a positive declaration intended to give confidence: He received assurances of support for the project. 2. promise or pledge; guaranty; surety: He gave his assurance that the job would be done. 3. full confidence; freedom from doubt; certainty: to act in the assurance of success.
Summary. Traumatic brain injury (TBI) happens when a bump, blow, jolt, or other head injury causes damage to the brain. Every year, millions of people in the U.S. suffer brain injuries. More than half are bad enough that people must go to the hospital. The worst injuries can lead to permanent brain damage or death.
Less commonly, the nerves leading to the olfactory center of the brain or to the brain itself can be damaged or deteriorate due to: 1  Aging. 2  Alzheimer's disease. 3  Brain aneurysm. 4  Brain surgery. 5  Brain Tumor (both cancerous and noncancerous) 6  Chemical exposures to certain insecticides or solvents. 7  Diabetes. 8  Huntington's disease.