Movement Disorders and Neuropsychiatric Conditions

Introduction and Overview

Caring for children with movement disorders involves substantial exposure to psychiatric diagnoses. This is especially the case in patients with functional (psychogenic) movement disorders, discussed in Chapter 23 . Subthreshold symptoms as well as overt psychiatric diagnoses commonly co-occur with many pediatric movement disorders (as well as myriad other symptomatic and genetic conditions involving cerebral cortex, basal ganglia, and cerebellum). To give just a few examples, in the case of Tourette syndrome, the majority of affected children seen in clinical settings have obsessive compulsive disorder (OCD), attention deficit hyperactivity disorder (ADHD), Anxiety, some combination of these, or other psychiatric diagnoses. In Wilsons disease, psychiatric symptoms may precede the neurological presentation. ^, Studies of dystonia show elevated risk for depression, anxiety, and suicide in patients as well as siblings, supporting both genetic and environmental contributions. ^, This may be underrecognized relative to mental health diagnoses, especially in Tourette syndrome and functional (psychogenic) movement disorders. Depression and anxiety are also more common among children with pediatric ischemic stroke involving the basal ganglia and/or thalamus when dystonia is present, compared to when it is absent. These and other neurology/psychiatry associations are described in phenomenology chapters in more detail.

The common co-occurrence of psychiatric diagnoses and neurological diagnoses has important implications for the clinician diagnosing and managing symptoms in children with pediatric movement disorders. First, it is important to maintain vigilance for the presence of psychiatric diagnoses and take a systematic approach to ascertainment, assessment of functional impairment, and referral for treatment. This assessment of functional impairment should include the impact on the child in the home, social, and school settings. ^, Second, when the referral involves prominent psychiatric symptoms, it is important to know that these can obscure neurological symptoms or delay neurological diagnoses. ^{, ,} Third, medications and neuromodulation used to treat neurological symptoms may induce, unmask, or exacerbate psychiatric symptoms. Conversely, psychiatric medications may induce, unmask, or exacerbate movement disorders. Finally, and most pertinent to this chapter, subtle neurological abnormalities are often identified during examinations of children with a variety of developmental or psychiatric conditions as well as in typically developing children. In the absence of known structural lesions in the brain, these findings are referred to as “neurological soft signs.”

The purpose of this chapter is to review common movements and subtle neurological findings in developmental and psychiatric disorders in childhood. This chapter will focus on the three most common developmental and psychiatric conditions likely to be seen in a pediatric movement disorder clinic: ADHD, OCD, and Autism Spectrum Disorder (ASD). Other behavioral and psychiatric disorders in the setting of the primary movement disorder are discussed in separate chapters. Referrals of these children to neurologists may come from pediatricians, mental health providers, geneticists, and other clinicians. While no group of motor findings is specific enough for clinical diagnosis, understanding these trends or patterns has potential clinical and research applications.

It is also important to interpret these subtle neurological findings in children in the context of the broad range of typical motor development in children. A systematic assessment of parental perceptions using the developmental coordination disorder scale showed that parents of children with ADHD or ASD judged their children to have impaired coordination and motor abilities relative to unaffected peers. Moreover, neurological soft signs can be seen during a routine, detailed neurological examination, and thus there is overlap between some typically developing children, children with neurodevelopmental disorders, and children with movement disorders. ^,

Documenting these in the patient record is useful. For example, if the child presents at a later time for evaluation of a possible drug-induced dyskinesia, referring back to the previously documented motor exam can help clarify whether the movements in question preceded exposure to the medication.

From a clinical research standpoint, a variety of formal scales may be used to evaluate these signs. Examples of formal assessment batteries include the Physical and Neurological Examination for Soft Signs scale and the Cambridge Neurological Inventory. Domains evaluated include motor and sensory function, development, and maturation of coordination and independence of bimanual movements. Ratings are based on the presence of preserved primitive reflexes, coordination and timing in performance of repeated and sequential finger movements, presence of/failure to inhibit mirror movements, and higher cortical sensory perception such as stereognosis and graphesthesia.

Uses of these motor assessment scales for “soft” neurological signs have several rationales. A typical study design involves evaluation of cases and controls, where children with a clinical categorical diagnosis are compared as a group with age and sex matched typically developing peers. Test batteries are scored in total, by domain, and by body side (right/left). Investigators test hypotheses about group differences to attempt to understand what structural and functional abnormalities, as indicated by differences in the motor system, may be present in a parallel fashion in circuits forming the substrate for emotional and cognitive dysfunction. Correlational analyses with clinical symptom severity rating scales and correspondence with other assessments such as IQ scores provide additional support for utility of these motor batteries.

A further aim is to use the motor symptoms and/or scale results to identify predictors of responses to standard pharmacological or behavioral interventions. ^, Corroborating the results with functional or connectivity imaging or quantitative neurophysiological findings could also provide a foundation for testing noninvasive or invasive brain stimulation at specific circuit nodes.

Finally, the relationship between motor abnormalities and a variety of psychiatric, developmental, and degenerative disorders has led to a motor system construct in the NIMH research domain criteria. Investigators have used the presence of movement disorders as a means for identifying meaningful subgroups within heterogeneous DSM5 diagnoses.

Attention Deficit Hyperactivity Disorder

In the Diagnostic and Statistical Manual of Mental Disorders, fifth edition (DSM-5), ADHD is defined based on the presence of at least six of nine symptoms from inattention criteria and/or at least six of nine from hyperactivity and impulsivity criteria. These must be present and cause difficulties in multiple settings, and onset must be present prior to age 12 years. Five of nine symptoms are sufficient at ages 17 years. The prevalence of ADHD in the United States in childhood is estimated to be 9.5%. While often considered a disorder of childhood, ADHD symptoms and complications can persist into adulthood.