Chapter 5. Paroxysmal Disorders

Three of the most common neurological paroxysmal disorders in childhood are headache, sleep disorders, and epilepsy. As these subjects are examined thoroughly in other chapters in this book, they will not be covered here. Instead, this chapter will cover non-epileptic neonatal events, breath-holding spells, syncope, paroxysmal dyskinesia, episodic ataxia, tics, panic disorder, and psychogenic non-epileptic seizures in children.

The following events may appear similar to seizures but are of non-epileptic origin.

Apnea

Definitions and Epidemiology

Short pauses in breathing are normal in infants. Apnea in a premature infant is longer than 20 seconds, and in a mature infant is more than 15 seconds. The more premature the infant, the greater the risk of apnea. There is often associated temporary paleness or bluish skin, and decreased muscle tone. In a premature infant, apnea can be associated with bradycardia. There is an increased risk of infant apnea if the infant is male, is of premature birth, has a teenage mother, or is one of multiples (twins or multiple-birth siblings).

Pathophysiology

In the neonate, apnea if often due to respiratory center immaturity. In an infant up to 1 year of age, apnea can be caused by a number of medical conditions. These include stroke, meningitis, hypoglycemia, infection, airway obstruction, gastroesophageal reflux, and medication effect. If apnea is associated with eye deviation or rhythmic jerky eye or body movements, one should consider the possibility of a seizure.

Treatment

Treatment is dependent on the underlying mechanism, if one can be found. Tactile stimulation of the infant during an event can often abort the apnea. An apnea monitor, continuous positive airway pressure (CPAP) machine or an oxygen hood may be used to treat the infant.

Benign Sleep Myoclonus

Definitions and Epidemiology

Hypnogogic myoclonic jerks are common in all ages and are commonly called "sleep starts." In infants before 3 months of age, benign myoclonic jerks are seen in non–rapid eye movement (NREM) sleep and are usually symmetric and bilateral. Usually, they involve both arms and legs but can rarely be isolated to a single extremity.

Clinical Presentation and Differential Diagnosis

Electroencephalography during the episode is normal. Movements can happen repetitively every 2 to 3 seconds sounding similar to a seizure.1 However, they only happen in sleep, and the child's examination and development is usually normal. If the child is awoken during these movements, they stop immediately. If the movements continue after the child is awoken, seizure should be considered. Benign sleep myoclonus is different than the many other causes of non-epileptic myoclonus.

Pathologic focal, multifocal, or generalized myoclonus can be seen during wakefulness or sleep. It is sometimes stimulus induced. Hypoxic-ischemic encephalopathy, metabolic encephalopathy, head trauma, stroke, and medications can all cause myoclonus.