Causalgia - An Overview

Introduction

Causalgia is a nervous system disease that can cause intense and long-lasting pain in the limbs (arms and legs). The pain is mostly due to trauma or an injury to a peripheral nerve. The peripheral nerves are nerves that extend from the brain and spinal cord into the arms, legs, and other parts of the body.

What Is Complex Regional Pain Syndrome?

Complex regional pain syndrome (CRPS) is a condition characterized by excessive pain and inflammation, usually affecting the arms or legs. Complex regional pain syndrome may develop after an injury, heart attack, stroke, or surgery. CRPS is believed to occur due to dysfunction of the central or peripheral nervous system. The central nervous system is comprised of the nerves that are present within the brain and spinal cord. The peripheral nervous system consists of nerves that transfer signals from the brain and spinal cord into the arms, legs, fingers, toes, and other organs. The abnormality in the functioning of these nerves can lead to overreaction to pain signals.

What Are the Types of Complex Regional Pain Syndrome?

Complex regional pain syndrome is of two types. They are as follows:

• Type 1 complex regional pain syndrome: It was initially known as reflex sympathetic dystrophy (RSD). Type 1 CRPS usually occurs after an injury or illness that does not directly damage the nerves of the affected arm or leg.

• Type 2 complex regional pain syndrome: It was formerly known as causalgia. Type 2 complex regional pain syndrome is caused due to direct injury of the specific nerve. Most people with type 2 complex regional pain syndrome have severe injuries that might cause damage to the nerves going to muscles leading to muscle shrinkage and weakness.

What Is Causalgia?

Causalgia is a neurological disease causing severe and long-lasting pain in the limbs due to a direct peripheral nerve injury. As peripheral nerves run from the brain and spinal cord to the extremities, it is commonly seen in hands, arms, legs, and feet. The brachial plexus is the most common site prone to injury in cases of causalgia. The brachial plexus is composed of a network of nerves that run from the neck into the arm. The injury to the nerves causes disturbances in the nerve signals that lead to pain and increased release of the neurotransmitter norepinephrine (chemical messenger which transmits signals across nerve endings to muscle cells or nerve cells).

What Are the Causes of Causalgia?

Causalgia is caused mainly due to peripheral nerve injuries. The various factors contributing to peripheral nerve injuries are as follows:

• Complex bone fractures.

• Certain surgeries.

• Soft tissue trauma like severe burns.

• Workplace injuries involving heavy types of equipment.

• Sprained tendon (a tissue that connects a muscle to a bone) or ligament (strong tissues that connect various bones).

• Crashing injuries like slamming the finger against a car door.

• Amputation (surgical removal of a body part due to any injury or disease).

What Are the Symptoms of Causalgia?

• Prolonged burning pain, usually in the leg, arm, foot, or hand.

• Decreased ability to move the affected body part.

• Swelling around the affected area.

• Sensitivity around the affected area might be triggered by cold or touch.

• Changes in skin color over the affected area. The skin color may change from white and pale to purplish-blue or red.

• Abnormal sweating of the affected area.

• Stiffness of the affected limb.

• Changes in the skin texture around the affected area may turn thin, shiny, and tender.

• Rapid hair growth (long and coarse hair) or rapid hair loss.

• Ridged nails (visible dents or lines in the nails) in the affected fingers or toes or decreased nail growth.

• Discomfort while applying pressure on the affected limb.

• Sudden changes in the temperature of the skin over the affected area alternating between sweaty and warm to cold.

• Muscle weakness and painful muscle cramps.

How to Diagnose Causalgia?

There is no definitive method to diagnose causalgia. However, the procedures that have been employed in diagnosing causalgia are as follows:

• Medical History and Physical Examination: The doctor takes a detailed medical history of the patient to rule out the possibility of other conditions that could cause similar symptoms and pain. The doctor makes a note of the symptoms experienced by the patient, especially severe unbearable pain following an injury. The doctor also observes for any changes in the temperature, texture, and color of the skin over the affected area. Even though a physical examination of the patient is carried out, most of the patients find it difficult to perform due to severe pain.

• X-Rays: X-rays are taken to find out fractures in the bones. Loss of bone minerals also becomes evident in the X-rays taken in the later stages of the disease.

• Magnetic Resonance Imaging (MRI): This imaging test is done to observe the soft tissue changes that might rule out other conditions. Abnormalities like damage to the underlying nerve can also be detected.

• Bone Scan: In this procedure, radioactive material is injected into a vein which allows the bones to be seen using a special camera. A bone scan helps to accurately find out any changes in the bones.

• Sweat Production Tests: These tests are used to measure the amount of sweat on both the arms and legs. Uneven sweating may indicate causalgia.

• Thermography: This test is conducted to measure and compare the blood flow and skin temperature of injured and non-injured limbs.

• Electromyography: Electromyography is a procedure to find out the health of the muscles and nerves that control the muscles. This test is mainly done to rule out the possibility of other nerve diseases which may cause similar symptoms.

How Is Causalgia Treated?

A combination of different treatment options helps in decreasing the pain and restoring the function of the affected limb. The treatment measures are as follows:

• Medications: Medications to reduce pain and swelling of the affected area are given. Topical patches and creams like Lidocaine may also be given to relieve the pain in mild cases. Certain anti-depressants and anti-convulsants are given to reduce the pain originating from a damaged nerve. In some patients, high blood pressure medications have been effective in controlling pain. Local anesthetic injections to block the pain fibers in the affected nerve has shown to reduce the severity of pain in certain patients.

• Transcutaneous Electrical Nerve Stimulation (TENS): This method is used to relieve pain by applying electrical impulses to nerve endings which in turn blocks the nerve fibers causing pain. TENS machines which are operated by battery can be used by the patient at home.

• Intrathecal Drug Pumps: In this method, medicines that relieve pain are introduced into the spinal cord fluid through an implanted catheter.

• Spinal Cord Stimulation: This method involves the surgical implanting of a pulse generator device in a region near the spinal cord. The device transmits low-level electrical currents into the spinal cord, which reduces or stops the pain signals being sent to the brain.

• Acupuncture: This method involves the insertion of thin needles into the affected area, which may increase the blood flow, thereby providing pain relief.

• Nerve Blocks: The lumbar sympathetic block involves injecting an anesthetic agent in the lower back region near the spine. This blocks the chain of pain signal transmission from the lower limbs into the brain and spinal cord. An anesthetic agent is injected at a region at the side of the neck to block the nerve fibers of pain in the upper limb.

• Physical and Occupational Therapy: Exercising the affected limbs and modifying daily activities under a trained therapist's guidance helps decrease pain, enhance the strength of the affected limb, and improve physical activities.

Conclusion

Causalgia is a condition that might interfere with daily activities affecting the quality of life. However, early diagnosis and following the right treatment options help improve the symptoms and lead a better life. Hence any prolonged pain interfering with the day-to-day activities of life should be noted and discussed with the doctor at the earliest.