Neuropathic%20pain Treatment

Trigeminal Neuralgia (TN)

• For patients with TN refractory to medical therapy, early surgical therapy may be considered
• Prior to considering surgery, eligible patients should have an MRI to eliminate other causes of compression of the trigeminal nerve
• Peripheral Techniques
  • Involve blocking or destruction of portions of the trigeminal nerve distal to the Gasserian ganglion
  • Low morbidity but 50% have pain recurrence after 1 year
• Percutaneous Procedures on Gasserian Ganglion
  
  • Preferred for elderly patients, those with multiple sclerosis (MS), with impaired contralateral hearing, and those with recurrent pain after microvascular decompression
  • Eg radiofrequency thermocoagulation, balloon compression rhizotomy, percutaneous retro-Gasserian glycerol rhizotomy
    • A median of 68% (range 55%-80%) of patients who underwent balloon compression remain pain-free after long-term follow-up
  • After percutaneous trigeminal radiofrequency, initial pain relief can be achieved in 98% of patients and 15-20% of patients may experience recurrence in 12 months
    • Pain-free period is reported at 4-5 years
  • Observational studies have shown that radiofrequency thermocoagulation produces higher rates of complete pain relief but is also associated with higher rates of facial numbness and corneal insensitivity
    • A median of 58% (range 26%-82%) of patients remain pain-free after long-term follow-up 
    • Severe facial numbness/anesthesia dolorosa and corneal numbness with keratitis occur in around 4% of patients

• Microvascular Decompression
  • Preferred procedure for young patients with typical TN
  • Major neurosurgical procedure involving craniotomy to reach the trigeminal nerve in the posterior fossa
  • Vessels compressing the nerve are identified and moved out of contact
  • Provides longest duration of pain relief while preserving facial sensation
    • Observational studies have shown a median of 77% (range 62%-89%) of patients remain pain-free at long-term follow-up (10-12 years)
  • Complications include aseptic meningitis, hearing loss, cerebrospinal fluid (CSF) leaks, infarcts, hematomas, transient diplopia and sensory loss
  • Associated with 0.5% mortality rate and 3-29% facial numbness rates
  • Increased risk for severe complications in older age groups

• Gamma Knife Stereotactic Radiosurgery
  • Least invasive procedure for TN
  • Treatment option for patients with comorbidities, high-risk medical illness or pain refractory to prior surgical procedures
  • Aims a focused beam of radiation at the trigeminal root in the posterior fossa
  • In a study, it showed that adequate pain relief were 75%, 60% and 58% at 1, 3, and 5 years, respectively
    • Pain-free period is reported at 3-4 years 
    • Onset of pain relief is variable with an average time of 1 month or median time of 2 weeks after treatment
  • Most common adverse effect is trigeminal nerve sensory dysfunction eg facial numbness, paresthesia