What is leg numbness?
Leg numbness is a term used to describe either a complete loss of sensation or a partial loss often accompanied by tingling feeling in the legs. This loss of sensation or tingling feeling might occur in either one leg or both the legs. In some cases, leg numbness may also be restricted to just a part of the leg such as the feet or the toes. Leg numbness is not the same as paralysis, even though it may be associated with cases of paralysis. Numbness refers to a loss of sensation, whereas paralysis is characterized by a loss of movement of the affected part.
What causes numbness or tingling in the legs?
The direct cause of leg numbness is either a damage to the sensory nerves or a lack of blood circulation in the leg. The damage to the sensory nerves or the lack of blood supply could occur due to many reasons. Some of these conditions are acute which is temporary and others may be chronic and irreversible.
- Prolonged compression: Sitting cross-legged or squatting for an extended period of time could lead to temporary numbness that goes away in a few minutes after the legs are extended and blood circulation improves.
- Pregnancy: The growth of the fetus in the womb may lead to herniated discs and compression of the spinal sciatic nerve even during normal activities such as walking or lying down. This can lead to temporary symptoms of leg numbness that usually go away after childbirth.
- Overexertion of the legs can sometimes cause tingling and numbness upon rest but this is short lived and usually resolves once the body recovers from the exertion.
- Spinal nerve damage due to disc herniation: Damage to the sciatic nerve that supplies the legs usually results from its compression by a herniated disc in the backbone (e.g. caused by lifting heavy weights). Leg numbness due to herniation of lumbar discs in the backbone can also occur due to degenerative disc diseases and the cauda equina syndrome. Symptoms of leg numbness in these conditions are also associated with lower back pain and incontinence of the bowel and the bladder.
- Lumbar spinal stenosis: Spinal stenosis refers to the narrowing of the spinal canal, resulting in compression of the nerves in the spinal cord. These conditions could be genetic, congenital (present since birth), caused by age-related degeneration in the spine or trauma due to some injury or surgical procedure. Lumbar spinal stenosis leads to leg numbness symptoms similar to those caused by herniated discs.
- Spinal tumors: Spinal nerves supplying the legs could also be compressed or damaged by growing tumors in the spine and nearby areas. The end results are symptoms similar to those caused by sciatic nerve compression.
- Trauma or surgery: Trauma or certain surgical procedures might lead to damage of the nerves going to the leg, leading to symptoms of leg numbness, pain or tingling. Lower limb paralysis caused by trauma to the nervous system can also be accompanied by a loss of sensation in the legs.
- Infections such as the tuberculosis of the spine can also lead to symptoms of leg numbness.
- Stroke: A lack of blood supply to the nervous system could also damage the nerves supplying the legs.
- Peripheral neuropathy is the term for disease of the nerves outside of the central nervous system. It can occur with a range of different conditions. Diabetic neuropathy is one such type that occurs when the elevated blood sugar levels cause irritation and eventually damage the nerves. The leg nerves are commonly affected in diabetic neuropathy.
- Tarsal tunnel syndrome: Compression of the tibial nerve in the foot due to any number of causes (e.g. tight fitting shoes, rheumatoid arthritis, trauma etc.) can lead to numbness in the foot.
- Genetics: Leg numbness is also a symptom in some of the hereditary diseases of the nervous system (e.g. multiple sclerosis) and the connective tissues (e.g. Marfan syndrome).
- Other: In addition to the above mentioned causes, a variety of factors of unknown origin could also lead to symptoms of leg numbness, tingling or pain. For example, restless leg syndrome is a neurological disorder that is characterized by a strong urge for leg movement due to uncomfortable feelings. The cause of this syndrome is not understood. Similarly, diseases of unconfirmed origin such as multiple sclerosis and transverse myelitis also lead to leg numbness in addition to other bodily symptoms.
How is leg numbness diagnosed?
Temporary numbness that goes away in a few minutes is usually not a cause for concern. However, if numbness or tingling sensation in the legs is chronic or recurrent in nature, then a visit to the doctor is advisable. A chronic or recurrent pattern of leg numbness, tingling or pain could indicate a more serious underlying cause such as nerve damage, trauma, tumor or stroke. The doctor will do additional tests to determine the exact cause of the symptoms of leg numbness.
The symptoms of leg numbness could include:
- A loss of sensation in the leg or a part of the leg.
- A tingling feeling in the leg or a part of the leg.
- A pins-and-needles sensation in the affected leg.
- A burning sensation in the legs.
- Pain starting in the lower back and radiating down the leg.
- Bowel or bladder incontinence.
- Paralysis of legs.
These symptoms can appear either gradually or suddenly. X-ray and MRI could help reveal any problems with the spine that could be causing the symptoms of leg numbness. Also, leg sensitivity tests reveal the identity of the involved nerves and help in finding the source of the symptoms. Additional symptoms occurring in other regions of the body can also help in diagnosing the underlying cause.
What is the treatment for leg numbness?
In some cases, leg numbness is not caused by any serious fatal disease and goes away in a few minutes. However, in other cases the cause might be a life-threatening condition such as a growing tumor or a stroke. Since there are many conditions that could lead to the common symptoms of leg numbness, the appropriate line of treatment can be decided by the doctor only after the diagnosis of the underlying cause.