An example of this is ‘glove anaesthesia’ where a patient complains of numbness in the hand, stopping at the wrist. This is invariably diagnosed as conversion syndrome because the sensory nerve that supplies the hand also supplies the arm and would not allow for this specific area of anaesthesia. Other localised areas of numbness occurring in the foot or leg (‘shoe anaesthesia’ and ‘stocking anaesthesia’) encounter the same problem.
Include symptoms which are known to occur in given circumstances
A classic example of this is whiplash injury, the neck injury often related to vehicle accidents. This is found to be more prevalent in countries where people are aware of the condition and how you are likely to get it. It is also found that membership of a support group or engaging in compensation claims for the injury tends to make it harder to get better, possibly because the symptoms are then constantly on the patient’s mind.
Susceptible to the placebo effect
Muscle cramping resulting in limb contracture (dystonia) can be treated with Botox injections. These take about 24 hours to have an effect. Sometimes, however, the Botox is found to work immediately, indicating a case of functional dystonia.
Can any of this help to throw light on the Bertha Pappenheim case?
The question of what is anatomically impossible is relevant to Bertha’s first visual disorder, a convergent squint. An eye specialist diagnosed this as due to a paresis of the abducens(sixth cranial nerve). Breuer discounted this, putting it down rather to hysteria. It has been suggested* that a psychogenic explanation would be impossible. As the abducens controls the external rectus muscle of the eye, a lesion to it makes it impossible to turn the eye outwards. At the same time, the now unopposed internal rectus muscle pulls the eye inward, causing the squint. This could not occur psychogenically as the voluntary motor pathways operated by the upper motor neurons govern entire movements and not individual muscles. So here it is the psychogenic explanation rather than the physical one which is an anatomical impossibility.
On the basis of the ‘whiplash’ scenario, we might expect hysterical symptoms to correspond with symptoms which the patient is already familiar with. It’s interesting to consider Bertha’s prosopagnosia (inability to recognise people’s faces) in relation to this criterion. Although now, thanks to Oliver Sacks, most people know what prosopagnosia is, there was so little awareness of it in the 1880s that not even Bertha’s doctor recognised it. It’s not likely then that she did and therefore even less likely that her subconscious would manage to conjure it up.
There’s no evidence that Breuer ever tried placebos with Bertha. But for contractures of the limb, use of a placebo is not the only means of revealing whether or not the problem is physical. In functional dystonia the muscles will usually relax during sleep or sedation. In a report discovered almost a century after the events, Josef Breuer describes Bertha’s contracture of the arm and leg. They would, he wrote, ‘relax neither when she was asleep nor under intoxication with 5.00 chloral’.
Three more nails in the coffin of Bertha’s hysteria diagnosis, I think.