Cheyne-Stokes breathing, the common and well-known waxing and waning type of cyclic ventilation reported by Cheyne in 1818 and later elaborated by Stokes, has for decades been ascribed to a prolongation of circulation time, as in congestive heart failure; but there are data that support a primary neural origin of the disorder, particularly the observation that it occurs most often in patients with deep hemispheral lesions of the cerebral hemispheres or advanced stages of metabolic encephalopathy. The level of consciousness in these circumstances parallels the respiratory pattern. During the apneic period the patient is less responsive. The onset of respiration is heralded by arousal, marked by eye opening and sometimes vocalization. At the peak of the hyperventilation phase, the patient is maximally awake. Consciousness then wanes followed by slowing of the respiratory rate and finally coma to complete a full cycle. The fact that the level of consciousness changes before the respiratory rate is altered implies that Cheyne-Stokes breathing is only one component of a cyclic autonomic brainstem phenomenon. (See Chap. 16 for further comments on the physiologic explanation for this pattern.)
Another striking aberration of ventilation is a loss of automatic respiration during sleep, with preserved voluntary breathing (Ondine’s curse). The term stems from the German myth in which Ondine, a sea nymph, condemns her unfaithful lover to a loss of all movements and functions that do not require conscious will. Patients with this condition are compelled to remain awake lest they stop breathing, and they must have nighttime mechanical ventilation to survive. Presumably the underlying pathology is one that selectively interrupts the ventrolateral descending medullocervical pathways that subserve automatic breathing. The syndrome has been documented mostly in cases of unilateral and bilateral brainstem infarctions, hemorrhage, encephalitis (neoplastic or infectious—for example, due to Listeria), in Leigh syndrome (a destructive process in the lower brainstem of mitochondrial origin), and with traumatic Duret hemorrhages in the lower brainstem. The issue of a loss of automatic ventilation as a result of a unilateral brainstem lesion has been addressed earlier. A state in which there is complete loss of voluntary control of ventilation but preserved automatic monorhythmic breathing has also been described (Munschauer et al). Incomplete variants of this latter phenomenon are regularly observed in cases of brainstem infarction or severe demyelinating disease, and may be a component of the “locked-in state.”
Often neglected is the dyspnea that patients experience with orthostatic hypotension (orthostatic dyspnea). In a questionnaire given to patients in an autonomic laboratory, Gibbons and Freeman (2005) reported that one-third had this symptom. They proposed that some form of mismatch between lung ventilation and perfusion was the cause.
The congenital central hypoventilation syndrome is thought to be an idiopathic version of the loss of automatic ventilation (see Shannon et al, 1976). This rare condition begins in infancy with apneas and sleep disturbances of varying severity or later in childhood with signs of chronic hypoxia leading to pulmonary hypertension. As mentioned in “Sleep Apnea and Excessive Daytime Sleepiness” in Chap. 18, several subtle changes in the arcuate nucleus of the medulla and a depletion of neurons in regions of the respiratory centers have been found in this condition, but further study is necessary.
Neurologic lesions that cause hyperventilation are diverse and widely located throughout the brain, not just in the brainstem. In clinical practice, episodes of hyperventilation are most often seen in anxiety and panic states. The traditional view of “central neurogenic hyperventilation” as a manifestation of a pontine lesion has been brought into question by the observation that it may occur as a sign of primary cerebral lymphoma, in which postmortem examination has failed to show involvement of the brainstem regions controlling respiration (Plum).