In allesthesias, patients do not perceive touch, temperature stimuli, or pain stimuli on the irritated area, but assign them to another part of the body. The cause is often a parietal lobe lesion, such as one that can be triggered by a cerebral infarction. Physical therapy training can bring about improvement.
What is allesthesia?
Allesthesia is a neurological perceptual change that results from brain lesions and has disease value. It belongs to the so-called asomatognosias, in which the perception of one’s own body is pathologically altered. In allesthesia, sensory stimuli such as pain, cold or touch are no longer perceived in the correct part of the body. There are several subtypes of allesthesia. In the visual and acoustic form, the patient no longer perceives visual or acoustic stimuli in the correct direction. Allesthesia is also called allachesthesia, alloesthesia, or allochiria. It differs from psychological perception disorders in that there is primarily a physical cause for the misperceptions. Allesthesia is often accompanied by other phenomena from the group of asomatognosia, such as anosognosia or anosodiaphoria. Similar to allesthesia are sensory disorders such as hyperesthesia, hypesthesia or dysesthesia. To be distinguished from allesthesia is the physiological phenomenon of allesthesia.
Causes
The cause of allesthesia is a cerebral lesion, usually located in the cerebral cortex. Localizations include the inferior parietal lobe, the interparietal sulcus, and the supramarginal or angular gyrus. These areas of the brain regulate the body sensation sphere and thus assign perceptions to a specific body location. Various Brodmann areas are located here. They play a role in the perception of one’s own body in space and thus also in movement planning. The brain regions mentioned thus analyze where things are located in space and also track objects on the skin. Through connections to the frontal brain, the motor plans of the brain regions are executed. A lesion in these areas is often preceded by a cerebral infarction or stroke in the corresponding regions. Somewhat less often, the pathological change in perception occurs in the context of an inflammatory reaction, such as that caused in the central nervous system by multiple sclerosis. Visual allesthesias can also be caused by an occipital lobe lesion or epilepsy and migraine. Tumors are rarely responsible for allesthesias. Symptoms of allesthesia vary according to subtype. Tactile allesthesias shift the conscious perception of a touch, temperature stimulus, or pain sensation to another part of the body. Thus, the affected person does not feel the tactile stimuli on the actual irritated site. In acoustic allesthesia, on the other hand, directional hearing is disturbed. Visual allesthesia causes visual illusions and seemingly shifts objects within the visual field from one half of the visual field to the opposite half. When the cause of allesthesia is damage to the parietal lobe, accompanying neurological symptoms usually occur. Dizziness and disorientation, for example, may be among them. This mainly concerns visual allesthesia, in which the dizziness is caused by the shifted visual field. Because of the causative damage to the brain, more or less severe headaches may also occur.
Diseases with this symptom
- Cerebral infarction
- Epilepsy
- Stroke
- Migraine
- Brain tumor
- Multiple sclerosis
Diagnosis and course
The first suspicion of allesthesia is obtained by the physician in the anmanesis and during various sensation tests. The diagnosis requires, above all, evidence of causative lesions in the brain. If such physical causes are not present, a psychologically induced perceptual disorder is probably present instead of allesthesia. Psychologically induced misperceptions must be excluded in the differential diagnosis. Brain lesions are detected by imaging of the brain, for example by MRI with contrast medium. The course of the disease in allesthesia depends mainly on the cause.Stroke-related allesthesias can often be largely reversed with training, especially in young patients.
Complications
Various complications can occur with allesthesia. This is due to the nature of the condition. Stimuli are not perceived at the site of stimulus exposure, but at another location. Thus, there is a wrong localization of the stimuli. For this reason, the reaction to the stimulus cannot be appropriate. If, for example, tactile allesthesia is present, a pain stimulus may be perceived at a wrong location. Suppose the patient burns his left thumb on a hot plate, but perceives the stimulus, i.e. the pain, in his right thumb. He will therefore first pay attention to his right thumb and look for the trigger of the pain in this place before he notices the burn of the left thumb. Thus, the response to the externally applied stimuli may not be adequate in allesthesia. This circumstance can lead to some complications as the actual affected body parts are exposed to the stimulus for a longer time. Of course, this occurs not only to pain stimuli but also to all other stimuli. Thus, it is of great importance to learn to deal with allesthesia and to achieve a correction of sensations via senses not affected by allesthesia. The mentioned complication should be seen only as an example; various other complications, some of them similar, may also occur in the patients’ daily life.
When should one go to the doctor?
If allesthesia is suspected, a physician should be consulted immediately. The sensation of pain cannot be attributed to any direct cause in everyday life. For this reason, there is a risk of not classifying it correctly. It is made more difficult because the pain stimuli occur at a location other than the site of the stimulus. This misdirection can lead to an incorrect assessment of the current situation. Waiting or hesitating is not recommended in the case of allesthesia. Since the cause of allesthesia is brain damage, the signs and symptoms are difficult for non-medical professionals to interpret and classify. Mistakenly, affected persons often assume that the symptoms are temporary. Unfortunately, this is not the case. Therefore, it is important to seek medical advice as soon as possible and to determine the cause via testing procedures. Often, allesthesia is preceded by a disease such as cerebral infarction or stroke. For this reason, an unpleasant sensation in a location other than the site of the stimulus is often attributed as an after-effect or side-effect of the previous illness or medication. This falsely causes a delay in seeking medical attention again. Allesthesia may be associated with irreversible brain damage. Although these do not necessarily result in total system failure, timely evaluation of the damage is recommended.
Treatment and therapy
The therapy of allesthesia predominantly corresponds to a therapy of the primary disease that is as causal as possible. Causative tumors, for example, are removed as much as possible. In the case of allesthesias in the context of multiple sclerosis or various types of epilepsy, causal therapy is not fully feasible. However, the diseases can be controlled relatively well by administering drugs such as immunosuppressants and neuroleptics. For the treatment of allesthesia, physiotherapies for sensory correction have also been proposed for some time. In these therapies, sensory systems or brain regions that are not impaired and thus still fully functional are trained and made to take over the tasks of damaged areas. Such compensations have been known for a long time from stroke therapy and are often crowned with success. Even if brain regions have been irreversibly damaged in the course of allesthesia, the patient does not necessarily have to live with a permanent perceptual disorder. At least improvements of the complaints can often be achieved by the therapies. The patient’s will and willingness to work are probably the most decisive influencing factors for success in learning compensation.
Outlook and prognosis
Initially, additional circumstances are of great importance for the prognosis of the course of the disease. For example, some allesthesias are so inhibitory that patients avoid physician contact with their symptoms.Without appropriate treatment, however, no improvement of the condition can be brought about in the case of allesthesia. Spontaneous healing initiated by the organism, as is the case with conventional wounds, cannot occur with a brain lesion. For a prognosis of the further course of the disease, it is important to determine the severity of the existing brain lesion. Above all, it is important to carry out a rapid diagnosis and subsequent therapeutic measures in order to exclude a further deterioration of the condition. A complete recovery is not to be expected in case of allesthesia, which is why an indefinite course of the disease must be expected. For a more accurate prognosis, the focus must first be on the cause of the disease. It can become between various causes. This can lead to further therapy options that mitigate the course of the disease. For example, after the removal of brain tumors, the prognosis of the course of the disease must be reassessed, since the removal can lead to both an improvement and a worsening of the condition. The further course of the disease is often also very dependent on the behavior of the patient. Thus, by treating the patient with medication and physiotherapy, erroneous stimuli and perceptions can be reduced. In the long term, this results in a much better prognosis than not treating the clinical picture appropriately.
Prevention
Allesthesia can be prevented in moderation, depending on the cause. At the very least, strokes can be prevented with a healthy lifestyle, early recognition of stroke risk, and appropriate prophylaxis with a relatively good chance of success.
Here’s what you can do yourself
Everyday life and self-help are an important element of an overall therapeutic concept for allesthetic sensory disorders, which also includes physiotherapeutic measures. In most cases, the incorrectly localized pain sensations or other haptic or even visual impressions are based on damage to specific regions in the brain. Similar to strokes, there is often a chance that the sensory disturbances can be compensated for by constant and consistent exercise of other brain regions. It takes a little patience to achieve corrective improvement in the localization of sensations with specifically designed exercises. It is recommended to compose the exercises together with a physiotherapist experienced in the field. If possible, self-help should be accompanied by moderate sport, by active relaxation exercises and by a balanced and varied diet. This will ensure that circulatory disorders and an insufficient supply of important micronutrients do not stand in the way of the possible success of the physiotherapeutic exercises. If the allesthesia mainly concerns wrongly localized pain sensation, additional attention training helps to mentally direct the pain sensation to the “right place” in order to pull the affected body part out of the danger zone as quickly as possible. For example, if a heat pain occurs in the right thumb that actually affects the left thumb, attention can be trained to recognize with only a slight time delay that the left thumb is actually affected and must be removed from the danger zone.
