Purpose:
Discuss neuropathic pain causes and mechanisms
Results:
Neuropathic pain described as pain initiated or caused by a primary lesion or dysfunction in the nervous system. Summarizes neuropathic pain conditions frequently seen in dental offices.
–Neuropathic orofacial pain – Spontaneous pain that is unprovoked, cannot be treated with conventional analgesics or opiods
–Pathophysiology – change in excitability of primary nociceptive afferents may be single most important factor in generation & maintenance of acute chemogenic pain or chronic neuropathic pain in humans
- Deafferentation is defined as continuous pain after complete or partial damage to the nerve-post endo trx reported as 3-6%
- Demylenation-degenerative process causing loss of myelin sheath of nerves-can become areas of ectopic sites of repetitive firing that occur spontaneously or as response to stimuli
-membrane remodeling affecting Na+ channels responsible for ectopic repetitive firing
-Local anesthesia used as diagnostic aid-stabilize membrane
1.Trigeminal Neuralgia (TN)-causes-idiopathic, demyelinating diagnosis, trauma,
a.2-27 people per 100k
b.Most often in women over 50, usually a trigger point, report a sharp, shooting, stabbing pain that last for up to a few minutes
- Pre-trigeminal neuralgia (PTN)
- presents as a dull aching pain (toothache or sinus like pain) with a sporadic sharp component-spontaneous w/o specific trigger point, then progresses to TN
-treatment of TN is pharmacotherapy or surgery
- Atypical Odontalgia-constant pain with a tooth with no obvious source of local pathology
- most often seen around age 50,most common in maxillary molar area, and is of moderate intensity
- unchanging persistent pain for at least 3 months-anesthetic may or may not alleviate symptoms
- no defined mechanism for disorder-have used TCAs and benzodiazepenes for treatment
- Post-herpetic neuralgia (PHN)-persists after outbreak of herpes zoster (varicella)
- Virus migrates most often to dorsal root ganglion of the thoracic spine (55% of cases)
- 15% virus is found in cranial nerve ganglion (V and VII) and 12% in cervical distribution of spinal nerves
- once “triggered” condition is “shingles”-usually unilateral and can be expressed in any branch of trigeminal system
- Reactivation of the dormant virus
- when triggered virus invades nerves and ganglion causing necrotizing action (primary cause of PTN)
- pain may or may not be associated with area where rash was present
- 87% of patient with PTN experience allodynia, hyperesthesia, dysethesia, or anesthesia-describe pain as deep, aching, burning, stabbing, itching, electrical, unbearable etc.
the older the patient is at outbreak, the more likely they are to develop PTN (avg. is 1 in 5)
- No cure-prevention w/ vaccine, pharmacotherapy, nerve blocks, topical meds, electrical stimulation, alternative trx