On its course from the brachial plexus to the forearm
and hand, the radial nerve( a cable that contains predominantly motor and some sensory fibers) spirals around the humerus (spiral groove).
This is where the compression occurs against the bone in patients with 'saturday night palsy'.
Sustained compression results in funtional impairment perhaps due to
- direct pressure on the nerve and/or
- inturruption of vascular supply due to compression on the 'vasa nervorum' which course over many nerves.
Nerve injuries are basically of 3 types: 'Neurapraxia', 'axonotmesis' and 'neurotmesis' .
'Neurapraxia',is one in which there is no anatomical interruption to the nerve but, only a funtional impairment(temporary).This is the type of injury that psesumably occurs in a 'saturday night palsy'.
''axonotmesis' is one in which the 'axon cylinders' of the nerve are broken but, the myeline sheath remains intact.This also eventually recovers but recovery may relatively prolonged.
'neurotmesis' is one in which the nerve itself is completely severed.This is the most serious of the nerve injuries.
In 'saturday night palsy', usually recovery occurs over a time-frame that can vary from days to longer than a year.
The wrist should be splinted in a neutral or functional position with a device to allow finger mobility (half cock-up splints). Passive, range-of-motion exercises are encouraged. B-comlex vitamins are generally prescribed.
MB BS, MS, FRCS(Edinburgh)