Functional weakness
Encyclopedia
Functional weakness is weakness of an arm or leg due to the nervous system not working properly. It is not caused by damage or disease of the nervous system. Patients with functional weakness experience symptoms of limb weakness which can be disabling and frightening such as problems walking or a ‘heaviness’ down one side, dropping things or a feeling that a limb just doesn’t feel normal or ‘part of them’. Functional weakness may also be described as 'dissociative motor disorder' and less helpfully as "conversion disorder
."
To the patient and the doctor it often looks as if there has been a stroke
or have symptoms of multiple sclerosis
. However, unlike these conditions, with functional weakness there is no permanent damage to the nervous system which means that it can get better or even go away completely.
The diagnosis should usually be made by a consultant neurologist
so that other neurological causes can be excluded. The diagnosis should be made on the basis of positive features in the history and the examination (such as Hoover's sign
). It is dangerous to make the diagnosis simply because tests are normal. Neurologists usually diagnose wrongly about 5% of the time (which is the same for many other conditions.)
Many patients with functional weakness suffer from not being believed. Although psychological factors can be important they are not exclusively so and the problem is not 'made up' or 'imagined'. Patients with functional weakness are as disabled and distressed by their symptoms as patients with multiple sclerosis.
Treatment involves understanding and believing the diagnosis and gradually restoring nervous system function with graded exercise, learning how to manage symptoms of fatigue and pain
when present and treatment of associated symptoms of worry or low mood if present. Hypnosis
may also be useful.
Conversion disorder
Conversion disorder is a condition in which patients present with neurological symptoms such as numbness, blindness, paralysis, or fits without a neurological cause. It is thought that these problems arise in response to difficulties in the patient's life, and conversion is considered a psychiatric...
."
To the patient and the doctor it often looks as if there has been a stroke
Stroke
A stroke, previously known medically as a cerebrovascular accident , is the rapidly developing loss of brain function due to disturbance in the blood supply to the brain. This can be due to ischemia caused by blockage , or a hemorrhage...
or have symptoms of multiple sclerosis
Multiple sclerosis
Multiple sclerosis is an inflammatory disease in which the fatty myelin sheaths around the axons of the brain and spinal cord are damaged, leading to demyelination and scarring as well as a broad spectrum of signs and symptoms...
. However, unlike these conditions, with functional weakness there is no permanent damage to the nervous system which means that it can get better or even go away completely.
The diagnosis should usually be made by a consultant neurologist
Neurologist
A neurologist is a physician who specializes in neurology, and is trained to investigate, or diagnose and treat neurological disorders.Neurology is the medical specialty related to the human nervous system. The nervous system encompasses the brain, spinal cord, and peripheral nerves. A specialist...
so that other neurological causes can be excluded. The diagnosis should be made on the basis of positive features in the history and the examination (such as Hoover's sign
Hoover's sign (leg paresis)
Hoover’s sign of leg paresis is one of two signs named for Charles Franklin Hoover.One is a maneuver aimed to separate organic from non-organic paresis of the leg. The sign relies on the principle of synergistic contraction. Involuntary extension of the "paralyzed" leg occurs when flexing the...
). It is dangerous to make the diagnosis simply because tests are normal. Neurologists usually diagnose wrongly about 5% of the time (which is the same for many other conditions.)
Many patients with functional weakness suffer from not being believed. Although psychological factors can be important they are not exclusively so and the problem is not 'made up' or 'imagined'. Patients with functional weakness are as disabled and distressed by their symptoms as patients with multiple sclerosis.
Treatment involves understanding and believing the diagnosis and gradually restoring nervous system function with graded exercise, learning how to manage symptoms of fatigue and pain
Pain
Pain is an unpleasant sensation often caused by intense or damaging stimuli such as stubbing a toe, burning a finger, putting iodine on a cut, and bumping the "funny bone."...
when present and treatment of associated symptoms of worry or low mood if present. Hypnosis
Hypnosis
Hypnosis is "a trance state characterized by extreme suggestibility, relaxation and heightened imagination."It is a mental state or imaginative role-enactment . It is usually induced by a procedure known as a hypnotic induction, which is commonly composed of a long series of preliminary...
may also be useful.