Numbness in a hand or foot, tingling, the feeling of «ants crawling» — many people know these sensations. In most cases they are caused by temporary compression of nerves after sitting in the same position for a long time or sleeping on your arm, and they pass within a few minutes. However, if numbness recurs frequently or persists, its cause should be investigated.
When should numbness be a concern?
The NHS recommends seeing a doctor if:
- the numbness is constant;
- the numbness goes away and keeps coming back.
Call 103 immediately if numbness or weakness started suddenly and affects one side of the body or the face, or if speech or vision is affected. This may be a sign of a stroke — more details in this article.
Possible causes of numbness
Persistent or recurring numbness can have many causes. Below we list the most commonly discussed ones; only an examination can show which applies to you.
Carpal tunnel syndrome
It is caused by compression of a nerve in the wrist. As described by the NHS, the main symptoms are pain, numbness and tingling in the fingers, hand or arm, and a weaker grip. Symptoms usually develop gradually and get worse at night.
According to the NHS, the diagnosis is often made by listening to the complaints and examining the hand; if the diagnosis remains uncertain, a nerve conduction test or imaging such as ultrasound or MRI may be carried out. The treatment approach depends on how severe the symptoms are: starting with a wrist splint at night, reducing activities that strain the wrist and physiotherapy, and moving on to injections or surgery if these do not help. The doctor decides which option suits you after the examination.
Risk factors include being overweight, pregnancy, repeatedly bending the wrist or working with vibrating tools, arthritis, diabetes, a family history of the condition and previous wrist injuries.
Peripheral neuropathy
This is damage to the nerves outside the brain and spinal cord. Symptoms:
- numbness and tingling in the feet or hands;
- burning, stabbing or shooting pains;
- problems with balance and coordination;
- muscle weakness, especially in the feet.
The NHS names diabetes as the main cause of peripheral neuropathy in the UK: blood sugar that stays high for a long time gradually damages the nerves. Other causes include nerve injuries, viral infections such as shingles (herpes zoster), side effects of certain medicines and drinking too much alcohol.
In peripheral neuropathy, treatment and outlook depend largely on the type of nerve damage and on whether the underlying cause can be addressed. For example, in people with diabetes, blood sugar control, stopping smoking and cutting down on alcohol may be part of the treatment plan. That is why it is important to find the cause of the numbness rather than focusing on the numbness itself.
Vitamin B12 deficiency
B12 deficiency can cause not only anaemia but also nervous system symptoms: numbness, tingling, muscle weakness, problems with balance and coordination, and changes in memory and mood. The NHS stresses that if left untreated, some of these problems can become irreversible — which is why early diagnosis matters.
Only a blood test can show your B12 level. Taking vitamin supplements without a doctor's prescription can make the diagnosis more difficult.
Other causes
Among the causes of persistent numbness, the NHS also lists nerve compression (for example, sciatica associated with a herniated disc in the lower back), multiple sclerosis, Raynaud's syndrome, certain medicines and chemotherapy, and an unhealthy diet. Numbness or weakness of movement in the face may be related to involvement of other nerves — for example, the facial nerve.
Investigating numbness
Neurological examination
The neurologist first asks about the nature of the complaints: which fingers go numb, whether it gets worse at night, whether it is symmetrical on both sides, diabetes, medicines you take, alcohol use. Then sensation, muscle strength and reflexes are checked during a detailed neurological examination.
EMG and nerve conduction test
Electromyography (EMG) is a test that checks the condition of the muscles and the nerves that control them. A nerve conduction test is usually carried out at the same time — it measures how fast and how strongly an electrical signal travels along a nerve. These tests are used to assess conditions such as carpal tunnel syndrome and peripheral neuropathy.
Blood tests
Depending on the suspected cause, the doctor may order tests to check blood sugar, vitamin B12 and other values.
Frequently asked questions
My hands go numb at night — what is it?
Hand numbness that gets worse at night is one of the typical signs of carpal tunnel syndrome, but it is not the only possible cause. The exact cause is determined by a neurological examination and, if necessary, EMG.
Can numbness in the feet be related to diabetes?
Yes, diabetes is one of the main causes of peripheral neuropathy. If you have diabetes and feel numbness or burning in your feet, be sure to tell your doctor.
Is EMG painful?
During the test a thin needle electrode is inserted into the muscle and electrical stimuli are applied, which may cause some discomfort in some people. The doctor explains how the test is performed beforehand.
This article is for information only and does not replace a medical examination. A diagnosis can only be made by a doctor, based on listening to the complaints and an examination. If you have worrying symptoms, you can book an appointment with neurologist Dr. Elvin Niftaliyev at Ganja International Hospital via the contact page.