Tympanic Membrane Perforation (TMP)
Definition
Rupture of the eardrum by blast overpressure, occurring at 35-103 kPa, well below the threshold for blast lung injury. The most sensitive primary blast indicator. Specifically sought at all blast autopsies because it is not apparent on external examination. Provides detonation-distance evidence when correlated with the device's overpressure profile.
- Onset threshold
- 35-103 kPa overpressure
- Sensitivity
- Most sensitive primary blast indicator
- External visibility
- Not apparent without otoscopic exam
- Evidentiary use
- Correlates with device overpressure profile for distance
Common questions
Why is TMP checked at every blast autopsy even when death was from other injuries?+
It is the most sensitive marker of primary blast exposure and requires no gross external sign, so a pathologist who skips otoscopic examination can miss the only direct evidence that a victim was within lethal or near-lethal overpressure range of the seat of the explosion.
Does the absence of TMP rule out blast exposure?+
No. Ear orientation to the blast wave, distance, and whether the ear canal was shielded or occluded all affect whether the membrane ruptures, so a negative finding lowers but does not exclude exposure, particularly if other primary blast signs are present.
How does TMP differ from blast lung injury as an indicator?+
TMP occurs at a much lower overpressure threshold than blast lung, so it can be present in survivors and less severely exposed victims who show no pulmonary primary blast injury, making it useful for reconstructing standoff distance across a wider range of the blast field.
Related terms
- Blast Lung Injury
- Bilateral pulmonary contusion and alveolar tear from primary blast overpressure. The most lethal primary blast mechanism. Characterised at autopsy by bilateral 'butterfly'...
- Primary Blast Injury
- Injury caused directly by the overpressure (blast) wave. Preferentially affects gas-containing organs (lungs, tympanic membranes, bowel). Blast lung (alveolar haemorrhage, barotrauma) is...
- Quaternary Blast Injury
- All blast-related injury not in primary/secondary/tertiary classes: burns (flash fireball + secondary fire), crush (structural collapse), and inhalation injury (CO, HCN, particulate)....
- Secondary Blast Injury
- Penetrating injury from fragments: device casing metal, pre-formed projectiles (nails, bolts, BBs), or environmental debris accelerated by the blast wave. The most...
- STANAG 2920
- NATO Standardization Agreement 2920, defining the fragmentation injury threshold for ballistic protection standards. Relevant in blast forensic pathology for relating fragment mass...
- Tertiary Blast Injury
- Blunt-force injury caused by physical displacement of the victim's body by the blast wind, followed by impact against surfaces. Morphologically identical to...