Hereditary neuropathies with a tendency to pressure paralysis are hereditary neurological diseases that belong to the group of neuropathies. The slightest pressure load on the nerves leads to symptoms of paralysis, which, however, regress completely or partially when the nerves are not under stress. The disease is not life-threatening.
What is hereditary neuropathy with a tendency to pressure paralysis?
According to ABBREVIATIONFINDER.ORG, hereditary neuropathy with a tendency to pressure paralysis is characterized by an increased sensitivity of the nerves to pressure. Even slight stress caused by physical activity can lead to symptoms of paralysis.
These diseases are a collective term for neurological disorders, the main feature of which is the restriction of nerve conductivity under pressure. Hereditary neuropathy with a tendency to pressure paralysis is abbreviated to HNPP. HNPP is derived from the English term “Hereditary Neuropathy with liability to Pressure Palsies”.
The disease is also known as tomacular neuropathy, which is characterized by the sausage-like swelling of the myelin sheaths. HNPP are hereditary diseases. Their prevalence is given as 1/50,000 to 1/20,000. HNPP is particularly common in Finland. There the prevalence is even 1/6250.
Since hereditary neuropathies with a tendency to pressure paralysis have a genetic basis, they cannot be cured. However, they can be treated well. The life expectancy of those affected is not limited. The disease is characterized by demyelination of the myelin sheaths, which causes them to swell. The myelin sheaths surround the nerve cells or their axons and provide their electrical insulation.
In HNPP, however, the myelin sheaths are destroyed. As a result, they can no longer adequately perform their protective function. The result is a reduction in nerve conduction velocity. The reduced conductivity causes the loss of important reflexes and the occurrence of numbness, discomfort and weakness. The lack of electrical insulation is mainly noticeable when pressure is applied to the nerves.
The reason for the demyelination of the myelin sheaths is a faulty myeloprotein PMP22. This protein is encoded by a gene on chromosome 17. The same gene is also responsible for the development of hereditary sensory motor neuropathy in the presence of corresponding defects.
However, many different mutations of the PM22 gene can also lead to hereditary neuropathy with a tendency to pressure paralysis. These are mostly deletions (shortenings). But point mutations can also lead to malformations of PMP22. About 80 percent of HNPP is due to deletions of the PMP22 gene. The remaining 20 percent is caused by point mutations in the same gene and mutations in other genes.
This also includes the genes MPZ and Connexin 32. The basis of pressure paralysis is the reduced ability of the demyelinated myelin sheaths to insulate the nerve cells. When the nerves are compressed, electrical short circuits occur, which limit nerve conductivity.
Symptoms, Ailments & Signs
The disease usually first appears in the second or third decade of life. In rare cases, however, it can also occur in childhood. However, there are also symptom-free patients who, despite a genetic predisposition, are never diagnosed with HNPP. The most common symptoms are sudden loss of sensation and muscle weakness along the course of individual nerves.
There is no pain involved. This loss of sensitivity of the respective nerve is due to a local pressure load. The pressure is caused by repeated movement or stretching on the affected area. The complaints often occur in the fibula, elbow, wrist or foot. In contrast to polyneuropathies, these are mononeuropathies because only individual nerves are affected.
Such symptoms as numbness and weakness of the hands, loss of sensitivity in fingers and hands, weakness in the arms or dropping feet are observed. When the pressure stops, symptoms resolve within days to months in 50 percent of cases. In the other cases, the symptoms improve, although residual symptoms remain. However, if the pressure is repeated, the symptoms reappear.
The suspected diagnosis of HNPP results from the repeated occurrence of mononeuropathies and a family history of these diseases. Furthermore, electrophysiological examinations and biopsies of nerve tissue are carried out to determine focal thickening of the myelin sheaths. The diagnosis can be made unequivocally by means of a genetic test.
This disease can severely limit everyday life and the quality of life of those affected. Signs of paralysis occur even with very simple and light pressure applications on certain regions of the body. Although these are decreasing, the affected person is often dependent on the help of other people in their everyday life. Life expectancy is not reduced by this disease.
Not infrequently, however, the patients also suffer from mental disorders and depression, so that in some cases suicidal thoughts can occur. Sensitivity disorders and muscle weakness occur. In general, the patient’s resilience decreases enormously. However, there is no pain. The paralysis leads to restricted mobility, so that the patient may be dependent on a wheelchair.
The paralysis recedes, but this can take up to a month. A causal treatment of this disease is not possible. The symptoms can also only be treated to a limited extent, with various therapies being used in particular. There are no complications. The patient’s relatives can also suffer from psychological problems and therefore often need psychological care.
When should you go to the doctor?
Although this disease is not life-threatening, a doctor should still be consulted at the first signs and symptoms. This can prevent further complications and symptoms, since self-healing usually does not occur.
A doctor should be consulted if there are disturbances in sensitivity or complaints in the muscles and general muscle weakness. These symptoms can occur in different parts of the body. Likewise, the disturbance of sensitivity can occur with pressure and not be present without pressure.
Weak or numb hands and feet also indicate the disease and should always be examined by a doctor if the symptoms do not go away on their own within a short time. As a rule, a general practitioner or, in the case of children, a pediatrician can be consulted in the first place for neuropathy with a tendency to pressure paralysis.
Further treatment is then carried out by various specialists, whereby the exact treatment also depends on the cause of the neuropathy with a tendency to pressure paralysis. However, the patient’s life expectancy is not reduced by the disease.
Treatment & Therapy
There is no causal therapy for hereditary neuropathies with a tendency to pressure paralysis because the disease is genetic. If the ability to walk is restricted due to increasing paresis, orthopedic aids should be used. These include orthopedic shoes, shoe lifter orthoses, knee orthoses, walking sticks, walkers and, if necessary, a wheelchair.
Surgical corrections are also carried out in the case of larger deformations on the feet. Physiotherapy and occupational therapy are also used regularly. However, some patients do not need any treatment at all because the symptoms resolve on their own after a while. The prerequisite for this, however, is the avoidance of mechanical loads.
Outlook & Forecast
Hereditary neuropathy with a tendency to pressure paralysis cannot be cured. It is a genetic disease. However, the prognosis of the disease is usually good. In half of the cases, the symptoms resolve completely. Therapy is not required in these patients.
In the other 50 percent of patients, there is incomplete resolution of the symptoms. Usually, residual symptoms are mild and do not become disabling. However, in some of those affected, the ability to walk is also restricted later on. Then orthopedic aids may be necessary. However, the restrictions are very variable, so that the use of these tools also varies.
For example, foot drop orthoses, knee orthoses, orthopedic shoes, walking sticks, walkers and sometimes even wheelchairs are used. If the hands are affected, writing and eating aids may also be needed. In the case of severe foot deformities, an operative correction is sometimes sought.
Physiotherapy and occupational therapy can also be used for certain limitations, such as paralysis in the hands. However, it is in the patient’s own hands to avoid triggering situations for pressure lesions. There are those affected who remain completely symptom-free for the rest of their lives. The use of neuropathy-inducing drugs such as high-dose penicillin or vitamin B6 as well as lithium, gold, vitamin A and many others must be considered individually.
If there is a family history of HNPP, human genetic counseling can be used. The disease is usually inherited in an autosomal dominant manner. People who are already affected by HNPP can prevent the typical symptoms from occurring by avoiding pressure loads.
This includes sitting for long periods with crossed legs, repetitive movements of the wrists or putting down the elbows. Even losing weight quickly is counterproductive. Furthermore, many drugs that have an amplifying effect on polyneuropathies should be critically examined. In particular, the use of vincristine should be avoided.
Following treatment of hereditary neuropathy with a tendency to pressure paralysis, it is helpful to use protective cushions for the affected joints. Patients receive appropriate information from their doctor on how they can protect their nerves well in the future. Excessive mechanical loads should be avoided if possible.
If the knees are affected, people should not cross their legs constantly and for long periods of time. If you have trouble with your elbows and wrists, it helps to avoid repetitive movements or frequent leaning on them. Rapid weight loss can also have a negative impact on physical well-being.
In consultation with the doctor, patients learn which medication they should no longer take. For example, vincristine is taboo. Reducing excessive movement and activity plays a key role in follow-up care and supportive treatment. Bandages and padded elements are also available, which reduce the pressure on the joints.
This will help prevent the overuse from occurring again. In addition to protecting against repeated damage, the nerves are protected. This gives the myelin structure a chance for successful regeneration.
You can do that yourself
A hereditary neuropathy with a tendency to pressure paralysis is always genetic and can therefore not be treated causally. Patients have to learn to live with the complaints and symptoms over the long term. You can do this by talking to friends and relatives, but also by visiting a self-help group. The doctor can support the patient to accept the disease in the long term.
Accompanying the therapy, measures must also be taken to alleviate the symptoms caused by the deformations. Physiotherapy and ergotherapy are among the most important measures – both can be supported by the patient with moderate sport, physiotherapy and yoga.
In some patients, the symptoms resolve on their own. Further treatment is not necessary in this case. However, patients should keep a complaints diary and consult closely with the doctor responsible.
If symptoms suddenly become noticeable again, this must be clarified immediately. Acute pain can be relieved with natural painkillers. Which preparations are suitable depends on the type of neuropathy and must always be decided by a doctor or naturopath.