by Tsu Dho Nimh

Created on: December 28, 2008   Last Updated: January 14, 2011

Closed head injuries are injuries to the brain that happen without damage to the skull. The injury can be a "diffuse injury" with damage spread throughout the brain tissues, or a "focal injury," with damage restricted to one or a few areas. The severity of a closed head injury can range from a mild concussion that you recover from in a week to a disabling injury that causes permanent physical, intellectual and personality changes, or even death. In many cases, prompt medical intervention and/or later rehabilitative therapy can minimize the long-term effects.

Your brain is especially vulnerable to injury because it has no supportive tissue such as ligaments or muscles. It is floating in the cerebrospinal fluid inside your skull. If your head (and brain) is moving rapidly, then abruptly stops moving or changes directions, as happens in vehicle accidents or football tackles, your brain will continue to move in the original direction until it collides with the inside of your skull. It may even bounce back and hit the other side of your skull. The sudden stop can damage your brain in one or more ways, although there might not be any apparent symptoms for hours, days, or even months after the incident.

If the impact with the inside of your skull breaks a blood vessel, the bleeding may increase the pressure (the intra-cranial pressure), which in turn may damage the brain tissues by cutting off the blood supply or directly damaging tissue from the pressure. Surgery to repair the blood vessel and remove the blood clots may be necessary.

Bruising without bleeding causes swelling as the damaged cells die and release their contents. The swelling may cut off the local blood supply, more cells may die, causing more swelling, and a cascade of damage begins. The usual treatment is to install a plastic valve to release the excess pressure, and sometimes give drugs or other therapies that minimize swelling.

The most serious and least repairable injury is the diffuse damage done by high-velocity impacts. Brain tissue is fragile and the force of the impact may cause "axonal shear injuries" where the brain tissue splits and shatters. This breaks the connections between neurons inside the brain, and a cascade of damage begins. The injuries are too small to show up in MRIs, CAT scans or X-rays - instead of one bleeding spot there are multiple microscopic injuries throughout the brain.

The invisible nature of closed head injury is a diagnosis and treatment dilemma. Even if they were

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