Is subarachnoid block safe in patients with a history of poliomyelitis?

Subarachnoid Block Safety in Patients with Poliomyelitis

Subarachnoid block is generally safe in patients with a history of poliomyelitis, and there is no evidence suggesting worsening of neurological status following this anesthetic technique. 1

Understanding Poliomyelitis and Its Sequelae

Poliomyelitis is an acute viral disease that attacks the brain and ventral horn of the spinal cord, causing damage to lower motor neurons. This typically results in:

• Asymmetric muscle weakness or paralysis, more severe proximally than distally
• Diminished or absent deep tendon reflexes
• Potential respiratory and swallowing difficulties in bulbar cases 2

After the acute phase, many patients experience partial recovery of muscle function, with prognosis usually established within 6 months after onset of paralytic manifestations.

Post-Polio Syndrome (PPS)

25-40% of individuals who had paralytic polio develop post-polio syndrome 30-40 years after the initial infection. Risk factors include:

• Longer time since acute infection
• Presence of permanent residual impairment after recovery
• Female gender 2, 3

PPS is characterized by:

• New muscle weakness
• Fatigue
• Muscle and joint pain
• Atrophy
• Fasciculations 4

Evidence for Subarachnoid Block Safety

A retrospective study of 123 patients with sequelae of poliomyelitis who underwent 162 surgical procedures provides the most relevant evidence regarding neuraxial anesthesia safety:

• 64.1% of procedures used neuraxial blocks (with epidural being most common)
• No patients developed postoperative complications or worsening of neurological status attributable to the anesthetic technique
• Minor complications included accidental dural puncture (0.61%), bradycardia (0.61%), hypotension (1.23%), and urinary retention (2.64%)
• Patients were followed for 22 months with no evidence of neurological deterioration 1

Considerations for Anesthetic Management

When planning anesthesia for patients with polio history:

1. Pre-anesthetic assessment:

   • Evaluate the extent of muscle weakness and respiratory function
   • Identify any bulbar involvement that might affect airway management
   • Assess for signs of post-polio syndrome

2. Anesthetic technique selection:

   • Neuraxial techniques (subarachnoid or epidural) appear safe based on available evidence
   • Consider patient positioning challenges due to skeletal deformities or contractures
   • Be prepared for potentially higher incidence of hypotension due to autonomic dysfunction

3. Perioperative monitoring:

   • Close monitoring for respiratory complications, especially in patients with history of bulbar involvement
   • Vigilance for temperature regulation issues

Potential Pitfalls and Caveats

• Respiratory function: Patients with history of respiratory muscle involvement may have reduced respiratory reserve, requiring careful postoperative monitoring
• Positioning: Skeletal deformities may make positioning for neuraxial blocks challenging
• Cold sensitivity: PPS patients often have increased sensitivity to cold, so maintain normothermia
• Fatigue management: Consider scheduling procedures earlier in the day when fatigue is less pronounced in PPS patients 3, 5

Conclusion

Based on the available evidence, subarachnoid block appears to be a safe anesthetic technique for patients with a history of poliomyelitis. The study by Brazilian anesthesiologists specifically examining this question found no evidence of neurological deterioration attributable to neuraxial anesthesia in these patients 1. However, careful pre-anesthetic assessment and consideration of the specific manifestations of the disease in each patient remain important for optimal perioperative management.