Abstract
Objectives
Severe symptomatic epidural hematoma (SSEH) is one of the most severe complications following percutaneous endoscopic unilateral laminectomy for bilateral decompression (Endo‐ULBD). Considering that this technique has been performed for a short time, no detailed reports have been recently published. Thus, it is critical to gain a better understanding of SSEH occurring in its postoperative period with regard to its incidence, possible causes, outcome, etc., in order to identify relevant management strategies.
Methods
Patients with spinal stenosis who had undergone Endo‐ULBD in our department from May 2019 to May 2022 were retrospectively analyzed. Of which, patients with postoperative epidural hematoma were followed‐up. The preoperative and postoperative physical conditions of each patient were recorded, and the information related to hematoma removal surgery was recorded in detail. Clinical outcomes were assessed using the visual analogue scale (VAS) and Oswestry disability index (ODI), and the results were classified into “excellent,” “good,” “fair,” or “poor” based on the modified MacNab criteria. The incidence of hematoma with different factors was calculated, and a bar graph was used to compare the difference of the indexes related to hematoma removal between cases, and a line graph was used to reflect the trend of the outcome of each patient within 6 months to evaluate the effect of the treatment.
Results
A total of 461 patients with spinal stenosis who underwent Endo‐ULBD were enrolled in the study. SSEH occurred in four cases, with an incidence rate of 0.87% (4/461). All these four patients underwent decompression of multiple segments, and three of them had a history of hypertension comorbid with diabetes. Notably, one patient had a past history of hypertension and coronary artery disease and was on postoperative low molecular heparin due to lower extremity venous thrombosis. According to the conditions of the four patients, three types of treatment were used. And with timely treatment, all patients recovered well.
Conclusion
Despite being a minimally invasive technique, postoperative epidural hematoma remains a severe complication of Endo‐ULBD. Therefore, during percutaneous endoscopic surgery, it is essential to enhance the comprehensive perioperative management of patients with Endo‐ULBD. Signs related to postoperative hematoma must be recognized and promptly managed. If necessary, satisfactory results can be achieved by using percutaneous endoscopy along the original surgical channel to remove the hematoma.
Keywords: Management strategy, Outcome, Percutaneous endoscopic, Postoperative epidural hematoma, Spinal stenosis
Epidural hematoma following endoscopic unilateral laminectomy for bilateral decompression (Endo‐ULBD) is a serious postoperative complication. It is important to grasp the effective management strategies to treat it. If necessary, satisfactory results can be achieved by using percutaneous endoscopy along the original surgical channel to remove the hematoma.
Introduction
With advances in percutaneous spinal endoscopic techniques, especially the advent and application of large access endoscopic instruments such as endoscopic visual annular saws, the efficiency of endoscopic treatment of osteochondral‐related hyperplastic structures in the spine has significantly improved. With the assistance of these techniques, endoscopic unilateral laminectomy with bilateral laminar decompression (Endo‐ULBD) is presently extensively applied for the treatment of lumbar spinal stenosis (LSS) with targeted, precise, and minimally invasive concepts and has achieved outstanding results. 1 However, despite the advantages of minimally invasive endoscopic spine surgery, such as lower volumes of blood loss, fewer postoperative complications, and faster recovery times, severe complications still develop in a minority of patients postoperatively. Commonly encountered postoperative complications include nucleus pulposus omission, nerve root injury, dural tear, visceral injury, nerve root induced hyperalgesia or burning‐like nerve root pain, postoperative dysesthesia, posterior neck pain, and surgical site infection. Meanwhile, rare complications, such as retroperitoneal hematoma (RPH), intraoperative seizures, and thrombophlebitis, may also occur. 2
Although spinal endoscopic surgery is a minimally invasive approach, the resulting trauma is relatively deeper, and postoperative drains are usually not inserted, and thus, the risk of local epidural hematoma is relatively high. Endo‐ULBD achieves bilateral decompression of the spinal canal through a unilateral single‐pass interlaminar approach with the assistance of spinal endoscopy, and the features related to the surgical approach are particularly prominent.
Postoperative epidural hematomas with rapid onset and severe symptoms need to be timely treated; otherwise, they may lead to permanent neurological deficits. Neurological sequelae of serious symptomatic epidural hematomas (SSEH) include lower extremity weakness, recurrent back and leg pain, numbness, and bowel or bladder dysfunction. 3 , 4 Following spinal decompression, early detection and drainage of hematomas are instrumental in avoiding nerve deterioration and improving clinical outcomes. The incidence of SSEH requiring surgical clearance after conventional lumbar decompression surgery has been reported to range from 0.27% to 0.69%, 5 , 6 , 7 and the associated risk increases as the number of intraoperative bone blocks removed increases. 8 In a bilateral channel endoscopic spine surgery (BESS) study conducted by Ahn et al., the incidence of clinical postoperative epidural hematoma was 2/142 (1.4%) and 8/95 (8.4%) in the conventional open surgery group and the BESS group, respectively. Interestingly, the incidence of postoperative hematoma was significantly higher in the BESS group than in the conventional open surgery group. 9
Given that Endo‐ULBD was recently discovered, the incidence of complications such as postoperative Endo‐ULBD‐related hematoma has not been reported so far. In this article, four cases of postoperative epidural hematoma that occurred among 461 ULBD procedures in the last 3 years at our hospital were described. We will conduct our discussion based on the following points: (i) the incidence of SSEH after Endo‐ULBD with different factors; (ii) possible causes of these cases of hematoma and the corresponding perioperative management strategies (including prevention and treatment); and (iii) clinical outcomes.
Methods
Inclusion and Exclusion Criteria
The inclusion criteria were as follows: (i) patients with significant spinal stenosis symptoms and typical spinal stenosis showed by CT or MR; (ii) patients who were treated with Endo‐ULBD; (iii) patients who experienced increased pain and loss of sensation and strength postoperatively; (iv) radiological examination showed a hematoma compressing the nerve in the area of surgery; and (v) patients who were followed up for more than 6 months.
The exclusion criteria were as follows: (i) patients who underwent spinal endoscopic surgery without bilateral decompression; (ii) patients who have undergone interbody fusion; (iii) radiological examination showed a hematoma with no associated symptoms; (iv) patients who did not follow the doctor's advice for reasonable rest after surgery; and (v) patients with incomplete information on follow‐up surveys.
Patients
Between May 2019 and May 2022, 461 patients with spinal canal stenosis (SCS) who underwent ULBD in our spine department, which performed a total of 4581 open and 1726 minimally invasive spine surgeries, were retrospectively analyzed. Neurological examinations, preoperative CT, and MRI were used to determine the location and type of spinal stenosis, and the patients were followed for more than 1 year postoperatively. There were 12 cases of cervical spine stenosis, 36 cases of thoracic spine stenosis, and 413 cases of lumbar spine stenosis, all of which were operated under general anesthesia. Clinical outcomes were evaluated using the visual analogue scale (VAS) and Oswestry disability index (ODI), and results were classified into “excellent,” “good,” “fair,” or “poor” based on the modified MacNab criteria.
Endo‐ULBD
Endo‐ULBD equipment used were Inter Laminar Endoscopic Surgical System (iLESSYS Delta, Joimax GmbH, Karlsruhe Germany) or the Plus Endoscopic Spine Surgical System (Endo‐Surgi Plus, Union‐tech GmbH, Beijing, China). Patients were operated on using general anesthesia.
Steps
The patient was placed in the prone position with the thorax and iliac region elevated. The skin incision was usually selected on the severely symptomatic side and was 1–2 cm in length, and its exact location with surface projection of the inner upper margin of the inferior pedicle was confirmed by fluoroscopy. Then, the serial dilators were advanced to the target through the incision. After placing the working cannula, the dilators were replaced by the endoscope.
Then, soft tissues such as muscle and fat were pulled from the surgical field in a stepwise manner, and the upper and lower vertebral plates and synovial joints were located. Following this, the inferior articular process of the superior vertebral body, the inferior vertebral plate of the superior vertebral body, and the superior vertebral plate of the inferior vertebral body were excised with a circular saw. After exposing the origin and termination of the ligamentum flavum, the bone of the sphenoid root corresponding to the operating segment was removed with a circular saw and decompressed along the ventral side of the contralateral vertebral plate. Following the removal of the ligamentum flavum, the dural sac and bilateral nerve roots were exposed. Hemorrhages were stopped by radiofrequency cauterization, and the crypt of the bilateral walking nerve roots was fully decompressed.
Finally, after confirming that the nerve root was relaxed and the dural sac was satisfactorily distended, the working cannula was pulled out, and the surgical wound was sutured.
Postoperative Management
The intravenous drip of analgesic is administered only on the first postoperative day, oral analgesic is administered from the second day postoperatively. The amount of bed rest is determined according to the patient's actual condition, is 1 or 2 days, usually no more than 2 days, remain in bed as much as possible during the first week postoperatively. It is required to walk around with the protection of waist support for 1 month postoperatively. After 1 month, appropriate low back muscle exercises are encouraged, but it is emphasized that they must be done gradually.
Outcome Measures
All participants completed the self‐administered questionnaire at particular times, including visual analogue scale (VAS) scores for low‐back and lower‐limb pain and Oswestry disability index (ODI) scores. They were evaluated preoperatively, on the first postoperative day, on the 7th day postoperatively, and at 3 and 6 months postoperatively. To evaluate clinical efficacy 6 months postoperatively, the modified MacNab criteria were used.
In addition, the surgery to remove the hematoma was recorded in detail, including surgical segment, operation time, incision length, intraoperative fluoroscopy number, and postoperative bed rest time, was recorded. Moreover, for a better comparison of the operation time, the average operating time per segment (operating time/the number of segments) was calculated for the different numbers of segments.
Statistical Analysis
In this study, we obtained follow‐up data from the medical database of our institution for all patients with ULBD and patients who suffered from SSEH in our department during a specific period. The incidence of hematoma with different factors was calculated. GraphPad Prism software was used to plot bar graphs to show the differences in the indexes related to hematoma removal between cases. And line graphs were plotted to reflect the relationship between prognosis and time based on the VAS and ODI questionnaires completed by the patients at different times.
Results
Information of Patients
Among the 461 patients with detailed clinical information who were strictly followed up, four manifested postoperative symptoms of epidural hematoma nerve compression. All these four patients had a range of 2–3 surgical segments; three of them had a history of hypertension and diabetes mellitus for more than 5 years, and the last patient suffered from hypertension and coronary artery disease and was on postoperative low molecular heparin because of lower extremity venous thrombosis (Table 1).
TABLE 1.
Demographic and clinical features of 4 cases with PEH
| Case no. | Sex / Age | BMI | Diagnosis | Range of blood pressure (mmHg) | Preoperative | ||
|---|---|---|---|---|---|---|---|
| Hypertension/years | High blood pressure at admission | Other complicating diseases (Length of time) | |||||
| 1 | F/70 | 27 | Lumbar spinal canal stenosis, Lumbar compression fracture | 40 | Yes/7 | Yes | Diabetes (30 years), Lumbar trauma (4 months) |
| 2 | F/77 | 30 | Lumbar spinal canal stenosis | 55 | Yes/10 | No | Coronary artery disease (8 years) |
| 3 | M/72 | 29 | Lumbar spinal canal stenosis | 35 | Yes/6 | Yes | Diabetes (6 years) |
| 4 | M/58 | 32 | Cervical spinal canal stenosis | 35 | Yes/5 | No | Diabetes (5 years), chronic nephritis (3 years), after lumbar vertebra operation (5 years) |
| Case no. | Intraoperative | Postoperative | |||
|---|---|---|---|---|---|
| Initial surgery (level) | Operating time | Blood loss | Symptom (occurrence time after operation) | Treatment (the time after operation) | |
| 1 | ULBD (L3‐5), PVP (L2) | 2 h 25 min | 50 mL | Pain in incision, buttocks and radiates to both lower extremities, with a progressive decline of muscle strength (12 h) | Remove hematoma through quadrant channel, L4/5, local anesthesia (24 h) |
| 2 | ULBD (L3‐5) | 2 h | 20 mL | Pain in incision, buttocks and radiates to both lower extremities, with a progressive decline of muscle strength (12 h) | Percutaneous endoscopic hematoma removal, L3‐5, local anesthesia (24 h) |
| 3 | ULBD (L2‐5) | 2 h 30 min | 20 mL | Numbness and pain in both lower limbs, Muscle strength grade 0. (wake up after operation) | Percutaneous endoscopic hematoma removal, L2‐5, local anesthesia (Instant) |
| 4 | ULBD (C4‐6) | 2 h 10 min | 20 mL | Numbness and pain in both upper limbs, the decline of muscle strength (2 days) | Glucocorticoids, Mannitol and Mecobalamin, ivdrip (2 days) |
Abbreviations: PEH, postoperative epidural hematoma; ULBD, unilateral laminotomy for bilateral decompression.
Incidence
In terms of age, we defined 45–59 years as middle‐aged and ≥60 years as elderly. Of the 461 patients treated with Endo‐ULBD for spinal stenosis (143 middle‐aged and 201 elderly), one case (0.70%) of SSEH occurred in the middle‐aged and three cases (1.49%) in the elderly. Of all 248 male patients, two (0.81%) experienced SSEH, and two (0.94%) of 213 females. Of the 461 patients (12 cases of cervical spinal stenosis, 36 cases of thoracic spine stenosis, and 413 cases of lumbar spine stenosis), four patients (0.87%) experienced severe postoperative symptoms owing to epidural hematoma nerve compression: one patient (8.3%) underwent ULBD for cervical stenosis, 0 patients (0%) for thoracic stenosis, and three patients (0.73%) for lumbar stenosis. Severe epidural hematoma nerve compression symptoms occurred in one case (0.22%) on the day of surgery, two cases (0.43%) on the first postoperative day, and 1 case (0.22%) on the (Table 2).
TABLE 2.
Postoperative epidural hematoma cases
| Variable | Case (rate %) |
|---|---|
| PEH | 4/461(0.87) |
| Age | |
| Middle‐age | 1/143(0.70) |
| Old | 3/201(1.49) |
| Sex | |
| Male | 2/248(0.81) |
| Female | 2/213(0.94) |
| Operation site | |
| Cervical vertebrae | 1/12(8.30) |
| Thoracic vertebrae | 0/36(0) |
| Lumbar vertebrae | 3/413(0.73) |
| Occurrence time | |
| The day of surgery | 1/461(0.22) |
| The first postoperative day | 2/461(0.43) |
| The second day postoperatively | 1/461(0.22) |
Note: Middle‐aged: 45–59 years old, old: ≥70 years old.
Abbreviation: PEH, postoperative epidural hematoma.
Treatment and Outcomes
With prompt recognition, diagnosis, and medical intervention, no severe complications occurred. Case 1: the patient underwent hematoma removal through the quadrant channel under local anesthesia 24 h postoperatively (Figure 1). Cases 2 and 3: the patients underwent percutaneous endoscopic hematoma removal under local anesthesia (Figures 2 and 3). It is worthwhile pointing out that the above three patients recovered after 1 week of physical therapy. In case 4, the patient's urgent MR displayed localized hematoma formation (Figure 4), but nerve compression was not severe. Therefore, only hormones, mannitol, and neurotrophic drugs were administered intravenously, after which the symptoms were partially relieved.
FIGURE 1.
Case 1 (A) Preoperative lumbar MR showed L4/5 spinal canal stenosis. (B) Pain in the incision and buttocks occurred on the second day after the operation, and radiates to both lower extremities, with a progressive decline of muscle strength, emergency examination of lumbar MR showed hematoma in the L4/5 operation area. (C) Hematoma evacuation was performed under the quadrant channel under local anesthesia 24 h after the operation. (D) The blood clot was taken out. (E) Re‐examination of lumbar MR after hematoma clearance showed that the hematoma had been removed.
FIGURE 2.
Case 2 (A, B) Endoscopic hematoma removal of the spine was performed under local anesthesia 48 h after surgery, and re‐examination of MR showed that L3/4 and L4/5 hematomas were cleared. (C) The incision of ULBD is small, and when there is blood leakage from the deeper part of the operation area, if no drainage is placed, it is easy to form a local hematoma to compress the nerve and cause related symptoms. (D) Drainage tube was placed and left for 1 day after hematoma removal. (E) The nerve was well decompressed after the first operation. (F) Large blood clot was seen in the operative area during the hematoma removal procedure. (G) Lumbar 3D CT shows that the spine structure remains very stable after ULBD surgery.
FIGURE 3.
Case 3 (A, B, C) Postoperative MR of ULBD shows that epidural hematoma occurred in multiple segments of the operated area. (D) The blood clot formed can be seen during the hematoma removal procedure. (E) The spinal nerve after the hematoma has been removed.
FIGURE 4.
Case 4 (A, B) Postoperative MR shows the presence of multisegmental epidural hematoma in the operative area. (C) The structure of the vertebral plate on cervical 3D CT after surgery.
Regarding the hematoma removal procedure for the three patients, detailed information, such as surgical segment, operation time, incision length, intraoperative fluoroscopy number, and postoperative bed rest time, was recorded. Moreover, for a better comparison of the operation time, the average operating time per segment (operating time/the number of segments) was calculated for the different number of segments. (Table 3, Figure 5).
TABLE 3.
Hematoma removal surgery
| Case | Surgical segment | Operating time (min) | Average operating time per segment (min) | Incision length (mm) | Intraoperative fluoroscopy number | Postoperative bed rest time (day) |
|---|---|---|---|---|---|---|
| 1 | L4/5 | 105 | 105.0 | 23.0 | 2 | 2 |
| 2 | L3‐5 | 95 | 47.5 | 13.7 | 3 | 1 |
| 3 | L2‐5 | 120 | 40.0 | 13.7 | 5 | 1 |
FIGURE 5.
The detailed information about 3 hematoma removal surgeries.
More importantly, the majority of patients recovered well with physical therapy 6 months after treatment. Clinical outcomes were assessed using the VAS and ODI. Based on the modified MacNab criteria, the outcome was found to be “excellent” in three patients and “good” in one patient (Table 4, Figure 6).
TABLE 4.
Clinical outcomes of four cases with PEH
| Case no. | Pre‐VAS (Leg/Arm) | Post‐VAS 1 day (Leg/Arm) | Post‐VAS 1 week (Leg/Arm) | Post‐VAS 1 month (Leg/Arm) | Post‐VAS 6 months (Leg/Arm) |
|---|---|---|---|---|---|
| 1 | 9 | 4 | 2 | 0 | 0 |
| 2 | 10 | 3 | 2 | 0 | 0 |
| 3 | 9 | 3 | 2 | 0 | 0 |
| 4 | 8 | 7 | 5 | 4 | 2 |
| Case no. | Pre‐VAS (Back/Neck) | Post‐VAS 1 day (Back/Neck) | Post‐VAS 1 week (Back/Neck) | Post‐VAS 1 month (Back/Neck) | Post‐VAS 6 months (Back/Neck) |
|---|---|---|---|---|---|
| 1 | 9 | 5 | 3 | 1 | 0 |
| 2 | 10 | 3 | 2 | 0 | 0 |
| 3 | 9 | 3 | 2 | 0 | 0 |
| 4 | 8 | 7 | 4 | 3 | 2 |
| Case no. | Pre‐ODI | Post‐ODI 1 day | Post‐ODI 1 week | Post‐ODI 1 month | Post‐ODI 6 months | Mac Nab |
|---|---|---|---|---|---|---|
| 1 | 44/45 (97.8%) | 24/35 (68.6%) | 18/45 (40%) | 8/45 (17.8%) | 2/45 (4.4%) | Excellent |
| 2 | 45/45 (100%) | 18/35 (51.4%) | 12/45 (26.7%) | 5/45 (11.1%) | 1/45 (2.2%) | Excellent |
| 3 | 43/45 (95.6%) | 16/35 (45.7%) | 11/45 (24.4%) | 6/45 (13.3%) | 0/45 (0%) | Excellent |
| 4 | 40/50 (80%) | 27/35 (77.1%) | 30/50 (70%) | 23/50 (46%) | 8/50 (16%) | Good |
Abbreviations: ODI, Oswestry disability index; PEH, postoperative epidural hematoma; VAS, visual analogue scale.
FIGURE 6.
Clinical outcomes of four cases with PEH. Case 1 was Removed hematoma through quadrant channel, case 2 and 3 were removed hematoma by Percutaneous endoscopy, and case 4 was treated with medications.
Discussion
In the above, we counted the incidence of SSEH after Endo‐ULBD with different factors and showed the information about the hematoma removal surgery and the outcomes under different treatments. We attempted to remove the hematoma by percutaneous endoscopy and got satisfactory outcomes. Then we conducted a detailed discussion on incidence, possible causes, management strategies, and outcomes.
Incidence
Numerous clinical studies have been performed on spinal epidural hematomas. The incidence of SSEH requiring reoperation after conventional open lumbar decompression surgery varied from 0.27% to 0.69%, 5 , 6 , 7 and its risk increased with an increased number of bone blocks removed intraoperatively. 8 As a spinal percutaneous endoscopic procedure, ULBD's working channel diameter is only 10.2 mm (with Endo‐Surgi Plus). Hence, bilateral decompression of the corresponding segment of the spinal canal can be achieved without postoperative drainage, and decompression of multiple segments of the spinal canal can be performed in a single operation. However, this procedure is technically demanding and has a steep learning curve, and thus the risk of developing postoperative epidural hematoma is relatively higher. From May 2019 to May 2022, a total of 461 ULBD procedures were performed by spinal surgeons with extensive experience in endoscopic surgery, and a total of four postoperative cases developed epidural hematoma with severe neurological compression, with an incidence of 0.87%. This incidence is considered relatively high in spinal surgery, which suggests that studies related to postoperative epidural hematoma after ULBD are extremely important and meaningful. However, to date, studies regarding this topic are limited.
In terms of spinal sites, it is in the cervical spine that the incidence of hematoma is relatively higher. In addition to the limited case number, the nature of interlaminar anatomical features of the cervical spine demands a greater degree of bone removal during surgery than in the thoracic and lumbar spine, which could elevate the risk of this complication.
Regarding the time of occurrence, the symptomatic epidural hematoma is more likely to occur within 48 hours after surgery, which is consistent with the report by Schroeder et al. 10 Due to being minimally invasive, the late occurrence of SSEH is rare.
Possible Causes
The primary benefits of percutaneous endoscopic spine surgery are less trauma, shorter recovery time, and fewer and less frequent postoperative complications. Despite severe postoperative complications after percutaneous endoscopic surgery being relatively rare, the occasional cases of significant postoperative symptoms encountered with an increasing volume of procedures should not be taken lightly. The fact that the incision for percutaneous endoscopic spine surgery is small, coupled with a narrow working channel, a larger internal treatment area for the intervention than the external one, and that postoperative drains are typically not inserted makes postoperative epidural hematoma a unique postoperative complication of percutaneous endoscopic spine surgery that requires considerable attention. Furthermore, as the number of sections performed under percutaneous endoscopy increases, the risk of postoperative epidural hematoma increases. 4
An in‐depth analysis was performed concerning patient conditions, as described below: to begin, emphasis should be placed on factors related to the patient's microcirculation. All four cases suffered from a history of hypertension for more than 5 years. Daily blood pressure recordings during hospitalization determined that both patients who developed symptoms on postoperative day 1 experienced systolic blood pressure fluctuations in the range of up to 40 mmHg during hospitalization. Yamada et al. reported that a substantial increase in blood pressure following lumbar spine surgery predisposes to SSEH and that an abrupt increase in blood pressure after fascial closure may lead to subfascial hemorrhage, which may eventually result in postoperative SSEH. Therefore, the anesthesiologist should carefully monitor the gradual return to the patient's normal blood pressure toward the end of the procedure to ensure that the bleeding is stopped under normal blood pressure conditions and to avert spontaneous postoperative epidural bleeding. Intraoperative hypotension should be avoided as well, especially in hypertensive patients. 11 Also, Fujiwara et al. evinced that there is a tendency for blood pressure to decrease during anesthesia on account of anesthetic drugs dilating the peripheral blood vessels. In patients with normal blood pressure, the autonomic response appropriately adjusts the intravascular size to prevent extreme hypotension, even under anesthesia. In contrast, “untreated” or “poorly managed” hypertensive patients are more susceptible to developing hypotension during anesthesia and hypertension after anesthesia is stopped because of the inability of autonomic mechanisms to regulate the internal diameter of blood vessels due to vascular sclerosis. 12 For ULBD surgery, the anesthesiologist generally regulates the patient's blood pressure to a low level intraoperatively. In other words, there is a higher risk of bleeding in the operative when postoperative blood pressure rises. Therefore, it is imperative to control blood pressure not only in the postoperative period but also in the preoperative and intraoperative periods in order to minimize the risk of SSEH.
There were three patients with a history of hypertension and diabetes mellitus for more than 5 years. The latter has been shown to be a high‐risk factor for poor postoperative spine surgery. Because diabetes is often associated with comorbidities (e.g., atherosclerosis and abnormal blood flow patterns, etc.) that predispose to micro/major vascular degeneration and impaired tissue healing, it can exacerbate the prognosis after spine surgery. 13 , 14 The vascular condition of the three patients in this study was aggravated by diabetes mellitus on top of chronic hypertension, and the poor healing ability of the tissue wound further induced the development of local hematoma after surgery.
One patient suffered from lower extremity deep vein thrombosis, and the preoperative D‐dimer level was 1030.00 μg/L (normal reference range: 0–500 μg/L). From the day of the operation, 0.4 mL of low molecular weight heparin sodium was injected subcutaneously twice daily. The patient manifested radiating pain from the lumbar region to both lower extremities on the first postoperative day, which worsened over time. By the second postoperative day, there was a significant loss of muscle strength in both lower extremities and a significant decline in skin pain sensation. Zeng and Peng previously reported that the use of LMWH significantly reduces the incidence of thrombosis and thromboembolic complications after spinal surgery but increases incisional bleeding and leads to an increased risk of symptomatic spinal epidural hematoma. 15 Notably, the dose of medication in this patient was higher than the guideline recommendations for prophylactic medication, which played a decisive role in the occurrence of postoperative symptomatic epidural hematoma.
In addition to the aforementioned findings, the intradural venous plexus has been reported to be a key source of bleeding in epidural hematomas. 3 As is well documented, patients with spinal stenosis often have dilated and aberrant growth of the epidural venous plexus owing to dural compression. 16 Also, a higher number of surgical segments increases the risk of venous plexus injury, and high intraosseous pressure leads to increased pressure in the spinal canal. 8 , 17 All of these factors can cause postoperative bleeding, thereby increasing the risk of SSEH. Therefore, caution is warranted when stripping tissues, nerves, and blood vessels during the endoscopic operation. Furthermore, unnecessary vascular damage should be avoided as much as feasible.
Management Strategies
After combining all the patients who underwent surgery in our department in the past 3 years and meticulously analyzing these four cases based on the existing reports, an integrated perioperative management approach was developed specifically for Endo‐ULBD (Figures 7 and 8).
FIGURE 7.
The integrated perioperative management for Endo‐ULBD. VTE: venous thromboembolism.
FIGURE 8.
Diagnosis and treatment of SSEH.
The analysis revealed that when the surgery involved multiple segments, particular attention should be paid to age, BMI, and a history of hypertension and diabetes. If the patient has diabetes or hypertension, then blood pressure and blood glucose levels need to be strictly monitored period to avoid drastic fluctuations. More specifically, it is essential to avoid relatively low blood pressure under intraoperative general anesthesia and high blood pressure after surgery. If it is challenging to control blood pressure and the intraoperative volume of blood loss is high, especially in patients undergoing multisegmental surgery, postoperative placement of drains could be considered, which are then removed when the patient wakes up from anesthesia in the ward, the blood pressure is stable, and the drainage volume is low.
Prophylactic application of antithrombotic medicines must be used carefully in patients who are at higher risk of venous thromboembolism (VTE). In spinal surgery, the implementation of an aggressive multimodal VTE prevention program with early initiation of anticoagulation significantly lowered the overall incidence of VTE, especially the development of DVT. Among them, low molecular weight heparin is considered a drug that can safely and effectively prevent VTE in the perioperative period and has been extensively used in the clinical setting. The majority of existing reports recommend that low molecular weight heparin should be administered early in the postoperative period in patients with a high risk of VTE, but it should be noted that the optimal time and dosage of the application vary for different types of surgeries. 18 Strom and Frempong‐Boadu 19 published a 5‐year retrospective study and concluded that a 24 h–36 h delay in administration might allow sufficient hemostasis while also providing the benefits of early prophylaxis. The endo‐ULBD procedure causes significant tissue damage at the deep region but minimal injury at the incision site, and postoperative drains are typically not inserted, especially when multiple segments are involved. Thus, the endo‐ULBD procedure is more likely to cause symptomatic postoperative epidural hematomas owing to bleeding than conventional surgery. Therefore, we propose delaying the administration of low molecular weight heparin until 24 h–36 h postoperatively.
If a patient suffers from a symptomatic postoperative epidural hematoma, it is important to promptly recognize and take relevant management measures. If pain is minimal, the patient can be closely monitored without specific treatment for the time being. However, it should be noted that strong analgesics should be given with caution when there is a high suspicion that the pain is aggravated by a hematoma in the operative area to avoid masking the actual symptoms and delaying treatment. When significant loss of sensation and muscle strength is present in the lower extremities, an MR examination of the operative area should be urgently performed. If the imaging results display a large epidural hematoma compressing the nerve, hematoma removal should be performed immediately. 20
Regarding the surgical methods of hematoma removal after percutaneous endoscopic surgery, minimally invasive surgery is the first choice for patients. Among the patients with postoperative symptomatic hematoma mentioned in this article, three cases underwent hematoma clearance, of which one case underwent hematoma removal under local anesthesia through the quadrant channel. Meanwhile, the hematoma formed adjacent to the incision site in two cases was removed using Endo‐Surgi Plus System tools (Union‐tech GmbH, Beijing, China) which can provide a wide endoscopic field of vision. 21
Outcome
Delamarter et al. 22 have described in a dog model that recovery from spinal cord compression is inversely proportional to the time of compression and that the onset of demyelination after compression is directly proportional to the time of compression. The spinal cord did not incur extensive tissue necrosis or tissue disorganization within the first hour of compression. However, when compression lasted for 6 h or more, there was no recovery of neurological function, and progressive necrosis of the spinal cord occurred. Numerous studies have established that rapid evacuation resulted in superior outcomes in neurologic recovery. 23 , 24
Therefore, when an epidural hematoma is identified and symptoms such as sensory and muscle weakness worsen, we propose an early intervention to remove the hematoma. Regarding the surgical approach, the hematoma was initially removed through the quadrant channel for a wide vision and ease of removal. This required extending the original surgical incision and was only indicated for a single segment presenting with a hematoma. In contrast, this method was overly traumatic for multiple segments with hematomas. Therefore, the percutaneous endoscopic approach was attempted in the two subsequent cases to remove the hematoma, and the intervention was uneventful. As illustrated in Figure 6, the average operating time per segment, incision length, and postoperative bed rest time for the two percutaneous endoscopic approaches were superior to the approach through the quadrant channel. Although the percutaneous endoscopic approach required more fluoroscopic imaging, the impact of this difference was negligible.
Strengths and Limitations
Endo‐ULBD is an advanced technique in minimally invasive spine surgery, and there are no specific reports on SSEH in its postoperative period. Thanks to our experienced spinal endoscopic surgeons and our comprehensive follow‐up system, patients suffering from SSEH were treated promptly and appropriately, and the entire treatment process was recorded and followed up completely. Therefore, we can obtain valuable case data for detailed analysis and reporting.
However, the limited number of cases in this study does not yet allow for a rigorous analysis to draw more definitive conclusions. We will continue to expand the number of cases to be able to analyze them in more depth in the future. Patients who undergo minimally invasive surgery recover quickly and can achieve a stable state 6 months after surgery, after which there are usually no major changes, so the follow‐up period is only 6 months.
Conclusion
Endo‐ULBD is a minimally invasive technique for decompression of the spinal canal; nonetheless, it can cause severe postoperative epidural hematoma (predominantly in multisegmental surgery). Therefore, it is essential to enhance the comprehensive perioperative management of patients with Endo‐ULBD. Additionally, the characteristics of Endo‐ULBD surgery were analyzed by combining the findings of relevant previous studies and the four cases of this study. Blood pressure, blood glucose levels, and the coagulation status of Endo‐ULBD patients should be strictly monitored and controlled during the perioperative period. Moreover, signs associated with postoperative hematoma must be promptly recognized and treated. If necessary, satisfactory results can be achieved by using percutaneous endoscopy along the original surgical channel to remove the hematoma.
Author Contributions
All authors contributed significantly to this work. Antao Lin wrote the main manuscript text, Shengwei Meng and Chao Wang provided important theoretical guidance. Xiaodao Zhao assisted in providing image information, Chuanli Zhou and Xuexiao Ma are responsible for this article, and others provided important data about this article. All authors reviewed the manuscript and agreed on the journal to which the article would be submitted; reviewed and agreed on all versions of the article prior to submission, during revision, acceptance of the final version for publication, and any significant changes introduced during the proofreading phase, and described the content of the article.
Conflict of Interest Statement
The authors declare that they have no conflicts of interest.
Ethics Statement
All procedures were approved by the ethics committee of the Affiliated Hospital of Qingdao University and approved number of IRB was QYFYWZLL27522. Written informed consent was received from all patients and/or their legal guardian(s) before the operation.
Acknowledgments
The authors are grateful to all operating room staff for their technical assistance and to the medical recorders who helped with patient data collection. We would also like to thank the editorial board of Orthopedic Surgery for reviewing and critiquing the manuscript to improve it. This work was supported by the funds from the National Key Research and Development Program of China (2019YFC0121400), the National Natural Science Foundation of China (81871804), and the Natural Science Foundation of Shan Dong Province (ZR2021MH020).
Contributor Information
Xuexiao Ma, Email: maxuexiaospinal@163.com.
Chuanli Zhou, Email: justin_5257@hotmail.com.
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