Functional Neurologic Disorder

Functional Neurologic Disorder – Introduction

• Patients with functional neurologic (conversion) disorder present with symptoms that negatively affect motor, sensory, and/or cognitive abilities. ¹ Symptoms might include paralysis, hyperkinetic movements, seizures, speech difficulties, dizziness, memory trouble, numbness, or blindness, among other symptoms.
• Symptoms can be sustained, intermittent, acute, or chronic. Diagnostic features provide evidence of internal inconsistency or incongruity with other recognized neurologic or medical disorders.
• The symptoms cause clinically significant distress and/or impairment in social, occupational, and other important areas of functioning and warrant medical evaluation.
• There may be a psychologic stressor present, although this is not required to establish the diagnosis based on the Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-5). ² The need to explicitly exclude malingering was also removed in the changes made from the DSM-4 to the DSM-5, a diagnostic consideration that is only relevant for a minority of patients. Functional neurologic symptoms are experienced as involuntary, with the biopsychosocial model as the prevailing conceptual framework for functional neurologic disorder.

Synonyms

• Functional neurologic symptom disorder
• Functional [psychogenic nonepileptic/dissociative] seizures
• Functional movement disorder
• Persistent postural perceptual dizziness
• Functional cognitive disorder
• Conversion disorder

Multiple ICD-10 CM Codes for DSM-5 “Functional Neurological Symptom Disorder” (DSM-5 300.11)
F44.4	Functional neurologic symptom disorder with abnormal movement
F44.4	Functional neurologic symptom disorder with weakness or paralysis
F44.4	Functional neurologic symptom disorder with speech symptoms
F44.4	Functional neurologic symptom disorder with swallowing symptoms
F44.5	Functional neurologic symptom disorder with attacks or seizures
F44.6	Functional neurologic symptom disorder with anesthesia or sensory loss
F44.7	Functional neurologic symptom disorder with mixed symptoms

Note: Although functional neurologic symptom disorder is the term used in the DSM-5, this chapter makes reference to functional neurologic disorder, which is the diagnostic label widely adopted by the international clinical and research communities ( www.FNDsociety.org ) as well as patient advocacy groups. Additionally, while not part of the DSM-5 diagnostic subtypes, many experts in the international FND community recognize persistent postural perceptual dizziness and functional cognitive disorder as additional subtypes of FND. ¹

EPIDEMIOLOGY & DEMOGRAPHICS ³

• •Incidence is estimated at 4 to 12/100,000 in the general population, with functional movement disorders (including functional limb weakness) and functional seizures as the most common presentations.
• •Generally seen in patients between the ages of approximately 15 and 50, although cases in prepubertal individuals and elderly populations have been described.
• •Female predominance, although males are well recognized to also develop functional neurologic disorder, including in veteran/military populations.

PHYSICAL FINDINGS & CLINICAL PRESENTATION ³

• •Presents with one or more motor symptoms (e.g., paralysis, tremor, gait difficulties, dystonia, nonepileptic seizures, stuttering), dizziness, and/or sensory symptoms (e.g., loss of sensation, blindness, deafness). Functional cognitive symptoms are also increasingly being recognized. ⁴ Mixed presentations are common.
• •Sudden onset, with maximal severity developing in a short time frame is a typical presentation; a history of spontaneous symptom resolution may also be reported. ⁵
• •Rule-in physical examination findings are incompatible with structural lesions in anatomic pathways, such as Hoover sign (weakness of hip extension returns to normal strength with contralateral hip flexion against resistance), collapsing/give-way weakness (limb collapses from normal position with only light touch), tremor entrainment (modification of tremor rhythmicity by performance of paced movements performed in a different body part), dragging monoplegic gait, splitting of midline sensory deficits, or tubular vision, among others. Asynchronous side-to-side head and truncal movements, forced eye closure at seizure onset, and lack of postictal confusion following a full body convulsion are semiologic features indicative of functional seizures. See Table E1 for a detailed list of positive rule-in signs across the complete transdiagnostic motor spectrum of functional neurologic disorder. ⁵
• •Diagnostic criteria for persistent postural perceptual dizziness and functional cognitive disorder have also been recently operationalized. ¹
• •Misdiagnosis rates are generally low, with cross-sectional diagnoses remaining generally stable over time. ⁶ Caution should be taken, however, not to frame bizarre neurologic presentations as “functional” simply because the clinician has not encountered similar cases previously.
• •Drawing attention to the body frequently worsens symptoms, whereas distraction may temporarily improve or resolve functional neurologic symptoms. ⁵
• •In addition to core functional neurologic symptoms, other commonly endorsed physical complaints include pain, fatigue, gastrointestinal, and genitourinary concerns. ⁷
• •May occur in the setting of comorbid medical illness (e.g., a patient with both epileptic and nonepileptic seizures; functional motor symptoms in individuals with Parkinson disease). ³
• •Psychiatric comorbidities are common, including major depression, generalized anxiety, panic disorder, posttraumatic stress disorder (PTSD), dissociative disorders, and/or personality disorders (e.g., borderline, histrionic, narcissistic, or obsessive-compulsive). ⁵

TABLE E1

Examples of Positive “Rule-in” Signs Across the Motor Spectrum of Functional Neurologic Disorder

Adapted from Perez DL et al: A review and expert opinion on the neuropsychiatric assessment of motor functional neurological disorders, J Neuropsychiatry Clin Neurosci 2021. doi: 10.1176/appi.neuropsych.19120357 ; and Baslet G et al: Evidence-based practice for the clinical assessment of psychogenic nonepileptic seizures: a report from the American Neuropsychiatric Association Committee on Research, J Neuropsychiatry Clin Neurosci 33(1):27-42, 2021.

GENERAL SIGNS Distractibility Variability Suggestibility TREMOR Variability Distractibility Entrainment Spread of tremor to another body part if the tremor is restrained JERKS Predominantly axial Distractibility Variability PARKINSONISM Excessive slowness without loss of amplitude Increased tone without cogwheel rigidity Concurrent functional tremor DYSTONIA Fixed posture (e.g., fixed ankle inversion) Lack of sensory trick/geste antagonist

WEAKNESS Hoover sign/hip abductor sign Give-way/collapsing/global pattern of weakness Arm drift without pronation Spinal injury center sign SEIZURES Asynchronous movements Side-to-side head or truncal movements Forced eye closure Ictal crying Memory recall in the context of a full-body convulsion GAIT Dragging monoplegic gait Knee-buckling Noneconomic posture TICS No voluntary suppression No or atypical premonitory urge Movements not stereotypical

ETIOLOGY & MECHANISMS

• •Complex interplay of neurologic and psychiatric factors, within the biopsychosocial model delineating predisposing vulnerabilities, acute precipitants, and perpetuating factors, is the prevailing framework for understanding the etiology of functional neurologic disorder.
• •The classic psychodynamic (Freudian) hypothesis is that the functional neurologic symptom is preceded by a psychologic conflict or stressor and functions to express and manage the psychologic distress—that is, “convert” it into a neurologic symptom. This model, though relevant for some, has been challenged because it ascribes a very specific mechanism to a likely etiologically and mechanistically heterogenous group of patients.
• •Associated with trauma (including childhood maltreatment), interpersonal conflicts, and other life stressors in many, although not all, patients. A stress-diathesis framework is a helpful approach through which to contextualize relationships between biologic and environmental (psychosocial) risk factors for functional neurologic disorder. ⁸
• •Emerging neurobiologic models for functional neurologic disorder emphasize that disturbances in self-agency, emotion processing, attention, interoception, and predictive processing/perceptual inference are important constructs in the pathophysiology of functional neurologic disorder. These constructs relate to disturbances in several brain networks. ⁹
• •Given the high frequency of psychiatric comorbidities in patients with functional neurologic disorder, there are likely elements of shared pathophysiology between affective disorders, trauma-related disorders, and functional neurologic disorder.
• •In addition to categorical psychiatric diagnoses, dimensional psychopathologic traits may be relevant in patients with functional neurologic disorder (e.g., alexithymia, dissociation, escape-avoidance coping, etc.). ⁵
• •Preexisting neurologic conditions can be present, such as intellectual disability.
• •A physical injury may be reported before symptom onset; ^1 , 3 symptom onset may also develop after general anesthesia or a medical/surgical procedure.
• •Family history of medical/neurologic and/or psychiatric illness is common. ⁵

Diagnosis

Diagnosis is specific to symptom type: ²

• •Functional (psychogenic nonepileptic/dissociative) seizures
• •Weakness or paralysis
• •Abnormal movement (tremor, dystonia, myoclonus/jerks, gait disorder)
• •Swallowing symptom
• •Speech or voice symptom (e.g., stuttering, foreign accent syndrome)
• •Persistent postural perceptual dizziness
• •Anesthesia or sensory loss
• •Special sensory symptom (e.g., visual, olfactory, auditory)
• •Functional cognitive
• •Mixed symptoms

Note: Though not included in the DSM-5, persistent postural perceptual dizziness and functional cognitive disorder are increasingly being recognized as variants of functional neurologic disorder. ⁴ Additionally, many patients present with mixed symptoms, whereas others initially exhibiting one discrete phenotype can go on to develop distinct functional neurologic symptoms over the natural course of their illness. As such, a transdiagnostic approach across the full sensorimotor spectrum of functional neurologic disorder should be emphasized.

DIFFERENTIAL DIAGNOSIS

A broad neuropsychiatric differential diagnosis should be considered, depending on presenting signs and symptoms, including movement disorders, seizure, stroke, spinal disorders, malignancy, vasculitis, infectious disease, autoimmune disorders, vitamin B ₁₂ deficiency, migraine, dystonia, limbic encephalopathy, stiff person syndrome, somatic symptom disorder, factitious disorder, and malingering. ¹⁰ Importantly, although the clinical history may raise the index of suspicion for a functional neurologic disorder, the clinical history itself is nonspecific. To confirm the diagnosis, emphasis should be given to neurologic examination findings and semiologic features, while remaining vigilant to appropriately evaluate for comorbid medical/neurologic/psychiatric conditions. ⁵

LABORATORY TESTS

Although physical examination is the gold standard for the majority of functional neurologic disorder presentations, a diagnosis of “documented” functional seizures can be confirmed by capturing a typical event on video electroencephalography. Additionally, electromyography may be a helpful adjunctive diagnostic test in difficult to diagnose cases of functional movement disorder. Other laboratory tests should be considered as clinically indicated to evaluate for possible comorbid neurologic conditions (e.g., nerve conduction studies with electromyography to evaluate for a cervical radiculopathy as a cause of pain-limited arm weakness). ⁵

TREATMENT

• •Education on the diagnosis is the first step in treatment. ¹¹ Guidelines for presenting a diagnosis of functional neurologic disorder and developing a patient-centered treatment plan are summarized in Table E2 . Neurosymptoms.org is a particularly helpful and widely used patient education resource.
• •Following the delivery of the diagnosis, it is important to consider the patient’s level of receptiveness to/acceptance of the diagnosis before more concretely considering other aspects of treatment.
• •Cognitive behavioral therapy is often used, although more research is needed to consider how to best pair a given patient to the most efficacious psychotherapy modality for their particular case. ¹²
• •A long tradition of psychodynamic therapy exists, although randomized controlled trials are needed to better understand the efficacy of this treatment modality. ¹²
• •Physical and occupational therapy are key in reestablishing normal motor function. Consensus recommendations for physical therapy and occupational therapy have been published this decade. ^13 , 14
• •Speech and language therapy is similarly key in the management of the communication, swallowing, cough, and upper airway symptoms of functional neurologic disorder, and consensus recommendations have recently been established. ¹⁵
• •Psychopharmacologic treatments do not treat functional neurologic symptoms themselves but can be helpful in addressing predisposing or perpetuating psychiatric comorbidities. ¹

TABLE E2

Recommendations for Presenting a Diagnosis of Functional Neurologic Disorder and Developing a Treatment Plan

Adapted from Stern TA et al: Massachusetts General Hospital handbook of general hospital psychiatry, ed 7, Philadelphia, 2018, Elsevier; and McKee K et al: The inpatient assessment and management of motor functional neurological disorders: an interdisciplinary perspective, Psychosomatics 358-368, 2018.

Presentation of the Diagnosis

Treatment Planning

1.Name the condition (e.g., functional neurologic disorder). Emphasize that this is a rule-in diagnosis based on physical exam findings.2.State clearly that this condition is common, real, brain-based, and treatable.3.Address that you do not believe the patient is “making up” their symptoms.4.Explain that symptoms are likely due to a problem with the function of the nervous system, rather than structural abnormalities. Consider using a brief explanatory model such as this being a “software” and “not a hardware” problem. Mind-body overload may be another useful explanatory model.5.Acknowledge the disability that symptoms have caused and the importance of developing a treatment plan that will improve the function of the nervous system and reduce disability.6.In those with prominent mental health comorbidities, introduce the idea that negative mood can significantly impact the frequency and severity of functional neurologic symptoms; their concurrent treatment is important in the patient’s recovery.7.Describe a treatment plan that includes integrated, multidisciplinary treatment from providers in psychiatry, neurology, and rehabilitation medicine specialties.

1.Develop an interdisciplinary and multidisciplinary team, generally comprised of mental health professionals, a neurologist, and rehabilitation specialists.2.Consider a psychotherapy referral, particularly cognitive behavioral therapy.3.Consider referrals to physical therapy, occupational therapy, and/or speech and language therapy based on phenotype.4.Psychotropic medications should be used to treat comorbid psychiatric symptoms (e.g., major depression).5.Triage and provide a treatment plan for other distressing bodily symptoms, such as referring a patient with chronic pain to an interdisciplinary chronic pain program where available.6.Safely and gradually taper medications that are no longer indicated to avoid unnecessary side effects (e.g., antiepileptic drugs in the case of isolated functional seizures).7.The development of new neurologic symptoms is common, and should be triaged with follow-up neurologic examinations.8.Ensure that other clinicians involved in the patient’s care and family members/caregivers are informed of the functional neurologic disorder diagnosis and supportive of the treatment plan.

GENERAL Rx

• •Antidepressants may be helpful for managing underlying mood, anxiety, and/or trauma-related disorders. ¹
• •Outpatient multidisciplinary treatment is the prevailing treatment model, but inpatient rehabilitation or inpatient psychiatric treatment may be required depending on acuity, comorbidities, and level of impairment. ¹

PEARLS & CONSIDERATIONS

COMMENTS

• •Potential positive prognostic factors: Short duration between diagnosis and treatment, and absence of other severe psychiatric or medical comorbidities. Potential poor prognostic factors: comorbid chronic pain disorders, severe disability, long duration of symptoms, and individuals on or pursuing medical disability. Some studies show a correlation between the severity of previously experienced childhood maltreatment and functional neurologic symptom severity, although investigations into the intersection of etiologic factors and disease mechanisms remain in their early stages. ( Table E3 ).
• •A strong therapeutic alliance and education about illness are essential treatment components.

TABLE E3

Biopsychosocial Factors in Patients with Functional Neurologic Disorder

From Jankovic J et al: Bradley and Daroff’s neurology in clinical practice, ed 8, Philadelphia, 2022, Elsevier.

Factors	Biologic	Psychologic	Social
Factors acting at all stages	Recognized structural/metabolic disease History of previous functional symptoms	Mood, anxiety, and trauma-related psychiatric disorders Personality disorder	Socioeconomic deprivation Life events and difficulties
Predisposing vulnerabilities	Female sex Chronic pain, fatigue, and functional somatic disorders	Perception of childhood experience as adverse Personality traits Alexithymia Poor attachment/coping style	Childhood neglect/abuse Poor family functioning Symptom modeling (via media or personal contact)
Acute precipitants	Abnormal physiologic event or state (e.g., hyperventilation) Physical injury/pain Preceding illness	Perception of life event as negative, unexpected Acute dissociative episode/panic attack	Interpersonal stressors Employment related stressors
Perpetuating factors	Plasticity in central nervous system motor and sensory (including pain) pathways Deconditioning Neuroendocrine and immunologic abnormalities similar to those seen in depression and anxiety	Illness beliefs (patient and family) Perception of symptoms as being due to disease/damage/outside the scope of self-help Not feeling believed Avoidance of symptom provocation	Poor communication amongst health care providers Social benefits of being ill Availability of legal compensation Stigma of “mental illness” in society and from medical profession Ongoing medical investigations and diagnostic uncertainty

References

1.Hallett , et al.: Functional neurological disorder: new subtypes and shared mechanisms . Lancet Neurol 2022; 21 (6): pp. 537-550.

2.American Psychiatric Association: Diagnostic and statistical manual of mental disorders , ed 5, Wasthington, DC, 2013, American Psychiatric Association.

3.Aybek , et al.: Diagnosis and management of functional neurological disorder . BMJ 2022; 376: pp. 1-19.

4.Ball H.A., et al.: Functional cognitive disorder: dementia’s blind spot . Brain 2020; 143 (10): pp. 2895-2903.

5.Perez D.L., et al.: A review and expert opinion on the neuropsychiatric assessment of motor functional neurological disorders . J Neuropsychiatry Clin Neurosci 2021;

6.Stone J et al: Systematic review of misdiagnosis of conversion symptoms and “hysteria,” BMJ 331(7523):989, 2005.

7.Butler M., et al.: International online survey of 1048 individuals with functional neurological disorder . Eur J Neurol 2021; 28 (11): pp. 3591-3602.

8.Keynejad R.C., et al.: Stress and functional neurological disorders: mechanistic insights . J Neurol Neurosurg Psychiatry 2019; 90 (7): pp. 813-821.

9.Drane D.L., et al.: A framework for understanding the pathophysiology of functional neurological disorder . CNS Spectr 2020; 1-29:

10.Stone J., et al.: Functional symptoms in neurology: mimics and chameleons . Pract Neurol 2013; 13 (2): pp. 104-113.

11.Carson A., et al.: Explaining functional disorders in the neurology clinic: a photo story . Pract Neurol 2016; 16 (1): pp. 56-61.

12.Gutkin M., et al.: Systematic review of psychotherapy for adults with functional neurological disorder . J Neurol Neurosurg Psychiatry 2020; 92: pp. 36-44.

13.Nielsen G., et al.: Physiotherapy for functional motor disorders: a consensus recommendation . J Neurol Neurosurg Psychiatry 2015; 86 (10): pp. 1113-1119.

14.Nicholson C., et al.: Occupational therapy consensus recommendations for functional neurological disorder . J Neurol Neurosurg Psychiatry 2020; 91 (10): pp. 1037-1045.

15.Baker J., et al.: Management of functional communication, swallowing, cough and related disorders: consensus recommendations for speech and language therapy . J Neurol Neurosurg Psychiatry 2021; 92: pp. 1112-1125.