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Six Years of Progressive Brain Disease Mistaken for Conversion Disorder

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A 62-year-old woman spent years experiencing worsening balance problems, weakness, falls, speech difficulties and cognitive decline. Two neurologists diagnosed her with conversion disorder, and she was subsequently treated for a presumed psychological explanation of her neurological symptoms. The actual cause was progressive supranuclear palsy (PSP), a serious neurodegenerative disease. By the time it was recognised, approximately six years had passed since her symptoms began, and her condition had deteriorated substantially.

The case was documented in a 2017 paper published in Neuropsychiatric Disease and Treatment, titled La belle indifférence revisited: a case report on progressive supranuclear palsy misdiagnosed as conversion disorder. What makes this case particularly troubling is not simply that the diagnosis was wrong. It is how readily psychiatric history, an unusual facial expression and initially inconclusive neurological investigations became part of the justification for that diagnosis.


Years of deterioration

The woman's symptoms began in 2009. She experienced weakness in her left arm and leg, difficulty maintaining her balance, repeated falls, intermittent double vision, problems with speech and memory, and increasing difficulty concentrating. By 2012, she had consulted two neurologists. Neither identified a neurological explanation sufficient to account for her presentation, and both diagnosed conversion disorder. A CT scan and subsequent MRI investigations were considered insufficient to explain her symptoms.

She underwent rehabilitation without success and was referred to a specialist centre for treatment of conversion disorder in 2013. During the assessment, clinicians considered her history of childhood sexual abuse, depression and avoidant personality characteristics. Her relatively expressionless, surprised facial appearance was also discussed in relation to la belle indifférence, a historically recognised but scientifically disputed concept involving an apparent lack of concern about serious symptoms.

The patient accepted the working diagnosis and participated in treatment, including acceptance and commitment therapy and psychosomatic physiotherapy. Psychological treatment helped her address some longstanding emotional difficulties, but her neurological condition continued to deteriorate. She developed worsening speech and swallowing difficulties, increasing falls and cognitive impairment. Eventually, she became too unwell to attend the clinic.

A third neurologist was consulted after the treatment team reconsidered the possibility of neurodegenerative disease. This examination identified abnormalities of vertical eye movements, slowed movements, rigidity and severe postural instability. MRI findings supported a diagnosis of probable progressive supranuclear palsy, Richardson's syndrome. The researchers reported that retrospective examination of MRI scans from 2012 and 2014 revealed midbrain atrophy, producing the characteristic hummingbird sign. Findings associated with the disease had therefore been present in earlier imaging, although their significance had not been recognised at the time.

The diagnosis was established in 2015, approximately six years after symptom onset. There was no curative treatment available, and the woman subsequently moved into a nursing home requiring extensive care.


When psychiatric history becomes diagnostic evidence

One of the most concerning aspects of this case is the role played by the woman's personal history. She had experienced childhood sexual abuse and suffered from depression, and clinicians considered these circumstances relevant to the conversion disorder diagnosis. Yet the authors acknowledged that no identifiable psychological event could be linked to the onset of her progressive neurological symptoms. Her trauma history was real, but it did not explain her neurodegenerative disease.

The interpretation of her facial expression was equally problematic. Her surprised appearance and reduced facial expression were considered in the context of la belle indifférence. In retrospect, these features could be explained by abnormalities associated with PSP, including impaired eye movements and reduced facial mobility.

The paper also cites a 2006 systematic review of la belle indifférence that found a median reported frequency of 21% among patients with conversion symptoms and 29% among patients with organic disease. Far from being a reliable indicator of conversion disorder, the phenomenon appeared at least as frequently in patients with recognised neurological or other medical conditions in the studies reviewed.

This raises an uncomfortable question: how much diagnostic weight should be given to someone's psychiatric history or apparent emotional response when neither establishes the cause of their neurological symptoms? In this case, those considerations contributed to a diagnosis that ultimately proved wrong.


The distinction that should never have been overlooked

Perhaps the most important admission appears in the authors' discussion of the initial neurological examinations. They acknowledged that there had been no positive neurological signs demonstrating incompatibility with recognised neurological disease. Instead, clinicians had observed fluctuations in the patient's symptoms, something that can also occur in neurological disorders, particularly during their early stages.

"Furthermore, there were no positive neurological signs in the sense of incompatibility with known neurological disorders in the first two neurological examinations; there were only signs of a fluctuating presence of symptoms, which can be seen not only in CD but also in several neurological disorders, especially at onset."

That passage deserves attention. The clinicians had not demonstrated that the presentation was incompatible with neurological disease. They had failed to identify its cause. Those are fundamentally different findings, yet the patient was diagnosed and treated for conversion disorder.

The case also exposes the limitations of treating an initially unrevealing examination or scan as though it settles the diagnostic question. Progressive neurological diseases can evolve over time, with characteristic clinical signs becoming apparent only later. In this instance, the eventual diagnosis depended on recognising abnormalities that earlier assessments had missed or not adequately investigated, including the eye movement disturbances characteristic of PSP.

Even the patient's improvement in psychological well-being did not establish that her neurological symptoms were psychologically caused. Her emotional difficulties responded to treatment while the underlying neurodegenerative disease continued to progress. Psychological improvement and neurological recovery are not interchangeable outcomes.


What this case demonstrates

The researchers concluded that progressive deterioration should prompt neurological reassessment, particularly when treatment directed at conversion disorder fails to improve the physical condition. They also recommended specific examination of eye movements when an unusual facial expression raises the possibility of PSP.

This was a single case report, so it cannot establish how frequently PSP or other neurological diseases are misdiagnosed as conversion disorder. Nevertheless, it documents a concrete diagnostic failure involving multiple neurological assessments, psychiatric interpretation and delayed recognition of progressive brain disease.

The central failure was not that clinicians initially struggled to identify a relatively uncommon neurological disease. Diagnostic uncertainty is sometimes unavoidable. The failure was allowing that uncertainty to become a psychiatric diagnosis without sufficient positive evidence, while the patient's neurological deterioration continued.

This was not the only documented case of progressive supranuclear palsy being mistaken for a functional disorder. A separate 2020 case report previously covered by FND Nope described another 62-year-old woman initially diagnosed with a functional voice disorder. Her diagnosis was revised to PSP after progressive deterioration and further neurological investigation. Unlike the 2017 case, where psychiatric history and la belle indifférence influenced the diagnosis, the later report questioned clinical observations interpreted as functional, including a preserved cough and the patient's use of sunglasses indoors. Two different patients, two different diagnostic pathways, and the same underlying neurodegenerative disease.

By the time the correct diagnosis was established, the woman in the 2017 report had lost years to an incorrect explanation of her symptoms. Her history of trauma had not caused her progressive supranuclear palsy. Her facial expression was not reliable evidence of conversion disorder. And her fluctuating symptoms had never ruled out neurological disease.

Not finding a neurological explanation is not the same as finding evidence of a functional disorder. This case is a documented example of what can happen when that distinction is lost.


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