Carpal tunnel syndrome

The carpal tunnel is a narrow passage at the front of the wrist, with a tight band of tissue across it, and the median nerve runs through it with several tendons. That nerve carries feeling from the thumb, the index finger, the middle finger and the thumb-side half of the ring finger, and it works some of the muscles at the base of the thumb. When the contents of the tunnel swell, or the space narrows, the nerve is squeezed and the symptoms begin.

Often there is no single cause. The things that make it likelier include:

• Work or hobbies that bend the wrist or grip hard over and over, or that use vibrating tools
• Pregnancy, when fluid in the tissues can crowd the tunnel; it often eases after the birth
• Diabetes, an underactive thyroid or an inflammatory arthritis, such as rheumatoid arthritis, whose swelling of the tendon linings can press on the nerve
• An earlier break or injury of the wrist
• Being overweight, or a close relative who has had it

It is commoner in women and becomes likelier after 40.

The trouble sits at the wrist, yet most of what you feel is in the fingers. The usual picture is:

• Tingling, pins and needles or numbness in the thumb, the first two fingers and half of the ring finger
• An ache or pain in the hand, the wrist or the arm
• Symptoms that are worse at night or first thing in the morning, and that shaking or rubbing the hand relieves
• In time, a weaker grip, clumsiness or dropping things, and fiddly tasks such as buttons becoming harder

The symptoms often begin slowly and come and go. Numbness that stays all the time, or a thumb pad that is wasting, means the nerve has been under pressure for longer and needs attention sooner, as the section on when to seek help sets out.

Most cases are recognised from the pattern of symptoms and an examination: which fingers are affected, whether the symptoms wake you, and whether bending the wrist or tapping over the nerve brings them on. A nerve conduction test, which measures how well signals pass along the nerve, or a scan such as ultrasound is used when the picture is not clear-cut, or before surgery. Part of the assessment is looking for something that may lie behind it, such as diabetes, an underactive thyroid or an inflammatory arthritis.

A scan of the wrist during the appointment can show the nerve where it enters the tunnel, and the same scan guides an injection if one is chosen; the ultrasound clinic page tells you more about it.

Treatment is matched to how bothersome the symptoms are and how long they have lasted:

• A wrist splint worn at night keeps the wrist straight and takes pressure off the nerve; it can take up to six weeks to help
• Changing how you use the hand: cutting down on the bending, gripping or vibrating tools that bring it on, with breaks during long tasks
• Painkillers may take the edge off for a short time, but there is little evidence that they treat the cause, so they are not relied on
• A steroid injection into the carpal tunnel, if a splint is not enough, brings down the swelling around the nerve; the relief can wear off after some months, and a second injection is sometimes needed. With an ultrasound-guided injection the needle is watched on the screen as it goes in
• An operation, carpal tunnel release, done by a hand surgeon on referral, if the symptoms are severe, are getting worse or keep returning despite these measures: under local anaesthetic, a small cut lets the tight band over the nerve be released, usually in about 20 minutes and without an overnight stay. It usually cures the condition; tingling often eases quickly, while grip and strength take longer, and after severe or long pressure feeling or strength may not fully return. Normal activities usually return within about a month

You and Dr Borukhson settle the plan together.

How you use the hand during the day makes a difference to how it feels at night:

• Keep the wrist as straight as you can during long tasks, and arrange the desk, keyboard and tools to spare it long spells of bending
• Break up gripping, typing or tool work with short pauses, and lighten your grip where you can
• Wear the splint at night as advised, and if the hand wakes you, hanging it over the side of the bed and shaking it gently often settles it
• Gentle hand exercises, of the kind the Chartered Society of Physiotherapy describes, may ease the symptoms, though the evidence for them is modest
• If you have diabetes or a thyroid condition, keeping it well controlled may help the nerve too

Carpal tunnel syndrome linked to pregnancy often fades in the months after the birth. For many other people a splint and some changes to how the hand is used bring real relief, and those who need more often do well with an injection or an operation.

For most people carpal tunnel syndrome is not dangerous, and most of its symptoms are for a GP or a booked assessment. A few pictures are not, and the two lists below route them; they include sudden weakness or numbness of a hand or arm, an injured wrist, an infected hand or an infection that has turned to sepsis, heart pain felt in the arm, and tingling that has come on alongside neck pain.

Treat any of these as a 999 or A&E emergency: call 999 and do not drive yourself to A&E.

• Severe illness with suspected sepsis: a high fever with shaking, confusion, rapid breathing, or feeling dramatically worse over hours
• With a fever or feeling unwell, a rash that does not fade when you press it, a stiff neck with eyes that cannot bear bright light, or skin, lips or tongue turning blue, grey, pale or blotchy, since these can be signs of meningitis or sepsis; on black or brown skin the rash and the change of colour may be easier to see on the palms of the hands or the soles of the feet
• A joint you cannot put weight on or move, or that has moved out of place, or, after a fall or injury, very bad pain or any tingling or numbness
• After an injury, a crack heard as it happened, or skin around it that has turned blue, grey or cold, since these can be signs of a broken bone
• Sudden weakness or numbness on one side, a drooping face or difficulty speaking, a sudden severe headache, sudden confusion or a seizure, or sudden loss of vision, any of which can be a stroke, even if it stops after a short time, and a hand or an arm that has suddenly gone weak or numb, with no injury behind it, is one of these signs
• An eye that suddenly and completely loses its sight
• Lips, mouth, throat or tongue that suddenly swell, a throat that feels tight, very fast breathing or a struggle to breathe or to swallow, skin, tongue or lips turning blue, grey or pale (on black or brown skin this may be easier to see on the palms of the hands or the soles of the feet), becoming suddenly very confused, drowsy or dizzy, or fainting and not being able to be woken, since this can be a severe allergic reaction, anaphylaxis, which can follow a dose of any medicine
• Chest pain that is crushing, tight or like a pressure, that spreads to an arm, the jaw, the neck, the stomach or the back, that comes with breathlessness, sweating, feeling sick or feeling light-headed, or that came on suddenly and does not go away
• Arm pain that comes on suddenly with pressure, heaviness or squeezing across the chest, which can mean a heart attack

Any of these needs an assessment that is urgent, on the same day, from your GP or NHS 111:

• A joint that is hot and swollen, with a fever or feeling unwell, since an infected joint has to be ruled out at once, at A&E or through NHS 111
• A joint that has become hot and very swollen suddenly, or is worsening quickly, even without a fever, since an infected joint does not always announce itself with one
• Joint pain with a fever, or feeling hot, cold or shivery, or generally unwell, since an infection in or around a joint has to be found the same day
• Arm pain that is brought on by exercise, stress, emotion or the cold, rather than by a particular movement of the arm, and stops within a few minutes of rest, which can mean angina, a sign of a heart problem; NHS 111 will tell you where to be seen
• A lump, a finger or the palm that has turned very painful, hot or red, or hand pain with feeling hot, cold or shivery, since an infection in the hand can show itself this way and has to be found the same day, at A&E or through NHS 111 if a fever comes with it or you feel ill, short of the signs that follow; a lump, or the skin of a finger or the palm, turned hot or red, with a very high temperature or feeling hot, cold or shivery, a fast heartbeat or fast breathing, purple patches on the skin, which may be less obvious on black or brown skin, feeling dizzy or faint, confusion, or skin that is cold, clammy or pale, is a 999 or A&E emergency: call 999 and do not drive yourself to A&E
• Tingling in a hand, or numbness or weakness there that has come on gradually, with neck pain, since a nerve trapped at the neck can bring it on, and seeing someone that day tells it apart from pressure on the spinal cord, as our neck pain guide explains

See a GP if tingling or a loss of feeling in the hand comes and goes, with no injury and no neck pain, keeps coming back, wakes you at night, or is getting worse or not improving despite a splint and changes to how you use the hand, and at any stage if you have diabetes. Tingling that spreads beyond the thumb, the first two fingers and half of the ring finger is for a GP as well, since a nerve trapped higher up, at the elbow or in the neck, can be behind it. Numbness that has stopped coming and going, dropping things, a grip that has weakened over time or a wasted pad of muscle at the thumb's base needs a GP within days: a nerve kept under pressure can end up with numbness or weakness that lasts, and freeing it early gives the best recovery. Symptoms that are worsening quickly need a GP within days too, since another cause can be behind them. Stiffness on waking that needs more than half an hour to ease off, a finger swollen along its whole length, or a wrist or hand that is warm, swollen and stiff also needs a GP within days, since an inflammatory arthritis can start this way. With neck pain, the same nerve signs go to the same-day list instead; a hand or arm that loses its strength or feeling all at once, or its feeling after an injury, goes to the first list. No referral is needed to be seen here; next-working-day appointments can almost always be arranged, and same-day appointments are sometimes possible. A wrist, hand or arm bent at an odd angle or misshapen since an injury, or a cut through which bone shows, is a 999 or A&E emergency; if a knock or a fall to the wrist could have broken a bone but none of those signs, and nothing in the first list, is present, NHS 111 can say whether you need an X-ray. If you cannot tell how urgent something is, asking is never a mistake.

A squeezed nerve recovers best when the pressure comes off early, before numbness becomes constant or the thumb muscles waste. An assessment confirms that carpal tunnel syndrome is the cause, looks for anything behind it, and starts the simplest treatment that will work. If your hand tingles or wakes you at night, that visit is worth making.

How do you confirm carpal tunnel syndrome?

Usually from your description and an examination of the hand: which fingers tingle, whether it wakes you, and whether tapping or bending the wrist brings it on. A nerve conduction test, or a scan such as ultrasound, is used when the picture is not clear. Dr Borukhson can scan the wrist during the consultation, and she also looks for a condition that may be behind it, such as an underactive thyroid, diabetes or an inflammatory arthritis.

Will carpal tunnel syndrome get better by itself?

Sometimes. Milder cases can settle over a few months, and in pregnancy it often fades after the birth. A night splint, which may need up to six weeks to make a difference, and cutting down on the gripping or wrist bending that brings it on, help many people. If the symptoms are getting worse, or home measures are not working, see a GP rather than waiting; the signs that need more than that are under When to seek help.

Will I need an operation?

Not usually at first. A wrist splint, and then a steroid injection into the carpal tunnel if the splint is not enough, ease the symptoms for many people, though an injection can wear off and need repeating. If the symptoms are severe, keep coming back or are getting worse, an operation to release the tight band over the nerve, done by a hand surgeon on referral, usually cures it, though after severe or long pressure feeling or strength may not fully return. It is done under local anaesthetic, without an overnight stay.

When does numbness in the hand need a doctor quickly?

A hand or an arm that turns weak or numb without warning, with no injury behind it, can be a stroke, and is a 999 or A&E emergency even if it passes; so is numbness or tingling after a fall or injury to the hand or wrist. Call 999 and do not drive yourself to A&E. Tingling or numbness that has crept on with neck pain needs your GP or NHS 111 the same day. Numbness that no longer comes and goes, dropping things or a weakening grip needs a GP within days, since the nerve does best when the pressure is taken off early.