Endoscopic assisted key-hole surgery for subacute subdural hematoma evacuation in emergency situations

Background Endoscopic removal of subacute subdural hematoma is seldom performed, but there is no standard technique till date. We investigated whether a simple endoscopic method is effective for the evacuation of subacute subdural hematoma. Methods A total of 51 patients with subacute subdural hematoma requiring surgery were enrolled in this study. Endoscopic hematoma evacuation was performed through a small bone window for 22 patients. Hematoma evacuation by open surgery was performed in 29 patients. Pre- and postoperative Glasgow coma scale (GCS), operation time, displacement of midline, and intraoperative blood loss were recorded and analyzed. Results 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). The average total blood loss was 50(30-50) ml for endoscopic group, and 250(200-300) ml for open surgery group (P<0.01). No patient showed post-operative re-bleeding in both groups. The mean preoperative mid-line displacement for the two groups was 11.51±3.51mm for study group vs 10.47±2.93mm for control group (P>0.05). Mid-line displacement showed significant improvement on the day after surgery to 5.29±1.91mm for study group vs 6.75±1.37mm for control group (P<0.01). At 1-month follow-up, the midline was normal in both groups. Computed tomography revealed almost no residual hematoma, representing an average evacuation rate of 100% in both groups. The mean preoperative GCS score was 13(12.25,15) for study group vs 13(12,14) for control group(P>0.05). GCS score on the day after the operation was improved to 15 for each patient in endoscopic surgery group, while 15(14,15)in the open surgery group (P<0.01). Conclusions Endoscopic subacute subdual hematoma removal through a small bone window achieved a satisfactory hematoma removal with minimally invasive method when compared to open surgery.


Introduction
Cranioplastic craniotomy, or even large decompressive craniectomy is needed for removing the acute subdural hematoma. 2,3,5,6 The surgical approach that is used for chronic cases is the Burr-Hole Drainage, 8 whereas subacute cases were treated by craniotomy or Burr-Hole Drainage. Burr-Hole Drainage is a less invasive procedure that is performed after complete liquefaction of the 3 hematomas. 7 We herein reported cases of subacute subdural hematoma requiring emergency surgery due to progressive neurological dysfunction or patients with a decreased level of consciousness. These patients were treated by means of small bone window craniotomy endoscopic hematoma evacuation, and achieved satisfactory results.

Patient population
A total of 22 patients were included in the study group, another 29 patients were enrolled as control group. Preoperative hematoma volume and postoperative residual hematoma volume were calculated automatically with 3DSlicer software (https://www.slicer.org/). Pre-and postoperative GCS, bleeding volume, operation time, and intraoperative blood loss were recorded. The study protocol was approved by the Hospital Ethics Committee (PLA General Hospital, Beijing China) and patients or their family members provided informed, written consent.

Inclusion and exclusion criteria
Patients with subacute subdural hematoma requiring surgery (based on the number of days from the time of injury and hematoma density from a cranial computed tomography [CT] scan) were included in the study. Patients with severe clotting disorders or for whom extensive craniotomy/craniotomy was contraindicated were excluded.

Localization of a small bone window
In the study group, For the most common frontal-temporal-parietal subdural hematoma, a bone window with diameter about 3.5cm was created posterior to the parietal protuberance since this allowed the hematoma to be viewed and removed more easily. For more limited cases, an optimal position near the hematoma center was selected based on surface projection of the hematoma within the head. for the control group, a relatively larger bone flap which can nearly cover the hematoma was designed.

Surgical procedure
An arc incision was made around the intended bone flap (which was opened forward to prepare for large bone craniotomy). After local anesthesia, the scalp was cut and a hole was drilled using a milling cutter to create a bone flap of about 3-3.5 cm in diameter. The dura and outer neomembranes of hematoma were cut open, resulting in liquefied hematoma outflow. An endoscopic aspirator was used to aspirate the solid hematoma visibly. The cavity was irrigated with warm saline until it was clean and there was no active bleeding. Drainage tube placement was monitored endoscopically, after which the dura was sutured, the bone flap replaced, and the scalp sutured. For the control group, the hematoma was evacuated and closed as common open surgery way.

Bipolar electrocoagulation with attractor
Since the bone window was small, the operation space was limited. We therefore developed a suction device with a bipolar coagulation function (Fig. 4) that allowed the surgeon to hold the endoscope in the left hand while using the right hand to perform hemostasis, thereby improving the efficiency of the procedure. Once the site of bleeding was identified, the blood was easily removed during coagulation. This method overcame the shortcomings of a one-handed operation that does not allow the surgeon to simultaneously perform the suction and stop the bleeding.

Imaging follow-up
Brain CT scans were performed on the day after and 1 month after surgery. 3DSlicer software was used to calculate the volume of hematoma, midline shift recovery changes.

Statistics
Pre-and postoperative GCS, operation time, Displacement of midline, and intraoperative blood loss were recorded and analyzed. P < 0.05 was considered statistically significant. Data were analyzed using SPSS v.19.0 software (SPSS Inc., Chicago, IL, USA).

Results
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). The average total blood loss was 50(30-50) ml for endoscopic group, and 250(200-300) ml for open surgery group (P<0.01). No patient showed post-operative re-bleeding in both groups. The mean preoperative midline displacement for the two groups was 11.51±3.51mm for study group vs 10.47±2.93mm for control group (P>0.05). Mid-line displacement showed significant improvement on the day after 5 surgery to 5.29±1.91mm for study group vs 6.75±1.37mm for control group (P<0.01). At 1-month follow-up, the midline was normal in both groups. Computed tomography revealed almost no residual hematoma, representing an average evacuation rate of 100% in both groups. The mean preoperative GCS score was 13 (12.25,15) for study group vs 13 (12,14) for control group(P>0.05). GCS score on the day after the operation was improved to 15 for each patient in endoscopic surgery group, while 15(14,15)in the open surgery group (P<0.01).Patient details are shown in Table 1.

Case 1
A 63-year-old male patient was admitted to our hospital following traumatic brain injury. He had undergone left carotid artery stent implantation 2 years before, and was on antiplatelet therapy since that time. Brain CT at the time of admission revealed a left frontal-temporal-parietal acute subdural hematoma with a midline offset of 0.84 cm (Fig. 1A). As the patient had no neurological dysfunction, he was given a conservative treatment. After 1 week, the patient exhibited a decreased level of awareness and abnormal behavior, and an emergency brain CT suggested a significant shift in the midline by about 1.31 cm (Fig. 1B). Endoscopic hematoma removal from the small bone window near the parietal protuberance was performed (Fig. 1F). The diameter of the bone window was about 3.5 cm (Fig. 1C). Brain CT performed on the next day revealed satisfactory hematoma evacuation, with a midline displacement of 0.63 cm (Fig. 1D). The patient regained full consciousness and fluency in his speech, and brain CT after 1 month surgery revealed a normal midline (Fig. 1E).

Case 2
A 35-year-old woman was admitted to our hospital with severe headache that persisted for 10 days. A brain CT revealed a space-occupying lesion with mixed density in the right frontal lobe (Fig. 2E), and a brain magnetic resonance imaging scan showed short T1 ( Fig. 2A), long T2 (Fig. 2B), and a strong signal on the T2-flair image (Fig. 2C). A diffusion-weighted scan indicated that the lesion was a mixed signal, with the main lesion showing a strong signal (Fig. 2D) and the enhanced scan showing a slightly enhanced circular area (Fig. 2F). The lateral ventricle was compressed and the midline was shifted, suggesting a subacute subdural hematoma. The distance of the midline shift was determined to be 0.86 cm from the preoperative T2 image (Fig. 3A). Based on the location of the hematoma, a 6 bone flap of 3 cm in diameter was created at a lateral position to the sagittal plane of the head and nearly parallel to the ground (Fig. 3D), and this was 4 cm next to the midline with its center at the coronal seal. This was positioned in such a way to remove the hematoma from the posterolateral partition of the lesion. We observed that most of the hematoma did not liquefy, and after complete endoscopic removal of the hematoma and repeated washes with saline, a drainage tube was placed (Fig. 3E). The brain CT scan performed on the following day showed complete clearance of the hematoma and reduction in the midline shift to about 0.26 cm (Fig. 3B). A brain CT scan performed 1 month later, which revealed brain tissue regeneration (Fig. 3F) and a normal midline (Fig. 3C).

Discussion
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 7 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 8 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.

Conclusion
In summary, endoscopic subacute subdual hematoma removal through a small bone window achieved a satisfactory result.

Ethics approval and consent to participate
The study protocol was approved by the Hospital Ethics Committee (PLA General Hospital, Beijing China) and patients or their family members provided informed, written consent.    The suction device with bipolar coagulation function is used in the study.