A rare complication of TN surgery
These notes are taken from the Facial Pain Association website.
What is Anesthesia Dolorosa?
Anesthesia Dolorosa (AD) literally means painful numbness. This painful condition occurs when the trigeminal nerve is damaged in such a way that the sense of touch is diminished or eliminated while a malfunctioning sensation of pain is left intact. AD is referred to as a deafferentation pain syndrome.
The cause of AD.
- AD can result from any surgery around the trigeminal ganglion.
- Many doctors feel the procedures most likely to produce AD are percutaneous (through the cheek) procedures using radiofrequency, balloon compression, or glycerol. AD may also occur following a trigeminal rhizotomy, in which a surgeon intentionally cuts the trigeminal nerve root.
Why AD occurs.
- Theory #1 – the touch-carrying nerve fibers are injured by surgery, while little or no damage occurs to pain-carrying fibers.
- Theory #2 - surgical injury may also prevent nerve fibers from overlapping as they normally should, resulting in distorted signals being sent to the brain.
- Theory #3 - AD pain is much like “phantom limb pain,” but is occurring to an “amputated” trigeminal nerve branch instead of an arm or leg. After surgery, when these pain signals suddenly stop, the brain may deal with this loss of input by remembering and replaying old pain signals.
What the pain of AD feels like.
- Pain for an AD patient is constant and is felt in their area of numbness. They describe it as: burning, boring, prickling, or as a feeling of heaviness, tightness, or pressure. Diagnosis is generally based on the description of symptoms.
Why it’s important to distinguish the difference between AD and TN.
- AD pain is usually constant with a burning or jabbing quality, while TN is intermittent, with sharp, electric-like jabs.
- The distinction between the two can affect the course of treatment. Further destructive procedures for an AD patient may make the condition worse.
Treatments for AD.
o Muscle relaxants (Baclofen, Zanaflex)
o Antidepressants like amitriplyline (Elavil), nortriptyline (Pamelor), clonidine (Catapres), paroxetine (Paxil)
o Anticonvulsants such as TN- carbamazepine (Tegretol, Carbatrol), oxcarbazpine (Trileptal), gabapentin (Neurontin), clonazepam (Klonopin), valproate (Depakote), topiramate (Topamax), phenytoin (Dilantin)
o Topical anesthetic (EMLA)
o Topical ointments (Zostrix, Capsazin-P)
o Anesthetic Injections (lidocaine), opiods, such as a transmucosal fentanyl (Actiq)
o Oral Morphine drugs (oxycontin)
- Complementary and Alternative therapies (CAM) include acupuncture, upper-cervical chiropractic, nutrition therapy, hot and cold compresses, biofeedback, and electrical stimulation (TENS, SCENAR).
- Medical Treatment: Anesthetic injections (nerve blocks), motor cortex stimulation (an implanted electrode gives constant electrical stimulation), Drez procedure (a last-ditch surgery, because arm-or leg-coordination difficulties may be post operative complications, this surgery injures the origin of the trigeminal nerve in the upper spinal cord.
As medical science better understands the brain, surgeons also are looking into the newer field of stimulating or selectively disabling parts of the brain that process pain signals.
From Wikipedia, the free encyclopedia
Anesthesia dolorosa or anaesthesia dolorosa or deafferentation pain is pain felt in an area (usually of the face) which is completely numb to touch. The pain is described as constant, burning, aching or severe. It can be a side effect of surgery involving any part of the trigeminal system, and occurs after 1–4% of peripheral surgery for trigeminal neuralgia. No effective medical therapy has yet been found. Several surgical techniques have been tried, with modest or mixed results. The value of surgical interventions is difficult to assess because published studies involve small numbers of mixed patient types and little long term follow-up.
- Gasserian ganglion stimulation is stimulation of the gasserian ganglion with electric pulses from a small generator implanted beneath the skin. There are mixed reports, including some reports of marked, some of moderate and some of no improvement. Further studies of more patients with longer follow-up are required to determine the efficacy of this treatment.
- Deep brain stimulation was found in one review to produce good results in forty-five percent of 106 cases. Though relief may not be permanent, several years of relief may be achieved with this technique.
- Mesencephalotomy is the damaging of the junction of the trigeminal tract and the periaqueductal gray in the brain, and has produced pain relief in a group of patients with cancer pain; but when applied to six anesthesia dolorosa patients, no pain relief was achieved, and the unpleasant sensation was in fact increased.
- Dorsal root entry zone lesioning, damaging the point where sensory nerve fibers meet spinal cord fibers, produced favorable results in some patients and poor results in others, with incidence of ataxia at 40%. Patient numbers were small, follow-up was short and existing evidence does not indicate long term efficacy.
- One surgeon treated thirty-five patients using trigeminal nucleotomy, damaging the nucleus caudalis, and reported 66% "abolition of allodynia and a marked reduction in or (less frequently) complete abolition of deep background pain."