Functional neurological symptom disorder

There are a great number of symptoms experienced by those with a functional neurological disorder. While these symptoms are very real, their origin is complex, since it can be associated with severe psychological trauma and idiopathic neurological dysfunction. The core symptoms are those of motor or sensory dysfunction or episodes of altered awareness: • Limb weakness or paralysis • Non-epileptic seizures – these may look like epileptic seizures or faints • Movement disorders including tremors, dystonia (spasms), myoclonus (jerky movements) • Visual symptoms including loss of vision or double vision • Speech symptoms including dysphonia (whispering speech), slurred or stuttering speech • Sensory disturbance, including hemisensory syndrome (altered sensation down one side of the body) • Numbness or inability to sense touch • Dizziness and balance problems • Pain (including chronic migraines) • Extreme slowness and fatigue ==Causes==

A systematic review found that stressful life events and childhood neglect were significantly more common in patients with FNSD than the general population, although some patients report no stressors. Converging evidence from several studies using different techniques and paradigms has now demonstrated distinctive brain activation patterns associated with functional deficits, unlike those seen in actors simulating similar deficits.  The new findings advance current understanding of the mechanisms involved in this disease, and offer the possibility of identifying markers of the condition and patients' prognosis. Recent studies on FND patients using functional magnetic resonance imaging (fMRI) reported differences in resting-state brain connectivity involving sensory, motor, and cognitive control networks. Other fMRI studies found reduced neural activation and coactivation in the anterior insula and dorsal anterior cingulate cortex. These findings expand current knowledge of FND, suggesting abnormalities in brain networks when processing bodily signals, along with trauma, may be linked to FND movement and cognitive symptoms, and dissociative difficulties. FNSD has been reported as a rare occurrence in the period following general anesthesia. ==Diagnosis==

A diagnosis of a functional neurological disorder is dependent on positive features from the history and examination. Positive features of functional weakness on examination include Hoover's sign, when there is weakness of hip extension, which normalizes with contralateral hip flexion. Signs of functional tremor include entrainment and distractibility. The patient with tremor should be asked to copy rhythmical movements with one hand or foot. If the tremor of the other hand entrains to the same rhythm, stops, or if the patient has trouble copying a simple movement, this may indicate a functional tremor. Functional dystonia usually presents with an inverted ankle posture or clenched fist. Positive features of dissociative or non-epileptic seizures include prolonged motionless unresponsiveness, long-duration episodes (>2 minutes), and symptoms of dissociation prior to the attack. These signs can be usefully discussed with patients when the diagnosis is being made. Patients with functional movement disorders and limb weakness may experience symptom onset triggered by an episode of acute pain, a physical injury, or physical trauma. They may also experience symptoms when faced with a psychological stressor, but this isn't the case for most patients. Patients with functional neurological disorders are more likely to have a history of another illness, such as irritable bowel syndrome, chronic pelvic pain, or fibromyalgia, but this cannot be used to make a diagnosis. DSM-5 diagnostic criteria The Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-5) lists the following diagnostic criteria for functional neurological symptom disorder: • One or more symptoms of altered voluntary motor or sensory function. • Clinical findings can provide evidence of incompatibility between the symptom and recognized neurological or medical conditions. • Another medical or mental disorder does not better explain the symptom or deficit. • The symptom or deficit results in clinically significant distress or impairment in social, occupational, or other vital areas of functioning or warrants medical evaluation. The presence of symptoms defines an acute episode of functional neurological symptom disorder lasting less than six months, while a persistent episode includes symptoms for more than six months. FNSD can also have the specifier of with or without the psychological stressor. Associated conditions Epidemiological studies and meta-analysis have shown higher rates of depression and anxiety in patients with FNSD compared to the general population, but rates are similar to those of patients with other neurological disorders, such as epilepsy or Parkinson's disease. This is often the case because of years of misdiagnosis and accusations of malingering. Multiple sclerosis has some overlapping symptoms with FNSD, potentially a source of misdiagnosis. ==Prevalence==

Non-epileptic seizures account for about 1 in 7 referrals to neurologists after an initial episode, while functional weakness has a similar prevalence to multiple sclerosis. ==Treatment==

Treatment requires a firm and transparent diagnosis based on positive features which both health professionals and patients can feel confident about. A multi-disciplinary approach to treating functional neurological disorder is recommended. Treatment options can include: For many patients with FNSD, accessing treatment can be difficult. Availability of expertise is limited, and they may feel that they are being dismissed or told "it's all in your head," especially if psychological input is part of the treatment plan. Some medical professionals are uncomfortable explaining and treating patients with functional symptoms. Changes in diagnostic criteria, increasing evidence, literature on how to make the diagnosis and explain it, and changes in medical training are slowly changing this. Controversy Wessely and White have argued that FNSD may merely be an unexplained somatic symptom disorder. FNSD remains a stigmatized condition in the healthcare setting. ==History==

Functional neurologic disorder, is a more recent and inclusive term for what is sometimes referred to as conversion disorder. There is a growing understanding that symptoms are real and distressing, and are caused by an incorrect functioning of the brain rather than being imagined or feigned. == See also ==