Temperature rhythm in aneurysmal subarachnoid hemorrhage.

Introduction: In the acute phase following brain injury, alterations in temperature regulation occur commonly and are associated with poorer outcome. However, few studies have examined temperature rhythm following brain insult, such as rupture and surgical management of ruptured cerebral aneurysms, and its association with clinical factors and outcome.
Methods: This study describes diurnal temperature patterns in patients hospitalized for acute management of cerebral aneurysms (n = 86). Temperature mesor, amplitude, and acrophase were estimated from recorded temperature measurements using cosinor analysis. The association of these patterns with clinical condition, mortality, and 6-month functional outcome was examined.
Results: Changes in the temperature cosinor parameters were varied and individual. Most patients experienced elevated mesors (Mean +/- SD, 37.8 +/- 0.4 degrees C) and blunted amplitudes (0.27 +/- 0.14 degrees C). Acrophases were widely dispersed, with only 27% in the normative 12 noon to 6 PM quadrant. Cosinor parameters (particularly the mesor) showed greater alteration in patients with worse initial condition (e.g. Hunt and Hess score > or = 2: P = 0.001, Glasgow Coma Scale < 15: P = 0.001) and poorer 6-month outcome (e.g. mortality: P = 0.013, Extended Glasgow Outcome Scale < 5: P = 0.018).
Conclusion: Abnormal cosinor parameters provided additional predictive information in relation to outcome, beyond the impact of initial neurologic condition. Further research is needed to understand the pathophysiology of temperature regulation following cerebral aneurysm rupture and to determine if temperature management strategies can alter outcome.