3.2. Spinal Anesthesia

@Chshegolkov_Evhenii

Previous section: 3.1. General Anesthesia

Spinal anesthesia, or subarachnoid block, is a form of neuraxial regional anesthesia in which a local anesthetic is injected into the subarachnoid space. It produces a temporary, reversible sensory, motor, and sympathetic block. In BESS/UBE, it may be used for selected lumbar procedures.

Patient selection and planning

The anesthesiologist selects spinal anesthesia according to the patient's condition, the expected duration and extent of surgery, tolerance of the prone position, and the possibility of conversion to general anesthesia. Before puncture, contraindications to neuraxial blockade, hemostatic status, and the use of antithrombotic drugs are assessed. The intervals for their discontinuation and resumption are determined according to the specific drug, its dose, renal function, and current recommendations.

Puncture and local anesthetic

In the practice described here, after local anesthesia, spinal puncture is performed at L3–L4 with 25–26 G needles, using bupivacaine. The anesthesiologist individually determines the puncture level, needle type and size, dose and baricity of the solution, patient position, and the timing of repositioning.

Intrathecal adjuvants

Dexmedetomidine has been studied as an adjuvant to bupivacaine, including in biportal endoscopic discectomy. However, intrathecal administration of dexmedetomidine is use via an unapproved route of administration (off-label). The decision to use it must be justified by the anesthesiologist, recorded in a documented protocol, and consistent with local rules and requirements for patient information and consent.

Block assessment, sedation, and monitoring

Before surgery begins, an adequate sensory level and degree of motor block are confirmed and documented. For motor function, the specific version of the Bromage scale, its scoring criteria, and the time of assessment are stated. Assessment of the established block is not conflated with assessment of recovery from it. The durations of sensory block, motor block, and analgesia are assessed separately; these parameters may vary between patients.

In our practice, sedation is usually unnecessary, but the anesthesiologist determines its need and depth individually. Regardless of sedation, anesthetic supervision, ECG, pulse oximetry, and monitoring of blood pressure, heart rate, and respiration are provided. During moderate or deep sedation, every effort is made to continuously monitor exhaled CO₂ alongside clinical assessment of ventilation. Temperature is assessed using instrumental monitoring when clinically significant changes are expected or suspected.

During lumbar BESS/UBE under spinal anesthesia, new headache or posterior neck pain may be early signs of an irrigation-related rise in epidural pressure. Impaired fluid outflow can also raise this pressure in the cervical region. If these symptoms occur, irrigation and surgical manipulation are temporarily stopped, outflow patency is checked, and the patient's condition is assessed together with the anesthesiologist [6–8].

A plan for an inadequate block, deterioration in breathing or hemodynamics, and the need for conversion to general anesthesia is established before the patient is positioned prone. Airway access, equipment, and the sequence of team actions are agreed upon in advance.

Tranexamic acid

The anesthesiologist individually determines the need for tranexamic acid, its dose, administration rate, and repeat dosing, taking expected blood loss, renal function, contraindications, and the local protocol into account. Its use does not replace meticulous surgical hemostasis.

References

1. Shchegolkov YeE. Comparative characteristics of the effectiveness of spinal anesthesia with intrathecal administration of bupivacaine and its combination with adjuvants. Emergency Medicine. 2024;20(1):51–57. doi:10.22141/2224-0586.20.1.2024.1658.

2. European Medicines Agency. Dexdor (dexmedetomidine): EPAR — Product information. Update dated 28.01.2026. Official EMA information.

3. Kopp SL, Vandermeulen E, McBane RD, Perlas A, Leffert L, Horlocker T. Regional anesthesia in the patient receiving antithrombotic or thrombolytic therapy: American Society of Regional Anesthesia and Pain Medicine Evidence-Based Guidelines (fifth edition). Reg Anesth Pain Med. 2025. doi:10.1136/rapm-2024-105766.

4. American Society of Anesthesiologists. Standards for Basic Anesthetic Monitoring. Revision dated 15.10.2025. Official ASA standard.

5. Upfill-Brown A, Olson T, Adejuyigbe B, Shah A, Sheppard W, Park CW, Heo DH, Park DY. Does the use of tranexamic acid intraoperatively reduce postoperative blood loss and complications following biportal endoscopic lumbosacral decompression? J Spine Surg. 2024;10(1):68–79. doi:10.21037/jss-23-129.

6. Ho S.-T., Suen T.-K., Yeung Y.-K. How to Establish the Unilateral Biportal Endoscopic Surgery in the Surgeons’ Daily Practice. In: Unilateral Biportal Endoscopy of the Spine: An Atlas of Surgical Techniques. Springer; 2022. P. 583–619; relevant passage: pp. 603–604.

7. Joh J.-Y., Choi G., Kong B.-J., Park H.S., Lee S.-H., Chang S.H. Comparative study of neck pain in relation to increase of cervical epidural pressure during percutaneous endoscopic lumbar discectomy. Spine (Phila Pa 1976). 2009;34(19):2033–2038. DOI: 10.1097/BRS.0b013e3181b20250.

8. Kang T., Park S.Y., Lee S.H., Park J.H., Suh S.W. Assessing changes in cervical epidural pressure during biportal endoscopic lumbar discectomy. J Neurosurg Spine. 2021;34(2):196–202. DOI: 10.3171/2020.6.SPINE20586.