A 35 year old marathon runner is brought in after falling down and developing a generalised tonic-clonic seizure lasting 3 minutes. He had been running for 5 hours continuously at that time, in a very hot climate. His medical history is unremarkable, and there is no family history of cardiac disease or early deaths. His random plasma glucose is 83.8 mg/dl.
On room air: PO2: 80 mmHg (> 75) PCO2: 37 mmHg (35 - 45) pH: 7.4 (7.35 - 7.45) HCO3: 24 mmol/l (22 - 26)
The EEG shows only generalized slowing compatible with a postictal state.
The CT scan demonstrates effacement of the cortical sulci and basilar cisterns. There is no midline shift, or evidence of hemorrhages or mass lesions.
Na+ 116 mmol/l (135 - 145) K+ 4.7 mmol/l (3.5 - 5.5) Cl- 97 mmol/l (95 - 105)