Childhood Habit Behaviors and Stereotypic Movement Disorder Clinical Presentation

The history consists of reports of observed specific behaviors associated with the individual habit. Intensity, severity, and duration may be variable. Habit behaviors may be present for a long time before consultation is sought. Complaints at the time of presentation for evaluation or treatment may be either physical or psychological sequelae of the habit (see Pathophysiology).

Common stereotypies

The range of habits or common stereotypies is described below in chronological order. These rarely require medical attention. In some children, a natural progression is seen, beginning with thumb or hand sucking and then progressing to body rocking and head banging and, later still, to nail biting and foot or finger tapping.

Thumb or hand sucking is first seen in utero, and is the earliest common stereotypy.^[22] Hand sucking rarely persists beyond infancy. Thumb sucking is not usually associated with medical sequelae unless it persists beyond the age of 4. It can then lead to dental malocclusion, digital deformities, temporomandibular disorders, and social stigmatization.

Body rocking is usually seen just before sleeping or after waking. Head banging often occurs during teething, ear infections, and temper tantrums. It may cause abrasions and callus formation, but only rarely does it lead to fractures or more serious injury.

Nail biting is the most common stereotypy of later childhood. It leads to shortened, irregular fingernails that may be aesthetically unpleasant. It also predisposes to paronychia and herpetic whitlow. Again, the behavior is increased with anxiety and stress.

Trichotillomania is the repeated plucking of scalp or body hair, leading to clinically significant hair loss. Most sufferers have no other comorbidities, but the condition is related to body dysmorphic disorders, personality disorders, and eating disorders.^[16] The most common sites, in order of decreasing frequency, are scalp, eyelashes, eyebrows, and pubic hair.

Bruxism can happen subconsciously at night as well as during the day. Complications include mechanical wear, teeth fractures, temporomandibular disorder pain, headache, and neck pain.^[14]

Complex motor stereotypies

Complex motor stereotypies may include flapping, waving, opening and closing of a fist, finger wiggling, or wrist flexion and extension. They can be primary or secondary, and the main concern for parents and professionals is that they may be manifestations of an underlying disorder.

No clinical features enable differentiation of stereotypies between normally developing children and those with autism or developmental delay. In both groups, the movements can last for more than a minute, and can occur multiple times in a day. In autism, they tend to occur for a longer duration overall.^[23] The movements can be associated with other clinical features, such as skin picking, mouth opening, facial grimacing, and involuntary noises.

The most common trigger is excitement or being happy. Concentration on a task, tiredness, and anxiety are also triggers. More than 1 trigger is present in most children. In most cases, movements cease if the child is distracted (eg, by calling his or her name). Movements also do not occur in sleep.

Atypical gazing at objects or fingers has been described in children with autism.^[18] These have been termed complex visual stereotypies and appear to occur only as secondary stereotypies. Abnormal pacing, running, or skipping have also been considered to be secondary stereotypies. Again, they are strongly associated with autism rather than other disorders.^[18]

The presence of other stereotypies, tics, or obsessive tendencies should also be sought in the history because in more than one third of children, they are associated with complex motor stereotypies.

Head nodding

The characteristics of head nodding are slightly different from those of complex motor stereotypies of the limbs. Head nodding is a regular rhythmical movement of the head and neck, which may be up-and-down, side-to-side, or shoulder-to-shoulder. It has an earlier age of onset than complex stereotypies of the limbs, and episodes occur more than once a day. Head nodding is unlikely to be associated with a family history, unlike other forms. In addition, most cases regress in later childhood.

Other components of history

A birth and developmental history should always be taken, including pregnancy, gestation, delivery, and developmental milestones. These may identify underlying disorders and so are essential for differentiating primary and secondary complex motor stereotypies. In autism, children show limited social and communication skills and a restricted range of activities. Even children with primary stereotypies may have mild language delay despite normal intelligence.^[21]

A comprehensive family history is important because 25% of children have at least 1 affected family member.^[19] The family history should also include asking about the presence of other developmental and movement disorders.

A drug history is also advisable. Although drugs are rarely implicated, clinicians should be aware that chronic neuroleptic drug use can lead to stereotypies, usually as part of a tardive dyskinesia. Amphetamine poisoning in children has been reported to cause self-injurious stereotypies, including head banging and hand biting.

Physical examination is guided by the history and the types of stereotypies present. Most childhood habits are benign and have no specific observable physical signs, aside from the movements themselves. However, when physical signs are present, they typically are nonpathologic and often were previously unnoticed. In severe cases, physical evidence of a habit may be related to an associated injury or physical sequelae of the specific behavior the child engages in.

Thumb and digit sucking continued beyond age 4-5 years can result in dental problems, especially malocclusion, mucosal trauma, decreased alveolar bone growth, and abnormal growth of facial bones. These children also have an increased risk of accidental ingestions and pica. Thumb callus and skin breakdown may occur. Deformities of the fingers and thumbs and paronychia occur relatively infrequently.

Nail biting can be associated with extremely short fingernails, paronychia, oral herpes, herpetic whitlow, damaged dentition, apical root resorption, fractures to the incisors, and gingivitis.

Epistaxis is the most common complication of nose picking. In rare cases, complications may include perforation of the nasal septum or infection.

Bruxism can result in chronic dental pain, dental fractures, wearing down of dental enamel, thermal hypersensitivity of the teeth, hypermobility of the teeth, injury to the periodontium, and pulpitis. Dysfunction of the temporomandibular joint and recurrent headaches may also occur.

In children who have breath-holding spells, Injury may result from a fall secondary to loss of consciousness and muscle tone. In some cases, a child may have a seizure secondary to the breath holding.

Head banging rarely causes physical or intracranial injuries, even when it is forceful. Head banging may cause callus formation, abrasions, and contusions at the site of the banging. The risk of injury is increased in children with bleeding disorders. Skull fractures, eye injuries, and dental injuries have rarely been reported.

Body rocking and rhythmic movements generally do not give rise to significant physical signs. In rare cases, self-injurious rhythmic movements may occur and result in various associated physical injuries.

Efforts should also be made to look for other movement disorders, such as tics or chorea. Sensory and motor examination identify underlying pathology. Blindness, deafness, hemiparesis, and cerebral palsy are causes of secondary stereotypies.