Tuesday, January 10, 2017

Diagnosing functional hyperkinetic movement disorders

van der Salm SM, van Rootselaar AF, Cath DC, de Haan RJ, Koelman JH, Tijssen MA. Clinical decision-making in functional and hyperkinetic movement disorders. Neurology. 2016 Dec 2. pii: 10.1212/WNL.0000000000003479. [Epub ahead of print]

Functional or psychogenic movement disorders (FMD) present a diagnostic challenge. To diagnose FMD, clinicians must have experience with signs typical of FMD and distinguishing features from other hyperkinetic disorders. The aim of this study was to clarify the decision-making process of expert clinicians while diagnosing FMD, myoclonus, and tics.
Thirty-nine movement disorders experts rated 60 patients using a standardized web-based survey resembling clinical practice. It provided 5 steps of incremental information: (1) visual first impression of the patient, (2) medical history, (3) neurologic examination on video, (4) the Bereitschaftspotential (BP), and (5) psychiatric evaluation. After full evaluation of each case, experts were asked which diagnostic step was decisive. In addition, interim switches in diagnosis after each informational step were calculated.
After full evaluation, the experts annotated the first impression of the patients as decisive in 18.5% of cases. Medical history was considered decisive in 33.3% of cases. Neurologic examination was considered decisive in 39.7%, the BP in 8%, and the psychiatric interview in 0.5% of cases. Most diagnostic switches occurred after addition of the medical history (34.5%). Addition of the neurologic examination led to 13.8% of diagnostic switches. The BP results led to diagnostic switches in 7.2% of cases. Psychiatric evaluation resulted in the lowest number of diagnostic switches (2.7% of cases).
Experts predominantly rely on clinical assessment to diagnose FMD. Importantly, ancillary tests do not determine the final diagnosis of this expert panel. In general, the experts infrequently changed their differential diagnosis.

“In general, the experts infrequently changed their differential diagnosis,” said Marina AJ Tijssen, MD, PhD, a neurologist at the University of Groningen and her colleagues. “Importantly, ancillary tests did not determine the final diagnosis of this expert panel.

”Patients with functional movement disorders report a range of involuntary movements — usually tremor, jerking movements, abnormal gait, and imbalance problems. Many neurologists believe that the symptoms are commonly feigned.

“Establishing a diagnosis in clinical practice can be difficult, but it has been shown in many studies that late diagnosis due to diagnostic delay in functional movement disorders (FMD) and other functional neurological symptoms results in a worse prognosis for full recovery,” Dr. Tijssen told Neurology Today. “Therefore, every clinician can learn from the diagnostic process of this expert panel, and this may help to establish the diagnosis of FMD sooner.”

“As can be gathered from our findings, even in very experienced hands, the diagnosis is challenging, and opinions can vary,” Dr. Tijssen said…

The study authors noted that one limitation of the study is the lack of information on the neurologist's motives for their responses. “It could be that the non-switching was a result of a lack of added value of the next step information as judged by the experts, or the consequence of the fact that current diagnosis was strengthened by the added information. Future studies should therefore investigate this aspect in the decision-making process as well.”

“Because the inter-rater agreement was moderate and opinions of the expert panel differed, we think that the honest answer is that there can be no ‘right’ diagnosis in some of the challenging cases of our cohort,” said Dr. Tijssen…

“The diagnosis of FMD cannot be made by any imaging or neurophysiologic tests, although they may provide supportive information,” he said. “The diagnosis relies on careful history and examination by an experienced movement disorders specialist, who often suspects the diagnosis immediately at the initial encounter.”

He added: “One issue that might contribute to the results in both studies is the fact that it was not based on an in-person examination but a web-based survey. The inability to personally interview and examine the patients may have influenced the results of both studies.”

“The take-home message for general neurologists is to initially refer patients with suspected FMD to a reputable movement disorder center rather than to a psychiatrist. Although psychiatrists can be helpful in unraveling some of the psychodynamic factors and helping the patient understand the role of stress in causation or exacerbation of the FMD, they should not be called up to make the diagnosis. This is the responsibility of a movement disorder specialist.”

Dr. Jankovic pointed out that although the Diagnostic and Statistical Manual-5 (DSM-5) no longer requires identifiable psychological etiology as a prerequisite for the diagnosis of FMD, nearly all patients with FMD have some underlying psychological issues, even though this may or may not be easy to uncover, particularly during the initial visit, and sometime additional visits are needed to better understand possible underlying mechanisms.

“I often see patients who initially deny any stressors as precipitants of their FMD, but later I find important conflicts or other stress factors that were likely relevant as triggers of the FMD,” Dr. Jankovic said…

Thomas Swift, MD, FAAN, professor emeritus of neurology at Medical College of Georgia in Augusta, said that “neurologists make a lot of instantaneous judgments.” He said that he is often right on his first impressions, although he admits that he once diagnosed functional movement disorder when the patient actually had Creutzfeldt-Jakob disease.

Dr. Swift said that it is not difficult to recognize symptoms of an organic movement disorder. He cited the case of a patient who was referred to him with complaints of numbness, and who had been in a wheelchair for a decade. He got her to stand up, then walk and finally run, but she got right back in her wheelchair at the end of the exam. “Telling her the weakness was not real did no good,” he said.


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