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Pediatric Functional Movement Disorders: Experience from a Tertiary Care Centre

Published online by Cambridge University Press:  28 September 2020

Kempaiah Rakesh
Affiliation:
Department of Neurology, National Institute of Mental Health and Neurosciences (NIMHANS), Hosur Road, Bangalore, Karnataka, India
Nitish Kamble
Affiliation:
Department of Neurology, National Institute of Mental Health and Neurosciences (NIMHANS), Hosur Road, Bangalore, Karnataka, India
Ravi Yadav
Affiliation:
Department of Neurology, National Institute of Mental Health and Neurosciences (NIMHANS), Hosur Road, Bangalore, Karnataka, India
Amitabh Bhattacharya
Affiliation:
Department of Neurology, National Institute of Mental Health and Neurosciences (NIMHANS), Hosur Road, Bangalore, Karnataka, India
Vikram V. Holla
Affiliation:
Department of Neurology, National Institute of Mental Health and Neurosciences (NIMHANS), Hosur Road, Bangalore, Karnataka, India
Manjunath Netravathi
Affiliation:
Department of Neurology, National Institute of Mental Health and Neurosciences (NIMHANS), Hosur Road, Bangalore, Karnataka, India
Shekhar Seshadri
Affiliation:
Department of Child and Adolescent Psychiatry, National Institute of Mental Health and Neurosciences (NIMHANS), Hosur Road, Bangalore, Karnataka, India
Pramod Kumar Pal*
Affiliation:
Department of Neurology, National Institute of Mental Health and Neurosciences (NIMHANS), Hosur Road, Bangalore, Karnataka, India
*
Correspondence to: Dr. Pramod Kumar Pal, Professor, Department of Neurology, National Institute of Mental Health and Neurosciences (NIMHANS), Bangalore560029, India. Email: pal.pramod@rediffmail.com
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Abstract:

Objectives:

Functional movement disorders (FMDs) pose significant diagnostic and management challenges. We aimed to study the socioeconomic and cultural factors, underlying psychopathology and the phenomenology of FMDs in children.

Methods:

The study is a retrospective chart review of 39 children (16 girls and 23 boys) who attended our neurology OPD and the movement disorders clinic at the National Institute of Mental Health and Neurosciences (NIMHANS) between January 2011 and May 2020. The diagnosis of FMD was based on Fahn and Williams criteria and the patients were either diagnosed as “documented” or “clinically established”. All the relevant demographic data including the ethnicity, socioeconomic and cultural background, examination findings, electrophysiological, and other investigations were retrieved from the medical records.

Results:

The mean age at onset was 12.69 ± 3.13 years. Majority of the children were from urban regions (56.41%) and belonging to low socioeconomic status (46.15%). Thirty (76.92%) were found to have a precipitating factor. Myoclonus was the most common phenomenology observed in these patients (30.76%), followed by tremor (20.51%), dystonia (17.94%), and gait abnormality (7.69%). Chorea (5.12%) and tics (2.56%) were uncommon. Tremor (37.5%) and dystonia (18.75%) were more common in girls, whereas myoclonus (39.13%) was more common in boys.

Conclusions:

The symptoms of FMD have great impact on the mental health, social, and academic functioning of children. It is important to identify the precipitating factors and associated psychiatric comorbidities in these children as prompt alleviation of these factors by engaging parents and the child psychiatrist will yield better outcomes.

Résumé :

RÉSUMÉ :

Les troubles fonctionnels du mouvement chez les enfants dans le contexte d’un établissement de soins tertiaires.

Objectifs :

Les troubles fonctionnels du mouvement (TFM) soulèvent des enjeux importants en matière de diagnostic et de prise en charge des patients. C’est ainsi que nous avons voulu nous pencher sur les facteurs socioéconomiques et culturels qui sous-tendent la psychopathologie et la phénoménologie des TFM chez les enfants.

Méthodes :

Cette étude est fondée sur une analyse rétrospective des dossiers de 39 enfants (16 filles et 23 garçons) qui ont fréquenté, entre janvier 2011 et mai 2020, notre service de consultations externes en neurologie et la clinique des troubles du mouvement du National Institute of Mental Health and Neurosciences (NIMHANS). Les diagnostics de TFM ont reposé sur les critères de Fahn et Williams. À noter que ces patients ont été divisés en deux groupes en ce qui regarde leur diagnostic : ceux étant probablement atteints (on dira « documentés ») et ceux dont le diagnostic a été établi sur le plan clinique. Toutes leurs données démographiques pertinentes, ce qui inclut leur appartenance ethnique et leur contexte socioéconomique, de même que leurs résultats d’examens, notamment d’un point de vue électro-physiologique, ont été obtenus à partir de leurs dossiers médicaux.

Résultats :

L’âge moyen d’apparition des premiers symptômes de TFM était de 12,69 ± 3,13 ans. La majorité des enfants provenaient de régions urbaines (56,41 %) et étaient issus de milieux socioéconomiques défavorisés (46,15 %). Sur ces 39 enfants, on a noté que 30 d’entre eux (76,92 %) donnaient à voir un facteur précipitant. La myoclonie est la manifestation clinique qui a été la plus observée chez ces patients (30,76 %) ; ont suivi les tremblements (20,51 %), la dystonie (17,94 %) et les anomalies de la démarche (7,69 %). La chorée (5,12 %) et des tics nerveux (2,56 %) se sont par ailleurs avérés peu fréquents. Enfin, les tremblements (37,5 %) et la dystonie (18,75 %) étaient plus fréquents chez les filles tandis que la myoclonie (39,13 %) l’était chez les garçons.

Conclusions :

Les symptômes de TFM ont un impact notable sur la santé mentale et sur le fonctionnement social et scolaire des enfants. Il importe donc d’identifier les facteurs précipitants et les comorbidités psychiatriques associées chez ces enfants car une atténuation rapide de leurs conséquences, en impliquant les parents et les pédopsychiatres, débouchera sur une meilleure évolution de leur état de santé.

Type
Original Article
Copyright
Copyright © The Author(s), 2020. Published by Cambridge University Press on behalf of The Canadian Journal of Neurological Sciences Inc.

Introduction

Functional movement disorders (FMDs) pose significant diagnostic and management challenges for the neurologist.Reference Morgante, Edwards and Espay1 These disorders (FMDs) are well characterized in adults, but childhood-onset FMDs have not been extensively studied.Reference Ferrara and Jankovic2 FMDs are also more common in adults and uncommon or rare in children.Reference Kamble, Prashantha and Jha3,Reference Stone, Wojcik and Durrance4 FMDs account for about 1.5% of all the patients attending neurology clinics and 17% of all functional neurological disorders.Reference Factor, Podskalny and Molho5 In the movement disorders clinic, the estimated prevalence is about 2%–10%.Reference Edwards and Bhatia6 About 10% of them are found to have associated organic disorder.Reference Hallett7 However, the exact prevalence is difficult to estimate due to the case definition, referral bias, difficulty in differentiating from the organic disorders, and low index of suspicion by the treating physician.

These disorders do not have any structural or biochemical abnormality, but are believed to be due to underlying psychological or psychiatric illness.Reference Czarnecki and Hallett8,Reference Gupta and Lang9 They are thus a part of functional neurological disorders. In recent years, there are controversies regarding the terminologies “psychogenic” or “functional” for these disorders.Reference Dallocchio, Marangi and Tinazzi10 The diagnostic criteria were initially laid by Fahn and WilliamsReference Fahn and Williams11 in patients with psychogenic dystonia that was later modified to include other FMDs.Reference Gupta and Lang9,Reference Fahn and Williams11

Given the paucity of literature on these disorders in children, the study of these disorders in children becomes essential as it affects the mental and social well-being of the child. In addition, it is associated with school absenteeism, poor scholastic performance, lack of self-confidence, and parental anxiety. Hence, we aimed to study the socioeconomic and cultural factors, underlying psychopathology and the phenomenology of FMDs in children.

Methods

The present study was a retrospective chart review of 39 children (aged ≤ 18 years) who attended our neurology OPD and the movement disorders clinic between January 2011 and May 2020. Among them, the clinical profile of 22 children has been published earlier.Reference Kamble, Prashantha and Jha3 The study was approved by the institute’s ethics committee. The diagnosis of FMD was based on the criteria described by Fahn and Williams and Gupta and Lang.Reference Gupta and Lang9,Reference Fahn and Williams11 All these children were examined by the senior movement disorder specialist (PKP and RY) with clinical opinion from the child psychiatrist (SS). All the relevant demographic data including the ethnicity, socioeconomic and cultural background were documented. Detailed history, examination findings, electrophysiological, and other investigations were also noted. The clinical videos were also reviewed. Most of these children had undergone electrophysiological evaluations such as surface electromyogram (EMG), long-loop reflexes, jerk-locked back averaging, and Bereitschaftspotential (BP) depending on the underlying phenomenology. The psychiatric notes were also reviewed and discussed with the child psychiatrist (SS). The treatment details and the outcome were also recorded.

Statistical Analysis

The statistical analysis was performed using the R software. All the variables were expressed as mean ± standard deviation, percentage, and range.

Results

Demographic and Clinical Characteristics (Table 1)

Thirty-nine children (16 girls and 23 boys) were evaluated during the 9-year period (2011–2020). The mean age at onset was 12.69 ± 3.13 years with a median duration of illness being 150 days (range 2 days– 6 years). About 56.4% of children were from urban regions. Majority (66.7%) of the children belonged to low-to-middle socioeconomic strata (low – 46.15%; middle – 20.51%). The onset of the illness was acute in 69.23% and chronic presentation in 25.64%. Antecedent illness was observed in 14 children with joint pains being the most common (28.57%). Other antecedent illnesses that were noted included fever (21.42%), loss of consciousness (14.28%), headache (7.14%), speech disturbance (7.14%), eye pain (7.14%), and abdominal pain (7.14%). Thirty children were found to have a precipitating factor in the form of stressors at school (36.66%), combined school and family stressors (26.66%), family stressors (23.33%), and societal pressures (13.33%).

Table 1: Demographic and clinical characteristics of the children

FMD Phenomenology (Table 2)

Table 2: Phenomenology of the movement disorders observed in children

Myoclonus was the most common phenomenology observed in these patients (30.76%), followed by tremor (20.51%), dystonia (17.94%), and gait abnormality (7.69%). Chorea (5.12%) and tics (2.56%) were uncommon. Tremor (37.5%) and dystonia (18.75%) were more common in girls, whereas myoclonus was more common in boys (30.76%). Gait abnormality was seen exclusively in boys (13.04%). Multiple FMD phenomenologies were seen in two girls and one boy. One girl presented with functional vocal tics and one boy with functional dysphonia.

Course and Outcome

Electrophysiological testing was performed in 17 children (43.58%) and FMD was confirmed in all of them. In patients with functional tremors, surface EMG showed variability, distractibility (Figure 1), and entrainability (Figure 2). BP was demonstrated in some patients with myoclonus (Figure 3). Placebo response was observed in 30.6% of children. Nineteen children (48.71%) required hospital admission. Twenty-two (56.41%) showed complete resolution of the symptoms and in 11.1%, there was a partial improvement. All 39 children in our study were referred to child psychiatry specialists for detailed evaluation and majority (n = 37, 94.9%) of them were diagnosed with a dissociative movement disorder. Associated psychiatric comorbidity was observed in 12.8% in the form of obsessive-compulsive disorder, depression, generalized anxiety disorder, schizophrenia, and psychosis.

Figure 1: Distractibility in a patient with functional tremor. During the mental task, there is abrupt cessation of tremor in the right upper limb.

Figure 2: Entrainability in a patient with functional tremor. During voluntary movements of the left upper limb, there is abrupt cessation and change in the tremor frequency and amplitude in the right upper limb.

Figure 3: Bereitschaftspotential (BP) in a child with functional myoclonus. BP is seen about 800 msec before the electromyogram (EMG) activity.

Discussion

FMDs are heterogeneous disturbances of motor function that are not explained by organic conditions and may occur in association with underlying psychiatric disease.Reference Schwingenschuh, Pont-Sunyer and Surtees12 FMD poses a great challenge for clinicians in diagnosis and management.

In our study, 39 children with documented and clinically established FMD were evaluated. The most common type of FMD observed was myoclonus, tremor, and dystonia. The exact prevalence or frequency of pediatric FMD varies between 2% and 3% of children attending the movement disorders clinic.Reference Ferrara and Jankovic2,Reference Schwingenschuh, Pont-Sunyer and Surtees12,Reference Fernández-Alvarez13 In a study involving 2280 children with neurological disorders, psychogenic etiology was observed in 6.4%.Reference Thomas14

In our study, FMD was more common in boys, which is similar to the previous two studies from India.Reference Kamble, Prashantha and Jha3,Reference Pandey and Koul15 However, some previous studies have shown the higher prevalence in girls.Reference Ferrara and Jankovic2,Reference Schwingenschuh, Pont-Sunyer and Surtees12,Reference Ahmed, Martinez and Yee16,Reference Canavese, Ciano and Zibordi17 In another study from our institute, about 48% of patients with the then-existing diagnostic category of hysteria were girls.Reference Srinath, Bharat and Girimaji18 The reason for predominance of FMD in boys is not clear, but it may be due to sociocultural practices prevailing in the Indian community wherein medical attention is sought more often and earlier for the boys than girls. Indian society is mainly patriarchal.Reference Prusty and Kumar19 There is a preference for a son in most of the Indian families and there is discrimination against girls especially in providing education and medical care.Reference Arnold, Choe and Roy20

In our study, majority of the children belonged to low-to-middle socioeconomic strata. In India, patients from low-to-middle socioeconomic populations more often visit government hospitals, like ours. However, to the best of our knowledge, there is no published literature from India on the prevalence of pediatric FMD based on socioeconomic status.

Abrupt onset of symptoms is one indicator toward FMD, which was seen in 69.2% of our cohort. In a study of 54 children, approximately 90% of children presented with an abrupt onset.Reference Ferrara and Jankovic2 Many other studies have also reported a preponderance of abrupt onset of illness.Reference Canavese, Ciano and Zibordi17 In addition, antecedent illness is commonly seen in these patients. In our study, nearly a third of the children had an antecedent illness which is similar to the other studies.Reference Kamble, Prashantha and Jha3,Reference Canavese, Ciano and Zibordi17

History of precipitating factors needs to be enquired in patients suspected of FMD. Most of the studies have reported precipitating factors ranging from 47.9% to 83.7% in adults.Reference Ertan, Uluduz and Ozekmekçi21,Reference Kim, Pakiam and Lang22 The various precipitating factors identified in these studies include physical injury, psychological insult, flu-like illness, death of a relative, poverty, family, or social stress.Reference Ertan, Uluduz and Ozekmekçi21Reference Thomas, Vuong and Jankovic23

In a study involving 38 children, significant stressors were identified in 27 that included academic difficulties in school, punitive parent, parental discord, financial difficulties, increasing workload, and sibling rivalry.Reference Srinath, Bharat and Girimaji18 Traumatic experience (physical or psychological) and emotional factors in the childhood have a significant impact on the pathogenesis of FMD.

Myoclonus followed by tremor and dystonia were the common phenomenologies observed in our study. However, tremorReference Ferrara and Jankovic2,Reference Canavese, Ciano and Zibordi17,Reference Srinath, Bharat and Girimaji18 and dystoniaReference Schwingenschuh, Pont-Sunyer and Surtees12,Reference Faust and Soman24 have been the most common FMD in other studies.

Detailed psychiatry evaluation is necessary for diagnosis and treatment of FMD. The various psychiatric comorbidities that have been associated with FMD include obsessive-compulsive disorders, depression, and anxiety.Reference Voon, Brezing and Gallea25

Clinically, it is challenging to diagnose FMD. However, some cues that may be useful for diagnosis can be categorized as historical (abrupt onset, static course, psychiatric comorbidity, precipitating factors, presence of multiple somatizations, pending litigation, etc.), clinical (incongruence, inconsistency, distractibility, variability, entrainability, fluctuating course, suggestibility/modulation, episodic occurrence with complete or incomplete remissions, spontaneous remissions, and additional movement disorders), and treatment related (response to psychotherapy, placebo).Reference Kim, Pakiam and Lang22 Electrophysiological methods such as surface EMG recording for tremors and BP in myoclonus may be helpful in determining the functional basis for the movement disorders.Reference Kamble, Prashantha and Jha3

Recent neuroimaging studies have implicated abnormal emotional processing, sense of agency, and top-down regulation from frontal areas as important pathophysiological components in FMD.Reference Voon, Brezing and Gallea25 Abnormal regional brain activations and functional connectivity have been demonstrated using functional MRI and positron emission tomography (PET).Reference Stone, Zeman and Simonotto26 Abnormal connectivity is found in right caudate, amygdala, prefrontal, and sensorimotor regions in patients with FMD with over 68% sensitivity and specificity.Reference Wegrzyk, Kebets and Richiardi27 In addition to the abnormal activation of supplementary motor area (SMA), patients with functional tremors and dystonia have abnormal activation in the right middle temporal gyrus or right temporoparietal junction.Reference Espay, Maloney and Vannest28 The cingulate cortex has been implicated in self-awareness, self-monitoring, and active motor inhibition.Reference Aybek, Nicholson and O’Daly29 In patients with functional tremors and dystonia, there is abnormal activation of the cingulate cortex.Reference Hedera30 In future, these advanced imaging techniques may be useful in the diagnosis of FMD. Currently, these studies have been done only in adults. There are no such studies in pediatric FMD.

In our study, 56.4% of children had complete resolution of symptoms, and in 11.1%, there was a partial improvement and 13.9% showed no improvement at all, which may be due to non-acceptance of functional nature of the disease by parents/patients. There was no child with a worsening of symptoms. Studies have reported response rates ranging from 5% to 57%.Reference Thomas, Vuong and Jankovic23,Reference Hedera30Reference Munhoz, Zavala and Becker33 Similar good outcome has been observed in previous studies from India.Reference Pandey and Koul15 In another study, the outcome was not described due to lack of follow-up which is a problem with patients with FMD.Reference Ferrara and Jankovic2 In a study by Schwingenschuh et al., 47% improved completely, 33% improved substantially, and 20% remained chronically and severely disabled.Reference Schwingenschuh, Pont-Sunyer and Surtees12 A summary of the previous and present studies is shown in Table 3.

Table 3: Spectrum of PMD phenomenology in other studies

Conclusions

In our study, we observed that FMD was more common in boys and myoclonus as the most common phenomenology. This is in sharp contrast to previous studies. This may be due to gender bias as well as social stigma in our country. The symptoms of FMD have a great impact on the mental health, social, and academic functioning of children. It is important to identify precipitating factors and associated psychiatric comorbidity in these children as prompt alleviation of these factors by engaging parents and the child psychiatrist will yield better outcomes. Electrophysiology and placebo effect may serve as useful supplementary tools for diagnosing FMD.

Conflict of Interest

None of the authors have any financial disclosure to make or have any conflict of interest.

Statement of Authorship

KR: Data collection, manuscript writing, study design, and data review.

NK: Data collection, manuscript writing, study design, and data review.

RY: Manuscript review.

AB: Data collection, statistical analysis.

VVH: Manuscript review.

MN: Manuscript review.

SS: Study design, supervision, data review, and manuscript review.

PKP: Conception of the study, study design, supervision, data review, and manuscript review.

Footnotes

*

Contributed equally to the manuscript. Hence both to be considered as joint first authors.

References

Morgante, F, Edwards, MJ, Espay, AJ. Psychogenic movement disorders. Contin Minneap Minn. 2013;19(5 Movement Disorders):1383–96.Google ScholarPubMed
Ferrara, J, Jankovic, J. Psychogenic movement disorders in children. Mov Disord Off J Mov Disord Soc. 2008;23(13):1875–81.10.1002/mds.22220CrossRefGoogle ScholarPubMed
Kamble, N, Prashantha, DK, Jha, M, et al. Gender and age determinants of psychogenic movement disorders: a clinical profile of 73 patients. Can J Neurol Sci J Can Sci Neurol. 2016;43(2):268–77.10.1017/cjn.2015.365CrossRefGoogle ScholarPubMed
Stone, J, Wojcik, W, Durrance, D, et al. What should we say to patients with symptoms unexplained by disease? The “number needed to offend”. BMJ 2002;325(7378):1449–50.10.1136/bmj.325.7378.1449CrossRefGoogle Scholar
Factor, SA, Podskalny, GD, Molho, ES. Psychogenic movement disorders: frequency, clinical profile, and characteristics. J Neurol Neurosurg Psychiatry. 1995;59(4):406–12.10.1136/jnnp.59.4.406CrossRefGoogle Scholar
Edwards, MJ, Bhatia, KP. Functional (psychogenic) movement disorders: merging mind and brain. Lancet Neurol. 2012;11(3):250–60.10.1016/S1474-4422(11)70310-6CrossRefGoogle ScholarPubMed
Hallett, M. Functional (psychogenic) movement disorders - Clinical presentations. Parkinsonism Relat Disord 2016;22(Suppl 1):S14952.10.1016/j.parkreldis.2015.08.036CrossRefGoogle ScholarPubMed
Czarnecki, K, Hallett, M. Functional (psychogenic) movement disorders. Curr Opin Neurol. 2012;25(4):507–12.10.1097/WCO.0b013e3283551bc1CrossRefGoogle ScholarPubMed
Gupta, A, Lang, AE. Psychogenic movement disorders. Curr Opin Neurol. 2009;22(4):430–36.10.1097/WCO.0b013e32832dc169CrossRefGoogle ScholarPubMed
Dallocchio, C, Marangi, A, Tinazzi, M. Functional or psychogenic movement disorders: an endless enigmatic tale. Front Neurol.6:37. Epub ahead of print February 27, 2015. DOI: 10.3389/fneur.2015.00037.10.3389/fneur.2015.00037CrossRefGoogle ScholarPubMed
Fahn, S, Williams, DT. Psychogenic dystonia. Adv Neurol. 1988;50:431–55.Google ScholarPubMed
Schwingenschuh, P, Pont-Sunyer, C, Surtees, R, et al. Psychogenic movement disorders in children: a report of 15 cases and a review of the literature. Mov Disord Off J Mov Disord Soc. 2008;23(13):1882–88.10.1002/mds.22280CrossRefGoogle Scholar
Fernández-Alvarez, E. Movement disorders of functional origin (psychogenic) in children. Rev Neurol. 2005;40(Suppl 1):S75–77.Google ScholarPubMed
Thomas, NH. Somatic presentation of psychogenic disease in child neurologic practice. In: Neurology. Lippincott Williams & Wilkins 530 Walnut St, Philadelphia, PA 19106-3621 USA; 2002. p. A28.Google Scholar
Pandey, S, Koul, A. Psychogenic movement disorders in adults and children: a clinical and video profile of 58 Indian iatients. Mov Disord Clin Pract. 2017;4(5):763–67.10.1002/mdc3.12516CrossRefGoogle Scholar
Ahmed, M a. S, Martinez, A, Yee, A, et al. Psychogenic and organic movement disorders in children. Dev Med Child Neurol. 2008;50(4):300–4.10.1111/j.1469-8749.2008.02043.xCrossRefGoogle ScholarPubMed
Canavese, C, Ciano, C, Zibordi, F, et al. Phenomenology of psychogenic movement disorders in children. Mov Disord Off J Mov Disord Soc. 2012;27(9):1153–57.10.1002/mds.24947CrossRefGoogle ScholarPubMed
Srinath, S, Bharat, S, Girimaji, S, et al. Characteristics of a child inpatient population with hysteria in India. J Am Acad Child Adolesc Psychiatry. 1993;32(4):822–25.10.1097/00004583-199307000-00017CrossRefGoogle ScholarPubMed
Prusty, RK, Kumar, A. Socioeconomic dynamics of gender disparity in childhood immunization in India, 1992–2006. PLoS One. 2014;9(8):e104598 10.1371/journal.pone.0104598CrossRefGoogle Scholar
Arnold, F, Choe, MK, Roy, TK. Son preference, the family-building process and child mortality in India. Popul Stud. 1998;52:301–15.10.1080/0032472031000150486CrossRefGoogle Scholar
Ertan, S, Uluduz, D, Ozekmekçi, S, et al. Clinical characteristics of 49 patients with psychogenic movement disorders in a tertiary clinic in Turkey. Mov Disord Off J Mov Disord Soc. 2009;24(5):759–62.10.1002/mds.22114CrossRefGoogle Scholar
Kim, YJ, Pakiam, AS, Lang, AE. Historical and clinical features of psychogenic tremor: a review of 70 cases. Can J Neurol Sci J Can Sci Neurol. 1999;26(3):190–95.10.1017/S0317167100000238CrossRefGoogle ScholarPubMed
Thomas, M, Vuong, KD, Jankovic, J. Long-term prognosis of patients with psychogenic movement disorders. Parkinsonism Relat Disord. 2006;12(6):382–87.10.1016/j.parkreldis.2006.03.005CrossRefGoogle ScholarPubMed
Faust, J, Soman, TB. Psychogenic movement disorders in children: characteristics and predictors of outcome. J Child Neurol. 2012;27(5):610–14.10.1177/0883073811422753CrossRefGoogle ScholarPubMed
Voon, V, Brezing, C, Gallea, C, et al. Aberrant supplementary motor complex and limbic activity during motor preparation in motor conversion disorder. Mov Disord Off J Mov Disord Soc. 2011;26(13):2396–403.10.1002/mds.23890CrossRefGoogle ScholarPubMed
Stone, J, Zeman, A, Simonotto, E, et al. FMRI in patients with motor conversion symptoms and controls with simulated weakness. Psychosom Med. 2007;69(9):961–69.10.1097/PSY.0b013e31815b6c14CrossRefGoogle ScholarPubMed
Wegrzyk, J, Kebets, V, Richiardi, J, et al. Identifying motor functional neurological disorder using resting-state functional connectivity. NeuroImage Clin. 2018;17163–168.Google ScholarPubMed
Espay, AJ, Maloney, T, Vannest, J, et al. Dysfunction in emotion processing underlies functional (psychogenic) dystonia. Mov Disord Off J Mov Disord Soc. 2018;33(1):136–45.10.1002/mds.27217CrossRefGoogle ScholarPubMed
Aybek, S, Nicholson, TR, O’Daly, O, et al. Emotion-motion interactions in conversion disorder: an fMRI study. PLoS One. 10(4):e0123273. Epub ahead of print April 10, 2015. DOI: 10.1371/journal.pone.0123273.10.1371/journal.pone.0123273CrossRefGoogle Scholar
Hedera, P. Metabolic hyperactivity of the medial posterior parietal lobes in psychogenic tremor. Tremor Hyperkinetic Mov N Y N. 2:tre-02-50-441-1. Epub ahead of print 2012. DOI: 10.7916/D87W69X8.Google ScholarPubMed
Fasano, A, Valadas, A, Bhatia, KP, et al. Psychogenic facial movement disorders: clinical features and associated conditions. Mov Disord Off J Mov Disord Soc. 2012;27(12):1544–51.10.1002/mds.25190CrossRefGoogle ScholarPubMed
Espay, AJ, Lang, AE. Phenotype-specific diagnosis of functional (psychogenic) movement disorders. Curr Neurol Neurosci Rep. 2015;15(6):32.10.1007/s11910-015-0556-yCrossRefGoogle ScholarPubMed
Munhoz, RP, Zavala, JA, Becker, N, et al. Cross-cultural influences on psychogenic movement disorders - a comparative review with a Brazilian series of 83 cases. Clin Neurol Neurosurg. 2011;113(2):115–18.10.1016/j.clineuro.2010.10.004CrossRefGoogle ScholarPubMed
Figure 0

Table 1: Demographic and clinical characteristics of the children

Figure 1

Table 2: Phenomenology of the movement disorders observed in children

Figure 2

Figure 1: Distractibility in a patient with functional tremor. During the mental task, there is abrupt cessation of tremor in the right upper limb.

Figure 3

Figure 2: Entrainability in a patient with functional tremor. During voluntary movements of the left upper limb, there is abrupt cessation and change in the tremor frequency and amplitude in the right upper limb.

Figure 4

Figure 3: Bereitschaftspotential (BP) in a child with functional myoclonus. BP is seen about 800 msec before the electromyogram (EMG) activity.

Figure 5

Table 3: Spectrum of PMD phenomenology in other studies