Being Kind To Your Nerves or The Saturday Night Palsy

You may be familiar with the picture, either personally or from a story somebody told you. A young man goes out for the evening, all dressed up and smelling of aftershave. He meets his mates in the pub and has a few beers, starting off the process of intoxication which continues most of the night. After the pub there is the nightclub and more drinking until it's time to roll out and round to the kebab house to have a snack. After a bit more hanging about he goes home or to one of his mates' houses to watch television, chat and perhaps drink a little more.

There is nothing exceptional in the story so far and our young man will not be shocked at all by the fact that he is very likely to feel hung over tomorrow. The surprise is due to what happens when he is watching the TV and he falls asleep. However, he has placed his arm over the back or the arm of the chair he is half lying in and that's the position in which he stays for some hours as he sleeps soundly. When he awakes he finds himself still in the chair with his arm over the back or the side, however he can't move his arm properly like he has slept on it and got a dead arm.

But what he has not realised is that he was drunk and that makes all the difference. If he was sober he would have woken up when his arm became uncomfortable and moved himself to a better position. What has happened is that a much greater pressure has been applied for a much longer time than usual to the tissues in his armpit. He starts to get worried when the arm does not recover quickly like he expected but remains semi-paralysed, numb and yet uncomfortable to some degree.

Reacting to stimuli is what nervous tissues are designed to do but they can react in negative fashion if the applied stimulus is too large or lasts too long. Pressure applied for a long period or a direct blow to an area can both cause nerve trauma, with honeymooners' palsy being the term for nerve damage caused by one partner using the other's arm as a pillow during sleep. Longer term nerve pressure can disrupt the blood supply to the nerve and compromise the function of the nerve, a condition called neurapraxia.

There are three broad categories of nerve damage classification: axonotmesis, neurapraxia and neurotmesis, with neurapraxia being the least severe nerve damage. There is no division of the nerve or a break of the nerve fibre axon in neurapraxia, meaning the nerve does not have to regenerate but just needs time to recover. The damaged area interrupts the impulse flow in the nerve, resulting in paralysis of the muscles and perhaps some sensory changes. The avascular state produced by the long period of pressure may be what damages the nerve.

The paralysis which leads to loss of function of the arm is temporary and can resolve in hours. However, in even average cases it can be six to eight weeks before the slow improvement occurs and normal strength returns to the arm. There is mostly a greater interruption of muscle power with feeling and sweating/circulation control of the arm less affected. As this can be serious the person should be examined by a doctor, for although there may be little to be done but wait, the sufferer needs to have the problem explained and be instructed how to look after their arm until it recovers.

Once the paralysis has occurred the arm will need to be supported by a sling to prevent shoulder problems and the person taught to check the arm regularly if there is any sensory loss. Sensory loss means that the arm can be damaged without the person realising it, so they have to be vigilant in looking after the limb until it recovers. Other ways of getting this kind of nerve trauma is in sport, by leaning against a solid edge for a long time or by falling asleep on the toilet for some hours.

Jonathan Blood Smyth, editor of the Physiotherapy Site, writes articles about Physiotherapy, back pain, orthopaedic conditions, neck pain, injury management and physiotherapists in Edinburgh. Jonathan is a superintendant physiotherapist at an NHS hospital in the South-West of the UK.