My hands go numb
It is the commonest reason for an appointment on this whole site, and also one of the worst diagnosed. Fourteen in every hundred people have tingling in the hand; only four really have carpal tunnel syndrome. The question that pays off most is not what is wrong with you: it is which fingers go numb.
The nerves that supply the hand travel a long way down from the neck, and along the route they pass through several narrow tunnels. When one of those tunnels squeezes, the nerve stops conducting properly and tingling, numbness and, later, weakness appear.
Which of them is the one being squeezed is answered by a very simple question, and it is worth asking it before any test.
Which fingers go numb
It is the most useful thing on this whole page.
Thumb, index finger, middle finger and half the ring finger. This is the territory of the median nerve, which passes through the carpal tunnel at the wrist. It gets worse at night, it wakes you, and it eases if you shake the hand or hang it over the side of the bed. Holding the phone is hard, small objects get dropped, driving and holding a newspaper become uncomfortable.
Little finger and half the ring finger. This is the territory of the ulnar nerve, which is almost always trapped at the elbow — in the cubital tunnel — and not in the hand. It gets worse when the elbow stays bent: talking on the phone, sleeping with the arm folded, resting the elbow on a desk or on the car door. In advanced cases the fingers claw and the hand loses the strength to spread them apart.
The whole hand, or both hands and the feet as well. Then it is probably not a trapped nerve but a polyneuropathy: diabetes is the commonest cause, and there are others. It typically starts in the feet and works its way up.
The whole arm, with pain running down from the neck. That points to a compressed nerve root in the cervical spine, which is a different picture and is treated differently.
That distinction is not a detail: it is the difference between operating on the wrist, operating on the elbow, treating the diabetes or looking at the neck.
The figures worth having
- In a population survey of nearly 2,500 people, 14.4 per cent reported pain, tingling or numbness in the territory of the median nerve. But only 3.8 per cent had clinically certain carpal tunnel syndrome.
- Put another way: of every four people with tingling in the hand, roughly three do not have carpal tunnel syndrome. That is probably the most reassuring and at the same time the most useful figure on this page, because it explains why the diagnosis needs an examination and why the symptom on its own is not enough.
On treatment, the most complete systematic review compared surgery against splinting across fourteen randomised trials and 1,231 participants, and the result has two sides that have to be read together:
- Surgery achieves clinical improvement more often than a splint, with moderate certainty of evidence.
- But the difference in symptoms and in function fell below the threshold considered clinically important. That is: surgery wins, but by less than you would expect.
- The adverse effects were 61 per cent with surgery against 41 per cent with a splint.
- And the decisive figure: 44 per cent of those treated with a splint ended up referred for surgery, against none of those operated on needing a second operation.
That last point is what tips the conversation in practice. Starting with a splint is reasonable and often enough; but almost half of those who start that way end up having surgery anyway, and it is better to know that from the outset than to discover it two years later.
When not to wait
Seek advice soon, without letting months go by, if any of these appears:
- Weakness or loss of muscle bulk: a hollow shows at the base of the thumb, or the fingers claw. Once the muscle has wasted, recovery after surgery is far poorer.
- Constant numbness, no longer coming and going but there all the time.
- Numbness or weakness that came on suddenly, within hours, or after an injury.
- Dropping things out of the hand without noticing.
- Numbness in both hands and in the feet as well, or numbness that is working its way up.
- And in pregnancy: carpal tunnel syndrome is common and usually settles after the birth, but progressive weakness deserves an appointment all the same.
The general rule is this: intermittent tingling can wait; weakness and permanent numbness cannot.
What you will hear that is not true
"It is the computer, the mouse or the phone." It is the cause everyone assumes, and the evidence does not support it. A systematic review of eight studies found insufficient evidence of a causal association, and several of those studies found risks below one. The pressures inside the tunnel during typical computer use are below the levels considered harmful. What is associated is manual work involving force and vibration, pregnancy, hypothyroidism, diabetes, rheumatoid arthritis and obesity.
"All tingling in the hands is carpal tunnel." Three out of every four people with the symptom do not have it.
"If the nerve conduction study is normal, there is nothing wrong with me." The diagnosis combines the clinical examination and the nerve conduction study, and the two do not always agree: there are clinically certain cases with normal electrophysiology, above all early on. The test helps to confirm the diagnosis and to measure severity; it does not decide on its own.
"The operation leaves damage, you lose strength." The available data says the opposite on one key point: none of those operated on needed a second operation, whereas 44 per cent of those treated with a splint ended up in surgery. That said, adverse effects are real: 61 per cent against 41 per cent. Most of them are discomfort around the scar that settles with time.
"A splint is always enough." The same figure the other way round: almost half end up having surgery.
"Tingling in the little finger is carpal tunnel too." No. The median nerve does not supply the little finger. If your little finger goes numb, look at the elbow.
What will happen at the appointment
You will be asked which fingers, at what time of day, and what makes it better. Waking at night and easing when you shake the hand is very characteristic of carpal tunnel syndrome.
Then the examination: sensation finger by finger, thumb strength, a search for wasting at the base of the thumb, tapping over the nerve at the wrist and at the elbow, and sustained flexion manoeuvres. Your neck will be examined too, to rule out the origin being there.
Electromyography with nerve conduction studies is requested when the picture is not clear, when several possible levels have to be told apart, or before surgery. It is uncomfortable but not dangerous.
And if the picture is mild and intermittent, the first step is usually a night splint holding the wrist in a neutral position, correcting whatever can be corrected, and a review in a few weeks.
Questions worth writing down before you go
- Which nerve is it, and at what level is it trapped?
- Do I have weakness or wasting on examination, or only sensory symptoms?
- Is electromyography needed in my case, and what for?
- Is there an underlying cause worth looking for: thyroid, diabetes, arthritis?
- If I start with a splint, how long do we give it before reconsidering?
- If I have surgery, what do you expect to improve first, and what may be slow or never come back?
The questions people ask most
Why do my hands go numb at night?
It is the most typical pattern of carpal tunnel syndrome: the wrist bends as you sleep, the pressure inside the tunnel rises and the nerve stops conducting properly. That is why it wakes you, and why it eases when you shake the hand or let it hang. If it is the thumb, the index finger and the middle finger that go numb, the picture is fairly characteristic.
Does carpal tunnel syndrome clear up on its own?
It can improve on its own when there is a temporary cause that resolves, such as pregnancy, and it can be kept under control for years with a night splint and changes to activity. But in the systematic review of surgery against splinting, 44 per cent of those treated with a splint ended up referred for surgery. Improving and being cured are not the same thing.
Is carpal tunnel surgery dangerous?
It is one of the commonest and best studied operations on the hand, it is done under local anaesthetic, and none of the patients operated on in the trials needed a second operation. That said, adverse effects were 61 per cent against 41 per cent for the splint: mostly discomfort around the scar that settles over the weeks.
My little finger and ring finger go numb. Is it the same thing?
No: that is the territory of the ulnar nerve, and the trapping is usually at the elbow, in the cubital tunnel, not at the wrist. It gets worse when the elbow stays bent for long stretches — the phone, sleeping with the arm folded, resting the elbow. It is a different picture and the treatment is different too.
Does using a computer cause carpal tunnel syndrome?
The available evidence does not support that link. A systematic review of eight studies found insufficient evidence of a causal association, and the pressures inside the tunnel during normal computer use are below the levels considered harmful. What is associated is manual work involving force and vibration.
Is electromyography painful or dangerous?
It is uncomfortable: it involves small electrical stimuli and, in one part of the test, a fine needle inside the muscle. It is unpleasant, but it is not dangerous and it leaves nothing behind. It takes between twenty and forty minutes.
Is carpal tunnel syndrome in pregnancy serious?
It is common and generally not serious: it is due to fluid retention and usually improves on its own after the birth. The usual management is a night splint. What does deserve an appointment during pregnancy is weakness or permanent loss of sensation.
When do you need surgery?
When there is weakness or wasting of the muscle at the base of the thumb, when the numbness has stopped being intermittent and is constant, or when properly done splint treatment has not been enough. Weakness and wasting are the firmest criterion, because a muscle that has already wasted recovers far less well.