Dental Neuralgia or Anesthesia Dolorosa

This information is designed to help patients talk to their neurosurgeons about their facial pain. It is not intended to give specific treatment guidelines.

 

Introduction

There are many different pathologies that can cause pain in the region of the face. The most common causes are dental (e.g. sore tooth) and sinus pain (e.g. sinusitis). Our clinic has focused on the types of pains caused by neurological conditions. These include the following:

trigeminal neuralgia
post-herpetic neuralgia
de-afferentation neuropathic pain
cluster headache
migraine
A more extensive list of the causes of facial pain includes the following:

dental problems (e.g. cavities, tooth abcess, gum disease)
skin problems (e.g. infections, trauma)
muscle problems (e.g. deep infections, trauma, tumors)
parotid gland problems (e.g. infection, stones)
ear problems (e.g. infections)
sinus problems (e.g. sinusitis, trauma, tumors)
skull problems (e.g. infection, trauma, tumors)
eye conditions (e.g. orbital infections or tumors)
TMJ syndrome
Neurological conditions (trigeminal neuralgia, post-herpetic neuralgia, nerve damage following dental misadventure or trauma, migraine, cluster headache)

Before you can begin treating a medical problem, you must understand its cause. This is true regardless of the medical condition but is absolutely crucial when dealing with facial pain. The perfect operation for trigeminal neuralgia will not help post-herpetic neuralgia. It is therefore vitally important that the first step in treating a facial pain condition is making the correct diagnosis.

 

De-afferentation Neuropathic Facial Pain

There are many different names for this pain syndrome. The most common is ‘dental neuralgia’ especially when the pain was caused by a dental procedure that damaged a nerve. It is sometimes called ‘anesthesia dolorosa’ if the nerve damaged was caused by a surgical procedure (e.g. rhizotomy). The conditions all have the same cause – a nerve injury causing a ‘central pain syndrome’. Patients who have a stroke causing numbness in their face will also sometimes get a very similar pain syndrome – ‘post-stroke facial pain’.

The best analogy to understand this phenomenon is phantom limb pain. Patients who have lost a limb occasional develop a pain syndrome in the absent limb. They may have no hand but their hand region hurts constantly. This is due to the abnormal changes in the brain dealing with the hand region. Even though there are no signals of pain coming from the hand (because it is not there) the region of the brain that would be activated by pain signals coming from the hand is somehow spontaneously active. This produces a constant pain that can be describes as burning, twisting, crushing, or a bursting pressure. Usually the pain varies throughout the day (usually getting worse as the day progresses) but it is often described as reaching a “10 out of 10” and it never goes away.

The same phenomenon can happen in the face if a branch of the trigeminal nerve is injured or completely cut. The most frequent cause of this is a dental surgery mistake. If one of the nerves to the teeth is damaged during a dental procedure, the area it was innervating will be immediately numb. Later (sometimes up to a year later) the numbness turns into a burning discomfort that heralds the onset of neuropathic pain. In this scenario, it is very common for the dentist to try additional procedures, incorrectly assuming the original cause for the pain has not been cured. In fact, this is a completely new type of pain – a neuropathic pain.

De-afferentation neuropathic facial pain can be caused anytime the normal sensation from the face is damaged. This can be from a peripheral cause such as cutting a branch of the trigeminal nerve (during a dental surgery or following a skull fracture when the nerve is cut by the fractured edge of the skull) or from a central cause (when the facial sensation pathway is destroyed by a stroke). Post-stroke facial pain is the second most common cause of de-afferentation neuropathic facial pain in our clinic.

The treatment of this condition will require a pain specialist or a neurologist with experience in this area. The great variety of medications recommended for this condition suggests that no one medication is clearly effective. Often a combination of powerful medications is required (including antidepressants and antiepileptics) to numb the pain. The continuous stress of this chronic pain often leads to depression and can destroy the patient’s family relationships.

There is hope for patients with this condition who have not been helped with all trials of medications. An operation called Motor Cortex Stimulation can significantly reduced the pain in up to 70% of patients.

 

The Surgical Treatment of Facial De-afferentation Pain

Motor Cortex Stimulation