A Case of Sporadic Creutzfeldt-Jakob Disease Presenting as Conversion Disorder
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A published 2017 case report describes a 64-year-old woman whose neurological symptoms were initially diagnosed as a functional neurological movement disorder. Within weeks, she deteriorated significantly. Repeat investigations became abnormal, and a brain biopsy ultimately confirmed sporadic Creutzfeldt-Jakob disease (sCJD).
The case is notable because the functional diagnosis was not based only on negative tests. Neurologists reported that her movements were distractible, variable and entrainable, features commonly used to support a functional movement disorder diagnosis.
The initial presentation
The patient had been experiencing symptoms for approximately two months before admission. She developed worsening tremulous and jerky movements of the right arm, right-sided numbness, ataxia, headaches and joint pain. On examination, she had an intermittent resting tremor involving the right arm and leg, reduced strength of 4/5 on the right, decreased right facial sensation and an ataxic gait.
There were also cognitive findings. She scored 22/30 on the Montreal Cognitive Assessment, recalled none of five items and had difficulty with serial subtraction and repeating numbers backwards. At this stage, however, she did not have some of the features that would later make CJD more apparent, including marked confusion and myoclonus.
Why it was considered functional
During her first week in hospital, neurologists observed that her tremors and other neurological symptoms were distractible, variable and entrainable. These findings were interpreted as supporting a functional neurological movement disorder.
Her initial investigations also failed to identify a cause. The workup included MRI of the brain and cervical spine, CT imaging, serial EEGs, CSF testing including 14-3-3, infectious investigations, lupus anticoagulant testing and a paraneoplastic panel. Endocrinology, infectious disease and rheumatology were involved.
Psychosocial factors were also considered. The patient had experienced significant recent life stressors, including bereavements, retirement, relocation and limited social support. She had no previous psychiatric history and denied depression or other psychiatric symptoms apart from anxiety about her health.
By the end of the first week, neurology gave her a provisional diagnosis of functional neurological movement disorder. Psychiatry maintained the diagnosis, citing her presentation, negative investigations and possible psychosocial contributors.
Consultants became less involved
The consequences of that interpretation are stated plainly in the case report:
"Since her presentation was thought to be mainly functional, many consultants became less involved in her care."
This happened while the patient was in the early stages of a rapidly progressive neurological disease, making the change in clinical involvement particularly significant in retrospect.
The patient deteriorated
By approximately two weeks into the admission, the clinical picture had changed considerably. She developed expressive aphasia and marked confusion, refused food and fluids, developed a rigid posture and began displaying bilateral upper-limb tremors and myoclonus.
Other possibilities were investigated. High-dose steroids were given for a possible autoimmune or inflammatory process, benzodiazepines were tried for possible catatonia, and because she had previously been treated for Lyme disease, intravenous antibiotics were also given for possible neuroborreliosis. None of these treatments resulted in improvement.
Repeat tests were now abnormal
Three weeks into the admission, a repeat 24-hour EEG showed focal slowing over the frontotemporal and central region. Psychiatry advocated for specialists to become involved again and for the medical and neurological investigation to be reopened.
At approximately four weeks, a repeat MRI showed new cortical T2/FLAIR hyperintensities. Another 24-hour EEG demonstrated triphasic waves, and neuron-specific enolase was markedly elevated. The evidence now pointed towards sporadic Creutzfeldt-Jakob disease, and a brain biopsy subsequently confirmed the diagnosis.
From functional diagnosis to CJD within weeks
The timeline was remarkably short. The patient had been symptomatic for approximately two months before admission, and by the end of the first week she had been provisionally diagnosed with a functional neurological movement disorder. By approximately two weeks, she was deteriorating significantly, while the report notes that consultants had become less involved because her presentation was considered mainly functional.
At approximately three weeks, repeat EEG testing showed a new abnormality. At approximately four weeks, repeat MRI and EEG testing provided further objective evidence and suspicion shifted towards CJD. Brain biopsy subsequently confirmed sporadic CJD, and she died approximately two months after admission and four months after the onset of symptoms.
What did the functional signs establish?
The important question is what the original functional signs actually established. Distractibility, variability and entrainment were observed, but at the same time the patient was developing an aggressive neurological disease that would become objectively apparent on repeat testing and prove fatal within months.
The authors themselves acknowledge uncertainty over whether the apparently functional symptoms represented an early manifestation of CJD or occurred alongside it. They also raise the possibility that subtle neurological changes caused by the disease may have produced symptoms that appeared functional. The signs therefore identified a pattern; they did not establish its cause, nor did they establish that an underlying neurological disease was absent.
The diagnosis became "immutable"
The authors describe what happened after the functional interpretation took hold:
"All of the patient's symptoms began to be viewed as functional, and the diagnosis became immutable."
That is difficult to separate from the earlier observation that consultants became less involved. The original investigations had not found the cause, features of the presentation were interpreted as functional, psychosocial stressors appeared to support that interpretation, and the resulting diagnosis began to influence how subsequent symptoms were viewed.
It was continued deterioration and newly abnormal objective testing that eventually forced the investigation back open. This case therefore raises a serious problem with treating positive functional signs as more specific than the evidence allows. The clinicians did observe distractibility, variability and entrainment, but what those observations did not tell them was why the patient had that presentation. In this patient, the answer that ultimately emerged was a rapidly progressive, fatal neurological disease.
Conclusion
This case demonstrates the limits of what positive functional signs can establish. Distractibility, variability and entrainment were genuinely observed, but they did not establish the cause of the patient's presentation. At the same time, she was developing a rapidly progressive neurological disease that would ultimately be confirmed as sporadic CJD by brain biopsy.
The initial tests were largely unrevealing. It was progression, repeat testing and newly emerging objective abnormalities that eventually forced the diagnosis back open. By then, the functional interpretation had already influenced her care, with the authors reporting that consultants became less involved and that the diagnosis had become "immutable."
The lesson is not that the observed signs were necessarily false. It is that recognising a functional phenotype should not be confused with explaining it. In this case, those signs provided far less diagnostic certainty than clinicians initially placed upon them, with serious consequences for how the patient's continuing deterioration was interpreted.
Source
Yegya-Raman N, Aziz R, Schneider D, Tobia A, Leitch M, Nwobi O. A Case of Sporadic Creutzfeldt-Jakob Disease Presenting as Conversion Disorder. Case Reports in Psychiatry. 2017;2017:2735329.
