Other symptoms include trouble with memory, concentration, attention or thinking. Mental fatigue is a common debilitating experience and may not be linked by the patient to the original (minor) incident. Narcolepsy and sleep disorders are common misdiagnoses. Moderate/severe brain injuries
Cognitive symptoms include confusion, aggressive, abnormal behavior, slurred speech, and coma or other disorders of consciousness. Physical symptoms include headaches that do not go away or worsen, vomiting or nausea, convulsions or seizures, abnormal dilation of the eyes, inability to awaken from sleep, weakness in the extremities and loss of coordination. In cases of severe brain injuries, the likelihood of areas with permanent disability is great, including neurocognitive deficits, delusions (often, to be specific, monothematic delusions), speech or movement problems, and intellectual disability. There may also be personality changes. The most severe cases result in coma or even persistent vegetative state. Symptoms in children
Symptoms observed in children include changes in eating habits, persistent irritability or sadness, changes in attention, disrupted sleeping habits, or loss of interest in toys.Presentation varies according to the injury. Some patients with head trauma stabilize and other patients deteriorate. A patient may present with or without neurological deficit. Patients with concussion may have a history of seconds to minutes unconsciousness, then normal arousal. Disturbance of vision and equilibrium may also occur.
Intracranial bleeding
Types of intracranial hemorrhage are roughly grouped into intra-axial and extra-axial. The hemorrhage is considered a focal brain injury; that is, it occurs in a localized spot rather than causing diffuse damage over a wider area. Intra-axial bleeding
Intra-axial hemorrhage is bleeding within the brain itself, or cerebral hemorrhage. This category includes intraparenchymal hemorrhage, or bleeding within the brain tissue, and intraventricular hemorrhage, bleeding within the brains ventricles (particularly of premature infants). Intra-axial hemorrhages are more dangerous and harder to treat than extra-axial bleeds. Extra-axial bleeding
Extra-axial hemorrhage, bleeding that occurs within the skull but outside of the brain tissue, falls into three subtypes:

Epidural hemorrhage (extradural hemorrhage)  which occur between the dura mater (the outermost meninx) and the skull, is caused by trauma. It may result from laceration of an artery, most commonly the middle meningeal artery. This is a very dangerous type of injury because the bleed is from a high-pressure system and deadly increases in intracranial pressure can result rapidly. However, it is the least common type of meningeal bleeding and is seen in 1% to 3% cases of head injury. Patients have a loss of consciousness (LOC), then a lucid interval, then sudden deterioration (vomiting, restlessness, LOC)
Head CT shows lenticular (convex) deformity. Subdural hemorrhage results from tearing of the bridging veins in the subdural space between the dura and arachnoid mater. Head CT shows crescent-shaped deformity
Subarachnoid hemorrhage, which occur between the arachnoid and pia meningeal layers, like intraparenchymal hemorrhage, can result either from trauma or from ruptures of aneurysms or arteriovenous malformations.