This came from the American Pain Foundation page.
http://www.nationalpainfoundation.org/articles/820/definitions
TRIGEMINAL NEURALGIA
Definitions
To avoid confusion when discussing trigeminal neuralgia, it is important to understand the words your health care provider is using and what they mean when he or she is talking about facial pain. Below are several definitions that have been and are still used to describe people with trigeminal neuralgia and facial pain:
Atypical TN is a term often used to describe pain that does not have the characteristics associated with classic or typical TN. Patients who have atypical TN often have pain that may be continuous and may be described as dull, aching, or throbbing.
Atypical facial pain is a confusing term and should never be used to describe patients with trigeminal neuralgia or trigeminal neuropathic pain. Strictly speaking, AFP is classified as a “somatiform pain disorder”; this is a psychological diagnosis that should be confirmed by a skilled pain psychologist. Patients with the diagnosis of AFP have no identifiable underlying physical cause for the pain. The pain is usually constant, described as aching or burning, and often affects both sides of the face (this is almost never the case in patients with trigeminal neuralgia). The pain frequently involves areas of the head, face, and neck that are outside the sensory territories that are supplied by the trigeminal nerve. It is important to correctly identify patients with AFP since the treatment for this is strictly medical. Surgical procedures are not indicated for atypical facial pain.
In order to simplify and clarify the diagnosis of the trigeminal neuralgia and eliminate some of the confusion produced by difference in terminology, Dr. Kim Burchiel (Professor and Chairman, Department of Neurological Surgery, Oregon Health Sciences University, Portland, OR) has proposed a new classification scheme for the diagnosis of facial pain. This scheme is based on the underlying causes of the pain and has implications for treatment:
This is a pain condition that happens after an injury to one or more branches of the trigeminal nerve. Trigeminal neuropathic pain curs as a result of nerve injury following dental procedures (tooth extractions, root canals, etc), facial fractures, nerve injury from sinus surgery, etc. This condition is NOT the same as trigeminal neuralgia. This pain is usually continuous and generally is of a burning quality. Many patients with TNP have documented loss of sensation on the face or forehead. It is important to make this distinction, since the surgical procedures that are effective in trigeminal neuralgia, are almost never helpful for TNP, and not uncommonly can make this condition worse.
Atypical Trigeminal Neuralgia
Atypical TN is a term often used to describe pain that does not have the characteristics associated with classic or typical TN. Patients who have atypical TN often have pain that may be continuous and may be described as dull, aching, or throbbing.
Atypical facial pain is a confusing term and should never be used to describe patients with trigeminal neuralgia or trigeminal neuropathic pain. Strictly speaking, AFP is classified as a “somatiform pain disorder”; this is a psychological diagnosis that should be confirmed by a skilled pain psychologist. Patients with the diagnosis of AFP have no identifiable underlying physical cause for the pain. The pain is usually constant, described as aching or burning, and often affects both sides of the face (this is almost never the case in patients with trigeminal neuralgia). The pain frequently involves areas of the head, face, and neck that are outside the sensory territories that are supplied by the trigeminal nerve. It is important to correctly identify patients with AFP since the treatment for this is strictly medical. Surgical procedures are not indicated for atypical facial pain.
In order to simplify and clarify the diagnosis of the trigeminal neuralgia and eliminate some of the confusion produced by difference in terminology, Dr. Kim Burchiel (Professor and Chairman, Department of Neurological Surgery, Oregon Health Sciences University, Portland, OR) has proposed a new classification scheme for the diagnosis of facial pain. This scheme is based on the underlying causes of the pain and has implications for treatment:
- Trigeminal neuralgia, type 1, (TN1): facial pain of spontaneous onset with greater than 50% of pain 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 procedures that are typically performed for treatment of trigeminal neuralgia (eg. neurectomy, gangliolysis, rhizotomy, radiosurgery, nucleotomy, tractotomy, or other denervating procedures)
- Symptomatic trigeminal neuralgia, (STN): pain resulting from multiple sclerosis.
- Secondary trigeminal neuralgia: pain resulting from anatomical abnormalities that affect the trigeminal nerve such as tumors, aneurysms, etc.
- Postherpetic neuralgia, (PHN): pain resulting from trigeminal Herpes zoster outbreak.
- Atypical facial pain, (AFP): pain predominantly having a psychological rather than a physiological origin.
Trigeminal Neuropathic Pain
This is a pain condition that happens after an injury to one or more branches of the trigeminal nerve. Trigeminal neuropathic pain curs as a result of nerve injury following dental procedures (tooth extractions, root canals, etc), facial fractures, nerve injury from sinus surgery, etc. This condition is NOT the same as trigeminal neuralgia. This pain is usually continuous and generally is of a burning quality. Many patients with TNP have documented loss of sensation on the face or forehead. It is important to make this distinction, since the surgical procedures that are effective in trigeminal neuralgia, are almost never helpful for TNP, and not uncommonly can make this condition worse.