Brain injuries occur due to a wide range of internal and external factors.

[citation needed] Impaired function of affected areas can be compensated through neuroplasticity by forming new neural connections.

[2] Symptoms of a mild brain injury include headaches, confusions, tinnitus, fatigue, changes in sleep patterns, mood or behavior.

[3] Mental fatigue is a common debilitating experience and may not be linked by the patient to the original (minor) incident.

Cognitive symptoms include confusion, aggressiveness, abnormal behavior, slurred speech, and coma or other disorders of consciousness.

Physical symptoms include headaches that worsen or do not go away, vomiting or nausea, convulsions, brain pulsation, abnormal dilation of the eyes, inability to awaken from sleep, weakness in extremities, and loss of coordination.

The symptoms of Wernicke's aphasia are caused by damage to the posterior section of the superior temporal gyrus.

Broca's aphasia is indicative of damage to the posterior inferior frontal gyrus of the brain.

[9] Lesions to the fusiform gyrus often result in prosopagnosia, the inability to distinguish faces and other complex objects from each other.

Lesions to the parietal lobes may result in agnosia, an inability to recognize complex objects, smells, or shapes, or amorphosynthesis, a loss of perception on the opposite side of the body.

Due to loss of blood flow or damaged tissue, sustained during the injury, amnesia and aphasia may become permanent, and apraxia has been documented in patients.

[19] Headaches, occasional dizziness, and fatigue—all temporary symptoms of brain trauma—may become permanent, or may not disappear for a long time.

[20] Emotional changes may not be triggered by a specific event, and can be a cause of stress to the injured party and their family and friends.

Wernicke's encephalopathy results from focal accumulation of lactic acid, causing problems with vision, coordination, and balance.

[29][30] Wernicke-Korsakoff syndrome is typically caused by conditions causing thiamine deficiency, such as chronic heavy alcohol use or by conditions that affect nutritional absorption, including colon cancer, eating disorders and gastric bypass.

IL-1 mediates ischaemic, excitotoxic, and traumatic brain injury, probably through multiple actions on glia, neurons, and the vasculature.

[34] Glasgow Coma Scale (GCS) is the most widely used scoring system used to assess the level of severity of a brain injury.

This method is based on the objective observations of specific traits to determine the severity of a brain injury.

In the first week after a traumatic brain injury, a person may have a risk of seizures, which anti-seizure drugs help prevent.

Mouse NGF has been licensed in China since 2003 and is used to promote neurological recovery in a range of brain injuries, including intracerebral hemorrhage.

Occupational therapists may be involved in running rehabilitation programs to help restore lost function or help re-learn essential skills.

Registered nurses, such as those working in hospital intensive care units, are able to maintain the health of the severely brain-injured with constant administration of medication and neurological monitoring, including the use of the Glasgow Coma Scale used by other health professionals to quantify extent of orientation.

Evidence based research reveals that serial casting can be used to increase passive range of motion (PROM) and decrease spasticity.

[43][44] Overall, studies suggest that patients with TBIs who participate in more intense rehabilitation programs will see greater benefits in functional skills.

[46] Other treatments for brain injury can include medication, psychotherapy, neuropsychological rehabilitation, neurotherapy and/or surgery.

However, in neural development in humans, areas of the brain can learn to compensate for other damaged areas, and may increase in size and complexity and even change function, just as someone who loses a sense may gain increased acuity in another sense—a process termed neuroplasticity.

In 1848, Phineas Gage was paving way for a new railroad line when he encountered an accidental explosion of a tamping iron straight through his frontal lobe.

[52][failed verification] Ten years later, Paul Broca examined two patients exhibiting impaired speech due to frontal lobe injuries.

It was not until Leborgne, informally known as "tan", died when Broca confirmed the frontal lobe lesion from an autopsy.

After his death, Wernicke examined his autopsy that found a lesion located in the left temporal region.