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.
It’s all pretty much going as expected so far. He won’t be surprised when he wakes up with a hangover tomorrow, but what he doesn’t realise is the effect his next actions are going to have. Sitting in the chair he hangs his arm over the back of the chair as he watches the television, but the late hour and the alcohol mean he falls asleep like that too. He wakes up several or many hours later in the same position, with his arm over the back of the chair, only to find he cannot move it and it feels odd, a bit like waking up with a dead arm at night.
If we adopt an odd or stressful position when we sleep the increasing discomfort in the part wakes us up or we naturally just move to a better posture. When we are drunk however we may not do this and this was the problem which allowed the bodily structures in his armpit to suffer significantly increased stresses for perhaps some hours before he finally woke. The arm will hardly move at all and he becomes concerned when it does not respond to shaking and rubbing by recovering its movement.
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.
Nerve damage is classified into three categories: axonotmesis, neurotmesis and neurapraxia. Neurapraxia is the mildest variety of nerve trauma and there is internal biochemical damage to the nerve but no break in the internal axon or the nerve itself. The nerve being intact, it does not need to regenerate but recover. Nerve impulse conduction is disrupted by the area of nerve trauma and gives paralysis of the muscle with some difference in feeling. Compression may cause avascular damage to the nerve, resulting in inflammatory changes.
While the arm will recover from the nerve insult which it has suffered, sometimes quite quickly, an average recovery time to good function is between six and eight. The major functional disruption is the loss of the ability to move the arm and the ability to feel the arm and control the circulation and sweating to it are either less affected or not affected. Examination by a doctor is useful to exclude more severe injury to the nerve and to caution the patient in how to look after their arm until it recovers, particularly if there is feeling loss.
Since the arm is paralysed to a greater or lesser degree a sling may be needed for shoulder support and to keep the arm out of the way. If there is loss of feeling the person needs to check carefully what they are doing with the arm and examine it regularly for signs of damage. Vigilance is important as the arm can be damaged without being aware of it. Nerve trauma like this can also occur in sporting activities or long term pressure events such as falling asleep on a toilet.
