Objective: To report a case of functional movement disorders (FMD) in a child with Asperger syndrome (AS).

Background: FMD can be found in adults[1] and children[2]. AS has been associated with a variety of movement disorders such as stereotypies and motor and phonic tics, although not with functional tremor or functional paralysis[3].

Method: A 14-year-old boy who started in September 2021 with tension headache preceded by “nausea and clenched throat sensation” and sometimes chest pain. In December 2021 he was hospitalized after adding incapacitating and continuous movements in both hands and a sudden and fluctuating loss of strength in both legs with gait limitation. He comes from an unstable family, has been bullied at school, has anxious and obsessive traits, deficits in social-emotional reciprocity, absence of symbolic play, inflexible adherence to routines and cognitive rigidity without intellectual or language compromise. The mother comments that he suffered a traumatic event prior to the development of his symptoms and that these are not observed during his sleep.

Results: Neurological examination showed simple motor and phonic tics (throat clearing and nose twitching). Tremor was observed in both hands at rest, postural and kinetic, rapid and of small amplitude, distractible and entrainable (motor inconsistency), not voluntarily suppressible, without premonitory urge nor sense of subsequent relief, which interferes when performing specific tasks. When he was asked to tap slowly or rapidly with one hand, the tremor of the contralateral hand mimicked this rhythm. Tremor at rest, postural and when performing multiple tasks and distraction maneuvers [figure 1] was evaluated with a neurophysiological analysis of the movement, confirming its functional nature. During the test, the patient reported a sudden loss of strength in the lower limbs, so at that time neurological examination, SSEP, nerve conduction study and EMG were performed, without finding abnormalities. No alterations were found in brain MRI, EEG, esophagogastroduodenal series, echocardiogram, EKG, CSF cytochemical data, thyroid profile, immunological profile, oligoclonal bands, and anti-NMDA antibodies.
A child psychiatrist evaluated him and diagnosed AS, starting treatment with risperidone and fluoxetine in addition to behavioral therapy.

Conclusion: We describe a novel case of AS associated with functional tremor, functional limb weakness and functional tics.

References: 1. Bhatia KP, Schneider SA. Psychogenic tremor and related disorders. J Neurol. 2007;254(5):569–74.
2. Wilkinson-Smith , Alison and Waugh JL. Functional Movement Disorder in Children. In: LaFaver K, editor. Functional Movement Disorder An Interdisciplinary Case-Based Approach. 1st ed. Springer; 2022. p. 183–95.
3. Ringman JM, Jankovic J. Occurrence of tics in Asperger’s syndrome and autistic disorder. J Child Neurol. 2000 Jun;15(6):394–400.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/functional-movement-disorder-with-mixed-phenotype-in-a-child-with-aspergers-syndrome/