Which type of head injury would cause total loss of memory?

Severe tbi: In a patient that has recovered and is awake and interactive and conversant, it is unusual for head injury to have caused total loss of memory (both short term and long term). However, the more severe the tbi, the more likely there will be diffuse enough damage to affect both hippocampi of the brain. These are structures deep within the brain that are vital to memory function.