Spinal Hernia Repair and Cauda Equina Repositioning After Lumbar Decompression under Three-Dimensional Microscopy: A Case Report and Literature Review

Summary

Dural hernia following spinal endoscopic surgery is a rare complication. Here, we report a case of nerve root hernia associated with the absence of dural repair, prolonged operation time, and increased abdominal pressure due to postoperative constipation. Early dural tear repair and monitoring postoperative constipation can help prevent cauda equina herniation.

Abstract

Cauda equina herniation (CEH) is a relatively rare and severe perioperative complication that may occur after lumbar spine surgery. Here, we present a case report of a 36-year-old female patient who experienced CEH after an endoscopic L5-S1 laminectomy and discectomy. The patient presented with right L5-S1 radiculopathy that correlated with findings in medical imaging and physical examination. Subsequently, she underwent endoscopic L5-S1 laminotomy and discectomy. A day after the operation, the patient developed urine leakage, hematochezia, aggravated constipation, and found no relief from pain in the right lower limb. MRI revealed cerebrospinal fluid leakage at the surgical site. After consultation with the urology and anorectal department, the patient was fitted with a urinary catheter, prescribed hemorrhoid medication, and underwent anal sphincter training as recommended by the doctor. After 1 week of treatment, the patient's urinary function returned to normal, but constipation persisted while the pain in the right lower limb eased. After 5 months, the patient was hospitalized due to radiating pain in both lower limbs and constipation. An MRI revealed herniation of the L5/S1 nerve root sac. Subsequently, L5/S1 total laminectomy decompression and dural sac repair were performed under a three-dimensional (3D) microscopy. Postoperatively, lower limb pain and constipation were alleviated. CEH following spinal endoscopy, though rare, demands significant clinical attention. The successful outcome in this case illustrates the value of surgical revision under 3D microscopic guidance, offering a viable strategy for patients presenting with this complication.

Introduction

Iatrogenic nerve root herniation is a rare complication of lumbar endoscopic surgery and may occur due to intraoperative dural tear and cerebrospinal fluid leakage^1,2,3. There are few reports on the symptoms of iatrogenic nerve root herniation, which are mainly attributed to spinal cord or nerve root compression^4,5. Percutaneous endoscopic is a safe and effective minimally invasive spinal surgery⁶. However, due to the requirement for continuous irrigation with a water medium, identifying cerebrospinal fluid leakage and dural tear during the operation is more challenging compared to traditional open surgery conducted in air medium⁷. This manuscript presents a case report of a patient who developed lumbar and leg pain, along with urinary dysfunction, as a result of nerve root herniation following percutaneous endoscopic lumbar decompression surgery. The symptoms were effectively alleviated through dural sac repair conducted under 3D microscopic guidance, emphasizing the precision and effectiveness of this minimally invasive surgical approach.

CASE PRESENTATION:
Initial surgery: A 36-year-old female presented with right L5-S1 radiculopathy (Figure 1) and underwent endoscopic lumbar decompression. An attempt at osteotomy with a ring saw led to a dural tear and CSF leakage. An experienced surgeon intervened, raising the irrigation solution to enhance visibility and employing a gelatin sponge to address the tear. Postoperatively, the patient continued to experience lower limb pain and difficulties with urination and defecation. An MRI confirmed CSF leakage and damage to the L5 endplate (Figure 2). The patient was managed with ibuprofen for anti-inflammatory and analgesic effects and cefoperazone-sulbactam for infection prophylaxis. She was also instructed in pelvic floor muscle and anal sphincter exercises.

Second Surgery: The patient was readmitted with pain in both lower limbs 5 months post-initial surgery. Radiography and magnetic resonance imaging (MRI) revealed an L5/S1 cauda equina herniation (Figure 3). A 3D microscopy-assisted total laminectomy and dural sac repair were performed, which included incision and exposure, lamina and facet joint removal, nerve root repositioning, and closure. Postoperatively, the patient experienced symptoms of dizziness, headache, and nausea, which were managed by adjusting the suction of the drainage tube and administering fluid resuscitation. By the third postoperative day, the patient's symptoms had resolved, and she showed significant improvement in bilateral lower limb pain, with the return of normal urination and bowel movements.

Diagnosis, assessment, and plan:
The patient initially presented with right L5-S1 radiculopathy, confirmed by medical imaging and physical examination. The first surgery led to a dural tear and CSF leakage, causing persistent lower limb radiation pain and incontinence. A follow-up MRI confirmed cerebrospinal fluid leakage and L5 endplate injury, diagnosing the patient with cauda equina herniation at the L5/S1 level. The first surgery's complications necessitated further intervention. Imaging revealed cauda equina herniation at L5/S1, resulting in bilateral lower limb pain. Postoperative symptoms included dizziness, headache, nausea, and vomiting, requiring neurosurgical consultation and management. The second operation involved a total laminectomy and dural sac repair using 3D microscopy. The procedure included incision and exposure, lamina and facet joint removal, nerve root repositioning, and closure. Postoperative care involved drainage for headache and dizziness, dexamethasone treatment, increased fluid intake, anti-infective measures, and drainage clip retention. The patient experienced pain relief in both lower limbs, and normal urination and defecation were restored.

Protocol

Informed consent was acquired from the patient before initiating the treatment, and the study underwent ethical review by the ethics committee.

1. Preoperative work-up for the first surgery

1. CT, MRI, DR, and physical examination were performed to identify the L5/S1 affected segment and determine the surgical method (Figure 1).
2. Lower limb vascular issues were ruled out, and the patient underwent an anesthetic assessment before selecting endoscopic L5/S1 decompression surgery.

2. Installation for the first surgery

1. Patient positioning: After general anesthesia, the patient was positioned prone on a spinal surgery table, with protective pads placed on vital areas to prevent pressure sores and abdominal compression.
2. Surgeon position: The surgeon and the assistant stood on the patient's right side, with the monitor and other equipment on the opposite side.

3. Procedure steps for the first surgery

1. Routine disinfection and draping were performed, followed by the use of a C-arm fluoroscope to localize the target segment. A gradually expanding channel was then placed at the L5 inferior lamina.
2. A working channel (10 mm) was inserted, and the lower edge of the channel was used to dissect the soft tissue of the L5 inferior lamina. An endoscope was then placed and connected to the irrigation and imaging systems.
   NOTE: Using a ring saw for osteotomy, the position being too medial and too deep, as well as tissue adhesion, resulted in damage to the upper endplate of the L5 vertebra and a dural tear. However, under the water medium, no obvious cerebrospinal fluid leak was detected (Figure 2).
3. To obtain a clearer view due to oozing from the bone surface, the irrigation solution was elevated to a height of 220 cm.
4. Plasma radiofrequency was used for hemostasis. The overgrown inferior articular process of the L5 vertebra and the superior articular process of the S1 vertebra were removed using a rongeur.
5. The hypertrophied ligamentum flavum was also excised. A nucleus pulposus forceps was utilized to clear the herniated disc tissue from the superior and axillary regions of the L5 nerve root.
6. After completing the spinal canal decompression, the dura mater had a tear. After the assessment, an open repair was unnecessary, so a gelatin sponge was used for packing, and the incision was then closed using a size #1 non-absorbable suture.

4. Post-operative management

1. After the patient regained consciousness, dexamethasone (10 mg) was administered once daily (qd) for its anti-inflammatory and analgesic effects, and cefuroxime (1.5 g) was given every 8 h (q8h) to prevent infection.
2. After regaining consciousness, the patient was administered ibuprofen (0.4 g) once daily (qd) for its anti-inflammatory and analgesic effects, and cefoperazone and sulbactam sodium (1.5 g) every 12 h (q12h) for infection prophylaxis. The patient still had radiating pain 6 h postoperatively in the lower limbs and urinary incontinence. Cerebrospinal fluid leakage was observed in the drainage tube.
3. On the day of the postoperative review, the patient's MRI revealed a cerebrospinal fluid leak. The suction on the drainage tube was adjusted from negative pressure to atmospheric pressure. The volume and characteristics of the drainage were monitored and recorded to ensure the tube remained unobstructed and the patient received ORT and IV therapy.
4. The patient was given oral rehydration fluids and IV infusions of a sodium, potassium, magnesium, and calcium glucose solution, 500 mL BID.
5. The drainage volume was less than 50 mL per day on the third day, and the drainage tube was removed. The patient experienced no discomfort, such as headache, dizziness, nausea, or vomiting.
6. The patient underwent a 3-day period of indwelling catheterization, along with pelvic floor muscle exercises and anal sphincter exercises.
   NOTE: After 2 weeks, the patient experienced some alleviation of lower limb pain and was discharged, although constipation still remained.

5. Preoperative work-up for the second surgery

NOTE: The patient was readmitted due to pain in the right lower limb 5 months later. Further imaging revealed a herniation of the L5/S1 dural sac (Figure 3).

1. After obtaining informed consent, a total laminectomy and dural sac repair were performed using 3D microscopic guidance.

6. Installation for the second surgery

1. Patient positioning: After general anesthesia, the patient was positioned prone on a spinal surgery table, with protective pads placed on vital areas to prevent pressure sores and abdominal compression.
2. Surgeon position: The surgeon and the assistant stood on either side of the patient, with the 3D microscope positioned on the patient's left side and connected to a secondary screen to facilitate coordinated operation between the surgeon and the assistant.

7. Procedure steps for the second surgery

1. Incision and exposure
   1. A central incision of approximately 5 cm was made over the L5 spinous process. The skin, subcutaneous fascia, and deep fascial layers were sequentially incised, with electrocautery used for hemostasis.
   2. Subsequently, a dissector was used to bluntly separate the paraspinal muscles laterally, ensuring comprehensive exposure of the transverse processes, articular processes, and full visualization of the L5 and S1 levels, followed by meticulous hemostasis to provide optimal visibility for the surgical field.
2. Laminectomy and articular process resection
   1. Under the guidance of a 3D microscope, using a rongeur and an osteotome, the bilateral laminae and a portion of the medial articular processes at L5/S1 were meticulously resected.
      NOTE: This process exposed a section of the ligamentum flavum, as well as the nerve roots and the dura mater.
   2. During the surgery, the protruding nerve roots were observed. The small joints that were compressing the nerve roots and the spinal canal were resected.
3. Nerve root repositioning
   1. Utilizing a nerve root dissector, the nerve roots and the dura mater were guided inward, facilitating the repositioning of the herniated nerve fibers back into the spinal cord.
   2. Subsequently, the dura mater and nerve roots were carefully relaxed and sutured with a 5-mm vascular suture. The effused cerebrospinal fluid was cleared, and the nerve roots and dura mater were skillfully repositioned.
   3. A drainage tube was placed, and the incision was then closed using a size #1 non-absorbable suture.

8. Post-operative management

NOTE: The morning after the surgery, the patient experienced dizziness, headache, nausea, and vomiting. The body temperature was 35.7 °C, with a severe headache.

1. After consultation with a neurosurgeon, the suction pressure of the drainage tube was adjusted from negative to atmospheric pressure to observe and record the amount and characteristics of the drainage. When the drainage was less than 50 mL per day, the drainage tube was removed.
2. The patient was supplemented with ample fluids and kept in a prone position. A pressure dressing was applied to the incision. The use of osmotic diuretics, such as mannitol, was avoided to alleviate headache and dizziness.
3. On the afternoon of the second day, the patient's dizziness and headache were relieved, with lower limb muscle strength above grade 4, and fluid intake was increased to 2000 mL, continuing with anti-infection treatment.
   NOTE: The aforementioned symptoms were alleviated by the third postoperative day. Postoperatively, the pain in both lower limbs was reduced, and normal urination and defecation were restored.

Results

Exoscopic repair of a dural hernia is a safe and effective treatment method. The surgery demonstrated that the use of 3D microscopy for dural hernia repair can improve the patient's quality of life. Figure 4 illustrates that 3D microscopy, with its microscopic assistance, provides a clear field of view and optimal lighting, ensuring the comfort of the surgeon. Its most notable feature is its ability to facilitate magnified dural repair, making it an invaluable tool in such surgical procedures. For this patient's dural hernia, we performed a total laminectomy and dural sac repair suture using 3D microscopy, achieving a favorable final outcome.

Figure 1: The preoperative images of the case. (A,B) Preoperative radiographic film for the lumbar spine demonstrated stability. (C,D) Preoperative lumbar MRI manifested disc herniation on the right side at L5/S1. (E,F) The preoperative lumbar CT scan was also in line with the MRI. Please click here to view a larger version of this figure.

Figure 2: Postoperative imaging of the case. (A,B) The MRI conducted on the third day after the operation revealed cerebrospinal fluid leakage and an injury to the lower endplate of L5. Please click here to view a larger version of this figure.

Figure 3: Images of the patient 5 months after the initial operation. (A,B) Postoperative radiographic film for lumbar spine. (C,D) The lumbar MRI conducted five months postoperatively revealed a cauda equina hernia at L5/S1, as well as cerebrospinal fluid leakage and injury to the upper endplate of L5. (E,F) Postoperative lumbar CT. Please click here to view a larger version of this figure.

Figure 4: Representative images before and after the second surgery. (A,B) Dural tear and cauda equina herniation observed under a microscope. (C,D) Postoperative MRI demonstrated repaired thecal sac. Please click here to view a larger version of this figure.

Discussion

There are few reports documenting nerve root compression resulting from dural sac herniation¹. Herniation of the spine can be categorized as spontaneous, iatrogenic, or traumatic⁸. In this case, the patient's condition was primarily attributed to dural injury and compromised arachnoid integrity. Long-term constipation experienced by the patient resulted from increased abdominal pressure, cerebrospinal fluid flow, arachnoid herniation, and compression of nerve roots, ultimately manifesting in lower limb symptoms and urinary incontinence^9,10. For this patient, the dura was torn by a reamer during the initial percutaneous endoscopic surgery. However, owing to the water medium, no obvious rupture was discerned under the microscope, and the dura was left unrepaired, with only gel foam being implanted. Despite the patient's youth and the absence of postoperative symptoms such as dizziness, headache, or vomiting, this aspect did not receive adequate attention from the surgeon. Consequently, the prolonged constipation led to an increase in abdominal pressure^11,12,13. The elevated spinal canal pressure resulted in the eventual herniation of the dural sac during increased daily activities.

Iatrogenic spinal hernia is a rare but serious complication of lumbar surgery. Nakashima et al. reported an incidence of 0.01% for spinal hernia after a dural incision, with the primary cause being dural sac injury or tear¹⁴. Zhang Wang and Gao Suning reported that, during spinal endoscopic surgery, the dural tear was not clearly visible under a water medium, and no suturing was carried out during the procedure. Postoperatively, the neurological symptoms in the lower limbs worsened and could not be relieved through conservative treatment. Unfortunately, an MRI examination was not promptly conducted after the operation. Subsequent to the second operation aimed at repairing the dural sac, the symptoms were alleviated^15,16. For this patient, the persistent constipation both before and after surgery resulted in elevated abdominal pressure during defecation, consequently increasing spinal canal pressure¹⁷. Due to the injury to the spinal cord adventitia and increased cerebrospinal fluid pressure, the arachnoid hernia may be a significant factor contributing to lower limb symptoms resulting from nerve root compression.

Spinal endoscopic surgery is a secure approach for treating lumbar spinal stenosis. It boasts comparable efficacy to traditional laminectomy but with fewer complications. However, it presents a greater challenge for revision compared to open surgery, particularly in cases of durotomy^18,19,20. 3D microscopy emerges as a secure alternative for lumbar spinal procedures, particularly in cases requiring dural sac repair. Offering a clear field of view and optimal lighting, 3D microscopy ensures excellent comfort for surgeons. Its most noteworthy attribute lies in its ability to facilitate magnified dural repair, proving to be an invaluable tool in such surgical interventions²¹. For the dural hernia in this patient, we employed 3D microscopy for total laminectomy and dural sac repair, yielding a favorable ultimate outcome.

To prevent the occurrence of a dural sac hernia, surgeons should adhere to several fundamental concepts. Primarily, it is not advisable to increase the speed of irrigation water beyond 200 mL/min during procedure²². Excessive water pressure can decrease the likelihood of dural tears but increases the risk of serious complications, such as postoperative intracranial hemorrhage following dural tears, which represents a catastrophic complication²³. Secondly, if a substantial dural tear is identified during the operation, it is imperative to decrease water pressure promptly and repair the dura in a timely manner. If deemed necessary, traditional open surgery should be undertaken to prevent complications such as postoperative cerebrospinal fluid leakage and dural herniation^24,25. However, there is controversy regarding the size of the dural tear that requires timely repair, predominantly relying on the surgeon's experience. Further research is warranted to address this issue.

Dural herniation is an infrequent but critical complication following spinal endoscopic surgery, potentially resulting from various factors²⁶. In this case, the occurrence of dural herniation was associated with the absence of prompt dural repair, excessive hydrostatic pressure during the endoscopic procedure, prolonged surgical duration, and increased intra-abdominal pressure due to postoperative constipation. Particularly in this instance, the patient's chronic constipation was noted to elevate intra-abdominal pressure, predisposing to the protrusion of the cauda equina through a dural weakness. Consequently, the utilization of laxatives in such patients is warranted to mitigate intra-abdominal pressure during defecation, thereby reducing the likelihood of cauda equina herniation²⁷.

This report presents a case of dural herniation that occurred following spinal endoscopic surgery, leading to nerve root compression manifested by bilateral lower limb symptoms. Successful amelioration of the condition was achieved through 3D microscopic-assisted dural sac repair, highlighting the significance of early intervention for dural tears and the necessity of preventing postoperative constipation. Preventing constipation is crucial as it may elevate intra-abdominal pressure in patients with dural tears, increasing the risk of dural herniation.

Additionally, we recommend the routine placement of a drainage tube following dural tear incidents. The rationale for this practice includes preventing the excessive pressure of leaked cerebrospinal fluid from affecting wound healing, increasing the risk of incisional infection, and reducing the likelihood of pseudomeningocele formation by ensuring adequate drainage of cerebrospinal fluid.

Materials

List of materials used in this article

Name	Company	Catalog Number	Comments
Kestrel View II	Mitaka Kohki Co., Ltd.	000 46	3D Microscope
Mersilk	Ethicon	SA87G	Suture