Unexplained and unrelenting: conversion disorder in the 21st Century
A hundred years ago, one of the most common psychiatric diseases in women was hysteria. A dazzling array of symptoms were attributed to this nebulous disease – from tremors, stiffness, and paralysis, to nervousness or lethargy. Harriet Brown, a PhD student at the Wellcome Trust Centre for Neuroimaging, explains what modern medicine can tell us about hysteria, and why functional symptoms still challenge our understanding of the human brain.
The word ‘hysteria’ originally came from the Greek word for ‘womb’ – a reference to the early belief that hysteria was caused by your womb moving around your body and causing trouble. In the early 20th century this theory was no longer credited, but hysteria was still regarded as a female condition. Hysteria was thought to be caused by ‘conversion’, an idea that originated with Freud. The theory was that deep emotional traumas would be ‘converted’ into physical symptoms, unless they were drawn out of the unconscious mind through psychoanalysis.
So what happened to hysteria? There’s certainly no reputable doctor who’d diagnose you with it today. Unfortunately however, it has not being eradicated like smallpox or polio. Some of the symptoms once associated with hysteria are now known to have a physical cause – like multiple sclerosis, or epilepsy. Others remain unexplained. There are still a large number of people – perhaps 20% of those who are sent to a neurologist in the UK (1) – who have, often crippling, medical symptoms with no apparent physical cause.
Of course, we no longer call these symptoms ‘hysteria’. Instead, we call them ‘conversion disorder’ or ‘functional symptoms’. They’re also not exclusive to women, although they are a lot more common in the female population. They don’t seem to be triggered by specific trauma, although people who have had difficult lives are more likely to develop them. What’s more common is the appearance of ongoing symptoms, with no apparent cause, after a minor injury or surgery.
Maybe we’ll find out over the next hundred years that the symptoms we now think of as psychological are actually signs of an as-yet-unknown physical disease. It’s possible – but I’d be willing to bet against it. Very few people diagnosed with functional symptoms are later found to have a physical cause for their problems: around 0.4% over ten years, in one study (2). People who get one functional symptom will often get another one, or a whole range, across their lifetime and, most convincingly of all, the symptoms are often biologically impossible. People with functional numbness often get it from shoulder to wrist, or just over the area a glove would cover. But that’s not the way the nerves are wired. The nerves supplying your arm each cover a strangely shaped, illogically placed patch (laid down in embryos which look more like fish than people). So it’s not possible that such a neat pattern of numbness could be produced by damage to the nervous system.
As you might expect from a disease that seems to have a psychological basis, functional symptoms are heavily influenced by your life experience. Whiplash injury – neck pain experienced after you’ve been in a car that stops suddenly – is vastly more common in countries where people know what whiplash is, and know how they might get it (3). Claiming compensation for your injuries, or belonging to a support group for people with similar problems, seems to make it harder to get better, maybe because you’re being reminded of your symptoms every day.
Treatment for functional symptoms remains difficult and unsatisfactory. Some patients do very well and recover completely, while some learn to manage their symptoms. Many remain severely affected for most of their lives. Occupational therapy, physiotherapy, and counselling can all help. Perhaps the most dramatic treatment, though, is the placebo effect. Some patients experience functional dystonia. This is when the muscles cramp up permanently, twisting an arm or a leg into a painful, stiff position. Injecting Botox, a muscle relaxant, is a good treatment for other types of dystonia, those with a known physical cause. If you give Botox to patients with functional dystonia, the muscles relax immediately, and the patient can move their arm or leg again (4). But that’s not how Botox works – it takes at least 24 hours to shut the muscles down. The instantaneous effect can only be the result of placebo.
We really know very little about how functional symptoms are caused. There has not been much interest in researching them – possibly because it’s so hard to know where to start. What we do know is that attention is a key factor in how severe the symptoms are. Distracting patients from their symptoms can improve them dramatically – but because the patient isn’t paying attention, they don’t notice the improvement. Recently, some patients with a functional hand tremor took part in a study where they wore a watch to measure their hand movements 24 hours a day (5). When they were asked how often they had the tremor, they all replied ‘All the time’. The watch, however, told a different story – it detected tremoring on average only 5% of the time. This discrepancy isn’t evidence that the patients were ‘faking it’ (many patients insisted that the watch must be broken), it was simply that whenever they paid attention to their hand to see if they were tremoring, they were.
Our current research is looking at whether attention also affects the severity of other symptoms. For these experiments, we’re using imaging techniques such as MEG (magnetoencehalography) which can measure brain waves while patients look, feel and hear. As well as (hopefully) elucidating the causes of these mysterious and disabling symptoms, we’re hoping to uncover characteristic changes in brain activity that show that the patients are definitely not feigning illness. This would be an important step in getting the wider public, and the medical community, to take this disorder seriously.
Although functional symptoms are extreme and crippling, they’re a vivid example of just how much influence our brain can have over our bodies. I’m sure we’ve all had an itchy scalp when someone’s talking about head lice, or felt tight in the chest when we’re exercising and are convinced we’re having a heart attack. What if we never quite shook that feeling off?
(1) Stone J, Carson A, Duncan R, Roberts R, Warlow C, Hibberd C, et al. Who is referred to neurology clinics?—the diagnoses made in 3781 new patients. Clin Neurol Neurosurg 2010a; 112: 747–51 PMID: 20646830.
(2) Stone J, Carson A, Duncan R, Coleman R, Roberts R, Warlow C, et al. Symptoms ‘unexplained by organic disease’ in 1144 new neurology out-patients: how often does the diagnosis change at follow-up? Brain 2009a; 132: 2878–88 PMID: 19737842.
(3) Ferrari R, Obelieniene D, Russell AS, Darlington P, Gervais R, Green P. Symptom expectation after minor head injury. A comparative study between Canada and Lithuania. Clin Neurol Neurosurg 2001; 103:184–90 PMID: 11532561.
(4) Edwards MJ, Bhatia KP, Cordivari C. Immediate response to botulinum toxin injections in patients with fixed dystonia. Mov Disord 2011; 26:917–18 PMID: 21394784.
(5) Paree´ s I, Saifee TA, Kassavetis P, Kojovic M, Rubio-Agusti I, Rothwell JC, et al. Believing is perceiving: mismatch between self-report and actigraphy in psychogenic tremor. Brain 2012b; 135: 117–23 PMID: 22075068.