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APNEA

Apnea may present to the neurologist either as a precise description of a prolonged respiratory pause in a neonate being monitored in the intensive care unit or as an imprecise description of a life-threatening episode. These presentations usually trigger a series of steps aimed at treating the apnea and finding its cause. These steps include: (1) close monitoring, (2) increased level of readiness to provide respiratory support, (3) clinical and laboratory investigations to determine the cause of apnea, and sometimes, (4) empirical or specific treatment to eliminate or correct the cause of apnea based on the results from the initial clinical and laboratory investigations.
A rational approach to determining the cause of apnea rests on clear understanding of the neuroanatomy of the breathing apparatus. Normal breathing occurs because of a well-orchestrated interplay among several neurological (Figure 13.1) and nonneurological structures.

Figure 13.1.— Neurological structures involved in normal breathing. A: midbrain; B: pons; C: medulla; D: cervical spine; 1: chemoreceptor; 2: dorsal respiratory group at the nucleus of the tractus solitarious; 3: ventral respiratory group at the nucleus ambiguus and nucleus retroambigualis; 4: upper airway motor neurons; 5: upper airway motor muscles; 6: phrenic center; 7: diaphragm; 8: intercostal muscle anterior horn cells; 9: intercostal muscles.