History and exam
Key diagnostic factors
common
unconventional behaviour during history
Presentation of patients with somatic symptom disorder may be vague, dramatic, or odd.[63]
emotional processing problems
Typical in both disorders, either due to an inability to be aware of emotions or tendency to suppress and avoid emotions, or due to high neuroticism and emotional reactivity. Evidence suggests links between somatisation and alexithymia (difficulty identifying and describing feelings); somatisation and deficits in affective theory of mind (the ability to know the emotional contents of someone else's mind); and somatisation and neuroticism (lifelong tendencies to experience negative affect and distress).[60][61][62][89]
recent psychological or physical stressors
Acutely stressful life events may precede onset of both disorders and include family/relationship problems and health problems.[32][65] In some patients, symptoms of functional neurological disorder are triggered by physical injury, surgery, or another neurological disorder such as migraine.[31] Note that patients may present without identifiable stressors.[30]
remote life stressors
Typical risk factors for both disorders, and sometimes are precipitating factors. Examples include history of sexual/physical abuse, and history of unstable childhood (witnessing domestic violence, exposure to verbal aggression, family dysfunction).[30][54][55][56][57][58][59] Note that patients may present without identifiable stressors.[30]
multiple illness behaviours
Patients exhibit behaviour in response to feeling unwell that is intended to relieve the illness symptoms and results in focusing attention on the illness (e.g., going to the doctor or accident and emergency department, avoiding perceived environmental triggers for the illness, adjusting lifestyle to anticipate the illness).
unusual neurological deficits
Distribution of motor or sensory deficits that do not conform to any nerve, root, truncal, or central distribution (e.g., sharp demarcation at the shoulder or groin, 'splitting the midline') can suggest functional neurological disorder.
give-way weakness
When testing motor strength, sudden collapse after several seconds of full resistance can suggest functional neurological disorder.
inconsistent examination findings
For example, severe leg weakness on strength testing in patients who are ambulatory; patients claiming to be blind who are able to avoid obstacles when walking. Can suggest functional neurological disorder. Weakness that varies from moment to moment, particularly when spontaneous activity is better than that performed during examination, can suggest functional neurological disorder.
paradoxical sensory findings
Some present as anaesthesia, paraesthesia, blindness, tunnel vision, diplopia, triplopia, olfactory distortions, deafness, midline sensory split, and lateralisation of the tuning fork. Can suggest functional neurological disorder.
distractible symptoms
Symptoms that abate during the examination when attention is drawn elsewhere (e.g., a tremor that stops when the patient is asked to walk or perform a cognitive task) can suggest functional neurological disorder.
generalised seizure-like motor movements without loss of awareness
Features most suggestive of functional seizures include prolonged duration (>5 minutes), eyes tightly closed, tearfulness, hyperventilation, and side-to-side head shaking.[73] Functional seizures can be asynchronous with stop/start quality, and may involve back arching, pelvic thrusting, stuttering, flailing motor movements, and speaking in a whisper or baby voice.[75] There is often an emotional or pain trigger and paradoxical worsening with anticonvulsant medications. Events may be either never witnessed or occur only in the presence of an audience.
gait disorders
Diagnosis of functional gait disorders is challenging as no single walking pattern is pathognomonic, and there is considerable overlap with other causes of gait disorders.[90] Astasia-abasia (paradoxical ability to use the legs normally except when standing or walking), collapsing gait, and non-economical gait can suggest functional neurological disorder. Other suggestive features may include an antalgic, buckling, or waddling gait.[90]
functional movement disorders
Apparent fixed dystonias that have variability in amplitude and frequency of movements; inconsistent movements; variable direction and pattern to the movements; suggestibility; distractibility; suppressibility; and active resistance to passive movement. Tremors and tics are also suggestive of functional neurological disorder.[72]
Other diagnostic factors
common
cognitive complaints
Many patients with somatic symptom or functional neurological disorder also commonly forget whole conversations, unintentionally use the wrong words, forget how to do basic activities or tasks that they should know, lose the ability to multi-task, and experience short-term memory problems.[67][68][69]
Hoover's sign
Involuntary extension of the seemingly weak leg when the unaffected leg is flexing against resistance can suggest functional neurological disorder.
speech disturbance
Aphonia, dysphonia, stuttering, and foreign accent syndrome can suggest functional neurological disorder.[91]
swallowing disturbance
People with functional neurological disorder may have globus pharyngeus or globus sensation (a painless sensation of fullness in the neck or difficulty swallowing).[92]
uncommon
pseudoclonus
Irregular, erratic flexion and extension at the ankle, unlike typical clonus, can suggest functional neurological disorder.
convergence spasm
Intermittent or excessive convergence of the eyes when patients are asked to stare at an object can suggest functional neurological disorder.
Risk factors
strong
history of sexual or physical abuse
adverse childhood events
Childhood traumatisation has been associated with somatic symptom and functional neurological disorders.[30][55][56][57] Witnessing domestic violence can be developmentally deleterious to later mental health stability, and exposure to verbal aggression may even be associated with abnormalities in white matter tract integrity.[58][59] Evidence from one study also suggests that, among functional neurological disorder patients, greater cognitive and somatic dissociative symptoms are associated with maternal (but not paternal) dysfunction.[55]
history of trauma-related disorders
Post-traumatic stress disorder, dissociative disorder, and acute stress disorder are associated with functional neurological disorder and somatic symptom disorder.
female sex
alexithymia
weak
previously poor doctor-patient relationships
Physicians who show lack of empathy or understanding by being overly dismissive, or, on the other hand, contribute to alarm over symptoms by overinterpreting test results or suggesting new symptoms, can perpetuate or increase symptoms.[63]
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