What Is Complex Regional Pain Syndrome?
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Complex Regional Pain Syndrome: Head and Neck

Published on Oct 22, 2021 and last reviewed on Apr 18, 2023   -  4 min read


This inflammatory dysfunctional pain syndrome is rare but manageable medically by physicians but is not always curable. Read the article to know more.

What Is Complex Regional Pain Syndrome?

Complex regional pain syndrome (CRPS) is a medical term used for the clinical condition of a patient suffering from chronic and consistent pain in the head and neck region. It would either be post-traumatic sequelae or a painful consequence of a nerve lesion or nerve injury, or irradiation.

What Are the Types of Complex Regional Pain Syndrome?

There are mainly two types of CRPS; type 1 and type 2.

  • Type 1 - It is associated with reflex sympathetic dystrophy (RSD).

  • Type 2 - It is associated with a partial nerve injury (causalgia) though the clinical symptoms of both types are extremely similar.

Complex regional pain syndrome (CRPS) always involves an autonomic component affecting pain severity and trophic changes in the soft tissues. The skin is extremely sensitive to tactile or temperature changes because of the vasculature affected by the sympathetic nerve, with its perceptions being altered in these cases.

The inflammation that is diminished after a sympathetic block or due to abnormalities in sudomotor activity is because the blood flow through the skin is altered. The evidence is that the skin vasculature develops an increased sensitivity to local cold temperature stimuli and catecholamines. This has been shown evidentially through experiments. Testing the thermoregulatory response to skin cooling and warming results in the inhibition and activation of sympathetic reflexes.

Tropical changes, such as abnormal nail growth, hair growth that is abnormally or suddenly increased, palmar and plantar fibromas, skin turning thin, patchy, or glossy, along with hyperkeratosis have all been hypothesized to occur due to inflammatory pathogenesis, and scintigraphic investigations strongly support an inflammatory component in CRPS.

What Are the Clinical Features of CRPS?

The term causalgia is now called complex regional pain syndrome (CRPS) which is type 2 or nerve-related causalgia. This was first described by Mitchell et al. in 1867 when they reported cases of soldiers suffering from this disorder during the American civil war. The clinical presentation of CRPS patients is heterogeneous, with pain being the common or predominantly prevalent symptom along with substantial variation in its characteristics. The pain can be spontaneous as well as evoked by stimuli, continuous or episodic, or paroxysmal. The regions of the extremities may be affected more with increased pain when the region is elevated.

Other abnormal sensations related to the pain that is found in CRPS patients include mechanical and thermal hyperalgesia (increased sensitivity to pain), hyperesthesia (increased sensations such as touch, smell, sound, and vision), allodynia (presence of pain without any obvious stimulus), hyperpathia (exaggerated pain sensation to a stimulus), and dysesthesia (pain with abnormal sensations such as pricking, burning, itching, stinging or tickling sensations). Additional signs of inflammation are present together with a number of typical abnormalities that are probably related to autonomic dysfunction. These include edema or an inflammatory swelling, abnormality of sweating, and skin changes (to tactility or touch, and texture of the skin may be altered). The skin of the affected side can be either warmer or colder compared to the other side.

How Is Complex Regional Pain Syndrome Diagnosed?

The diagnosis of CRPS is mainly clinical; on the other hand, the following objective diagnostic procedures have been reported in the literature to confirm the diagnostic impression of autonomic, sensory, and motor dysfunction.

  1. Quantitative sensory tests.

  2. Laser Doppler flowmetry.

  3. Infrared thermography.

  4. Quantitative sudomotor axon reflex test.

  5. Bone scintigraphy (gives information about bone vascularity changes).

  6. Plain radiographs.

  7. Sympathetic nerve blocks - This is a therapeutic, as well as a diagnostic modality wherein a local anesthetic, intravenous Phentolamine, or regional intravenous block, is used at the level of the sympathetic ganglion along with an adrenergic blocking agent.

What Is the Pathophysiology of Complex Regional Pain Syndrome?

The mechanism by which pain and other physical abnormalities develop in CPRS is not fully understood. Trauma is understood as the precipitating factor in the pathogenesis causing damage to a peripheral nerve, thereby causing neurobiological changes in both peripheral and central components of the nervous system. This produces an abnormal afferent input that creates a painful sensation in the head and neck as the nociceptors may be affected, and the impact of trauma is indirect or direct on the CNS (central nervous system). The following sequelae may occur relating to the mechanism of pain:

  • Sensitization of nociceptive fibers.

  • Cross-activation between injured afferent fibers (ephaptic crosstalk).

  • Sprouting of somatic afferent fibers from adjacent intact nerves.

  • Activation of afferent fibers by sympathetic afferents.

  • Neuroma formation.

What Are the Available Treatment Modalities For Complex Regional Pain Syndrome?

  1. Many medications have been helpful in evidentially treating this neuropathic pain in CRPS. However, non-steroidal anti-inflammatory drugs (NSAIDs) have been helpful in some cases as a mainline strategy alongside corticosteroids to address or relieve the peripheral component of the pain.

  2. Opioid painkiller drugs have also been advised by physicians in some patients but should be used with caution as they can be a source of addiction in chronic use.

  3. Membrane stabilizers acting on sodium channels, such as Phenytoin, and Carbamazepine along with the use of local anesthetic agents, have been suggested with the purpose of reducing the ectopic firing of neurons that gives symptomatic or sudden pain.

  4. Amitriptyline is the most commonly used drug amongst tricyclic antidepressants along with painkillers.

  5. Gabapentin is a comparatively new drug that is also being used in trigeminal neuralgia and has been suggested for the treatment of other kinds of nerve-related pain, and it has also been used for the treatment of CRPS.

  6. The use of topical capsaicin, N-acetylcysteine, has also been documented evidentially to show benefit.

  7. Other methods that have been used are the administration of oxygen-free radical scavengers and deep brain stimulation in the sensory thalamus. Apart from the technique of medial lemniscus, epidural spinal cord stimulation has also been proven to be effective to an extent.


CRPS is a complex pain syndrome that is manageable by physicians to a greater extent with the current modalities of drugs available. However, it still remains a partially treatable pain syndrome as it is a chronic, painful, and inflammatory disease that affects the head and neck region in the affected individuals.

Frequently Asked Questions


Is CRPS a Psychological Condition?

The crippling chronic pain illness, CRPS, can negatively affect one's physical, emotional, and social well-being. Afflicted patients may experience depression, anxiety, trauma, sleeplessness, and drug use problems. Effective therapy should be multidisciplinary since the etiology of CRPS appears multifaceted.


CRPS: Is It a Neurological Condition?

Complex regional pain syndrome (CRPS) is a neurological disorder that most frequently affects the hand and produces pain and other symptoms in the extremities. For CRPS, there are several therapeutic options. The more quickly people get a diagnosis and start treatment, the more likely the symptoms will go away.


What Effects Does CRPS Have on the Brain?

Complex regional pain syndrome (CRPS), an uncommon yet crippling pain condition, typically develops following upper limb injuries. Numerous investigations found changed brain function in people with CRPS, but little is known about potential effects on brain anatomy.


Does an MRI Reveal CRPS?

MRI cannot distinguish CRPS patients and those without CRPS. However, in patients with suspected CRPS, MR imaging aims to rule out other diseases that might more adequately account for the patient's symptoms. It might be difficult to diagnose CRPS, and this is done by ruling out other diseases.


Can CRPS Be Shown on an X-Ray?

Later stages of the illness may cause mineral loss from the bones, which will be seen on an X-ray. X-rays often seem normal during the early stages of CRPS (zero to three months), but osteopenia manifests in them in the later stages (three to 12 months). Positive results can be seen in chronic phases, although they can also be linked to atrophy from inactivity.


Which Clinical Trait Is Regarded as the Defining Characteristic of CRPS?

After an accident or surgery, complex regional pain syndrome (CRPS), a very incapacitating disorder, typically affects the limbs. Severe pain, swelling, loss of range of motion, changes in body temperature, and changes in the appearance of the skin are the prominent symptoms.


How May CRPS Can Be Demonstrated?

After an accident or surgery, complex regional pain syndrome (CRPS), a very incapacitating disorder, typically affects the limbs. Severe pain, swelling, loss of range of motion, changes in body temperature, and changes in the appearance of the skin are the prominent symptoms.


What Does the Spreading of CRPS Feel Like?

If the CRPS spreads, it often does so to the opposite limb or the same side of the body. As a result, it is crucial to pay attention to nearby body parts. Monitor both the left arm and the right leg, for instance, if a person has CRPS in the left leg. Stress can exacerbate CRPS. The symptoms may not improve with time and rest.


What Occurs if CRPS Is Not Treated?

If CRPS is not identified and treated promptly, it might worsen to cause increasingly debilitating signs and symptoms. Waste of tissue (atrophy). The skin, bones, and muscles may degenerate and weaken if a person avoid or find it difficult to move an arm or a leg due to discomfort or stiffness.


Do Neurologists Provide CRPS Care?

Treatment for CRPS often needs a team of doctors, each of whom must know the condition. For instance, according to Cruciani, who works at a facility for CRPS patients, his team also consists of neurologists, anesthesiologists, rehabilitation specialists, psychiatrists, and a psychologist.


Could CRPS Cause MS?

It is a condition that might impair the brain and central nervous system and result in nerve degradation or irreversible injury. The fact that the body's immune system assaults its tissue qualifies MS as an autoimmune illness. There is no relationship between CRPS and multiple sclerosis because it is not an autoimmune condition.

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Last reviewed at:
18 Apr 2023  -  4 min read




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