Hyperventilation and seizures in an adolescent female

A 16 year-old girl was admitted after suffering from recurrent episodes of dyspnea and stridor, cyanosis, loss of contact, stiffening of all four limbs, clenching of the jaw and eye retroversion that lasted for a few seconds to a minute, followed by slow recovery of consciousness without any loss of sphincter control. These symptoms began at the age of 11 and worsened over time. Prolonged rate corrected QT intervals was observed with an ECG. Two cardio-respiratory monitorings were performed (one during daytime hours while the patient was awake, and one at night time while the patient slept). Daytime recordings showed 17 central apnoeas and 97 central hypopneas, with an apnea-hypopnea index (AHI) of 13.2 events/hour, that were associated with severe oxyhemoglobin desaturation. In contrast, night time recordings were normal (AHI=1.1 events/hour). The patient underwent diurnal monitoring of transcutaneous pCO2(PtcCO2), transcutaneous O2(PtcO2), SpO2 and end tidal CO2 (PETCO2), with simultaneous monitoring of regional cerebral oxymetry (rSO2) which showed values of PtcCO2 between 8 and 15 mmHg, suggesting several episodes of marked hyperventilation. Twenty-nine episodes of severe arterial desaturation (SpO2<50%) were registered, all after the same number of apnea events, with ascent of PtcO2 up to 28 mmHg at the end of apnea. During the final phase of apnea, the patient showed cyanosis, contact disturbance, grimaces, oral movements of rhyme, and, on three occasions, partial seizures. A mask was packaged and applied daytime to the face of the patient during episodes of hyperventilation to prevent, together with a psychiatric follow up, rapid falls of PaCO2 levels determining central apnoeas.