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Prognosis of Functional Limb Weakness
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- The authors present the findings from the largest and longest follow-up study of patients with functional limb weakness. They followed 107 patients with functional limb weakness and compared outcomes with those of 46 other neurological patients and 38 healthy controls, with a mean follow up of 14 years. In the patients with functional limb weakness, the weakness completely resolved in 20%, improved in 31%, and remained the same or worsened in 49%. Misdiagnosis was very rare: In only 1 patient was it felt that the diagnosis of functional limb weakness was incorrect and that the limb weakness was in reality attributable to multiple sclerosis. A total of 6 patients with functional limb weakness went on to develop an additional neurological disorder: 3 with ischemic stroke, which was most likely unrelated, and 3 with neurodegenerative disease, which may be, in a sense, related. This phenomenon of functional disorders seen during the prodromal phase of neurodegenerative disease has been previously described in Parkinson’s disease; in this study, 3 of these patients had Huntington's disease, Parkinson’s disease, and idiopathic cerebellar degeneration.
- This study, following a large group of patients over a significant amount of time, suggests greater treatment for this patient population, given the very significant number of patients who will continue to suffer symptoms chronically, as well as the possibility that neurodegenerative prodromes may be identified.
– Sarah Matteson Kranick, MD
abstract
This abstract is available on the publisher's site.
Access this abstract nowReliable data on the prognosis of functional motor disorder are scarce, as existing studies of the prognosis of functional motor disorder are nearly all retrospective, small and uncontrolled. In this study we used a prospectively recruited, controlled cohort design to assess misdiagnosis, mortality and symptomatic and health outcome in patients with functional limb weakness compared to neurological disease and healthy control subjects. We also carried out an exploratory analysis for baseline factors predicting outcome. One hundred and seven patients with functional limb weakness, 46 neurological and 38 healthy control subjects from our previously studied prospective cohort were traced for follow-up after an average of 14 years. Misdiagnosis was determined in a consensus meeting using information from records, patients and their GPs. Numbers and causes of death were collected via death certificates. Outcome of limb weakness, physical and psychiatric symptoms, disability/quality of life and illness perception were recorded with self-rated questionnaires. Outcome measures were compared within and between groups. Seventy-six patients (71%) with functional limb weakness, 31 (67%) neurological and 23 (61%) healthy controls were included in follow-up. Misdiagnosis was found in one patient in the functional limb weakness group (1%) and in one neurological control (2%). Eleven patients with functional limb weakness, eight neurological control subjects and one healthy control subject had died. Weakness had completely remitted in 20% of patients in the functional limb weakness group and in 18% of the neurological controls (P = 0.785) and improved in a larger proportion of functional limb weakness patients (P = 0.011). Outcomes were comparable between patient groups, and worse than the healthy control group. No baseline factors were independent predictors of outcome, although somatization disorder, general health, pain and total symptoms at baseline were univariably correlated to outcome. This study is the largest and longest follow-up study of functional limb weakness. Misdiagnosis in functional limb weakness is rare after long-term follow-up. The disorder is associated with a higher mortality rate than expected, and symptoms are persistent and disabling. It appears difficult to predict outcome based on common baseline variables. These data should help inform clinicians to provide a more realistic outlook of the outcome and emphasize the importance of active and targeted therapy.
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The Prognosis of Functional Limb Weakness: A 14-Year Case–Control Study
Brain 2019 Jun 05;[EPub Ahead of Print], JM Gelauff, A Carson, L Ludwig, MAJ Tijssen, J StoneFrom MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.
Functional neurological disorder (FND) is among the most common conditions encountered by neurologists,1 yet, until recently, it has been largely neglected by physicians and scientists alike. In the article by Gelauff and colleagues published in the recent issue of Brain, the authors report on the largest prospective case–control outcome study conducted in patients with functional limb weakness to date. With an average follow-up period of 14 years, several important observations were made: 1) misdiagnosis rates were low in the FND cohort (only 1 in 89 patients) and comparable (if not lower) to misdiagnosis rates in those with other neurological disorders; 2) 1 in 5 patients with functional limb weakness completely remitted, whereas 49% were the same or worse at follow-up; 3) 48% of individuals with functional limb weakness had not received treatment; 4) baseline factors associated with a poor prognosis included pain and a comorbid somatization disorder; and 5) factors traditionally linked to poor prognosis in FND, including medical disability, work status, and illness perceptions, did not correlate with outcome.
The findings of this article are noteworthy, in particular because of the added confidence and encouragement provided for neurologists to diagnose FND based on “rule-in” signs on physical examination such as collapsing/give-way weakness or a Hoover sign.2 Given that FND is common, chronic in many, and access to evidence-based treatments is limited, a striking unmet public health need remains that necessitates increased clinical and research engagement across the neurosciences.3 The next generation of neurologists and allied clinicians (psychiatrists, psychologists, physical and occupational therapists, etc) requires specific training in the assessment and management of FND.4 A caveat to the findings of this article is that the landscape of evidence-based treatments in FND is rapidly evolving, and it remains an unanswered question what baseline factors influence response across the motor rehabilitation and psychological components of treatment.5 Lastly, this study highlights that the intersection of functional motor symptoms, pain, and somatization disorder are clinically relevant and warrant attention in treatment planning and research.
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