The Blast Wave and the Brain: How Explosions Cause Concussion and TBI

By Dr. Claudia Munoz, MD, MPH — Board-Certified Neurologist & Epileptologist, Medical Expert Witness

An explosion can cause a concussion or a more serious traumatic brain injury (TBI) without anything striking the person's head. The pressure wave from the blast can be enough. This is sometimes called a "concussion wave" in everyday language; clinically, it is the blast wave, or blast overpressure.

This article explains how explosions injure the brain, why the injury can be hard to see, and what that means for evaluating civilian explosion cases such as industrial accidents, gas explosions, and product failures.

What Is a Blast Wave?

An explosion releases energy as a rapidly expanding wave of high pressure, followed by a brief phase of negative pressure. That wave travels outward from the source and can pass through the body. Its force depends on the size of the explosion, the person's distance from it, and the surroundings. Energy falls off with distance, and enclosed spaces can amplify the effects.

The Four Mechanisms of Blast Injury

Blast injuries are classified into four categories, and a single event can involve more than one:

Primary: injury from the blast wave itself, with no object touching the person.
Secondary: injury from debris or fragments propelled by the explosion, which can cause penetrating head injury.
Tertiary: injury from being thrown, such as striking a wall, the ground, or a vehicle.
Quaternary: everything else attributable to the explosion, including burns, crush injuries, toxic gas inhalation, and worsening of existing medical conditions.

Secondary and tertiary injuries resemble trauma from other causes, such as a fall or a car crash. Primary blast injury is what makes explosions distinct.

How Can a Pressure Wave Injure the Brain?

Research shows that exposure to a blast wave alone, with no fragment impact, can cause primary blast-induced TBI. Computer modeling suggests the wave can transmit directly into the head and travel through brain tissue. Researchers have also studied indirect pathways, in which the wave acts on other parts of the body and affects the brain through the circulatory system.

The honest scientific position is that the exact mechanisms are still being worked out. Studies, including animal and computer models, do not all agree on which processes matter most or on which structural changes (for example, axonal injury) the wave produces. Researchers also continue to study how much of a mild blast TBI comes from the wave itself versus acceleration forces. Any expert opinion should reflect that uncertainty rather than overstate it.

From Concussion to Severe Injury

Blast TBI follows the same mild, moderate, and severe framework as other TBI. Many people exposed to a blast experience a concussion-type injury, with symptoms such as headache, difficulty concentrating, memory problems, dizziness, sleep disturbance, and mood changes. More severe exposure can cause structural injury, including swelling and bleeding.

Because brain tissue sits in fluid and is vulnerable to pressure changes, the brain is considered one of the organs particularly susceptible to primary blast effects. Blast TBI can also be more complex than TBI from a single impact, since several mechanisms may act at once.

Why It Can Be Hard to Identify
No visible head injury. Primary blast injury may leave no external sign.
Standard imaging may look normal. Concussion-level injury is largely functional, and routine CT or MRI may not show it.
Overlapping conditions. Symptoms can overlap with post-traumatic stress disorder and with effects of other injuries from the same event, which makes careful clinical evaluation important.
Several injury mechanisms at once. Separating the effects of the pressure wave from debris, a fall, or burns requires a detailed review of the records and the event.
What This Means for Civilian Explosion Cases
No head contact does not rule out TBI. A pressure wave is a recognized injury mechanism.
The details of the event matter. Distance from the blast, whether the space was open or enclosed, and whether the person was thrown or struck by debris all affect the analysis.
A normal scan is not the end of the evaluation. A neurological and neuropsychological assessment, along with a careful symptom timeline, carries significant weight.
Claims should still be supported by the record. Consistent documentation of symptoms and their onset is what makes a clinical opinion credible, whichever side it supports.

Each case depends on its specific facts and medical history. This article summarizes general research findings, not an opinion on any specific case.

Work With a Medical Expert Witness

If you are handling a case involving an explosion or blast exposure, a thorough neurological evaluation can help clarify whether the clinical picture is consistent with the mechanism of injury.

I provide independent medical examinations, medical record review, expert report writing, and deposition and trial testimony for plaintiff and defense attorneys handling traumatic brain injury cases across the full range of causes and severity.

📩 doctor.claudia@gmail.com | info@drclaudiamunoz.com

Dr. Claudia Munoz, MD, MPH Neurologist | Epileptologist | Medical Expert Witness

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