When the meninges and/or skull are broken and the brain penetrates one or both, that is called an open head injury. This is especially dangerous because a bone fragment or cerebrospinal fluid may enter the substance of the brain and significantly damage the tissue. Considerable local damage can occur in the area of the brain immediately below the impact area, as well as more widespread damage. The chances of infection are also high. Fortunately, open head injuries are typically diagnosed and treated immediately. 

The direct application of physical forces damaging nerve fibers, blood vessels and other brain tissue are commonly referred to as the “primary” mechanisms of this type of traumatic brain injury. Further complications are often called “secondary” mechanisms of brain injury. 

A large number of secondary complications may occur including: hemorrhage (bleeding), hematoma or blood clot, raised intracranial pressure, hypoxia (loss of oxygen), brain swelling and post-traumatic epilepsy. Such complications require close monitoring and medical management.