Burning Pain
AUTHOR: Judson J. Somerville, M.D., 
The Pain Management Clinic of Laredo

One type of pain which is least understood is called "symptomatically mediated pain".  Unfortunately the medicine terms used to describe illnesses are large and cumbersome.  There are two main types of this pain complex regional pain syndrome (CRPS) Type I and Type II.  As a rule we refer to them as "cryps" Type I and II.  The old terms for these ailments (though this may not make it easier) are reflex sympathetic dystrophy (RSD) and causalgia respectively.  What these diseases have in common are abnormal functioning of the nervous system following injury.  This abnormal functioning is essentially a seizure.  These seizures are not the way you normally think of as a seizure with muscle twitching and biting of the tongue.  These "seizures" consist of injury to the nervous system just as it occurs to the brain of people with "the seizures" we are more familiar with.  However, these seizures cause burning pain, alteration of blood flow to the affected part of the body and sometimes increased sweating, color changes and sensitivity to hot and cold.  In the past and even now manyu patients who suffer from this type of pain are often told "it's all in your head" because of the way it affects the sufferers.  This type of pain has the symptom of a pain out of proportion to physical findings.  What this means is the patient has severe pain, but no visible bodily injury giving the impression the person is not really hurt.  Stories have been told about patients with "Cryps" Type I and II, due to its unusual symptoms and the fact that their doctors may not be familiar with these disorders, who are accused of fabricating their pain.  Patients have been told they put a tourniquet on their arm or leg before they saw their doctor to cause the severe swelling.  Trust me they didn't.  As with all chronic pain, "Cryps" I and II can cause poor sleep and depression in the patient.  The following is a description of "Cryps" Type I and II as well as other types of sympathetically mediated pain.

For "Cryps" Type I it initially starts with a trivial injury, such that the patient may not even remember having been injured.  Initially the normal ache and sharp pain of the injury occurs.  Then the person may be fine for several weeks to a month.  Then burning pain will start and due to the long time period they may not correlate initial injury with new pain.  Often there are symptoms of burning pain, color changes, swelling and sensitivity to hot and cold in the affected limb.  Also light touch to the affected area can cause pain.  These patients will see several physicians concerning their symptoms and have multiple examinations usually with no definitive diagnosis given to the patient due to their physician being unfamiliar with this disease.  Early treatment is important as the longer this type of pain goes on the more difficult it becomes to treat.  The treatment consists of nerve blocks.  For example, if this pain starts in the legs the small sympathetic nerves that run along the anterior part of the spine, would be blocked.  The function of these nerves are to control the blood flow, the sweating and relay the dull burning pain.  These blocks are done in the operating room with the first injections being diagnostic and potentially therapeutic.  With the first injections these nerves are blocked and if the patient receives no pain relief then there is another reason for the pain.  If on the other hand the sympathetic nerves are blocked and the patient experiences pain relief then we have the diagnosis and we are treating it.  Typically it takes a series of nerve blocks to permanently relief the pain.  We are looking with each set of injections for progressively longer pain relief and once the pain returns it has decreased after each block.  If, however, the patient receives the block and the pain is reduced for the appropriate amount of time (a couple of days), but the pain comes back to the same level, then one other block will be tried a week later.  If this also produces reduction of the pain, but only for a short period of the time and the pain comes back just as strong as before the block, then stronger treatments need to be performed.  As with all types of pain oral medications will be given. These medications consist of anti-seizure medication and anti-depressant, which help calm the nerve "seizures" and reduce the amount of pain.

"Cryps" Type II has most of the same symptoms as "Cryps" Type I, but typically it occurs after a traumatic injury to one of the extremities.  This occurs from surgery or was very common during war after a gunshot wound.  However, with "Cryps" Type II in addition to having the sympathetic nerves with abnormal functioning one also has a sensory or motor nerve injury.  This means the patient has damaged the nerves that control the muscles or sensation.  Again, this pain may not start for weeks to months following the injury witht he same symptoms burning, swelling, color changes, light touch causing pain and sensitivity to hot and cold in the affected extremity.  One aspect of "Cryps" Type I and II which makes diagnosis confusing is the symptoms don't follow the normal dermatome.  Each sensory nerve has a certain part of the body a dermatome to which it gives sensation and it's fairly well defined from person to person.  However, with the sympathetic nerves its area of coverage is very diffuse and can vary significantly from patient to patient.  The treatment of "Cryps" Type II consists initially of the same medications and nerve blocks as are used in "Cryps" Type I.  If someone were to have an injury in the arm causing "Cryps" Type I once the diagnosis made they would be placed in the hospital and have a cervical catheter placed in the operating room and receive daily nerve blocks through this catheter.  This catheter would be similar tot he epidural catheter used during delivery in pregnant women.  While receiving these nerve blocks they would do aggressive physical therapy to try to "reeducate" the sympathetic nerves to treat its disease.  However, if the blocks do not achieve a significant prolonged reduction of pain other options are necessary.  One option is destroying the sympathetic nerves and this can be done with injections of alcohol or other strong chemical.  One can also do radiofrequency ablation.  During this procedure a special needle is placed close to the nerve and the same type of energy  as is used in a microwave oven is used to destroy the nerve.  Another option is to use a spinal cord stimulator which is like a "spinal cord" pacemaker (an article will be forthcoming on this device) to constantly block the pain with electricity.

The last type of sympathetically mediated pain can occur in other parts of the body.  This is usually seen in patients who've undergone lower abdominal surgery.  After weeks they start experiencing burning pain and swelling in their groin.  The patient may not make the connection between the surgery and the pain for this reason they suspect theya re suffering from a urinary tract infection or a hernia.  Usually with one examination no hernia or urinary infection is found.  The treatment is again nerve blocks and oral medications as described above.  The nerve blocks are diagnostic and potentially therapeutic with this type of pain.  If, like in "Cryps" Type I and II the pain is reduced, but only temporarily following the nerve blocks, then one may have to go the radiofrequency ablations to get long-term pain relief.  This type of pain has also been seen in patients who come in with upper abdominal pain, which is burning in nature.  They do not experience much swelling however they have pain on light touch to the skin.  Some patients have had x-rays, endoscopy, MRI's and CT Scans, which were all negative looking for intra-abdominal problems, only to find the pain secondary to a sympathetic nerve "seizure".  Usually it starts from a pinch nerve in the thoracic spine region with most of the pain in the upper abdomen along the dermatome of that nerve.  Because, there is more pain in the abdomen these patients seek abdominal doctors for this type of pain and are worked up for abdominal problems, but in fact the problem is coming from their back.  These patients that have this type of pain also need oral medications and nerve blocks to help reduce the pain.

"Cryps" Type I and Type II and sympathetically mediated pain are chronic pain problems that can be treated, but the earlier they are diagnosed the better chance one has for long term pain relief.  These types of pain are described as pain out of proportion to symptoms.  This means the patients have excruciating pain, but there is no obvious crush injury, cut, and the patient is not bleeding to death.  For this reason these patient's pain is not appreciated when in fact they are experiencing substantial pain equal to the pain they actually would have with a major laceration or crush injury.  Treatments starts with oral medications and nerve blocks.  The treatment becomes more aggressive depending upon how they respond to the initial treatment.  As with all types of chronic pain it can bring about depression and loss of sleep.  These painful conditions require the simplest, easiest and safest treatment available and the earlier they are treated the better the chance the pain can be controlled.