space of the posterior fossa and narrowing of the fourth ventricle [Figure 1a]. Magnetic resonance imaging (MRI) demonstrated a mass in the subdural space of the bilateral cerebellar hemispheres. On T1-weighted images, it ranged from hypo- to hyper-intense; on T2-weighted images, it was hyperintense. These findings were suggestive of CSH [Figure 1b and c]. Under a diagnosis of bilateral spontaneous CSH, she underwent surgery to prevent further neurological deterioration.
With the patient under general anesthesia and in the prone position, we used the midline suboccipital approach and performed bilateral suboccipital craniectomy [Figure 2a]. Intraoperatively, we encountered unexpected bleeding from a single occipital sinus that wound to the right and was well developed [Figure 2b]. Noncontrast CT and magnetic resonance angiography did not show its course. Bleeding was stopped with hemoclips. The outer membrane of the CSH was observed after dural incision [Figure 2c]. Dark brown fluid was evacuated, and the cavity was irrigated with saline. We resected the outer membrane in our field of vision and coagulated the residual outer membrane. As there was insufficient cerebellar re-expansion, we placed a drain in the subdural space and closed the wound. The outer membrane specimen was examined histopathologically.
Immediately after surgery, her dizziness and consciousness disturbance disappeared. The drain was removed on the postoperative day (POD) 1. CT and MRI studies showed no residual mass effect in the fourth ventricle [Figure 1d-f]. Her earlier vertebral compression fracture and rheumatoid arthritis worsened, and she underwent delayed rehabilitation. On POD 19, she was transferred to a rehabilitation hospital without neurological disturbance.