Movement Disorders (18)
Benign Nenoatal Sleep Myoclonus. Benign neonatal sleep myoclonus is the most common quasi-epileptic disorder (19, 20). It usually occurs during sleep and begins early in infancy, often in the first weeks or months of life; however, it can be seen in older infants and even in young children. The disorder occurs during non-rapid eye movement (NREM) sleep. Rapid, forceful jerks may occur in the distal extremities, such as the hands or feet, or in the more proximal muscles, moving the entire limb or the trunk. The jerking usually recurs every 2 to 3 seconds, and episodes may last as long as 30 minutes, although most subside in 1 to 3 minutes only to recur repeatedly during the night. The movements migrate from one muscle group to another. Movements occur on both sides of the body. The involvement usually is synchronous, but it need not be. However, prolonged, repetitive involvement of the same muscles or repetitive synchronous involvement of the same muscle groups on the right and left sides of the body are more likely to be a true seizure. The movements of benign neonatal myoclonus are not stimulus sensitive, and the EEGs taken during sleep reveal that epileptiform activity is not present while the events are going on. The source of the myoclonic movements is thought to be in the brainstem. The movements stop if the child is awakened. When alert, the infant is seen to be developing normally and to have a normal neurologic examination.
Benign neonatal myoclonus is extremely disturbing to parents, but the movements rarely interfere with the infant's sleep and normally do not require treatment. If absolutely essential, the movements can generally be reduced by giving a small dose of clonazepam before bed. The prognosis for these infants is a good one. If the movements begin in early infancy, they tend to disappear in 3 to 4 months. Those few children who develop sleep myoclonus later in infancy may continue to exhibit the movements into the second year of life. There is no indication that benign neonatal myoclonus is associated with a higher incidence of epilepsy or abnormal neurologic development later in life.
Head Banging and Other Rhythmic Parasomnias. Repetitive episodes of head banging can occur as an infant is falling asleep and may be mistaken for a seizure because, unlike diurnal episodes of stereotyped movements, they are not associated with emotional disturbances such as anxiety or frustration (21, 22). Other rhythmic movements of the neck and trunk, such as head rolling, body rocking, and leg banging, can occur in children during stage 2 of sleep. These movements are unassociated with EEG abnormalities and can easily be differentiated from seizures by video-EEG or polysomnographic monitoring. If the movements are violent enough to require treatment, they can usually be modified by giving clonazepam before bedtime. Periodic leg movements do not appear to quantitatively alter the quality of sleep in adults (23).
Paroxysmal Hypnogogic Dyskinesia. Hypnogogic paroxysmal dyskinesia or dystonia is a rare disorder in which sleep is interrupted for brief periods of time (usually less than 1 minute) several times each night by severe dystonic, ballistic, or choreic movements sometimes accompanied by screaming (21). The motor patterns are complex with bimanual/bipedal activity, rocking axial and pelvic movements, and sometimes ambulation. Prolonged attacks are believed to be epileptic and arise from the frontal lobe from areas that cannot be accessed by scalp tracings. Thus, the interictal EEG is usually normal as are many ictal EEGs, although carbamazepine often reduces the number of events. Many patients with this disorder go on to develop other forms of diurnal seizures. The disorder indicates how difficult it may be to separate epileptic from nonepileptic events (24, 25).
Apnea. Disturbances of breathing during sleep are common in infants and children. Periods of apnea without other signs are rarely epileptic when they occur during sleep, but the abrupt cessation of respiration can sometimes be the only sign of a seizure in infants and young children (26, 27). The associated electrical abnormality is usually focal and in the temporal area; however, apnea has been described as the only manifestation of diffuse epileptiform discharges as well.
Usually disorders leading to periods of apnea during sleep are classified as central, obstructive, or mixed (28). Most premature infants and some older infants have apneic events that can be central, secondary to delayed maturation of the centers that control breathing (29), or obstructive, resulting from partial constriction of the upper airway. Polysomnography uses airflow monitors and strain gauges to relate movement of the chest and abdominal musculature to effective rhythmic inspiration and expiration. In obstructive apnea, movements of chest or abdominal musculature continue while the flow of air is markedly decreased or stopped. This is followed by a significant drop in the oxygen saturation of the blood. In central apnea, muscle movements decrease coincident with the drop in airflow. More sophisticated measures of Pco2 and transesophageal pressure may identify more subtle disorders of breathing during sleep (30, 31).
Central apnea has been reported with tumors of the brainstem or compression of the medulla or upper cord by a mass, bony deformities of the upper spine or foramen magnum (32), partial herniation of the brain, or a Chiari malformation. Metabolic or infectious disorders that damage the respiratory center in the medulla may result in loss of automatic control of respiration during sleep (Ondine's curse), producing long periods of apnea sufficient to cause further brain damage or even death.
Obstructive or mixed forms of apnea are frequently seen in young children with cranial-facial deformities that narrow the oropharynx or with adenotonsillar hypertrophy (33, 34). Aspiration may cause similar problems and is more likely to occur in infants or children with significant neurologic damage. However, gastroesopha-geal reflux can occur in children who are neurologically normal and produce significant repeated periods of apnea in sleep as well as in the waking child.
The behavioral parasomnias noted in children that are often mistaken for epileptic activity include sleepwalking (somnambulism), night terrors (pavor nocturnus), and nightmares (36, 37). The violent behaviors in non-REM sleep in older adults that can result in injury to themselves or to others are rarely seen in children (38).
Sleepwalking. Sleepwalking usually begins between 5 and 10 years of age and can persist into adult life (39). Approximately 15% of all children sleepwalk at least one time. Repeated episodes are much less frequent involving less than 2% of the population. Sleepwalking is often confused with automatisms seen with complex partial seizures. The cause of the disorder is not known, but there is a definite increase in the prevalence of sleepwalking in the family members of children who suffer from the problem. Sleep-disordered breathing is also a predisposing factor. Episodes of sleepwalking usually occur 1 to 3 hours after sleep begins. The child arises and walks about the room or the house in a trance and then walks back to bed. Semipurposeful behavior such as undressing and dressing may occur during the attack. The child's eyes are open and the child rarely walks into objects. The child often mumbles, but there is no purposeful speech. Sleepwalkers can sometimes be directed back to bed, but they often become agitated if restrained. If the child is left alone, physical violence is usually not a part of the attack. The child has no memory of the event the next morning. Attacks sometimes increase with stress.
Usually no treatment is required other than providing for the safety of the child, and the disorder subsides spontaneously over a period of several years. Frequent or prolonged attacks can be treated with benzodiazepines. Polysomnography may reveal a predisposing sleep disorder. Treatment of the underlying problem may also reduce or eliminate episodes of sleepwalking (37).
Night Terrors (Pavor Nocturnus). Night terrors are most commonly seen in children between 5 and 10 years of age. The disorder also occurs in the first 3 hours of sleep in stages 3 or 4 of slow-wave sleep. It may be confused with complex partial seizures. The cause is not known, but there is a familial predisposition. As with sleepwalking, night terrors can be associated with disturbed sleep and a result of disordered breathing or periodic leg movements. Night terrors do not appear to be related to the presence or development of epilepsy or other neurologic or psychiatric disorders. Approximately 3% of all children have this disorder. The child often screams and then sits up. The child continues to scream and appears to be terrified. There are signs of increased sympathetic activity such as excessive sweating and dilated pupils. The attack can last up to 10 minutes, after which the child falls back to sleep. When awakened, the child has no recollection of the event.
Nightmares. Night terrors must be distinguished from nightmares. The latter usually occur later in the night during REM sleep. The EEG is normal. The child may be restless during the dream but usually does not scream. The child often recalls the nightmare and develops a fear of sleeping alone.
Complex partial seizures that occur during sleep are usually associated with automatisms other than walking or with episodes that can be mistaken for night terrors (41). The behaviors are usually abrupt at onset, and if there are movements, they are frequently the same in each attack. The patient may appear anxious, but screaming and sympathetic overactivity are not seen unless someone tries to interrupt the seizure. The child may be incontinent. A video-EEG is sometimes needed to make a diagnosis.
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