Neuropsychological Conditions Information: Acquired Brain Injuries

Traumatic Brain Injury

Traumatic Brain Injury (TBI) results from the sudden application of mechanical forces to the brain. TBI is the leading cause of acquired brain injury (ABI), affecting two in every 1000 people. TBI affects roughly three times more males than females. Those between the ages of 15 and 24 years are at the highest risk of sustaining a TBI.

Open Head Injury

An open head injury occurs when the dura matter, a protective membrane covering the brain, is penetrated by an object. Open head injuries account for less than 10% of TBIs.

Closed Head Injury

A closed head injury results from rapid acceleration and deceleration forces. Damage to the brain is caused when it moves within the skull vault and collides with the inner surface of the skull, especially along the bony irregularities at the base of the skull. The frontal and temporal lobes of the brain are particularly susceptible to bruising from these forces. Another mechanism of injury is diffuse axonal injury. This is when nerve cells in the brain are stretched and sometimes torn due to the rapid acceleration and deceleration forces. This occurs more globally throughout the brain, and especially in areas with abundant white matter tracts. Secondary complications such as bleeding, hydrocephalus and swelling of brain tissue can cause further damage.

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Stroke

There are two main types of stroke, ischaemic and haemorrhagic. Because stroke varies significantly in the parts of the brain that are affected, there is no single neuropsychological profile for stroke. To a large extent, the neuropsychological phenomena associated with stroke depend on the vessel and side of the brain affected. For example, ischaemic stroke of the right middle cerebral artery territory is highly associated with the phenomenon of unilateral spatial neglect, whereas stroke of the left middle cerebral artery territory is associated with dysphasia.

Ischaemic Stroke

This is where there is a disruption to the blood supply to the brain, which causes neurons (brain cells) to dysfunction and in many cases die. Ischaemic stroke accounts for over 60% of all strokes and usually affects those over the age of 55 years.

Haemorrhagic Stroke

This is where a blood vessel in the brain ruptures. This can cause bleeding either within or around the brain. Half of those that have a haemorrhagic stroke will die as a result. Of the 50% that survive, outcome is usually better than that of those who sustain ischaemic strokes. Haemorrhagic stroke accounts for many of the strokes that occur under the age of 45 years.

Substance Related Brain Injury

Substance Use

Excessive and/or chronic substance use can have a substantial effect on neuropsychological functioning. Substance use disorders are mainly classified into two categories: Substance Abuse and Substance Dependence. Substance abuse is where there is clear and direct harm arising from substance use. In Substance Dependence, a person requires more and more of a substance to achieve the same level of intoxication and experiences withdrawal symptoms when they have not taken the substance for some time. Both of these disorders can result in neuropsychological impairment, most of which depends on the substance(s) that have been used.

Alcohol Related Cognitive Impairment

Alcohol is the most widely abused substance in the western world. Significant chronic alcohol use results in diminished cognition over time, even when a person is sober. A severe and irreversible result of significant long-term alcohol consumption is the Wernicke-Korsakoff Syndrome. This syndrome results in a dramatic loss of ability to learn and remember new information, amongst other cognitive and behavioural difficulties. Those with the syndrome have clear physical brain changes, particularly to the mammillary bodies, which are essential structures in the memory network.

Multiple Sclerosis / Neurodegenerative Conditions

Multiple Sclerosis (MS) is an autoimmune conditions that effects the white matter in the brain. A common effect of white matter loss is slowing in thinking, speech and movement. The white matter degeneration in MS may also affect other cognitive functions such as memory and executive functioning. In rare cases, the neurodegeneration may be so severe as to warrant a diagnosis of MS dementia.

Other neurodegenerative conditions include Huntington’s Disease, Progressive Supranuclear Palsy and Parkinson’s Disease. These conditions each have the potential to affect cognitive, behavioural and emotional (as well as physical) functioning.

Epilepsy

Cognitive dysfunction is common in those with a diagnosis of epilepsy. However, it can be difficult to determine whether such cognitive impairment is caused by epileptic activity, such as seizures (or interictal discharges), the underlying cause of the seizures, or anticonvulsant medication. Neuropsychological assessment may assist with identifying the cause by accurately describing the profile of cognitive impairment.

Hypoxic Brain Injury

Hypoxic Brain injury occurs when the oxygen supply to the brain has been significantly disrupted. The lack of oxygen causes cells in the brain to die. Hypoxic brain injury may be subtle or severe and neuropsychological assessment can determine the impact of damage on cognitive functioning.

Brain Infection (e.g., AIDS, Herpes)

Brain infections are rare. They are caused by infiltration of the brain by either a virus or bacteria. Some examples include HIV/AIDS and Herpes Simplex. Different infectious agents tend to affect different parts of the brain, and therefore a neuropsychological assessment can assist with both diagnosis and treatment of infectious brain conditions.

Brain Tumour / Neurosurgery

Brain tumours are an abnormal growth of cells in the brain. There are various types of brain tumours, including glioblastoma, oligodendrocytoma, and astrocytoma. The extent and nature of cognitive impairment resulting from a brain tumour depends on the size and location of the tumour, among other factors.