Functional Neurologic Disorder (FND)

https://www.ncbi.nlm.nih.gov/books/NBK551567

Definition: Functional neurologic disorder (FND), formerly known as conversion disorder, involves sensory or motor symptoms that are inconsistent with recognized neurological diseases or medical conditions and significantly impair patient functioning. Symptoms are involuntary and not intentionally produced.

Etiology:

• Psychological factors: Trauma, acute or chronic stress, childhood abuse, poor coping skills, internal conflicts, and coexisting psychiatric disorders (e.g., depression, anxiety) may contribute.
• Social/Biological factors: Lower socioeconomic status, lower education levels, physical injuries, or existing neurological illness (e.g., stroke, migraine) can act as triggers.
• Model Hypotheses:
  • Psychodynamic models: Suggest symptoms reflect repressed emotional conflicts or inadequate coping mechanisms developed earlier in life.
  • Cognitive-behavioral models: Propose that symptom formation can stem from excessive worry or activation of representations in memory, leading to genuine physical symptoms.

Epidemiology:

• Prevalence: FND is the second most common reason for neurology consultations.
• Australian Context: Represents 15-20% of neurology outpatient presentations.
• Gender Disparity: FND is more common in women, particularly between the ages of 35 and 50 years.
• Misdiagnosis Rate: The condition has a low misdiagnosis rate of approximately 5%.
• Coexisting Conditions: FND can co-occur with established neurological conditions like Parkinson’s disease or multiple sclerosis, a phenomenon termed “overlay.”
• Terminology: Historical terms like ‘conversion disorder’ are replaced with ‘functional neurological symptom disorder’ (DSM–5-TR).

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Aetiology

• Nervous System Dysfunction:
  • FND is considered a “functional” problem in brain signaling rather than a structural brain disorder.
  • Patients may be informed that their symptoms arise from incorrect messages being sent or processed by the brain, akin to a software issue in a computer (as opposed to a hardware issue).
• Neuroimaging Evidence:
  • Emerging studies indicate structural alterations in areas like the sensorimotor cortex, prefrontal regions, thalamus, and limbic system, but the clinical significance remains under investigation.
• Biopsychosocial Model:
  • Predisposing Factors:
    • Prior illness
    • adverse life experiences
    • trauma
    • psychological stressors
  • Precipitating Factors:
    • Onset of symptoms may follow :
      • acute stress
      • injury
      • illness
      • emotional trauma.
  • Perpetuating Factors:
    • maladaptive beliefs about illness
    • deconditioning
    • avoidance behaviours
    • continued stressors

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Differential Diagnosis:

Psychiatric Disorders:

• Illness Anxiety Disorder:
  • Preoccupation with disease despite minimal symptoms.
• Another Mental Disorder
  • Explanation: If the presenting symptoms are better explained by another mental disorder, that diagnosis should be prioritized.
  • Co-Existence: Conversion disorder may still be diagnosed if it is present alongside another mental disorder.
• Somatic Symptom Disorder (SSD)
  • Compatibility with Pathophysiology: Unlike conversion disorder, most symptoms in SSD (e.g., pain, fatigue) do not require evidence of incompatibility with pathophysiology.
  • Psychological Features: SSD involves excessive thoughts, feelings, and behaviors about symptoms, which are often absent in conversion disorder.
• Factitious Disorder and Malingering
  • Intentional Symptom Production: Conversion disorder does not require judgment about conscious intent, as assessing intent can be unreliable.
  • Definite Feigning: If there is clear evidence of symptom feigning (e.g., functional capacity inconsistently present at home vs. during examination), diagnoses of factitious disorder (aim: assuming a sick role) or malingering (aim: external incentives) may be considered.
• Dissociative Disorders
  • Symptom Overlap: Dissociative symptoms are common in conversion disorder; both conditions can be diagnosed concurrently if present.
• Body Dysmorphic Disorder (BDD)
  • Focus of Symptoms: BDD involves preoccupation with perceived physical defects rather than sensory or motor dysfunction, distinguishing it from conversion disorder.
• Depressive Disorders
  • Symptom Differentiation: Depressive disorders often present with general heaviness in limbs, whereas conversion disorder typically shows more focal weakness. Core depressive symptoms (e.g., persistent low mood) further differentiate depressive disorders.
• Panic Disorder
  • Transient Neurological Symptoms: Panic disorder can cause episodic neurological symptoms like tremors and paresthesias, but these are transient and typically linked to cardiorespiratory symptoms during panic attacks.
  • Non-Epileptic Attacks: Loss of awareness with amnesia and violent limb movements during attacks may suggest conversion disorder but not panic disorder

Neurological Disorders:

• Multiple Sclerosis: Presents with central nervous system dysfunction. Diagnosis via MRI and clinical findings.
• Epilepsy: Differentiated from PNES with EEG findings and serum prolactin levels.
• Myasthenia Gravis: Neuromuscular transmission disorder, diagnosed with serologic and electrodiagnostic testing.
• Stroke and Spinal Disorders: Characterized by specific neurological deficits and anatomical patterns.
• Movement Disorders: Differentiated from functional movement disorders through careful observation and physical examination.

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Symptoms

Sensorimotor Symptoms: These may include:

• Weakness
• abnormal movement patterns:
  • tremor
  • myoclonus (sudden, brief, involuntary jerks)
  • dystonia (abnormal muscle tone)
  • gait disturbances
• Sensory Changes:
  • Numbness
  • paresthesias
  • visual disturbances.

Speech and Swallowing Dysfunction:

• Dysarthria: Slurred speech.
• Dysphasia: Difficulty with language expression or comprehension.
• Dysphonia: Voice abnormalities.
• Globus Sensation: Feeling of a lump in the throat
• Mutism

Cognitive Disturbances:

• Fatigue: Persistent tiredness not explained by any physical disease.
• slowed processing speed
• Brain fog
• impaired concentration
• reduced memory

Dissociative Attacks/Psychogenic Non-Epileptic Seizures (PNES)

• Excessive Movements: Limb, trunk, and head movements resembling tonic-clonic seizures.
• Hyperventilation and generalized limb shaking.
• Lack of postictal confusion

Dissociative Symptoms: Loss of Responsiveness

• Depersonalisation: Disconnection from one’s own body or thoughts.
• Derealisation: Feeling detached from the environment.

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Signs

1. Psychogenic Non-Epileptic Seizures (PNES)
   • Convulsions with closed eyes or resistance to eye opening.
   • Hyperventilation
   • generalized limb shaking
   • Lack of postictal confusion
   • No EEG changes during episodes, differentiating from epileptic seizures.
2. Paralysis or Weakness
   • Affects one side of the body or specific limbs without anatomical distribution.
   • Hoover’s Sign: Absence of hip extension when the opposite leg is lifted.
   • Co-Contraction Sign: Contraction of opposing muscles during movements.
   • Collapsing Weakness: Sudden collapse of a limb under light pressure.
3. Abnormal Movements
   • Tremor Entrainment Test:
     • When an individual is asked to perform a rhythmical movement with their unaffected hand, the functional tremor may:
       • Match the rhythm (“entrain”) of the unaffected hand’s movements.
       • Change or Suppress: The tremor may alter or even stop completely during this task, suggesting a functional rather than an organic cause.
       • Lack of Consistent Rhythm: Functional tremors often do not maintain a simple or predictable rhythm, unlike most organic tremor
   • Gait Disorders: Non-typical patterns such as sudden knee-buckling or “walking on ice.”
   • Dystonia:
     • Inconsistent movements with severe pain, sometimes resolving after placebo or suggestion.
   • Myoclonus: Irregular and variable jerking.
4. Sensory Loss
   • Non-anatomical sensory distribution, e.g., hemisensory loss.
   • Midline Tuning Fork Test: Used to detect inconsistencies in sensory loss.
5. Special Sensory Symptoms
   • Visual Disturbances: Reports of severe monocular or binocular vision issues, often with intact pupillary reflex and preserved optokinetic nystagmus.
   • Hearing and Olfactory Loss: Often with preserved taste or startle reflex responses.

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History and Physical Examination for Functional Neurologic Disorder (FND)

History Taking:

• Patient Comfort & Trust Building: Ensure the patient feels at ease, facilitating open discussion of their symptoms. Building rapport is essential.
• Symptom Documentation: Ask the patient to list all current and past symptoms, allowing for tracking of changes over time. Focus on any somatic complaints they have received treatment for or prior suspected neurologic diagnoses.
• Comprehensive Timeline: Document the onset, duration, and any context or life stressors related to the symptoms.
• Psychiatric and Family History: Include psychiatric conditions, childhood trauma, or emotional stressors. Document any past similar symptoms, diagnoses, or interventions and their outcomes.
• Patient Perspective: Invite patients to share their perceptions about their symptoms, previous medical evaluations, and their expectations from the clinician.

Physical Examination:

• Approach: The diagnosis of FND is not purely one of exclusion but relies on identifying positive clinical findings, inconsistency, and incompatibility of symptoms with organic disease patterns.
• Inconsistencies and Findings:
  • Negative Labs/Imaging: No organic findings on laboratory or imaging tests.
  • Comorbid Psychiatric Disorders: Presence may increase suspicion of FND.

Diagnostic Features According to DSM-5TR:

One or More Symptoms: Altered voluntary motor or sensory function. Incompatibility: Evidence of inconsistency with known medical or neurological conditions. Exclusion: Symptoms not better explained by another disorder. Significant Impact: Symptoms cause distress or impair function Symptom Type Specifiers Specify symptom type: – With weakness or paralysis – With abnormal movement (e.g. – tremor, dystonic movement, myoclonus, gait disorder) – With swallowing symptoms – With speech symptom (e.g. – aphasia, dysphonia, slurred speech) – With seizure attacks or seizures – With anesthesia or sensory loss – With special sensory symptom (e.g. – visual, olfactory, or hearing disturbance such as tinnitus) – With mixed symptoms Episode and Stressor Specifier Specify if: – Acute episode: Symptoms present for less than 6 months. – Persistent: Symptoms occurring for 6 months or more. Specify if: – With psychological stressor (specify stressor) – Without psychological stressor note: that pain is not a part of the diagnostic criteria for conversion disorder

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Diagnosis:

• diagnosis of functional neurological disorder is made through identification of positive symptoms (e.g. – symptoms resolve with distractibility) rather than as a diagnosis of exclusion.
• when an individual is distracted, there is usually a reduction or even disappearance of the movement disorder

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Treatment / Management:

• Build Therapeutic Alliance:
  • Avoid revealing the diagnosis too early
  • instead, foster open discussions and validate the patient’s experiences.
• Patient-Centered Education and Communication:
  • Emphasize that symptoms are real and impactful, and explain the absence of structural damage and the reversibility potential.
  • Compare to conditions influenced by stress (e.g., irritable bowel syndrome).
  • Clearly explain the basis of diagnosis, highlighting differences with organic conditions.
• Interdisciplinary Treatment
  • Involves coordination among multiple healthcare professionals, including physiotherapists, psychologists, occupational therapists, and speech therapists.
• Psychotherapy:
  • Graded Motor Relearning: Progressive motor exercises to normalize movement patterns.
  • Sensory Reintegration: Addressing sensory symptoms through therapy.
  • Cognitive-Behavioral Therapy (CBT): Addressing sensory symptoms through therapy.
    • Effective in reducing dissociative seizures and improving functional outcomes.
  • Psychodynamic Psychotherapy:
    • Useful for addressing past trauma and understanding emotional conflicts.
  • Group and Family Therapy:
    • Provides support, improves communication, and fosters learning from peers.
• Physical Therapy:
  • For Functional Motor Symptoms:
    • Focuses on encouraging normal movement patterns, reducing secondary weaknesses, and reinforcing that symptoms are taken seriously.
• Pharmacotherapy:
  • When Comorbid Mental Illness is Present: Antidepressants, anxiolytics, or mood stabilizers based on specific diagnoses.
  • Targeting Symptoms: Antidepressants that affect pain perception, such as serotonin-norepinephrine reuptake inhibitors (SNRIs), may be beneficial.
  • Antipsychotics: Quetiapine has shown efficacy in reducing symptoms with fewer extrapyramidal side effects compared to traditional antipsychotics like haloperidol.
• Neuromodulation and Experimental Treatments:
  • Transmagnetic Stimulation (TMS): Potential but not well-supported by controlled studies.
  • Paradoxical Intention Treatment: Controversial and of limited support.
• Frequent Follow-Up:
  • Importance: Regular follow-ups are crucial to prevent frequent emergency visits and ensure cohesive care.

Barriers to Care:

• Many patients face delays in diagnosis and limited access to specialized services, especially outside metropolitan areas.
• Telehealth services are helping bridge this gap, but more dedicated FND services are necessary.

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Prognosis:

• Overall Outlook: The prognosis for FND is generally considered poor, though certain factors can improve outcomes.
• Factors Influencing Positive Prognosis:
  • Sudden Symptom Onset: Better outcomes often observed.
  • Early Diagnosis and Short Symptom Duration: Early intervention is linked to improved outcomes.
  • Absence of Comorbid Psychiatric Disorders: Patients without coexisting conditions, such as personality disorders, have better outcomes.
  • Identifiable Stressors: The presence of identifiable triggers may facilitate targeted treatment.
  • Positive Patient-Clinician Relationship: Trust and communication play a critical role in therapeutic success.
• Negative Prognostic Indicators: Patients with a high number of physical complaints, poor functioning prior to diagnosis, or longstanding symptoms may have a poorer prognosis.

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Complications:

• Disability and Quality of Life:
  • Patients with FND may suffer from significant physical disability, comparable to chronic neurological disorders like Parkinson’s disease or multiple sclerosis, depending on the symptom subtype.
  • Psychological disability rates can be even higher than those seen in organic neurologic conditions.
• Follow-up Challenges: Some patients may become lost to follow-up or not adhere to prescribed treatment regimens, further complicating outcomes.

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Deterrence and Patient Education:

• Educational Focus:
  • Patient education is vital, including providing resources for self-education and family involvement.
  • National support groups for conversion disorder/FND can be useful resources.
• Family Involvement:
  • Family members should be educated to reinforce the legitimacy of the patient’s symptoms and offer positive support.
  • Families can help identify stressors, encourage follow-ups, and participate in therapy.
  • It’s essential to recognize and address any additional stress placed on families by the diagnosis.

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Driving

https://austroads.com.au – 7.2.9 Psychogenic nonepileptic seizures (PNES)

Overview of Psychogenic nonepileptic seizures (PNES) and Driving Risk:

• Psychogenic nonepileptic seizure episodes can mimic epileptic seizures or syncope but have psychological origins.
• Most patients with PNES self-report a loss of awareness/responsiveness, which can pose a driving safety risk.

Driving Safety Recommendations for Psychogenic nonepileptic seizures:

1. Three-Month Non-Driving Period:
   • Individuals should refrain from driving for at least three months after a PNES episode involving loss of awareness/responsiveness.
2. Criteria for Return to Driving:
   • Patients may resume driving if they have had no further episodes for three months and meet additional safety criteria.
   • Individuals with active PNES should generally not drive if they:
     • Lose awareness/responsiveness during episodes.
     • Have a history of seizure-related injuries.
     • Exhibit seizure semiology suggesting impaired driving ability.
3. Consideration for Driving Under Private Standards:
   • A person with active PNES may drive under private standards after 12 months if episodes occur only in non-driving contexts or due to triggers not encountered while driving.
   • This condition must be well-documented and supported by reliable witnesses.

Diagnosis and Differentiation:

• PNES diagnosis requires confirmation of psychological origins, often through video or video-EEG recordings.
• Around 20% of PNES patients also have epilepsy, necessitating a clear distinction between PNES and epileptic seizures.
  • Seizure and epilepsy standards may apply in cases where epileptic events are also involved.
  • If the type of attack remains uncertain, “blackouts of uncertain mechanism” standards may be applied, with the longer non-driving period prevailing.

Specialist Involvement and Licensing:

• Referral: It is considered good practice to refer individuals with PNES to a specialist for accurate diagnosis and treatment.
• Liaison with Licensing Authority:
  • General practitioners/treating doctors may communicate with driver licensing authorities about private vehicle criteria.
  • Only specialists can liaise regarding commercial vehicle driving criteria.