The back of the legs becomes numb when sitting

Normally, our nerves continuously carry information from all over the body to the brain. If some information, for example about touch and pain, cannot be passed on, we have a feeling of numbness in the affected area. This means that either there is always a strange feeling or a touch on the arm cannot be perceived as such. An example of this is when one leg fell asleep because pressure was applied to a nerve for too long. There are many different causes for this, most of which are completely harmless, but some also require direct treatment.

Also read the article on the topic:Numbness in the leg

causes

The causes of numbness in the foot are varied. One possibility is external pressure on a nerve, which is colloquially referred to as a foot asleep. Deafness can also occur after insect bites. After a tick bite, neuroboreliosis can also lead to numbness of the feet. Pressure on the nerve can also develop further centrally, for example if a nerve is pressed in by an intervertebral disc in the lumbar spine.

A stroke can also cause numbness in one foot or other parts of the body. Multiple sclerosis can also begin with numbness in one arm or leg. After an accident, numbness in the foot can indicate damage to the spinal cord.

Read more on the subject at:deafness

After twisting an ankle / accident

In the event of an accident, there can be a great deal of violence on nerves. This can be the case either in the center of the spine or on a single nerve in the leg. The twisting of the foot means that one side of the joint is tensed and all structures running there are also under tension. This also includes the sensitive nerves that transport contact information to the brain.

In rare cases, such nerves can even tear and thus permanently lead to numbness or paralysis. In most cases, however, it is a matter of decreasing numbness after the twisting, which can also only occur after the actual accident due to the swelling.

Also read the article on the topic: Ankle twisted - what to do?

Herniated disc of the lumbar spine

Between the individual vertebral bodies of the spine there are cushioning discs, the so-called intervertebral discs. If the stress is incorrect, these can be destroyed and depress the nerves that come off the spinal cord. Depending on the severity of the herniated disc, this can lead to pain and numbness in the affected areas. If there is numbness in the thigh, it may be a herniated disc of L2 or L3. A herniated disc at level L4 affects the outside of the thigh and the front inside of the lower leg up to the big toe.

In L5, the outside of the lower leg and the other toes, as well as large parts of the sole of the foot, are more likely to be affected by numbness. S1 affects the little toe and pulls on the outer edge of the sole of the foot, over the outer calf to the buttocks. Numbness of the inner calf and inner heel is caused by an incident in S2. In the case of mild complaints, those affected can benefit from strengthening the muscles and physiotherapy. If the symptoms are more severe and if paralysis occurs in addition to the numbness, an operation on the intervertebral disc may be necessary.

Further information on the subject can be found at:Herniated disc of the lumbar spine

Polyneuropathy

A polyneuropathy is a term that stands for many different nerve diseases. Those affected usually have numbness and abnormal sensations in their feet or hands. The most common cause of this is diabetes, as the high blood sugar leads to nerve damage. Alcohol abuse, autoimmune diseases, poisoning and infectious diseases can also trigger polyneuropathies.
Due to the numbness, those affected do not notice small damage, such as a stone in the shoe, and can therefore develop sores on the feet. The perception of the feet is therefore regularly tested in diabetics.

Read more on the topic:Symptoms of polyneuropathy

After a disc surgery

A herniated disc can itself lead to a feeling of numbness in the toes, which does not have to go away completely even after an operation. However, numbness can also occur as a complication during intervertebral disc surgery. The operation takes place in a very sensitive area near many nerves and irritation of a nerve during the operation can lead to later feelings of numbness. Immediately after the operation, the inflammatory reaction in the operating area can also exert pressure on the nerves for a short time.

Further information on the subject can be found at: Operation of a herniated disc

diagnosis

In the event of numbness in the foot, the family doctor first examines the most common causes. During a physical examination, the doctor looks for other symptoms, such as tense muscles or other neurological abnormalities. If a stroke or multiple sclerosis is suspected, the person concerned is immediately sent to a hospital.
In the case of a herniated disc, imaging, i.e. a CT or X-ray, can be arranged. Multiple sclerosis is also diagnosed through imaging and laboratory tests. In the case of a stroke, a CT is done and therapy is started immediately.

Other accompanying symptoms

With a herniated disc, the affected person often not only suffers from numbness, but also from pain in the back. Tense muscles are also possible. In the event of paralysis, a doctor must be consulted immediately. In the case of a stroke, the arm on the same side is often also affected and paralysis can also occur on one side of the face. Typical here are drooping corners of the mouth and a drooping eyelid. Language and eyesight can also be changed. This is an absolute emergency and should result in an emergency call. Often one of the first symptoms of multiple sclerosis is deterioration in vision.

Back pain

The combination of back pain and numbness in the foot is almost proof of an irritated nerve from an intervertebral disc or a tense muscle. The back pain is often exacerbated when bending forward. A hot water bottle often helps with tension, while the intervertebral disc patients often do not receive any relief from heat. For many sufferers, taking over-the-counter pain relievers does not help, or only for a very short time.

Treatment / therapy

In the case of tension, the supply of heat from a hot water bottle is often sufficient. In the case of longer symptoms, a pain injection or massage can be prescribed and thus help the person affected. A herniated disc is usually not that easy to regress because it is a wear and tear on the disc. An improvement in symptoms can be achieved with pain relievers and physiotherapy.

For some people, however, surgery on the intervertebral disc is the only way to help. The operation is also not a solution that has the desired success for all those affected. When you have a stroke, therapy is about time. The sooner treatment begins, the greater the likelihood that the numbness and all other symptoms will go away. The blocked blood vessel can be opened with medication or the blockage can be removed with a catheter through the groin. Surgery is required for a bloody stroke. Antibiotic therapy is required for neuroboreliosis. Multiple sclerosis is treated with drugs such as cortisol and beta interferon, but there is no cure. The therapy is divided into a basic therapy and a relapse therapy.

Which doctor treats this?

When choosing a doctor, it depends on the cause of the numbness. For most of those affected, the family doctor is the first point of contact. If a herniated disc is suspected, the person concerned is referred to an orthopedic surgeon. Multiple sclerosis, neuroboreliosis or a stroke are among the diseases that neurologists continue to treat.

If there is tension, the family doctor can often help himself or the person affected is prescribed massages or physiotherapy. If the tension is triggered by chronic stress or is psychosomatic, a specialist in psychosomatic medicine can also help.

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Duration

How long numbness lasts depends on the cause. In the case of tension, the numbness is over as soon as the pressure on the nerve subsides. Herniated discs often last significantly longer. Even after surgery, an area of ​​the skin may remain numb. In the case of strokes, early treatment is important. With timely treatment, the symptoms can go away immediately. In MS, the numbness usually lasts for a few days and then disappears again until the next episode, which, however, can also affect other parts of the body.

Tension is usually a completely regressive disease. Those affected often have to struggle with a herniated disc for many years. Neuroboreliosis or meningitis must be treated quickly and can either heal completely or, in extreme cases, be fatal. Multiple sclerosis (MS) is a chronic, progressive disease that cannot be cured. Since there are different forms of MS, it cannot be clearly stated how long people can live independently.

Numbness when cycling

When cycling, especially on a racing bike, the posture is very stressful for the back. The person concerned bends forward permanently and at the same time has to exert a lot of force over the legs. This posture can damage the intervertebral discs and initially only cause problems with the aforementioned stress. If the load continues, the symptoms can also occur independently of cycling. Simple city bikes or Dutch bikes are more back-friendly, as the back stays straight.

Numbness after skiing

Many winter sports enthusiasts do relatively little sport in everyday life and then go skiing once a year. This unusual strain can lead to tension in the back and legs and thus trigger a feeling of numbness in the feet. This is often already reduced by relaxation and warmth. After an accident, however, the nerves in the back or ankles can also be injured, which can also be accompanied by a feeling of numbness.

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Quality assurance by: Dr. Nicolas Gumpert | Last change: 03.04.2021