Functional neurological disorder: Investigating an invisible illness

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Loretta had been hoping for a promotion. Instead, she woke up one morning to find that her entire left side, from her face to her leg, had stopped working. A&E suspected she’d had a stroke, but a battery of tests revealed nothing. Six weeks later, Loretta was still housebound. “I would have some days that both my legs were completely numb,” she explained. “My right arm would just not work, two days a week, and I was unable to write or hold a pen.”

Loretta is one of many patients with functional neurological disorder (FND). Around a third of all patients in hospital medical clinics experience a form of FND. It is a disorder of the nervous system in which there is no damage or disease, but patients exhibit symptoms ranging from limb weakness or numbness to shaking, blackouts, and dissociation – feeling like their limbs are not part of them. Symptoms arise from issues with how the brain processes the information. Essentially, the problem lies either in how the brain sends messages to the body or how it interprets the messages it receives. Such changes aren’t physical, which is why they cannot be detected through conventional tests such as MRIs.  This is a software rather than a hardware problem.

Because of this, FND is a stigmatized illness. We still don’t understand why or how symptoms develop, and many doctors are reluctant to give an FND diagnosis, fearing they are making a mistake. Clinicians may suspect the patients are faking it, and patients themselves worry that they are imagining it.

Becky was in her early forties when, like Loretta, she suffered sudden onset left sided weakness. A few weeks later, she started having seizures. Over the next few years she experienced many strange symptoms: she would weep constantly for months from her left eye only; she would have sudden bouts of dizziness or flooding head pain. Every so often she would relapse, losing her muscle strength and seizing over and over. Her doctors were at a loss to explain her symptoms and couldn’t offer her a prognosis. “There seemed to be an unwillingness to debate or define what was happening and as with so many other sufferers, my family and I had become more marginalized and isolated,” she said. “We very much felt we were ‘out on our own’ and left to deal with whatever may happen next.”

In an effort to better characterize FND, researchers from the University of Edinburgh and the University of Groningen, Netherlands, performed a follow up study of over 100 patients with functional limb weakness, recently published in the journal Brain. This is the largest study of its kind, with the longest follow up period. The researchers aimed to provide clearer evidence regarding the prognosis of functional limb weakness, the rates of misdiagnosis and the long term consequences of this disorder. The study showed that 80% of the patients with FND still experienced symptoms in their limbs an average of 14 years after their initial diagnosis. This clearly demonstrates that FND is a persistent and disabling disease. Professor Jon Stone from the University of Edinburgh’s Centre for Clinical Brain Sciences, who was involved in the research, explained: “This study shows the importance of neurologists staying involved with the long-term management of patients to guide treatment and detect additional neurological conditions, which can rarely occur years after the start of FND.”

Importantly, the study found that misdiagnosis was extremely rare, with only one patient clearly misdiagnosed. The researchers further showed that FND was associated with a higher than expected mortality rate. “[This study] should also help clinicians provide a more realistic prognosis for patients with FND when it causes limb weakness, and stresses the importance of active and targeted treatment which many of these patients didn’t have,” concluded Prof. Stone.

Indeed, there is hope for FND patients. With a more widespread understanding of this disorder, they will be able to get the assistance they need. Fourteen months after her first symptoms, Loretta had not regained full use of her hands or legs. She was in chronic pain and had difficulty controlling her bladder. “I have a mobility scooter and a wheelchair to use, and these have become my new best friends,” she said. “I may get a mobility car, to help me be able to get out the house by myself and hopefully get my independence back.” Since there is no permanent damage to the brain’s hardware, further research may uncover ways to reboot the software. Becky eventually became one of Prof. Stone’s patients. After three weeks of intense neurophysiotherapy, her seizures subsided. Using crutches, she was able to walk small distances, and she could finally eat a meal without extreme exhaustion. “There is no cure, but there is treatment,” she explained. “[There are] no guarantees, no quick fix, no magic medication, but with hard work, a slow, painful process could begin whereby those errant parts of the brain that had stopped communicating could begin to talk once more.”

This article was written by Helena Cornu and edited by Miles Martin

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