“Difficult to treat” facial pain: Anaesthesia Dolorosa

Facial Pain

What is Anesthesia Dolorosa?

Anesthesia Dolorosa (AD) literally means painful numbness, is one of the most dreaded complications of the treatment of trigeminal neuralgia. 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 deafferentation pain syndrome.

Cause:

AD can result from any surgery around the trigeminal ganglion,  any percutaneous (through the cheek) procedures using radiofrequency, balloon compression, or glycerol around the ganglion. AD may also occur following a trigeminal rhizotomy, in which a surgeon intentionally cuts the trigeminal nerve root or accidentally as during injury to the trigeminal nerve for some other reason.

Why Anesthesia Dolorosa Occurs

The touch-carrying nerve fibres are injured by surgery, while little or no damage occurs to pain-carrying fibres. Surgical injury may also prevent nerve fibres from overlapping as they normally should, resulting in distorted signals being sent to the brain. 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.

Symptoms

Pain for an AD patient is constant and is felt in their area of numbness. The two main symptoms of AD are facial numbness (much like the numbness from a dental anaesthetic injection) and constant pain.  The pain is usually burning, pulling, or stabbing but can also include a sharp, stinging, shooting or electrical component. Pressure and “heaviness” can also be part of the pain symptoms. Often there is eye pain.  Cold increases the feeling of numbness, sometimes making a face feel frozen. Diagnosis is generally based on the description of symptoms.

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

Unfortunately, there is no known effective treatment for AD.  A multidisciplinary, pain-management-oriented approach is most appropriate. Some helpful strategies include anticonvulsants, antidepressants, opiates, psychological support, and complementary and alternative therapies. There are no good surgical options at this point, but motor cortex stimulation has shown some promise in preliminary studies.

MEDICATIONS

  • Muscle relaxants (Baclofen, Zanaflex)
  • Antidepressants like amitriplyline (Tryptomer), nortriptyline, clonidine, paroxetine
  • Anticonvulsants such as – carbamazepine (Tegretol), oxcarbazpine, gabapentin, clonazepam, valproate, topiramate, phenytoin.
  • Topical anesthetic (EMLA)
  • Topical ointments (Capsaicin)
  • Anesthetic Injections (lidocaine),
  • Opioids- Oral Morphine drugs, fentanyl patch, buprenorphine patch.

COMPLEMENTARY AND ALTERNATIVE THERAPIES

Include acupuncture, hot and cold compresses, biofeedback, and electrical stimulation (TENS).

PROCEDURES/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.

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