Approach to Pediatric Neurology Signs and Symptoms: Pediatric Functional Movement Disorders

Introduction

In the previous articles of the “Approach to Pediatric Neurology Signs and Symptoms” series, I explored the evaluation of children presenting with movement disorders. To ensure a systematic and rational approach, the “CELE” framework was applied, encompassing:

C – Confirmation by identifying Characteristic features, Constellations, and Clues
E – Emergency considerations
L – Localization of the site of the lesion
E – Evaluation for Etiology

This article focuses on the approach to children presenting with Functional Movement Disorders (FMDs), a subset of Functional Neurological Symptom Disorder (FNSD). These disorders involve involuntary movements without a structural or neurodegenerative cause and can mimic organic neurological conditions.

FMDs are relatively common in children, often presenting with motor symptoms that may cause significant distress to both the child and their family. Accurate diagnosis is essential, as it allows for appropriate management and avoids unnecessary testing and treatments, which can be costly, invasive, and emotionally taxing. Furthermore, recognizing FMDs helps to prevent prolonged uncertainty and misdiagnosis, which can impact the child’s development, school performance, and overall quality of life.

Recent studies on the pathophysiology of Functional Neurological Disorders (FND), specifically Functional Movement Disorders (FMD) and functional seizures, highlight several key findings:
1.Comorbidities and Symptoms: FMD patients tend to have more comorbid functional somatic syndromes and preceding medical issues, while they show fewer dissociative symptoms and a lower incidence of suicidal ideation compared to those with functional seizures.
2. Attention and Executive Dysfunction: Attention plays a significant role in FND, with symptoms improving with distraction and worsening with focus. Studies indicate that FMD patients exhibit impaired executive control of attention, particularly during tasks that require conflict resolution, reflecting executive dysfunction. They also show attentional bias away from negative emotions, particularly sadness.
3. Abnormal Inhibitory Control: FMD patients exhibit impaired impulse inhibition and action cancellation, suggesting abnormalities in inhibitory control.
4. Gait Disorders: A study on functional gait disorders showed that while patients had slower gait during explicit tasks, their gait normalized during implicit tasks, but they struggled to re-normalize when switching back to the original task, indicating difficulties with motor learning and rehabilitation potential.
5. Biomarkers: Progress has been made in identifying biomarkers for FMD. For example, contingent negative variation (CNV), related to motor preparation and attention, is absent in FMD patients but normalizes with physiotherapy. Additionally, reduced drift rate, which quantifies information accumulation, further supports attention-related abnormalities in FMD.

These findings highlight the critical role of attention and inhibitory control in FMD and suggest potential biomarkers for diagnosis and treatment monitoring.

FMDs in children can be broadly categorized into different types based on the movement abnormalities observed. These include:
1. Functional Tremor – Characterized by rhythmic, involuntary shaking movements, often with variable frequency and amplitude.
2. Functional Dystonia – Involves abnormal posturing or twisting movements, usually affecting specific muscle groups.
3. Functional Myoclonus – Rapid, jerking movements often triggered by stress or movement.
4. Functional Gait Abnormalities – These may include altered walking patterns or abnormal posturing, often resulting in an unsteady or uncoordinated gait.
5. Functional Tics – Sudden, repetitive movements or sounds that are usually suppressible but may increase in frequency with stress.
6. Functional Seizures (also known as Psychogenic Non-Epileptic Seizures) – Episodes resembling epileptic seizures but without underlying electrical disturbances in the brain.

By using the “CELE” framework, we can systematically assess and manage FMDs while distinguishing them from other movement disorders.

C – Confirmation: Identifying Key Features of Pediatric FMDs

The first step in evaluating a child with suspected Functional Movement Disorder (FMD) is clinical confirmation. This involves identifying characteristic features that differentiate FMDs from organic movement disorders, through a systematic approach.

Step 1: Detailed History-Taking

A thorough and structured history is the cornerstone of diagnosing FMDs. Here, the clinician should:

1. Assess the Onset and Progression of Symptoms

It is important to determine when the symptoms first appeared and whether they have worsened, improved, or remained stable. A sudden onset often suggests an acute triggering event such as stress or trauma.

2. Take a Detailed History of the Phenomenology of Abnormal Movements

Understanding the nature of the movements (e.g., tremors, dystonia, myoclonus) is crucial. For example, the clinician should inquire whether the movements are rhythmic, jerky, or spasmodic, and note any variability in the frequency or location of the movements.

3. Evaluate Background Risk Factors and Developmental Status

Background factors such as developmental milestones, family history of neurological disorders, or a history of significant medical events (e.g., head injury) should be explored. This can help identify potential underlying conditions that may coexist with FMD.

4. Identify Potential Triggers

Identifying triggers such as stressful events (e.g., trauma, accidents, or family issues) is essential. Often, FMD symptoms are precipitated or worsened by stress, anxiety, or emotional strain.

5. Assess Psychosocial Factors

It is crucial to explore the psychosocial environment, including current or past stressors, anxiety, depression, and early-life trauma. Psychological factors can significantly influence the manifestation and persistence of FMD symptoms.

Step 2: Clinical Examination

The clinical examination aims to identify signs and features specific to FMDs. The clinician should observe the child carefully and note the following:

1. The Diagnosis is Based on Direct Observation or Video Clips

Direct observation of the child’s movements is essential, and video clips may be helpful in capturing the movements for further analysis. This can provide a more objective view, especially if the child’s movements are inconsistent or change when not being observed.

2. Look for Inconsistencies or Incongruities in Motor Symptoms

FMDs often exhibit inconsistent symptoms. For example, movements may come and go, change in type, or diminish when the child is distracted or focused on another task.

3. Key Signs to Observe Include

Variability: Phenomenology changes over time, which is a hallmark feature of FMDs. Symptoms may appear in different patterns, times of day, or severity.
Distractibility: Movements often diminish or disappear when the child is asked to perform mental tasks or engage in other activities.
Suggestibility: Symptoms may worsen or improve depending on external cues, such as observation or the suggestion to move in a specific way.
Selectivity: FMD symptoms are often present only in specific contexts, such as during certain activities or when the child is observed.

4. A Thorough Neurodevelopmental Assessment is Essential

A comprehensive neurodevelopmental assessment should be conducted to understand the child’s developmental history and identify any delays or abnormalities that may complicate the diagnosis of FMD.

Step 3: Identification of Key Features of FMDs

To confirm the diagnosis of FMD, clinicians should be able to identify key distinguishing features:

1. Sudden Onset

FMD symptoms often appear suddenly, often following stress or minor physical events. The abrupt onset is a strong indicator that the movement disorder may be functional rather than organic.

2.Variability and Inconsistency

Symptoms of FMDs tend to fluctuate in severity and type. The ability to modify or alleviate symptoms by distraction is a hallmark sign of FMDs.

3. Distractibility and Entrainment

Movements in FMDs often improve or stop when the child’s attention is diverted, such as by engaging in mental tasks. This is in contrast to organic movement disorders, where symptoms typically persist regardless of distraction.

4. Non-Anatomical Distribution

Movements do not follow typical neurological pathways (e.g., non-physiological tremors or gait disturbances). Unlike organic disorders, which often have a predictable, anatomical distribution, functional movements can be widespread or irregular.

5.Selective Impairment

FMDs often show selective impairment, meaning that children may have normal movements in some contexts but abnormal movements in others. This selective pattern can help differentiate FMDs from organic conditions, which typically involve more consistent neurological deficits.

Step 4: Exclusion of Organic Disorders

While Functional Movement Disorder (FMD) is a distinct condition, it may coexist with organic neurodevelopmental disorders, such as:
- Global developmental delay
- Autism spectrum disorder
- Epilepsy
- Wilson’s disease, among others.

Step 5: Use of Neurophysiological Testing (If Needed)

If necessary, advanced neurophysiological testing can help differentiate FMDs from organic movement disorders:

1. Electrophysiology (e.g., EMG-EEG, jerk-locked back-averaging) to assess motor patterns.
2. Functional MRI (fMRI) and PET scans to study brain connectivity changes in FMD patients.
3. Tremor Analysis using surface EMG and accelerometry to assess tremor frequency, variability, and entrainability.
4. Video EEG to confirm seizures are epileptic or functional.

By following this systematic approach—starting with C – Confirmation to establish the diagnosis through clinical observation, followed by a detailed history, careful clinical examination, identification of key FMD features, and, when needed, neurophysiological testing—the clinician can effectively diagnose pediatric Functional Movement Disorders (FMDs). This ensures appropriate management and differentiation from organic movement disorders.

E – Emergency Considerations

While FMDs are not inherently life-threatening, they can present dramatically and be misdiagnosed as neurological emergencies. It is essential to differentiate functional symptoms from acute neurological crises.

Situations That Mimic Emergencies:

1. Functional Paroxysmal Events vs. Seizures:

FMDs: No postictal phase, variable semiology, stop with reassurance or distraction.
Seizures: Stereotyped, with altered mental status and electrographic abnormalities on EEG.

2. Functional Weakness vs. Stroke:

FMDs: Give-way weakness, normal reflexes, Hoover’s sign positive.
Stroke: Focal neurological deficits, reflex asymmetry, and imaging abnormalities.

3. Functional Gait Disturbances vs. Spinal Cord Compression:

FMDs: Swaying, inconsistent limb use, rapid improvement with encouragement.
Spinal Cord Compression: Progressive weakness, bladder/bowel involvement, MRI abnormalities.

When to Consider Hospitalization:

If symptoms cause significant distress or functional impairment requiring rehabilitation.
If the possibility of an organic neurological disorder has not been excluded.
If there is coexisting psychiatric instability requiring inpatient care.

L – Localization of Functional Movement Disorders

Unlike organic movement disorders, FMDs do not localize to specific neurological lesions or regions of the brain or spinal cord. The movements associated with FMDs are not correlated with any identifiable neuroanatomical dysfunction. This means that, while organic movement disorders typically involve distinct patterns of motor symptoms that can be traced to a specific lesion or abnormality in the nervous system (e.g., basal ganglia, cerebellum, or cortical regions), the involuntary movements in FMDs do not correspond to such a neuroanatomical site.

E – Evaluation for Etiology

The final step is evaluating the underlying triggers and contributing factors of FMDs. These disorders are not fabricated but represent involuntary dysfunction in voluntary motor control, often linked to psychological or environmental stressors.

Key Factors in Etiology Evaluation:

1. Psychosocial Triggers:

History of stress, anxiety, school difficulties, bullying, or recent trauma.
Family reinforcement of symptoms (secondary gain).

2. History of Preceding Events:

Often follows minor injury, illness, or emotional distress.
Sudden onset suggests functional rather than neurodegenerative etiology.

3. Coexisting Psychiatric Conditions:

Anxiety, depression, obsessive-compulsive disorder (OCD).
History of prior somatic symptoms (e.g., abdominal pain, non-epileptic seizures).

4. Exclusion of Organic Causes:

Normal MRI, EEG, and metabolic testing.
Lack of progression over time.

Conclusion

In conclusion, the approach to pediatric Functional Movement Disorders (FMDs) requires a comprehensive, systematic evaluation that distinguishes these conditions from organic movement disorders. By applying the “CELE” framework—Confirmation, Emergency considerations, Localization, and Evaluation for Etiology—clinicians can effectively diagnose and manage FMDs in children. This approach begins with a detailed clinical history and examination, focusing on key features such as variability, distractibility, and non-anatomical distribution of symptoms. Neurophysiological testing, when needed, further aids in differentiating FMDs from other neurological conditions. Understanding the psychosocial and environmental triggers that contribute to FMDs is also crucial for appropriate management. Early recognition and correct diagnosis of FMDs prevent unnecessary treatments, reduce patient distress, and ensure optimal outcomes for the child’s physical and psychological well-being.

Algorithm approach to a child with Functional Movement Disorders

References

Jain R, Pandey S, Raghav S. Movement Disorders in Children. Indian Pediatr. 2021 Sep 15;58(9):861-870. Epub 2021 May 20. PMID: 34016797.

Kola S, LaFaver K. Updates in Functional Movement Disorders: from Pathophysiology to Treatment Advances. Curr Neurol Neurosci Rep. 2022 May;22(5):305-311. doi: 10.1007/s11910-022-01192-9. Epub 2022 Apr 19. PMID: 35441333; PMCID: PMC9017419.

Larsh T, Wilson J, Mackenzie KM, O’Malley JA. Diagnosis and Initial Treatment of Functional Movement Disorders in Children. Semin Pediatr Neurol. 2022 Apr;41:100953. doi: 10.1016/j.spen.2022.100953. Epub 2022 Feb 5. PMID: 35450668.
Park JE. Functional Movement Disorders: Updates and Clinical Overview. J Mov Disord. 2024 Jul;17(3):251-261. doi: 10.14802/jmd.24126. Epub 2024 Jul 1. PMID: 38950896; PMCID: PMC11300393.