The prognosis of functional limb weakness: a 14-year case-control study

Area of Science:

• Neurology
• Clinical Neuroscience
• Psychosomatic Medicine

Background:

• Prognosis data for functional motor disorder, specifically functional limb weakness, are limited due to small, retrospective, and uncontrolled studies.
• Accurate assessment of misdiagnosis, mortality, and long-term outcomes is crucial for patient care and clinical understanding.

Purpose of the Study:

• To prospectively assess misdiagnosis, mortality, and symptomatic/health outcomes in functional limb weakness over 14 years.
• To compare outcomes of functional limb weakness with neurological disease and healthy controls.
• To explore baseline factors predicting long-term outcomes.

Main Methods:

• A prospectively recruited, controlled cohort design was employed.
• 107 patients with functional limb weakness, 46 with neurological disease, and 38 healthy controls were followed for an average of 14 years.
• Misdiagnosis, mortality, and outcomes (limb weakness, physical/psychiatric symptoms, quality of life) were assessed via consensus meetings, death certificates, and self-rated questionnaires.

Main Results:

• Misdiagnosis was rare (1% in functional limb weakness, 2% in neurological controls).
• Mortality was higher in the functional limb weakness group (11 deaths) and neurological controls (8 deaths) compared to healthy controls (1 death).
• Symptom remission occurred in 20% of functional limb weakness patients, with improvement in a larger proportion compared to neurological controls (P=0.011); outcomes were comparable between patient groups but worse than healthy controls.

Conclusions:

• Functional limb weakness has a low rate of long-term misdiagnosis.
• The disorder is associated with increased mortality and persistent, disabling symptoms, with outcomes similar to neurological conditions.
• Predicting outcome based on baseline variables is challenging, highlighting the need for realistic patient outlooks and targeted therapies.