Radial nerve palsy (wrist drop): causes, symptoms, recovery and treatment

The radial nerve is one of the main nerves of the arm. NHS Lothian explains that it is formed from nerve roots exiting from the upper spinal cord, travels down the upper arm, at times very close to the humerus (upper arm bone), and then gives off several branches, the largest of which is known as the posterior interosseous nerve. It carries the signals that lift the wrist and straighten the fingers and thumb, and it carries sensation from part of the back of the hand.

When the nerve is squeezed, stretched or injured, the muscles that lift the wrist stop working properly and the hand hangs down, which is the origin of the name wrist drop. NHS Lothian says the radial nerve may be damaged at the level of the humerus or in the elbow and forearm. A radial nerve palsy therefore is not a disease of the wrist itself but a problem of nerve conduction higher up the arm.

According to NHS Lothian, people with radial neuropathy notice a weak wrist that is often unable to be straightened. The fingers are weak and may be difficult to straighten, which it calls wrist and finger drop. They may also notice weakness of the thumb and, if the problem is close to the origin of the nerve, a weak elbow. Numbness or tingling is often present over the back of the thumb and sometimes the forearm.

In practice this means difficulty gripping because the wrist cannot be held in the position that makes the fingers work well, trouble opening the hand fully to release an object and a hand that hangs when the arm is held out in front. The Kaiser Permanente patient article, a US source, also lists pain, weakness, numbness, tingling and trouble lifting the wrist or fingers as possible symptoms, and describes the problem arising if you fall asleep in a way that puts pressure on the nerve, such as with an arm hanging over a chair.

NHS Borders and NHS Lothian both describe two main places where the nerve is usually damaged. At the upper arm (humerus), a fracture may cause a traumatic injury. They say that the most common cause of radial neuropathy, however, is sitting or sleeping with the arms over the back of a chair, which compresses the radial nerve against the bone, and note that it is often seen after heavy alcohol use, when a person may remain in an uncomfortable position for a long time. It is for this reason that radial neuropathy is also called Saturday night palsy.

In the forearm, they say the radial nerve may become trapped or damaged at the elbow by fractures, other injury or repetitive use. A doctor will therefore ask about injuries, sleeping position, alcohol and any recent procedures when assessing the cause.

See a GP, or contact NHS 111 if you cannot reach your surgery, if you wake with a weak wrist or fingers or numbness over the back of the hand, so that the diagnosis can be confirmed and other causes excluded. If the weakness follows an injury, a fall or a fracture, seek assessment promptly, because the nerve may need to be checked or the bone may need treatment. The NHS Lothian page says that if there has been an injury to the arm, the person may need an X-ray or further tests.

The Kaiser Permanente article advises contacting a doctor now or seeking immediate medical care if you have new or worse numbness, new or worse weakness or new pain or pain that is getting worse in the arm, wrist or hand. That is a reasonable general rule: any progression of symptoms, rather than slow improvement, deserves a prompt review. Sudden weakness of the face, arm and leg together, speech difficulty or confusion is a stroke emergency, not radial nerve palsy, and needs 999.

Diagnosis is usually clinical. A doctor or physiotherapist will examine how well you can extend the wrist, fingers and thumb, check sensation over the back of the hand and look for signs that point to where along the nerve the problem lies. NHS Lothian says that if the patient wakes up with a non-traumatic radial nerve palsy, especially if they remember sleeping in a chair, then no further tests are necessary.

If the cause is not obvious, there has been an injury, or recovery does not occur as expected, further tests may be arranged. NHS Lothian mentions an X-ray or further tests after injury, and the Kaiser Permanente article mentions nerve tests or an MRI. Nerve conduction studies and electromyography are tests that measure how well the nerve and muscle work, and your doctor will decide whether you need them.

Both NHS Scotland sources say that non-traumatic radial nerve palsy has a good prognosis and usually recovers over weeks to months, and that sometimes a wrist splint is helpful to maintain a functional hand position. NHS Lothian adds that a splint keeping the wrist in a straight position is useful as it places the hand in a better position for use.

The Kaiser Permanente article, which reflects US practice, says that in most cases no treatment is needed and strength and feeling slowly return over weeks or months, that physical or occupational therapy is sometimes used to keep up muscle strength, and that if the person does not get better or the injury is more serious, surgery might be needed to fix the nerve or remove something pressing on it. Following a hand therapist's instructions on splint wear and exercises matters; Frimley Health NHS Foundation Trust has a hand therapy leaflet describing a radial nerve glide exercise, noting that some discomfort, a pulling sensation and tingling is expected during the movement, that these symptoms should go away immediately or within a few minutes of finishing, and that you should stop and be reviewed by your hand therapist if you have any ongoing or new pain after doing it.

While the nerve recovers, keep the fingers and wrist moving through their available range as advised by a therapist so that the joints do not stiffen, and use the splint as directed. Avoid resting your arm over a chair back or sleeping in a position that presses on the inner side of the upper arm. If alcohol played a part, as the NHS Scotland pages note is common in the Saturday night pattern, being aware of positioning is the main preventive step.

Recovery can be slow and frustrating, and it is common to feel that nothing is changing for a few weeks. Keep your follow-up appointments, mention any change, and ask what signs of recovery to look for, such as the return of wrist lift or sensation in the thumb.

On the NHS, most people are seen by their GP or in an urgent care or emergency setting, with referral to physiotherapy or hand therapy for a splint and exercises. The NHS Borders page is written for GPs and sets out who to refer and how. Private physiotherapists, hand therapists and neurologists can offer assessment and nerve conduction testing more quickly. Whichever route you use, ask for a written plan covering splint wear, exercises, expected timescales and when to return if there is no improvement.