Episodic Analgesia

Last updated: Sun, Mar 9, 2025

During World War II a U.S. Army doctor observed that sometimes soldiers came into the field hospital with very extensive injuries but stated that they weren't in pain and refused medication. The doctor attributed this to the relief these soldiers must feel at escaping combat still alive. Other observers during the Yom Kippur War in the 1970s witnessed the same thing, but noted that the victims were depressed, not elated. Subsequent studies have seen the same phenomenon in hospital emergency rooms.

In these latter observations the victims were not soldiers but trauma patients. Of over one hundred consecutive patients, over a third stated they had felt no pain at the time of injury. The percentage was higher for cutaneous injury than for deep injury. The researchers made these observations:

• The condition (being free of pain) is not related to the location or severity of the injury.
• There is no clear relation to the circumstances of the injury. The injury may have occurred in a fraught situation or may have been entirely unexpected. Diversion of the victim's attention at the time of the injury is sometimes involved, but not always.
• The victim can be fully aware of the injury yet feel no pain.
• Analgesia is instantaneous.
• By the next day, all victims were in pain.
• The analgesia is limited to the site of injury. The victim is normally pain-sensitive, for example, to an injection in an uninjured limb.

The researchers conclude that this episodic analgesia occurs because the victim needs to be coherent until they receive help, after which the pain kicks in.1 If this interpretation is correct, it would be another example of the behavioral flexibility afforded by the descending pain modulation systems. (The Descending Tracts and Descending Pain Modulation.)