Characterization of functional weakness

January 01, 0001

Characterization of functional weakness

Functional weakness is weakness without any recognizable neurological disease, but typically consistent with the patients health belief model. These Scottish researchers aimed to describe the incidence and characteristics of cases with functional weakness and to compare these with controls with weakness due to neurological disease. Patients were recruited from neurologist in Southeast Scotland. Participants had physical examination, Structured Clinical Interview for the Diagnostic and Statistical Manual of Mental Disorders, Short Form (36) Health Survey, Hospital and Anxiety Depression Scale, and Illness Perception Questionnaire.

The researchers report: "In total, 107 cases (79% female, mean age 39 years, median duration of illness 9 months) were recruited. This number suggests a minimum annual incidence of 3.9/100 000. Forty-six controls (83% female, median age 39 years, duration 11 months) were also recruited. Compared to controls, cases had similar levels of disability but more physical symptoms, especially pain. They had a higher frequency of psychiatric disorders, especially current major depression (32 versus 7%), generalized anxiety disorder (21 versus 2%), panic disorder (36 versus 13%) and somatization disorder (27 versus 0%). There was no difference in median self-rated anxiety and depression scores. Paradoxically, they were less likely than controls to agree that stress was a possible cause of their illness (24 versus 56%). Cases were twice as likely as controls to report that they were not working because of their symptoms (65 versus 33%)."

The authors concluded: "Functional weakness is a commonly encountered clinical problem. Patients with this symptom are as disabled as patients with weakness of similar duration due to neurological disease. There is a paradox between the frequency of depression and anxiety diagnoses and the patient’s willingness to accept these as potentially relevant to their symptoms. We discuss the theoretical and practical implications of these findings for the concept of conversion disorder."

This study points out important aspects of functional weakness, including its resultant disability and its complex links with other psychiatric diagnoses.

For the full abstract, click here.

Brain 133(5):1537-1551, May 2010
© 2010 Stone et al.
The symptom of functional weakness: a controlled study of 107 patients. Jon Stone, Charles Warlow and Michael Sharpe. Correspondence to Jon Stone:

Category: N. Neurological, P. Psychological. Keywords: functional weakness, conversion disorder, disability, depression, anxiety, controlled study, journal watch.
Synopsis edited by Dr Paul Schaefer, Toledo, Ohio. Posted on Global Family Doctor 15 June 2010

Pearls are an independent product of the Cochrane primary care group and are meant for educational use and not to guide clinical care.