Causalgia: what is this disease?

Pain can be defined as sharp or dull, stabbing or aching, pressing or bursting. The list of definitions can be continued, but here is a special medical term - causalgia - which denotes strong, prolonged pain of a burning nature.

Epidemiology

Targeted identification of cases of CRPS type II has begun relatively recently, so statistics are very limited. Thus, 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 hand, 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 the descriptive and ranking scale of pain intensity assessment, 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 following traumatic nerve injury – complex regional pain syndrome type II (CRPS II).

What are the causes of its occurrence? If CRPS type I occurs after damage to soft tissues or bones, then causalgia syndrome is the result of damage and dysfunction of peripheral nerves, including sensory and autonomic nerve fibers. This concerns 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) coming out of 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 related to injury, fracture, strong blow, possible nerve damage due to stretching, burns or surgery, and in some cases – amputation.

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

Pathogenesis

How pain sensations arise is described in detail in the publication – Pain.

Neurologists explain the pathogenesis of causalgia by the participation of the sympathetic nervous system fibers that innervate the affected area, which play an important role in the blood supply to the skin and the perception of pain. For more details, see Neuropathic pain.

But why don't all people with similarly severe injuries develop CRPS II, or causalgia? The multifactorial mechanism for the development of this condition has not yet been fully elucidated.

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

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

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

Symptoms causalgia

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

Three stages of its development are defined: at the first, the key symptoms include:

• prolonged, intense pain with a burning sensation, which can be constant and intensify in fits and starts;
• local swelling of the soft tissues of the affected limb;
• increased pain sensitivity (hyperalgesia) and increased skin sensitivity (hyperesthesia);
• hypertrophic sensitivity of the skin to touch and light pressure (allodynia) in the area innervated by the damaged nerve;
• changes in the temperature and color of the skin of the injured arm or leg associated with impaired microcirculation;
• paresthesia (tingling and numbness);
• muscle cramps;
• increased sweating.

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

Atrophic wasting of muscle tissue and the spread of burning pain throughout the entire limb; tremor or twitching of the limb, severe 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 causalgic syndrome – if it is not detected and treated at an early stage – manifest themselves in the form of impaired muscle tone with muscle rigidity, stiffness and decreased range of motion. [ 7 ]

Diagnostics causalgia

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

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

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

Differential diagnosis

Differential diagnostics of causalgia is carried out with other pain syndromes, in particular, central pain syndrome (caused by damage to the central nervous system), radicular and radicular syndromes, muscle-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), which have an analgesic effect. See - Tablets for neuralgia [ 9 ]

Also prescribed are anticonvulsants - Carbamazepine or Gabapentin (Neurontin); corticosteroids (Prednisolone and Methylprednisolone); calcium channel blockers - Nifedipine or Phenigidine.

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

The use of electrical neurostimulation (transcutaneous electrical stimulation of nerves) and hyperbaric oxygenation is quite effective.

Long-term pain relief can be achieved with sympathetic novocaine blockade.

And complete relief is provided by surgical sympathectomy – cutting the sympathetic nerves in the injured limb.

Injections of drugs from the group of biophosphonates, such as Pamidronate, combat 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 for complex regional pain syndrome type II depends on the cause and age: as a rule, treatment of causalgia gives better results in younger people.