Hyperventilation syndrome from MedLink Neurology available at www.medlink.com

Historical note and nomenclature According to 1 consensus definition, "hyperventilation syndrome is a syndrome characterized by a variety of somatic symptoms induced by physiologically inappropriate hyperventilation and usually reproduced in whole or in part by voluntary hyperventilation" (Lewis and Howell 1986). Acute hyperventilation with obvious tachypnea accounts for about 1% of all cases of hyperventilation (Lum 1975). The other 99% of cases are due to chronic hyperventilation where there may be a modest increase in respiratory rate or tidal volume, which may not even be apparent to the patient or a medical observer. The symptoms of hyperventilation syndrome have been recognized for at least 125 years. In 1871, Da Costa published a paper, On Irritable Heart; a Clinical Study of a Form of Functional Cardiac Disorder and its Consequences, describing 300 Union soldiers in the American Civil War with a mysterious illness (Da Costa 1871). He felt the condition could be seen in private practice as well. Symptoms included palpitations, chest pain, shortness of breath or oppression on exertion, indigestion, abdominal distention, and diarrhea. Headache, giddiness, disturbed sleep, and dizziness were "all indicative of disturbed circulation in the cerebro-spinal centres." Da Costa reasoned that "the heart has become irritable, from its over-action and frequent excitement...." During World War I, similar symptoms often associated with fatigue were also attributed to cardiovascular dysfunction and described as "soldier's heart" (Lewis 1919) or "neurocirculatory asthenia" (Levine 1965). In contrast, Gowers used the terms "vagal" and "vaso-vagal" for these symptoms, which could include numbness and tingling of the extremities (Gowers 1907). In 1922, Goldman was the first to make the connection between "forced ventilation" and tetany and postulated that the tetany was due to alkalosis (Goldman 1922). Kerr and colleagues introduced the term "hyperventilation syndrome," and they described the variety of symptom complexes caused by physical phenomena associated with anxiety states, which could often be reproduced in the examining room with the "hyperventilation test" (Kerr et al 1937; 1938). Lewis contended that acute and chronic hyperventilation syndrome occurred frequently and described the common and atypical presentations, pathophysiology, and therapy (Lewis 1953). He reported that paresthesias were occasionally asymmetrical and could even be unilateral. Tavel described patients with hyperventilation syndrome presenting with unilateral paresthesias at times associated with subjective unilateral weakness that involved the left side of the face and body more commonly than the right (Tavel 1964).