What are cerebrovascular diseases? - Chapter 14

What is a cerebrovascular disease?

If the blood supply to the brain is disturbed for some reason, it is called a vascular disorder.  A cerebrovascular disease (CVD) is most common after the age of 65. In eight out of ten cases there is a infarct: due to an obstruction of an artery, the blood supply to a specific area in the brain is impaired or blocked. In two out of ten cases there is a cerebral haemorrhage: the rupturing of a weak spot in a blood vessel's vascular wall causes bleeding in or around the brain. A CVD manifests itself in the acute phase by symptoms of failure in an arm or leg movement on one side of the body; a hanging mouth corner and speak with a double tongue. In the case of an infarct, the person often remains conscious; with a cerebral haemorrhage consciousness will decrease. An MRI or CT is made to determine whether it is an infarction or a haemorrhage. Due to the increasing aging of the population, prevalence of CVD rises. 

What is the aetiology of infarcts and haemorrhages?

An infarct

The embolism (blood clot) causes a temporary obstruction of an artery or arterial branch. These embolisms commonly consist of coagulated blood platelets (thrombi) or fragments of calcifications in the vascular wall of the blood vessels. However, an obstruction can also be the result of local stenosis of a blood vessel causing obstruction of the bloodstream. The third way in which a cerebral infarction can be caused is by inadequate blood flow (perfusion) to the brain. In approximately 80% of cases, an infarct affects the middle cerebral artery. A TIA is a 'transient ischemic attack': the loss of function that occurs in a TIA is by definition temporary, but persistent cognitive disorders are described among patients who have suffered a TIA. At least 30% of those patients who have experienced a TIA will suffer from a stroke within the next five years. If possible, thrombolysis is performed within the first few hours after an infarct: a powerful drug is injected into the bloodstream in order to disperse the clot in the blood vessel. Age is the main risk factor for an infarct. A second important risk factor is atherosclerosis (caused by smoking, diabetes mellitus, obesity, hypercholesterolaemia, or hypertension). High blood pressure increases the risk of an infarct with four to six times.

A cerebral haemorrhage

Intracerebral haemorrhage is the most common type of brain haemorrhage. Most haemorrhages are caused by long-term hypertension (Brott, Thalinger & Hertzberg, 1986). Other causes are arteriovenous malformation (the smallest blood vessels are poorly formed), inflammation of the vascular wall, coagulopathy, and brain tumor. Lobar bleeding is more superficial and may be caused by amyloid angiopathy (a degenerative cerebrovascular disorder found in the elderly). Haemorrhagic infarct primarily involves a blockage in an artery, but there is also blood leakage to the affected area during reperfusion because of damage to the vascular walls. In subarachnoid haemorrhage (SAH) the bleeding does not occur in the brain, but in the space between the meninges surrounding the brain (subarachnoid space). In the acute phase the patient experiences severe headache for hours followed by neck stiffness. 5% of all CVDs are SAHs. In most cases, an SAH is caused by a rupture of an aneurysm. The aneurysm will almost always have to be surgically closed. If the bleeding and therefore the intracranial pressure is too severe, an operation to relieve this pressure may be considered.

What are the neuropsychological consequences of stroke?

The infarction itself can damage the surrounding areas, but also the more remote areas of the brain (diaschisis) because the connections to such areas are disrupted and therefore those areas also malfunction. The differences between the neuropsychological effects of haemorrhages and infarcts are most obvious during the early stages after a stroke. Following a brain haemorrhage, consciousness is often decreased, disorders may be severe and diffuse, and often the patient feels confused and disoriented. This is partly a direct result of damage to specific areas, but in particular it is a consequence of increased intracranial pressure and the presence of a haematoma. In comparison with patients with an infarct, people often experience a faster and better recovery after a major haemorrhage. As soon as the intracranial pressure has been normalised and the haematoma has disappeared, normal functioning may be restored. In the case of an infarct, the damage is restricted to the arterial areas; in the case of a brain haemorrhage, the damage is not restricted to the arterial areas. This is because the damage after an infarct is limited to the supply area of the artery, whereas after the rupture of a blood vessel the resulting hematoma may affect an extensive area. 

What are neuropsychological effects of a stroke?

The pattern of neuropsychological impairments as a result of a stroke is fairly stable after three, six and fifteen months (Van Zandvoort, 2001). In the first three to six months after the stroke there is a dynamic recovery process.

Is the memory affected?

In up to 50% of all stroke patients, memory disorders are found, and are still present in 11-31% of patients after 1 year (Snaphaan & De Leeuw, 2007). Memory impairments mainly occur after an infarct of the middle cerebral artery, when the medial temporal lobe is affected (in particular the hippocampus). Memory disorders are more clearly if there is bilateral damage or damage in the left hemisphere. Most patients experience anterograde amnesia immediately after the stroke. When non-medial parts of the temporal lobe or structures close to the separation left-right hemisphere are damaged, retrograde amnesia sometimes occurs. Damage in the left hemisphere (such as in linguistic areas) also leads to modality-specific problems (such as storing linguistic information). Problems in the non-verbal memory are the result of damage to the right medial temporal lobe or damage to the thalamus, mammillary body and basal frontal lobe. After an infarct the declarative memory is mainly affected: the non-declarative (procedural)memory is intact (unless the basal ganglia is affected).

Are attention and speed of information processing affected?

Approximately 40% of stroke patients experience attention problems, both in alertness (falling asleep without adequate stimulation) and in more complex attention functions (they are quickly (more) distracted).

Is language affected?

21-38% of stroke patients suffer from aphasia in the acute phase. In the months following the infarct, these language difficulties usually decrease considerably (Pedersen, Vinter & Olsen, 2004). Language disorders are most marked after an infarct in the area supplied by the middle cerebral artery in the left hemisphere. In that case it is often a mixed aphasia or in serious cases a global aphasia. If the region around the gyrus angularis is damaged, there may also be a pure agraphy and a pure acalculia. If the infarction has occurred in the area of the posterior cerebral artery in the left hemisphere, reading impairments (alexia) may also occur. Specific language impairments may also be manifested after an infarct in the area of the anterior cerebral artery in the left hemisphere. Transcortical aphasia can also appear. In many patients there is often a (at least) subtle form of word finding problems and patients regularly have some difficulty with language comprehension.

Is perception affected?

If the area of ​​the cerebral posterior artery is damaged, a visual field defect is a common consequence. If there is a homonymous hemianopsia, stroke patients often experience hallucinations in the blind field of vision in the first few weeks. A visual agnosia or a color agnosia may also occur. Prosopagnosia and apperceptive agnosia are the result of a bilateral infarction in the same catchment area. Cortical blindness (Anton's syndrome) is rare but noteworthy after such lesions. In 25% of patients who have had an infarction in the cerebral artery region of the right hemisphere, there is neglect (the parietal lobe is most strongly involved in this disorder, but the frontal and temporal regions also play a role). Problems in body perception can also occur after such damage within the parietal lobe (such as finger diagnosis or specific disorders in the mental representation: both body image and body scheme may be affected). The time perception is also often affected.

Are executive functions affected?

50% of stroke patients experience problems in executive functioning, especially when the area of ​​the cerebral anterior artery (the frontal lobe) is affected. Difficulty planning, keeping track of situations, and regulating behaviour can appear. A rare, extreme disorder in executive functions is called 'abulia': the inability to take initiative.

Is motor activity affected?

Buccofacial apraxia, in addition to language disorders, the result of damage in the basin of the cerebral artery in the left hemisphere.

Does social cognition change?

Emotional functioning requires the involvement of both right hemisphere and left hemisphere: the right side is related to initiating emotions while the left hemisphere is mainly concerned with inhibiting and controlling emotions (Gianotti, Azzoni & Zoccolotti). In the case of damage to the frontal lobe, behavioral changes often occur: there may be more (inappropriate, inhibited) behavior or, on the contrary, fewer (such as apathy). Even if the cerebellum is damaged, behavioral changes can occur such as inhibition behavior and flattened affect ("cognitive-affective syndrome"). The lack of insight into the disease appears to occur more frequently with damage to the right hemisphere, but more research into this will have to provide a definitive answer.

What is vascular dementia?

Vascular dementia is diagnosed in about a quarter of all stroke patients 3 to 12 months after the incident (Desmond and colleagues, 2000). This makes vascular dementia the second most common dementia (Alzheimer's is in the first place). The risk factors are the same for both types of dementia (smoking, hypertension, obesity, and high cholesterol levels). Vascular dementia is rarely caused by a single, strategic cerebral infarction (such as in the thalamus); it is often the result of multiple infarctions (large or small) that occur in the brain simultaneously or shortly after one another in multiple places in the brain. This almost always goes together with leukoaraiosis: progressive damage to the deep white matter in the brain. Small vessel disease - only progressive damage to the smallest blood vessels - can also cause vascular dementia. Within the clinical picture, psychomotor slowness and executive function disorders stand out. For some, cognitive functioning deteriorates step by step and for others gradually. The umbrella term for all disorders that are the result of vascular problems is 'vascular cognitive impairment', or VCI.

What other consequences are there after a stroke?

Disorientation

In the acute stage, almost half of all patients are disorientated with regard to place, person, and time. If a patient is properly oriented, they often have a better prognosis. Delirium of a temporary nature occurs often as well. However, this is mostly the result of medication use, metabolic disorder, an infection or another cause: not so much the infarction itself. Advanced age, delirium in the anamnesis, premorbid dementia, and severe visual disorders are factors that increase the risk of a delirium. Sometimes a delirium (especially after a stroke in the right hemisphere) is accompanied by a reduplicative paramnesia (Pick, 1903): the patient does not recognize his / her environment and insists that his / her family is not his / hers.

Fatigue

More than half of the stroke patients suffer from fatigue, also in the long term. The reasons for this are yet unclear. Possible treatment focuses on a gradual increase in physical activities, combined with cognitive-behavioural therapy and psychoeducation.

Depression

Almost all patients experiences mood changes after a stroke (Ferro, Caeiro & Santos, 2009) and nine out of ten still experience this after three to nine months. The estimated prevalence of depression is set at a third, but this estimate fluctuates between 5-67%. Half of all patients with sadness complaints can be diagnosed with a depressive disorder; the other half with a dysthymic disorder. The depression can be temporary or long-lasting. No consensus has yet been reached on whether the depression is caused by the stroke or whether it is a response to the life-threatening situation (in the latter case, a 'reactive depression' is referred to). According to Aben and colleagues (2003), the prevalence of depression after an infarction is just as great as the prevalence after bleeding. This is supporting evidence for the reactive depression. In contrast, Krishnan and colleagues (2006) argue that the depression is the result of damage to specific brain networks. A combination of both is probably closest to the truth.

A catastrophic reaction

If a patient has enormous anxiety in the first few days after the stroke, is pathologically crying, is very aggressive or is very apathetic, this is a so-called catastrophic reaction. Such a reaction is linked to a poor prognosis.