The incidence of subacute subdural hematoma (SSH) is increasing in our aging society. As we all know, many patients were treated with anticoagulants or antiplatelets prior to injury. Traumatic brain injury (TBI)patients with antiplatelet and anticoagulant were associated with increased risk of delayed hematoma enlargement, leading to the risk of increased morbidity and mortality. Creation of a large bone flap during craniotomy for evacuation of hematoma might be due to more trauma and bleeding than burr hole surgery 12. Evacuation cannot be achieved by bur hole drainage if the hematoma is not fully liquefied. There is currently no standard approach for the treatment of subacute subdural hematomas.4,10,13
We previously reported that endoscopic removal of intracerebral hematomas arising from spontaneous non-vascular malformations achieved satisfactory results.9 In this study, endoscopic removal of subacute subdural hematomas was performed. The small bone window created in the present study group was slightly larger than that made in burr hole drainage, but a much smaller window was created than that used in common bone flap craniotomy in control group.
Feasibility of endoscopic subacute subdural hematoma removal through a small bone window
When only a part of the hematoma is liquefied, burr hole drainage cannot achieve complete evacuation. Since the brain tissue is compressed for a relatively prolonged period of time, it does not immediately recover during the hematoma removal. So, the surgeon has enough space to remove the hematoma that is located in the proximal to distal of the bone window. As there is no active bleeding at this stage. The neurosurgeon does not require searching for the bleeding point after hematoma evacuation most of the time.1
Advantages of endoscopy
Endoscopic subacute subdural hematoma removal through small bone window can overcome the shortcomings of burr hole drainage, wherein the inner part of the hematoma capsule cannot be observed. The endoscope allows easy removal of the hematoma under direct visualization through a small bone window, ensuring safety of the operation. Coagulation at the bleeding site can be induced by an aspirator with bipolar hemostasis capability. The endoscope can guarantee optimal position of the drainage tube.11
Hematoma removal skills
After opening the dura, evacuation of the hematoma was facilitated by endoscope-guided suction under direct visualization. In some patients, a bridge vein was observed in the capsule cavity, wherein a great care should be taken to avoid injury. The hematoma cavity can be repeatedly rinsed with Ringer’s solution until the water turns clear to reduce the osmotic pressure of the hematoma capsule. Aspiration should be gentle and meticulous to avoid brain injury and bridge vein damage. If bleeding occurs, electrocoagulation for hemostasis can be induced by bipolar hemostasis by using a suction device. After endoscopic placement of a drainage tube within the capsule in the optimal position, the periosteum can be removed to repair the dura and prevent the entry of epidural blood into the hematoma capsule. The bone flap is then replaced and fixed.
In this study, the median time from incision to suture completion was 40 min (range: 31.25–43.75 min) for endoscopic group, and 70 min (range: 65–80 min) for open surgery group (P<0.01). Moreover, the endoscopic surgery was more micro-invasive, causing less iatrogenic injury, with less intraoperative bleeding and better GCS recovery the day after surgery.
Patients with acute subdural hematoma were excluded from this study due to the following reasons. 1) In cases with acute subdural hematoma, the hematoma volume continued to increase, making the site of bleeding difficult to find; and sometimes the combined brain contusion injury requires evacuation. 2) These patients often had high brain pressure during hematoma evacuation, with quick brain tissue swelling. This would in turn make the removal of distant hematoma through the bone window difficult or would require stretching of the brain by brain retractor to create working canal, probably leading to tissue damage. 3) In some of these patients, decompression of the bone flap is needed, which is not possible by our endoscopic method.
Although endoscopic evacuation of subacute subdural hematomas is promising, the sample size in the present study was small. So, a prospective randomized controlled study is warranted to more thoroughly evaluate the effectiveness of this approach.