A new classification for facial pain

• Trigeminal neuralgia, type 1, (TN1): facial pain of spontaneous onset with greater than 50% limited to the duration of an episode of pain (temporary pain).
  
  
• Trigeminal neuralgia, type 2, (TN2): facial pain of spontaneous onset with greater than 50% as a constant pain.
  
  
• Trigeminal neuropathic pain, (TNP): facial pain resulting from unintentional injury to the trigeminal system from facial trauma, oral surgery, ear, nose and throat (ENT) surgery, root injury from posterior fossa or skull base surgery, stroke, etc.
  
  
• Trigeminal deafferentation pain, (TDP): facial pain in a region of trigeminal numbness resulting from intentional injury to the trigeminal system from neurectomy, gangliolysis, rhizotomy, nucleotomy, tractotomy, or other denervating procedures.
  
  
• Symptomatic trigeminal neuralgia, (STN): pain resulting from multiple sclerosis.
  
  
• Postherpetic neuralgia, (PHN): pain resulting from trigeminal Herpes zoster outbreak.
  
  
• Atypical facial pain, (AFP): pain predominantly having a psychological rather than a physiological origin.

• PURPOSE
  A patient-oriented classification scheme for facial pains commonly encountered in neurosurgical practice is proposed.

• CONCEPT
  This classification is driven principally by the patient's history.

• RATIONALE
  The scheme incorporates descriptions for so-called "atypical" trigeminal neuralgias and facial pains but minimizes the pejorative, accepting that the physiology of neuropathic pains could reasonably encompass a variety of pain sensations, both episodic and constant.
  Seven diagnostic labels result: trigeminal neuralgia Types 1 and 2 refer to patients with the spontaneous onset of facial pain and either predominant episodic or constant pain, respectively.
  Trigeminal neuropathic pain results from unintentional injury to the trigeminal nerve from trauma or surgery, whereas trigeminal deafferentation pain results from injury to the nerve by peripheral nerve ablation, gangliolysis, or rhizotomy in an intentional attempt to treat either trigeminal neuralgia or other facial pain.
  Postherpetic neuralgia follows a cutaneous herpes zoster outbreak (shingles) in the trigeminal distribution, and symptomatic trigeminal neuralgia results from multiple sclerosis.
  The final category, atypical facial pain, is synonymous with facial pain secondary to a somatoform pain disorder.
  Atypical facial pain can be suspected but not diagnosed by history and can be diagnosed only with detailed and objective psychological testing.

• CONCLUSION
  This diagnostic classification would allow more rigorous and objective natural history and outcome studies of facial pain in the future.