Patients of hyperalgesia experience mildly painful stimuli with a higher intensity. This reduction in pain threshold is mediated by either the central or peripheral nervous system. Therapy is provided by conservative treatment steps such as pain management.
What is hyperalgesia?
Pain threshold is a variable quantity and thus subject to fluctuation. People consequently have different pain thresholds. Detection of pain is the responsibility of the nociceptors. These free nerve endings of the sensitive neurons from the spinal cord are found in all tissues that are considered sensitive to pain. Accordingly, nociceptors detect surface pain, deep pain, and pain in organs. The variable sensitivity of Noziz receptors explains the person-dependent pain threshold. The pain threshold corresponds to the stimulus threshold that causes nociceptors to form an action potential. This threshold is not only subject to fiber-dependent and individual variations, but may also be pathologically altered in the context of various diseases. By the term hyperalgesia, medicine refers to an excessive sensitivity to pain that results in an abnormally strong response to painful stimuli. Painful stimuli may include pressure, cold, heat, or inflammation. Hyperalgesia is classified as one of the hyperesthesias and thus one of the stimulus hypersensitivities.
Causes
Hyperalgesia is divided into a primary and a secondary variant depending on the cause. Primary hyperalgesia is present whenever the peripheral nervous system mediates the hypersensitivity. Secondary hyperalgesia, on the other hand, corresponds to centrally mediated hypersensitivity and thus has the central nervous system as its basis. Primary hyperalgesia results in an excessive stimulus response by decreasing the threshold for nociception in the peripheral nervous system. This form of hyperalgesia primarily includes hypersensitivity to cold stimuli and heat stimuli. Typically, secondary hyperalgesia manifests as hypersensitivity to mechanical stimulus. Various diseases of the nervous system may be associated with hyperalgesia. The most common primary cause of pathologic change in pain sensitivity is neuropathic pain syndrome following lesions of the nervous system. Basically, hyperalgesia is merely a symptom rather than a disease itself and thus may be associated with, for example, polyneuropathies, herpes zoster, Sudeck’s disease, MS, or stroke. Patients of hyperalgesia react to hardly painful stimuli with an exaggerated reaction. It is important to note here that the stimuli causing the pain are indeed generally painful stimuli. Another person would therefore also assess the stimuli as painful, but would perceive their intensity as significantly less than a patient of hyperalgesia. Allodynia must be distinguished from hyperalgesia in this context. Patients of allodynia, unlike those of hyperalgesia, suffer from pain sensations in response to a stimulus that is not painful in the least. For example, they feel pain when stroked with a feather. This is not true for patients of hyperalgesia. Depending on the cause of hyperalgesia, the symptom is associated with many other symptoms. The type of pain sensation also depends on the primary cause. For example, in neuropathic pain syndrome, the pain shoots in like an attack and is usually described as dull.
Diseases with this symptom
- Polyneuropathy
- Shingles
- Sudeck’s disease
- Fibromyalgia
- Multiple sclerosis
- Stroke
Diagnosis and course of the disease
The first clues to hyperalgesia are obtained by the physician through the medical history. To confirm the initial suspicion, a neurological examination is performed. As part of the diagnostic procedure, the affected areas of the skin are lightly run over with a broken wooden stick, for example. A patient with hyperalgesia then complains of excessive pain. In order to be able to assess the cause of the insensitivity, imaging techniques are predominantly used. Lesions of the central nervous system and a neuropathic syndrome based on them can be clarified by an MRI, for example. The prognosis for patients with hyperalgesia depends on the primary cause of the sensory disturbance.Lesions in the central nervous system are prognostically less favorable than peripherally mediated reduction in pain threshold because central nervous tissue may not regenerate.
Complications
Hyperalgesia, or excessive pain sensitivity, often results from neuropathic pain syndrome. This refers to pain that results from damage to the central or peripheral nervous system. Thus, hyperalgesia in itself is not a disease, but a symptom. One such example is shingles (herpes zoster). As complications, various organs can be affected, including, for example, an encroachment of the disease on the brain (encephalitis) or the meninges (meningitis), but also on the eye and, in rare cases, on the ear. In the worst cases, it can even lead to paralysis. Other diseases of a neuropathic pain syndrome are polyneuropathies, respectively diseases of the nerves, which can lead to [[Diabetes mellitus|Diabetic foot, i.e. a reduced sensation on the foot and the danger for diabetics that it can lead to unnoticed wounds, which can even lead to amputation. Further, heart attacks can occur that go unnoticed because the sensitive nerves are not functioning properly. Multiple sclerosis (MS) can also lead to hyperalgesia and characteristic complications can occur. As the disease progresses, it leads to muscle weakness and, in later years, disability leading to the need for long-term care, as well as urinary and fecal incontinence. This can be compounded by dementia, personality change, and decreased learning ability.
When should you see a doctor?
The extent to which someone with existing hyperalgesia needs to see a doctor depends in part on his or her subjective state of mind. Since hyperalgesia denotes an above-average sensitivity to pain, those affected often suffer greatly from it. This is because it is not only injuries or abuse that trigger excessive pain here, but already bodily stimuli such as heat, cold and pressure. Of course, people with hyperalgesia also suffer extremely from the usual pain associated with many diseases, which is generally considered unpleasant but bearable. Hyperalgesia is not a disease in its own right, but a syndrome, usually due to increased nervous sensitivity to pain. For the treatment of hyperalgesia, the affected person best goes into the hands of a neurologist. He will try to alleviate the pain. In addition, he will give his patient tips on how to organize his daily life in order to limit the effects of hyperalgesia as far as possible. At the same time, however, the specialist will also clarify whether the hyperalgesia is not based on a serious disease requiring treatment, for example of the nerves themselves. If a patient affected by hyperalgesia is currently suffering acutely from an illness associated with pain, such as influenza with headache or dental suppuration, the treating internist or dentist is of course also called upon, ideally in collaboration with the neurologist.
Treatment and therapy
Treatment of hyperalgesia depends on the specific cause. A peripheral-mediated reduction in pain threshold can be treated causally and may be curable. Pain management offers conservative treatment approaches. When hyperalgesia is associated with impaired nerve cell metabolism, repetitive nerve blocks using local anesthetics can occur. A continuous variant is also an option in the form of implanted catheters. Thus, pain stimulus conduction is interrupted on the one hand. Vegetative nerves are blocked on the other hand, so that blood pressure increases and the disturbed metabolism is improved. Continuous anesthetic catheters are implanted through a cannula. In the case of central nervous lesions as the origin of hyperalgesia, there are hardly any treatment options available. In this case, treatment can only be symptomatic, since the causative lesion of the central nervous system cannot be reversed. Therefore, the symptomatic therapy of a neuropathic pain syndrome usually corresponds to a conservative pharmacological treatment, which can encompass drug groups such as antidepressants, anticonvulsants, opioids and topicals such as lidocaine or capsaicin. Experience has also shown that the body’s pain threshold lowers as soon as a person experiences great pain.Hyperalgesia patients should not induce pain situations, of course, however they should not avoid them excessively either.
Outlook and prognosis
In hyperalgesia, there is a severe reduction in quality of life. Affected individuals feel even mild pain very intensely, which has a negative impact on everyday life. Hyperalgesia can be identified relatively well by the physician by applying a mild stimulus to the skin. In this case, the affected person complains of severe pain, which in fact does not occur. With the help of an MRI, further examinations can be performed, with which the cause of the hyperalgesia can be identified. Treatment can be done in a variety of ways and depends largely on the cause of the hyperalgesia. In many cases, stimuli can be limited by pain management. Catheters can also be inserted in affected individuals to interrupt pain conduction while relieving symptoms. In some cases, antidepressants are also used to lower the psychological sensations of pain. It cannot be generally predicted whether success will occur with treatment. It also depends greatly on how long the patient has been complaining of hyperalgesia and how widespread it has become. Hyperalgesia can be prevented by a healthy lifestyle.
Prevention
Hyperalgesia is the symptom of damage to the central or peripheral nervous system. Hyperalgesia can be prevented only to the extent that lesions of the central nervous system or peripheral lesions can be prevented. For example, because the symptom is associated with strokes and other conditions, preventive steps include taking precautions to avoid strokes.
Here’s what you can do yourself
Even mild pain is perceived by sufferers to such an extent that their quality of life suffers significantly. Since diagnosis is not always easy, sufferers often cannot be helped quickly enough. A doctor cannot feel the pain of his patient and so only stimuli on the corresponding nerves help. After that, it is possible to quickly determine the cause of the disease by means of MRI. After successful diagnosis, differentiated treatments, which also bring different prognoses, must be considered. Often, an individual pain therapy already enables a future free of complaints. Another very useful therapy is the interruption of pain transmission. In this case, a catheter is inserted permanently, which permanently numbs the pain, thus relieving the corresponding symptoms and significantly improving the quality of life. Antidepressants have the effect of reducing the psychologically induced sensitivity to pain. Great success can also be achieved with this and the affected person can experience everyday life free of pain. However, whether an improvement in the quality of life can be achieved in every case cannot be predicted in principle. Important for the treatment success of hyperalgesia are, as with many other diseases, an early diagnosis and no large spread of the disease. As a general preventive measure, a generally healthy lifestyle is the best prerequisite.