What are the complications of thoracic segmental spinal anesthesia?

Complications of Thoracic Segmental Spinal Anesthesia

Thoracic segmental spinal anesthesia carries a very high risk of severe hypotension and bradycardia—significantly higher than general anesthesia—along with potential catastrophic neurological complications including total spinal anesthesia, spinal cord injury, and neuraxial hematoma. 1

Cardiovascular Complications

Hypotension and Bradycardia

• Hypotension occurs with 12-fold higher odds compared to general anesthesia (OR 12.23,95% CI 2.81-53.28), representing the most common complication of thoracic segmental spinal anesthesia 1
• Bradycardia occurs with 11-fold higher odds compared to general anesthesia (OR 10.95% CI 2.94-40.74), resulting from blockade of cardioaccelerator sympathetic fibers (T1-T4) 1, 2
• These hemodynamic disturbances stem from sympathetic blockade affecting cardiac accelerator fibers when the block extends to upper thoracic levels 2
• Aggressive hemodynamic management with vasopressors and chronotropic agents is frequently required 3

Neurological Complications

Catastrophic Spinal Complications

• Total spinal anesthesia represents a life-threatening complication that can occur from inadvertent placement of the needle through an intervertebral foramen, puncture of a long dural cuff, or intraneural injection with central spread 4
• Direct spinal cord injury from needle trauma is the primary concern driving reluctance to use this technique, as the spinal cord extends to approximately T12-L1 in adults, making thoracic puncture inherently higher risk 2
• Cephalad spread of local anesthetic can cause complete spinal block with respiratory paralysis requiring immediate airway management and ventilatory support 2, 4

Neuraxial Hematoma

• Regional anesthetic techniques are contraindicated in patients at risk of neuraxial hematoma formation due to thienopyridine antiplatelet therapy, low-molecular-weight heparins, or clinically significant anticoagulation 5
• This represents a Class III recommendation (should not be performed) from ACC/AHA guidelines 5
• The risk is particularly concerning in thoracic approaches where epidural space is narrower and spinal cord vulnerability is greater 5

Infectious Complications

• Epidural, spinal, or subdural abscess can occur following neuraxial techniques 5
• Meningitis represents a serious infectious complication requiring strict aseptic technique 5
• Catheter-related complications occur in approximately 3.7% of cases when epidural catheters are placed, including meningitis, retained catheter fragments, and temporary nerve palsies 5

Cerebrospinal Fluid-Related Complications

• Spinal headache occurs from CSF leakage through the dural puncture site 5
• Persistent CSF leaks may require epidural blood patch for resolution 5
• Subdural hematoma has been reported after procedures involving spinal fluid drainage, though this is more commonly associated with therapeutic CSF drainage rather than diagnostic puncture 5

Patient Discomfort and Psychological Complications

• Most patients require intravenous sedation to overcome anxiety and discomfort during the procedure, as remaining awake during major surgery causes significant psychological stress 1
• Surgeons may experience difficulty with the technique during certain procedures (such as axillary clearances) due to patient twitching from cautery 1
• Patient cooperation is required throughout the procedure, which may be challenging in lengthy operations 3

Technical and Procedural Complications

• Inadequate anesthesia requiring conversion to general anesthesia can occur if the block fails to achieve adequate segmental coverage 2
• Unilateral or patchy blocks may necessitate supplementation with local infiltration or conversion to general anesthesia 2
• The technical difficulty of thoracic spinal puncture is substantially higher than lumbar approaches, increasing the risk of multiple attempts and traumatic puncture 2

Critical Contraindications and High-Risk Scenarios

The ACC/AHA guidelines specifically state that regional anesthetic techniques should not be used in patients with active anticoagulation or antiplatelet therapy due to catastrophic bleeding risk 5. This is particularly relevant given that many patients considered for thoracic segmental spinal anesthesia have cardiovascular comorbidities requiring antiplatelet or anticoagulant medications 5, 6.

Context for Risk-Benefit Assessment

Despite these significant complications, thoracic segmental spinal anesthesia may be considered in highly selected patients with severe pulmonary dysfunction who cannot tolerate general anesthesia and mechanical ventilation 6. However, the technique should only be performed by experienced practitioners with immediate resuscitation capabilities available, given the high odds of severe cardiovascular complications and potential for catastrophic neurological injury 1, 2.