As printed in the journal New Jersey Pediatrics Fall 2017 – njaap.org
Children with developmental disabilities, such as autism spectrum disorder, mental retardation and genetic diseases, often experience a variety of movement disorders that may be difficult to diagnose and to distinguish from normal movements of childhood. When present they are often disturbing or concerning to parents. This article will review such movement disorders, providing information on diagnosis, etiology and potential treatments.
Habits are repetitive, coordinated movements commonly seen in normal individuals, particularly during periods of boredom, anxiety, self-consciousness, or fatigue. Some habits are considered to be a normal part of development, such as thumb sucking. Thumb sucking usually disappears by age 3-4 years, but it has been reported to occur in 30% of 12 year-olds, typically when they are tired. After age 9, thumb sucking is associated with emotional immaturity. Biting fingernails, pens or pencils is another common habit which is reported by 40-50% of adolescents. These actions are associated with stress and anxiety. Some habits,such as nose picking, are considered socially inappropriate. Other common habits include finger tapping or drumming, leg shaking, pushing up eyeglasses, nose rubbing, and hair twirling. Behavioral therapy can be used to reduce or eliminate bothersome and persistent habits. Note that an important factor in properly diagnosing childhood movement disorders is paying close attention to “the company it keeps”. Thus, a particular movement, say finger tapping, could represent a habit, a stereotypy, a tic or a compulsion in a given individual. Long duration or the movement in a person with mental retardation or autism suggests it is a stereotypy, coexisting obsessions suggests it is a compulsion, and absence of any of these suggest it is a habit (see below).
Mannerisms are peculiar characteristic ways of performing a normal activity, such as an odd (e.g. wiggling, stork-like steps) gait, an unusual speech pattern, or movement flourishes. Mannerisms serve to attract attention to an individual and are typically associated with personality disorders or schizophrenia.
Stereotypies are coordinated, rhythmic, repetitive, patterned movements, postures or vocalizations that are carried out virtually the same way over and over again for prolonged periods of time. Like tics, they can be divided into simple and complex forms. Examples of simple stereotypies are body rocking, head nodding, finger flapping, and moaning. Walking in circles, standing/sitting, repetitive words or phrases would be considered complex stereotypies. Also, like tics stereotypies can be of motor or vocal types. Stereotypies are commonly associated with mental retardation, with one study showing them present in about one-third of institutionalized adults (rhythmic movements in 26%, posturing in 13% and object manipulation in 7%). Some stereotypies can be self-injurious, such as head banging, skin scratching or eye poking, particularly in individuals with intellectual disability. Steretypies are also commonly seen in patients with autism. A particular type, hand knitting, wringing or washing-like movements, point to the autistic disorder Rett syndrome. Two opposing hypotheses have been presented to explain the occurrence of stereotypies, particularly in those with autism. One proposes that autism represents a type of sensory and social isolation and that stereotypies are attempts by the individual at self-stimulation (they are therefore sometimes referred to as “stims”). An alternate view is that the repetitive actions are attempts to filter out and decrease what is felt to be an overstimulating environment. The fact that stereotypies frequently occur in people with congenital blindness and deafness (noises in deaf children but not blind) has been used to support the notion that they occur in the setting of sensory deprivation or perhaps represent a manifestation of inappropriate processing of external stimuli. Stereotypies are generally treated when they are self-injurious or otherwise disabling. Due to evidence of increased brain dopamine with stereotypies, dopamine receptor blockers (antipsychotics) and dopamine depletors (tetrabenazine and newer derivatives) can be used.
Compulsions are repetitive and seemingly purposeful behaviors that are often performed in response to obsessions, according to rules (ritualistic), or to ward off future harm or a dreaded event. Attempts are made to ignore, resist or suppress the behavior. When compulsions are disabling, the diagnosis obsessive-compulsive disorder (OCD) is applied. Common compulsions include checking, counting, ordering/lining up, perfectionism and hand washing. Compulsions have been linked to abnormalities in the basal ganglia of the brain and disturbed serotonin neurotransmission. Cognitive behavioral therapy, selective serotonin reuptake inhibitors and atypical antipsychotics are standard treatments; deep brain stimulation (usually invoking the nucleus accumbens) is used in severe cases.
Tics are involuntary movements (motor tics) or sounds (vocal tics). Simple motor tics consist of quick twitches or jerks, such as eye blinking, facial movements, head jerks. Complex motor tics involve more complex or purposeful-looking movements, such as touching, tapping, hopping, skipping. Simple vocal tics are sounds and noises like throat clearing, grunting, coughing, humming, etc. When there is linguistic meaning to the utterances (syllables, words, phrases) they would be considered complex vocal tics. These may include obscene or socially inappropriate verbalizations (coprolalia), but this phenomenon is uncommon in patients with tics. The presence of chronic (present for at least 1 year) motor and vocal tics in the absence of a primary cause such as medication-induced or an underlying brain disease (e.g. head trauma, encephalitis) signifies a diagnosis of Tourette’s syndrome (TS). Tics are common in children with autism and mental retardation. In this circumstance, they are considered secondary to the primary brain disorder and the diagnosis of TS is not used. Since they commonly occur together, there is often an overlap between the phenomena of tics and compulsions (“compultics” such as having to tap a certain number of times) and impulsiveness (“impultics” such as kicking or punching someone or having an urge to touch a hot stove). These overlap symptoms typically require treatment aimed at both phenomena to gain full control. Disabling tics can be treated with habit reversal behavioral therapy, an alpha-agonist such as guanfacine and an antipsychotic drug (classical or atypical). Derivatives of tetrabenazine have recently become available and they show evidence of suppressing tics.
Children with brain developmental disorders, often with cerebral palsy, commonly experience the movement disorders athetosis (flowing, wriggling and twisting movements; athetoid cerebral palsy) or dystonia (slow twisting or tightening movements). Anticholinergic or muscle relaxing medications (e.g. baclofen) may be helpful, but local intramuscular injection of botulinum toxin has become the standard treatment.
Finally, it is important to consider the possibility that any observed involuntary movements might be side effects of medications prescribed for other purposes, particularly antipsychotics or antiemetic drugs. These include acute dystonia when the drugs are initiated and, usually with more chronic use, parkinsonism, tardive dyskinesia, and akathisia (motor restlessness often associated with pacing, getting up and down from chairs).
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