A 53-year-old female patient presented to our emergency room with subarachnoid hemorrhage (SAH) and intracerebral hemorrhage (ICH) after undergoing burr hole trephination and catheter drainage at a local hospital. She did not exhibit any neurologic deficits and only complained of severe headache. Upon reviewing her transfer request, we discovered that she had experienced progressive headache, transient motor weakness, and mild dysarthria for a month. Preoperative neuroimaging assessments with magnetic resonance (MRI) and angiography (MRA) revealed no abnormalities other than a subdural hygroma with arachnoid cyst (Figure 1). The local hospital was unable to find any other cause for the mild dysarthria and transient motor weakness; therefore, they determined that the subdural hygroma was the cause of the patient's symptoms. She underwent evacuation of the subdural hygroma through burr hole trephination. A subdual drainage catheter (12 Fr round catheter) was placed in the subdural space, but only 130 cc of cerebrospinal fluid (CSF) was drained over a 24-hour period and the headache persisted postoperatively and became more severe. An emergency brain computed tomography (CT) scan revealed a newly developed ICH and SAH in the contralateral hemisphere and SAH in the ipsilateral hemisphere (Figure 2). Thereafter, the local hospital transferred the patient to our emergency room for evaluation and treatment of the remote hemorrhage.

No other causes of remote hemorrhage in the contralateral hemisphere (e.g., vascular abnormalities) were identified upon reviewing the findings of the previous brain MRA examination (Figure 3). According to the local hospital's medical records, she was not on any anticoagulation and antiplatelet medications and her coagulation panel showed findings within the normal limits (prothrombin time [PT] time 10.0 seconds, PT international normalized ratio [INR] 0.93 and activated partial thromboplastin time [aPTT] 21.8 seconds). During the operation, the patient's condition was stable and blood pressure (BP) was within the normal limits. Therefore, the remote hemorrhage was suspected to be related to CSF overdrainage through the subdural drain after the burr hole trephination. We closed the subdural catheter and the patient's headache gradually subsided. Follow-up brain CT scans were performed 5 and 14 days after the catheter closure. SAH and ICH had resolved and the subdural space was refilled with CSF. One month later, the patient returned to a normal daily life.

A 78-year-old female patient presented to our outpatient department with complaints of progressive general weakness and cognitive impairment that began a month ago. She was diagnosed with mild dementia and was admitted to a convalescence hospital but was not prescribed any medications. Despite the patient's ability to self-care at the onset of symptoms, she was unable to take care of herself or walk at the outpatient visit. Brain CT revealed bilateral subdural hygroma or bilateral CSDH with the loss of sulci markings on the cerebral hemispheres. Brain atrophy was also observed (Figure 4). Considering the rapid progression of symptoms, surgery was performed to treat the bilateral lesions. CSDH can often be misdiagnosed as a subdural hygroma on brain CT. However it was thought be SDH due to reddish brown fluid with clots in the operation filed. The patient underwent evacuation through 2 burr holes (one at each parietal eminence) and catheters were placed into the subdural space through both the holes to prevent further blood accumulation. The vital signs, including BP, were normal during surgery. The patient showed improvements in cognitive and motor functions postoperatively. There was no catheter drainage on the first two days postoperatively; however, 400 cc of subdural fluid with CSF and blood was drained from the right side drainage catheter over a 24-hour period on postoperative day 3. The patient did not exhibit any changes in the neurologic symptoms, but complained of intermittent headache. An emergency brain CT scan revealed a newly developed hemorrhage in the right subdural space and a small amount of intraventricular hemorrhage (Figure 5). CSF overdrainage was considered a possible cause of the remote hemorrhage; therefore, we removed the drainage catheters. When we reviewed the previous images, suspected arachnoid cysts were observed in the right temporal lobe (Figure 4). One month after the surgery, a follow-up CT scan showed absorption of the hemorrhage and the area where the suspicion of the arachnoid cyst was disappeared.