In the last five weeks I've seen a lot of patients with chronic lower back pain. Depending on the cause, they can also present with other symptoms which can be quite mystifying unless you have a detailed knowledge of the lumbosacral plexus - the network of nerves which leave the spine in the lower back and control the motor and sensory function of the lower body.
The problem is, the lumbosacral plexus is rather complicated. That is, it has always been considered complicated until just this week when I realized that it can be easily understood in terms of the battle of Waterloo. A little bit of work and voila! This aide memoire inventee a moi pour la purpose de la education medique, as they say in France.
To use it, simply note that the French commanders are in blue, the Allied commanders are in red (British), grey (Prussian), and black (Brunswick), and the local villages and farm buildings are in brown. (The Dutch are not included in this diagram since they correspond better to the visceral innervation.)
For example, if a patient came in complaining of lower back pain and sudden onset ineffectual cavalry charges in the genital area, the diagram clearly shows that this is the fault of Marshal Ney, and that the underlying lesion lies somewhere in the vicinity of the sleepy hamlets of Rossomme and Papelotte. Or if the patient instead complained of lower back pain and surprise arrival on their flanks of a brigade of horse artillery, the diagram indicates that this is related to the activity of General Bulow of Prussia.
Every patient is different, of course, so please use these suggestions with caution and don't leap to conclusions. But it's definitely worth asking, when your next patient comes in with long-standing back pain unresponsive to conventional treatment, whether or not a whiff of black powder or a snifter of grape-shot might help!