16.2. Nerve injury

Injury to neural structures within the dural sac during BESS/UBE is a potentially severe complication. Depending on the intervention level, it may involve the spinal cord or intradural nerve roots, including the cauda equina in the lumbar spine. These structures lie in the subarachnoid, not the subdural, space.

Incidence:

• The cited sources do not establish a separate incidence of intradural neural injury in BESS/UBE.
• Overall rates of nerve injury cannot be applied to this specific complication.

Mechanism:

Direct trauma:

Instruments (for example, a burr, Kerrison punches, or other instruments) may enter through a dural tear and injure the nerve fibers inside. This may occur if the tear is not detected promptly or the surgeon continues manipulation in the area of the defect.

Thermal effects:

Radiofrequency (RF) coagulation or bipolar instruments used too close to the dura mater may transmit heat through the dura to the nerves, causing burns or necrosis.

Compression or tension:

Excessive displacement of neural structures during decompression (for example, during removal of a large herniation) may cause axonal microtrauma or impaired nerve blood supply.

Secondary injury:

A postoperative hematoma or neural tissue edema may cause additional compression and deterioration in neurological function.

Symptoms:

Immediate:

• Limb weakness (paresis).
• Loss of sensation (anesthesia or hypoesthesia) in the corresponding dermatomes.
• Acute neuropathic pain or tingling.

Delayed:

• Chronic pain due to scarring or neuropathy.
• Motor deficit (up to paralysis) in spinal cord injury.
• Bladder and bowel dysfunction (for example, urinary incontinence) in cauda equina injury.

Causes:

• Technical errors: Imprecise instrument positioning in a narrow surgical field, especially when visualization is inadequate due to irrigation or bleeding.
• Anatomical factors: a narrow spinal canal, scarring, adhesions, and individual anatomical features make safe manipulation difficult.
• Complexity of the pathology: Large calcified herniations or fibrous tissues adherent to the dura increase the risk of deep instrument penetration.
• Insufficient experience: learning BESS/UBE requires appropriate training, mentorship, and gradual increases in surgical complexity.

Diagnosis:

Intraoperative: visual confirmation of dural and neural injury.

Postoperative:

• Clinical assessment (strength, sensation, and reflex testing).
• MRI or CT to identify a hematoma, edema, or direct neural tissue injury.

Treatment:

Intraoperative:

1. Immediate cessation of manipulation in the injured area.
2. If neural injury is accompanied by a dural tear, we close the defect using the strategy described in §16.1.

Postoperative:

1. Conservative:

In our practice, we use high-dose corticosteroids for intraoperative neural injury, taking contraindications and risks into account. Drug administration must not delay emergency assessment and relief of compression.

We select analgesia individually. Gabapentin may be used when indicated to control neuropathic pain.

We select rehabilitation according to the neurological deficit and the patient’s clinical condition.

2. Surgical:

1. Revision surgery for decompression (removal of a hematoma or fragments compressing nerves).

Duration of recovery:

1. Mild injuries: recovery may be partial or complete; its duration is individual.
2. Severe injuries (spinal cord disruption): the prognosis is unfavorable, and permanent loss of function is possible.

Prognosis:

• Mild injuries: For example, transient nerve root irritation usually resolves without sequelae.
• Severe injuries: injury to the spinal cord or a substantial number of nerve roots may lead to irreversible neurological deficits (paralysis, chronic pain, and bladder and bowel dysfunction).

Prevention:

Technique:

• Avoid instrument use within the dural sac, even when a tear is present.
• We use RF coagulation near neural structures cautiously: short activations, the appropriate system mode, and continuous free fluid outflow.

Visualization: Continuous endoscopic monitoring of the surgical field to avoid blind spots.

Patient selection: Avoid BESS/UBE in high-risk cases (developmental anomalies, previous operations with extensive fibrosis).

Conclusion:

Intradural neural injury is a potentially severe complication. Recovery depends on the type and severity of injury and timely elimination of reversible causes. Persistent deficits are possible even without spinal cord injury. A new or progressive neurological deficit requires emergency assessment to exclude compression or another treatable cause.

References

1. Ju CI, Lee SM. Complications and management of endoscopic spinal surgery. Neurospine. 2023;20(1):56–77.

DOI: 10.14245/ns.2346226.113

2. Fehlings MG, Alvi MA, Evaniew N, et al. A Clinical Practice Guideline for Prevention, Diagnosis and Management of Intraoperative Spinal Cord Injury: Recommendations for Use of Intraoperative Neuromonitoring and for the Use of Preoperative and Intraoperative Protocols for Patients Undergoing Spine Surgery. Global Spine J. 2024;14(3 Suppl):212S–222S.

DOI: 10.1177/21925682231202343

3. Jung SB, Kim N. Biportal endoscopic spine surgery for cervical disk herniation: a technical notes and preliminary report. Medicine (Baltimore). 2022;101(27):e29751.

DOI: 10.1097/MD.0000000000029751

4. NICE. Neuropathic pain in adults: pharmacological management in non-specialist settings. CG173.

NICE CG173 — official guideline

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