Overview
Definition:
Functional Neurological Disorder (FND) is a condition where patients experience neurological symptoms, such as movement, sensory, or cognitive problems, that are not explained by a structural neurological disease
In adolescents, it's characterized by the presence of involuntary or voluntary motor, sensory, or cognitive symptoms that are incongruent with recognized neurological pathways
It is considered a disorder of brain function rather than a structural brain abnormality
Historically referred to as conversion disorder, the term FND emphasizes the neurological dysfunction
This is not a conscious fabrication or malingering.
Epidemiology:
FND is relatively common in pediatric neurology clinics, with estimates ranging from 10-30% of new referrals in some tertiary centers
It affects females more commonly than males, with a typical onset during adolescence, though it can occur at any age
There is a higher prevalence in lower socioeconomic groups and among individuals with a history of trauma or significant life stressors
Specific incidence data for adolescents is limited but is estimated to be significant enough to warrant attention in pediatric practice.
Clinical Significance:
FND in adolescents poses significant challenges due to its varied and often disabling symptoms that mimic serious neurological conditions
Misdiagnosis can lead to unnecessary investigations, delayed appropriate treatment, and iatrogenic harm
Early recognition and accurate diagnosis are crucial for effective management, improving quality of life, and preventing long-term functional impairment
Understanding FND is vital for pediatricians, neurologists, and mental health professionals to provide comprehensive care and support to affected adolescents and their families
Preparation for DNB and NEET SS exams requires a solid grasp of this complex condition.
Clinical Presentation
Symptoms:
Motor symptoms are most common: Weakness or paralysis in limbs
Tremors or shaking
Gait disturbances
Abnormal movements (dystonia, myoclonus)
Speech difficulties (dysarthria, mutism)
Swallowing difficulties (dysphagia)
Sensory symptoms: Numbness or tingling
Vision changes (blurred vision, tunnel vision)
Hearing loss
Cognitive symptoms: Memory problems
Dissociative experiences
Seizure-like episodes (pseudoseizures or psychogenic non-epileptic seizures - PNES).
Signs:
Positive FND signs: Hoover's sign (leg extension against resistance during attempted leg raise)
Sensory extinction (inability to detect a stimulus on one side when presented simultaneously with a stimulus on the other)
Graphesthesia extinction
Variability and inconsistency of neurological signs
Symptoms that are inconsistent with anatomical pathways
Normal vital signs in most cases unless secondary to anxiety or hyperventilation.
Diagnostic Criteria:
Diagnostic criteria for FND (based on DSM-5) include: 1
A
One or more symptoms or deficits affecting voluntary motor or sensory function
B
Clinical findings incompatible with recognized neurological or other medical conditions
C
The symptom or deficit is not better explained by another medical or mental disorder
D
The symptom or deficit causes clinically significant distress or impairment in social, occupational, or other important areas of functioning
Diagnostic considerations also include the presence of incongruent findings (e.g., weakness that fatigually improves with attention) and the absence of neurological signs or tests that would support a structural neurological diagnosis.
Diagnostic Approach
History Taking:
Detailed history of symptom onset, evolution, and triggers
Inquire about recent stressors, trauma, family history of neurological or psychiatric conditions
Assess for co-occurring mental health conditions like anxiety, depression, or PTSD
Ask about previous medical workups and their findings
Crucially, identify any inconsistencies or "red flags" that suggest a neurological cause, such as progressive deficits, asymmetry not explained by FND, or signs of brainstem involvement.
Physical Examination:
Comprehensive neurological examination focusing on motor strength, sensation, reflexes, coordination, gait, cranial nerves, and mental status
Crucially, perform specific FND tests like Hoover's sign, sensory testing for extinction, and observe for fatigability of weakness or sensory loss
Careful attention to any objective neurological abnormalities that cannot be explained by a functional cause.
Investigations:
Investigations are primarily aimed at excluding organic neurological disease
Brain MRI (structural) is often performed to rule out lesions
EEG may be used if seizures are suspected, especially to differentiate from PNES
Nerve conduction studies and EMG can be useful in assessing peripheral nerve or muscle involvement
Lumbar puncture may be considered if inflammatory or infectious causes are suspected
However, in most cases with clear FND signs, investigations may be normal, reinforcing the diagnosis by exclusion.
Differential Diagnosis:
Multiple sclerosis (MS), Guillain-Barré syndrome, myasthenia gravis, stroke, spinal cord compression, peripheral neuropathy, epilepsy (especially PNES), functional movement disorders, factitious disorder, malingering
Distinguishing FND from organic neurological disorders relies on the presence of incongruent findings on examination, lack of objective neurological deficits on testing, and a history suggestive of functional factors
PNES are a common co-occurring condition or differential for seizure-like activity.
Management
Initial Management:
The cornerstone of management is building a trusting therapeutic relationship
Directly but gently naming the diagnosis as FND (avoiding overly technical jargon initially) is essential
Reassurance that it is a real condition and not "in their head" or "imagined" is vital
Emphasize that it is treatable and that the goal is recovery
Avoid extensive diagnostic testing if a clear diagnosis of FND can be made based on clinical grounds, as this can reinforce the idea of a serious underlying disease.
Medical Management:
There are no specific medications for FND itself
Pharmacological interventions are targeted at co-occurring conditions like anxiety or depression, which can exacerbate FND symptoms
Selective serotonin reuptake inhibitors (SSRIs) or other antidepressants may be beneficial for mood and anxiety symptoms
Low-dose antipsychotics or benzodiazepines are sometimes used cautiously for severe agitation or anxiety, but are not first-line treatments for FND itself.
Psychological Therapy:
Cognitive Behavioral Therapy (CBT) is the primary evidence-based treatment
It focuses on identifying triggers, developing coping strategies, and challenging unhelpful thought patterns
Physical therapy with a therapist experienced in FND can help regain motor function and reduce disability
Occupational therapy can assist with daily living activities
Trauma-informed therapy is crucial if a history of trauma is present.
Supportive Care:
Family psychoeducation is critical to help families understand FND and support their adolescent
Encouraging gradual return to school and social activities is important for rehabilitation
Peer support groups can be beneficial
Close collaboration between medical, psychological, and educational teams is essential for comprehensive care.
Complications
Early Complications:
Social isolation and withdrawal
School absenteeism leading to academic decline
Development of chronic pain related to deconditioning or immobility
Increased anxiety and depression
Stigma and misunderstanding from peers and sometimes family.
Late Complications:
Chronic functional impairment and disability
Long-term reliance on disability support
Increased risk of developing other somatoform disorders
Difficulties with employment and independent living
Social and romantic relationship challenges.
Prevention Strategies:
Early and accurate diagnosis
Prompt initiation of appropriate psychological and physical therapy
Effective management of co-occurring mental health conditions
Comprehensive family support and education
Minimizing unnecessary medical investigations once FND is suspected or diagnosed.
Prognosis
Factors Affecting Prognosis:
Younger age at onset
Shorter duration of symptoms before diagnosis and treatment
Absence of significant co-occurring mental health disorders, particularly severe depression or PTSD
Strong social support system
Patient's motivation and engagement in therapy
Presence of positive FND signs can sometimes be associated with a better prognosis than purely subjective symptoms.
Outcomes:
The prognosis for FND in adolescents is generally good with appropriate treatment
Many adolescents experience significant improvement or full recovery
Early intervention is associated with better outcomes
However, some individuals may have recurrent episodes or persistent symptoms that require ongoing management.
Follow Up:
Regular follow-up with the treating physician (neurologist or pediatrician) and therapist is crucial
Monitoring for symptom recurrence, treatment adherence, and management of any evolving co-occurring conditions
Facilitating a gradual return to school and social activities with ongoing support
Long-term follow-up may be necessary for individuals with more complex presentations or persistent symptoms.
Key Points
Exam Focus:
FND is a diagnosis of exclusion but relies on positive clinical signs incongruent with organic disease
Key differentials include MS, epilepsy, and conversion disorder (historical term)
Hoover's sign is critical for diagnosing functional leg weakness
Management is primarily psychological (CBT, physiotherapy) and addressing co-occurring mental health issues
Early diagnosis and treatment improve prognosis.
Clinical Pearls:
Build rapport and trust before disclosing the diagnosis
Use clear, non-judgmental language
Emphasize that the symptoms are real and treatable
Involve the family heavily in the treatment plan
Be mindful of the high rate of co-occurring PNES and other psychiatric conditions
Avoid unnecessary neuroimaging once FND is clinically evident to prevent reinforcing illness beliefs.
Common Mistakes:
Over-investigation leading to misdiagnosis and increased patient anxiety
Dismissing symptoms as "all in their head" or malingering, which erodes trust
Failure to consider and manage co-occurring psychiatric conditions
Lack of a multidisciplinary approach involving mental health professionals and therapists
Insufficient family involvement in the treatment plan.