Erythromelalgia | Erythermalgia

AKA Acral vasomotor syndrome
 
Etymology
  • Erythros: red
  • Melos: extremities
 
Etiology
  • Primary
    • Autosomal dominant mutation in the SCN9A gene
      • Codes voltage-dependent sodium channel NAV1.7
      • Found on peripheral sensory neurons, especially nociceptors and sympathetic neurons
      • Mutation → decrease in channel’s activation → hyperexcitability → inflammatory pain
 
Epidemiology
  • Women > men (3:1)
 
Clinical presentation
  • Intense burning sensation
  • Accompanied by diffuse edematous erythema, which intensifies in the evening and often persists throughout the night, causing insomnia
  • Feet (90%) > hands (25%) > ears
  • Acrocyanosis
  • Livedo reticularis
  • Necrosis
  • Ulceration
 
Diagnostic criteria
  • Presence of paroxysmal painful attacks symmetrically affecting the hands and feet
  • Worsening of symptoms in hot weather
  • Relief from cold
  • Presence of erythema in the affected areas
  • Local increase in temperature
 
Abordagem
  • Consider: doppler, nerve tests
  • Genetic testing
 
Prognosis: ⅓ worsen, ⅓ remain, ⅓ improve
 
Treatment
  • Identificar e tratar causa subjacente
  • Aspirin 50-100mg qd (first line)
    • Heparin & warfarin do not help (microthrombi do not require thrombin function to form)
  • NSAIDs
  • Anagrelide and hydroxyurea for severe thrombocythemia
  • Beta-blockers, diltiazem, nitroprusside (kids w/ HTN)
  • Topical and oral meds for neuralgias
    • Topical lidocain, capsaicin, TCA, SSRI, gabapentin
    • Systemic or local lidocaine
    • Oral mexiletine
  • IV lidocain, epidural, intrathecal opiates
  • Sympathetic ganglion blockade
  • Endoscopic sympathectomy
  • Other Pentoxifylline, dipyridamole, anticonvulsants (carbamazepine, phenytoin), antidepressants, analgesics for neuropathic pain (gabapentin, pregabalin), vasodilators (nitroglycerin, calcium channel blockers) and antimigraine drugs (ergotamine, methysergide)