A diagnosis of a<unk><unk> al disorder is dependent on positive features from the history and examination. Positive features of<unk>  weakness on examination include Hoover's sign, when there is weakness of hip extension which normalises with contralateral hip flexion, and thigh abductor sign, weakness of thigh abduction which normalises with contralateral thigh abduction. Signs of<unk>  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<unk>  tremor.<unk>  dystonia usually presents with an inverted ankle posture or clenched fist. Positive features of dissociative or non-epileptic attacks include prolonged motionless unresponsiveness, long duration episodes (>2minutes) and symptoms of dissociation prior to the attack. These signs can be usefully discussed with patients when the diagnosis is being made. Patients with<unk>  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<unk><unk> al 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. FND does not show up on blood tests or structural brain imaging such as MRI or CT scanning. However, this is also the case for many other<unk> al conditions so negative investigations should not be used alone to make the diagnosis. FND can, however, occur alongside other<unk> al diseases and tests may show non-specific abnormalities which cause confusion for doctors and patients. ICD-11 diagnostic criteria The International Classification of Disease (ICD-11) which is due to be finalised in 2017 will have<unk>  disorders within the neurology section for the first time. Differential diagnoses<unk><unk> al symptom disorder can very rarely mimic many other conditions. Some alternative diagnoses for FND that are often considered include: * Hemiplegic migraine * Multiple sclerosis * Parkinson's * Autoimmune disorders * Stroke * Vitamin B12 deficiency or pernicious anaemia * Myasthenia gravis * Mast cell activation syndrome * Histamine intolerance
Functional neurologic disorder
Basal ganglia disease
Postmenopausal confusion
Acquired brain injury
Cancer-related fatigue
Somatosensory disorder
Neurodegenerative disease
Post-encephalitic parkinsonism