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Motor Stereotypies
Introduction and Overview
The definition, characteristics, classification, pathophysiology, disorders, and treatment of motor stereotypies continue to evolve. Historically, stereotypic movement disorders in children have been linked to autism and intellectual impairment, although they commonly occur in typically developing children. Motor stereotypies can be readily classified into two groups: “primary,” indicating an otherwise typically developing individual, and secondary, for those associated with other neurodevelopmental problems (e.g., autism). Both types of stereotypies usually begin in early childhood, frequently persist into adulthood, and are often a source of concern for parents. Although viewed by some as behaviors produced to alter a state of arousal, there is increasing evidence to support neurobiological mechanisms.
Definitions
In the absence of biological, neurophysiological, or diagnostic biomarkers for stereotypies, this hyperkinetic movement disorder is defined chiefly by phenomenology. Several cited definitions include (1) “involuntary, rhythmic, repetitive, fixed (fashion, form, amplitude, and location) movements that are prolonged in duration, appear purposeful, but are purposeless (serve no obvious adaptive function or purpose, i.e., non-goal directed), and stop with distraction” ; (2) “a non-goal-directed movement pattern that is repeated continuously for a period of time in the same form and on multiple occasions, and which is typically distractible” ; and (3) “involuntary, coordinated, patterned, repetitive, rhythmic, purposeless but seemingly purposeful or ritualistic movement, posture or utterance.” Excluded movements are those that arise from the physiologic effect of a substance, delusional beliefs or obsessive thoughts, and mannerisms. The Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition, (DSM-5) criteria for a stereotypic movement disorder includes (1) repetitive, seemingly driven, and apparently purposeless motor behavior; (2) the behavior must interfere with social, academic, or other activities or cause self-injury; (3) onset is in early development; and (4) is not attributable to a substance or neurologic condition, nor better explained by another neurodevelopmental or mental disorder.
Clinical Characteristics, Classifications, and Differentiation
Characteristic Features
Motor stereotypies typically begin before age 3 years. Movements occur in bursts, are prolonged in duration (last from to minutes or longer), appear multiple times per day, have a fixed pattern, are associated with periods of engrossment, excitement, stress, fatigue, or boredom, and stop with distraction. Each child typically has his or her own repertoire that may evolve gradually over time. See section on Diseases and Disorders for an expanded description of movements and etiologies.
Classifications
Stereotypies can be classified based on phenomenology or on etiology (see Table 8.1 ).
Table 8.1
Classification of Stereotypies
| I. Phenomenology |
| Simple type |
| Head nodding |
| Complex motor |
| II. Etiology |
| Primary (physiologic) |
| Stereotypies in typically developing individuals. |
| Secondary (pathologic) |
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|
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| Head nodding: |
| Rhomboencephalosynapsis; bobble-headed doll syndrome; Sandifer syndrome, Spasmus nutans, oculomotor apraxia |
Phenomenology
Based on phenomenology, stereotypic movements have been classified into three categories: simple, head nodding, and complex. An expanded discussion of each of these disease categories is within the Diseases and Disorders section.
- (a)
Simple stereotypies are repetitive behaviors that often involve a single extremity and can include behaviors such as thumb sucking, nail/lip biting, hair twirling, body rocking, leg swinging, self-biting, and head banging. Often labeled as habits, they are relatively common in childhood and generally most regress.
- (b)
Head nodding stereotypies have been variably placed into their own category or considered a complex stereotypy. These involve periodic, rhythmic head nodding, without associated nystagmus. These head movements may be either side-to-side (“no-no” movement), up-and-down (“yes-yes” movement), or a shoulder-to-shoulder (“figure of eight”) movement.
- (c)
Complex motor stereotypies (CMS) are bilateral and typically include flapping, rotating, or opening and closing of the hands, fluttering fingers in front of the face, flapping/waving arm movements, and flexion and extension of the wrists. , Additionally, affected individuals often have accompanying movements such as mouth opening, head tilting, body rocking, leg shaking, jumping, and pacing Involuntary vocalizations may also accompany motor stereotypies. Additional characteristics are discussed in the Diseases and Disorders section, below.
Etiology
Based on etiology, stereotypies have been divided into two groups, primary and secondary.
- (a)
Primary stereotypies indicate that the child is otherwise developmentally normal, although mild delays in either language, social, or motor development have been reported. Although the precise prevalence is unknown, repetitive motor stereotypic behaviors are common in typically developing children.
- (b)
Secondary stereotypies imply the individual has other developmental problems or diagnoses (e.g., autism, Rett syndrome [RS], intellectual impairment, or sensory deprivation) ( Table 8.1 ). While some investigators have suggested that a particular movement, complexity, duration, frequency, or accompanying vocalization may be more indicative of a secondary type, , others have emphasized that there is considerable overlap in movements observed in primary and secondary affected individuals.
Differentiating Stereotypies from Other Movement Disorders
The diagnosis of stereotypies requires the exclusion of other disorders such as mannerisms, complex motor tics, obsessive compulsive behaviors, paroxysmal dyskinesias, and seizures. Visualization of the movements is essential for proper diagnosis. Motor stereotypies should also be considered distinct from the multiple domains of repetitive behaviors often mentioned with autism, for example, restricted interests and routines, cognitive rigidity symptoms, unusual sensory responses, social communication difficulties, preoccupations, circumscribed interest patterns, and abnormal object attachments.
- (a)
Mannerisms are gestures or individual flourishes/embellishments that are components of normal activity (e.g., a baseball player's rituals before a pitch). These movements tend to be unique to the individual can be repetitive, do not appear in clusters, are of brief duration, and are less complex than stereotypies.
- (b)
Complex motor tics: Stereotypies are often misdiagnosed as complex motor tics (see Table 8.2 and Chapter 7 ), a confusion generated, in part, by the fact that both may occur in the same patient. , , Complex motor tics are quick, rapid, repetitive movements that involve either a cluster of simple motor tics or a more coordinated sequence of movements. Complex tics have several features in common with stereotypies; for example, they are often repetitive, patterned, and intermittent and may be precipitated by excitement. Several characteristics, however, are helpful in differentiating stereotypies from complex motor tics. Stereotypies have an earlier age at onset (<3 years) than do tics (mean onset 5–8 years). They are consistent and fixed in their pattern as compared to the marked variations in frequency, intensity, and pattern of tics. In terms of body location, stereotypies frequently involve arms, hands, or the entire body rather than the more common tic locations of eyes, face, head, and shoulders. Stereotypies are more fixed, rhythmic, and prolonged in duration than are tics which, except for the occasional dystonic tic, are brief, rapid, random, and fluctuating. Stereotypies, in contrast to tics, are not associated with premonitory urges, preceding sensations, or an internal desire to perform. Both occur during periods of anxiety, excitement, or fatigue, but stereotypic movements are also common when the child is engrossed in an activity. Both tics and stereotypic movements are reduced by distraction, but the effect on stereotypic movements is more dramatic. Additionally, temporal and spectral analyses using a force sensitive platform showed that stereotyped movements differ from tics both quantitatively and qualitatively. Lastly, it is important to emphasize that both stereotypies, irrespective of whether primary or secondary, and tics can occur in the same individual. , ,
Table 8.2Factors Distinguishing Stereotypies From TicsAdapted from Mahone et al. [ ].Features Tics Stereotypies Age at onset 3–10 years <3 years Pattern Variable, wax and wane Fixed, identical, patterned, predictable Movements Blink, grimace, twist, shrug Arms/hands (flap, wave), body rock/head nod Vocalizations Sniffing, throat clearing Moan, humming with movement Rhythm Rapid, sudden, random Rhythmic Duration Intermittent, brief, abrupt Intermittent, continuous, prolonged Premonitory urge Yes No Precipitant Excitement, stress, relaxation, boredom Excitement, stress, engrossment, stimulation, or lack of it Suppression Brief, voluntary (but have increased “inner tension”) With distraction, rare conscious effort Distraction Reduction of tics Stops Family history Frequently positive Positive, 25% Force sensitive platform analysis Brief, less rhythmic Longer duration: more rhythmic qualities Treatment Behavior therapy, clonidine, guanfacine, D2 receptor antagonists Behavioral therapy - (c)
Compulsions are repetitive behaviors that are performed to prevent or reduce distress or some dreaded event or situation and are driven by an obsessive thought or by intrinsic rules that must be applied rigidly. The compulsion is either (a) unrealistically connected to distress reduction or contingency prevention or (b) clearly excessive. Compulsions are often associated with obsessive thoughts that intrude into consciousness and are typically experienced as senseless or alien.
- (d)
Paroxysmal dyskinesias are generally shorter in duration and usually occur as dystonic or choreoathetoid movements that are precipitated by voluntary movement (paroxysmal kinesigenic dyskinesias), exertion of exercise (paroxysmal exertional dyskinesia), or are less predictable, arising from normal background activity (paroxysmal nonkinesigenic dyskinesias) (see Chapter 9 ).
- (e)
Masturbation, or self-stimulation of the genitalia, is a normal part of human sexual behavior that occurs in both males and females. In some infants and young children, such self-gratifying behavior can manifest as patterned, coordinated, repetitive movements, usually consisting of crossing and extending of legs or repetitive pelvic movements that may be classified as a stereotypy. , Observation of movements on a video can often clarify the diagnosis and eliminate the need for unnecessary diagnostic tests. The most challenging aspect of this form of stereotypy is to help the parents understand the benign and self-remitting nature of this behavior.
- (f)
Seizures, or more specifically automatisms in the context of epileptic seizures, are also within the differential diagnosis of stereotypies. In 17 patients, motor stereotypies were associated with prefrontal cortex (PFC) seizure activity. Although not mentioned, it is assumed that the seizure was not aborted by a sensory stimulation. Sunflower syndrome can also cause diagnostic confusion. This is a rare photosensitive epilepsy with a characteristic stereotypic handwaving motion in front of the face that can either be a mechanism of seizure self-induction or a component of the seizure. ,
Pathophysiology
The underlying pathophysiological mechanism for stereotypies in both primary and secondary categories is unknown, with hypotheses ranging from psychological concerns to neurobiological abnormalities.
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