Causalgia: what is this disease?

Pain can be defined as sharp and dull, stabbing or aching, pressing or bursting. The list of definitions can be continued, but here is a special medical term - causalgia - which means severe prolonged pains of a burning character.

Epidemiology

Targeted identification of cases of CRPS type II is relatively recent, so statistics are very limited. So, according to some foreign studies, the incidence of causalgia syndrome does not exceed one case (0.82) per 100 thousand patients with limb injuries. [1]

After surgery on the radius of the arm, CRPS type II occurs in 2-5% of cases, and after surgery on the foot and ankle - in 1.8% of cases. [2]

Causes causalgia

According to a descriptive and rank  scale for assessing the intensity of pain , causalgia (from the Greek kausis - burning and algos - pain) corresponds to 10 points, that is, unbearable pain. 

Since the mid-90s of the last century, the International Association for the Study of Pain (IASP) has defined causalgia as a syndrome of intense burning pain after traumatic nerve injury -   type II complex regional pain syndrome (CRPS II).

What are the reasons for its occurrence? If CRPS type I occurs after damage to soft tissues or bones, then the causalgia syndrome is the result of damage and dysfunction of peripheral nerves, including sensory and autonomic nerve fibers. This applies to the tibial and sciatic nerves passing from the spine to the lower extremities, as well as the long branches of the nerves of the upper extremities (musculocutaneous, median and ulnar) leaving the brachial plexus. [3]

Thus, causalgia is a type of chronic pain in the form of neurogenic pain syndrome.

Risk factors

The main risk factors for causalgia are associated with injury, fracture, severe shock, possible damage to the nerve due to sprains, burns or surgery, and in some cases, amputation.

According to experts, the intensity of the manifestation of this syndrome is not related to the severity of the lesion, and a characteristic feature is the disproportion between pain and the severity of the injury, but post-traumatic stress and depression can aggravate the symptoms and aggravate the patient's condition. [4]

Pathogenesis

How pain occurs is detailed in the publication -  Pain .

And neuropathologists explain the pathogenesis of causalgia by the participation in its occurrence of fibers of the sympathetic nervous system innervating the affected area, which play an important role in the blood supply to the skin and the perception of pain. For more information, see -  Neuropathic Pain .

But why does not all people with similar severity develop CRPS II, that is, causalgia? The multifactorial mechanism for the development of this condition has not yet been fully disclosed.

It is assumed that the causalgic syndrome is associated with an increased response to pain signals - an individual hypersensitivity of nerve fibers, which may be caused by an abnormality of the sensory axons of peripheral nerves, for example, in violation of their myelination (the formation of an insulating myelin sheath). 

There is a hypothesis for the development of an excessive inflammatory response to trauma, especially during the acute stage of CRPS II, with the release of proinflammatory cytokines by cells of damaged tissues, and the peripheral nerves release the corresponding neuropeptides (bradykinin, glutamate, substance P), which activate peripheral and secondary central nociceptive (transmitting pain impulses) neurons.

And the progression of this pain syndrome to a chronic state is seen in a decrease in the level of catecholamine neurotransmitters in the blood (in particular, norepinephrine) and subsequent compensatory activation of peripheral alpha-adrenergic receptors. [5]

Symptoms causalgia

In most patients, the first signs of causalgia (type II complex regional pain syndrome) appear within 24 hours after injury.

Three stages of its development are identified: in the first, key symptoms include:

• prolonged intense pain with a burning sensation, which can be constant and increase paroxysm;
• local edema of the soft tissues of the affected limb;
• increased pain sensitivity (hyperalgesia) and increased skin sensitivity (hyperasthesia);
• hypersensitivity of the skin to touch and light pressure (allodynia) in the area that is innervated by the damaged nerve;
• change in temperature and skin color of an injured arm or leg associated with a violation of microcirculation;
• paresthesia (tingling sensation and numbness);
• muscle cramps;
• increased sweating.

In the second stage, the pain intensifies and captures more distant areas; the swelling of the injured limb also expands and can be hard to the touch; the structure of the hair and nail plates changes (nails can become brittle and hair coarse); bone density decreases with the appearance of focal  osteoporosis . [6]

Atrophic wasting of muscle tissue and the spread of burning pain throughout the limb; tremor or twitching of the limb, pronounced limitation of its mobility are signs of the third stage of CRPS II.

Complications and consequences

In addition to local and diffuse osteoporosis, complications and consequences of the causalgic syndrome - if it is not detected and treated at an early stage - manifest themselves in the form of a  violation of muscle tone  with muscle rigidity, stiffness, and decreased range of motion. [7]

Diagnostics causalgia

Comprehensive diagnosis of type II regional pain syndrome is carried out on the basis of medical history and clinical symptoms.

More information in the material -  General principles of clinical examination of patients with pain

Instrumental diagnostics helps in determining the diagnosis: X-ray and MRI of the bones of the extremities, electroneuromyography and  thermography , ultrasound of the nerves.

Differential diagnosis

Differential diagnosis of causalgia with other pain syndromes, in particular, central pain syndrome (caused by damage to the central nervous system), radicular and radicular syndromes, muscular-tonic pain and fibromyalgia, degenerative-dystrophic neuropathy, polyneuropathy, plexopathy, etc. [8]

Treatment causalgia

Treatment of neuropathic pain  in CRPS type II (causalgia) involves the use of NSAIDs (non-steroidal anti-inflammatory drugs) that have analgesic effects. See -  Tablets for neuralgia [9]

Anticonvulsants are also prescribed -  Carbamazepine  or  Gabapentin  (Neurontin); corticosteroids (Prednisolone and Methylprednisolone); calcium channel blockers - Nifedipine or  Phenigidin .

Local anesthetics relieve pain (ointments with sodium diclofenac, ibuprofen, capsaicin), as well as applications with novocaine and dimexide.

The use of electroneurostimulation (transcutaneous electrical nerve stimulation) and hyperbaric oxygenation is quite effective  .

Sympathetic novocaine blockade can provide long-term pain relief  .

And complete relief is provided by surgical sympathectomy - the intersection of the sympathetic nerves in the injured limb.

By injecting drugs from the biophosphonate group, for example,  Pamidronate , they fight osteoporosis. [10]

Prevention

Preventive measures to prevent causalgia have not been developed. And in case of bone fractures, experts recommend taking vitamins. [11]

Forecast

The prognosis of type II complex regional pain syndrome depends on the cause and age: as a rule, in younger people, treatment of causalgia gives better results.