Cooling below normothermia in adult TBI (I assume that is what you are talking about here because peds is another story) has not been conclusively demonstrated to improve outcomes. Therapeutic normothermia, i.e. fever suppression, does appear to be helpful. However, the length of time that this is beneficial is not known. I would not use an interventional device like an intravascular cooler or an Arctic Sun after cerebral edema has started to recede, because there are risks to these devices and the polypharmacy needed to ameliorate microshivering has real consequences. However, ATC acetaminophen and a cooling blanket I would use for at least 7 days if not longer if the fevers are high and sustained. But that is just my preference, and the risk/benefit ratios as determined by other clinicians leads to divergent practice patterns. There is also the question of whether fevers due to sympathetic storming after TBI are as detrimental as infectious or drug fevers.
Mechanistically, you want to avoid cellular stress (via fever here) when the remaining neurons are at their weakest and most primed for further degeneration, and by day 7 the neuroinflammatory state has reached macrophage infiltration and microglial adaptation for mop-up and remodeling. Certainly there is still axonopathy at this stage and probably some energetic failure in some regions, but you have to de-escalate care at some point and 7 days seems to be a good time to let the patient take back control of some of these physiologic parameters.
Ideally they'd never have fevers because I'm sure the remodeling stages of neurologic response to TBI in the weeks to months after injury are also adversely impacted by inflammation and fever, but at a certain point it just isn't feasible to keep someone on an Arctic Sun with a demerol drip and Precedex to control shivering.
All that said, I've had patients that needed pentobarb coma and cooling to 92F for > 20 days just to keep them from herniating despite a bucket handle crani. But refractory severe global cerebral edema and routine management of TBI are different animals.
