There are many neurological disorders that can produce apnea. The neurological disorders that can produce apnea may involve the neuroaxis at different levels. Apnea may occur due to lesions in the brain, brainstem, spinal cord, or phrenic and upper airway muscle motor units.

Brain lesions produce apnea by two mechanisms: seizures and transtentorial herniation.

Seizures
Electroencephalographic seizures are an important cause of apnea in neonates (Figure 22.1). Apnea due to seizures may be associated with other clinical manifestations, such as paroxysmal motor events, or it may occur without any associated clinical manifestations.

Figure 22.1.— Mixed (central-obstructive) apnea. Left-sided electroencephalographic seizure. The apnea is associated with tachycardia and desaturation.

The seizure may be due to a metabolic problem (hypoglycemia or hypocalcemia) or structural supratentorial lesions. The most frequent supratentorial causes of apneic seizures are hemorrhage (Figure 22.2) and herpetic encephalitis involving the temporal lobes. The clinical presentation encountered in neonates with apnea due to seizures depends on the cause of the seizures. Apnea triggered by seizures occur during any behavioral state, are not associated with bradycardia unless longer than one minute,and can be either central or mixed.

Figure 22.2.— MRI of the brain demonstrating left temporal lobe hemorrhage.

During apnea triggered by seizures, the EEG recording will show an electroencephalographic seizure. The origin of the electroencephalographic seizure is usually the temporal lobe. The EEG pattern that usually occurs with apneic seizures consists of rhythmic alpha activity.Neonates with apneic seizures should undergo MRI of the brain because of the possibility of a structural brain lesion, and a metabolic evaluation because of the possibility of a metabolic disorder.