More Than "Just Another Conversion Reaction!" A Case of Hyperventilation Syndrome

Case: A 26 years old woman was admitted to the emergency unit of Trakya University Hospital (Edirne, Turkey), which is 8 km from the city center. The first encounter at this center is made by a family physician with special training in emergency medicine. Other specialists are asked for consultation according to necessity.

The patient was admitted with complaints of spasms of hands and feet, and paraesthesia at her whole body. Her complaints began four hours ago and she had vomited once. She had spasm like twisting in the hands. She reported a similar history, but in a milder form without contractions 8 years ago, when she entered the national university entrance exam. Her personal medical history was unremarkable. She underwent two cesarean sections and had two healthy children at the ages 2 years and 6 months. Family history and drug usage history was unremarkable as well. She looked anxious and had flexion contractions in both hands. Her respiration was fast (24/min) and deep. Chvostek finding was positive. Other systemic physical examination findings were normal. Her clinical picture was in concordance with hypocalcaemia. After obtaining a blood sample for laboratory investigation, she was asked to breath into a bag and simultaneously an IV calcium gluconate infusion was started. The laboratory analysis including electrolytes was normal (Table 1). Electrocardiography showed a slight increase in the QT interval (0.46s). Arterial blood gas analysis was performed, which revealed respiratory alkalosis (pH: 7.63, pCO₂: 15.4 mm Hg, pO₂: 122 mm Hg, HCO₃: 16.5 mEq/L). The clinical picture was considered as decreased ionized calcium levels caused by respiratory alkalosis, which in turn was induced by a hyperventilation syndrome. She rapidly recovered by re-breathing into a bag. Her symptoms started to improve within the first 5 minutes of the therapy and she completely recovered after 1 1/2 hours. Her control blood gas analysis was normal (pH: 7.45, pCO₂: 26.3 mm Hg, pO₂: 84.7 mm Hg, HCO₃: 19.7 mEq/L). 

Table 1: Initial laboratory evaluation results.

Discussion
Conversion is a frequently encountered clinical presentation at the emergency units. Its signs and symptoms are typically neurological (4). Due to the contractions in her hands and paresthesias throughout her body, our first image of this patient as having a conversion reaction. Sensorial symptoms, diffuse pain, carpopedal spasm, and spasms at the facial muscles led us to more vigorous evaluation and the diagnosis of hypocalcaemic tetany. Tetany is usually presented with sensorial symptoms such as paresthesias at the lips, tongue, fingers, and feets, a carpopedal spasm, which may be long lasting, diffuse myalgia, and spasms at the face muscles. Tetany is typically the result of severe hypocalcaemia. However, also a decrease in the ionized fraction of plasma calcium can lead to tetany without the presence of hypocalcaemia, such as in the case of severe alkalosis (5).