There are many different types of amnesia that can cause memory loss to a patient after the brain has been injured. Some of the major forms of amnesia related to brain injury include:

• Anterograde amnesia. Memory loss related to events that occur after damage to the brain. Anterograde amnesia involves the inability to learn and recall new information. Patients typically struggle to remember day-to-day events, but have less difficulty remembering events from their childhood.
  
  
• Retrograde amnesia. Memory loss related to events that occurred before damage to the brain. Patients are unable to retrieve long-term memory of events and information that occurred prior to the brain trauma.
  
  
• Transient global amnesia. Sudden and temporary loss of the ability to store new memories, usually due to a malfunction of the temporal lobe brought on by seizures, delirium or transient ischemic attacks (temporary disturbance of blood supply to an area of the brain). Patients with transient global amnesia often find themselves confused about time and place and may struggle to identify other people. Episodes tend to occur just once during a person’s lifetime and may last for anywhere from 30 minutes to 12 hours. Transient global amnesia can be disorienting while it lasts, but full recovery typically occurs.