Introduction
Classically, stroke is a sudden phenomenon of cerebral ischaemia that lasts for more than 24 hours and results in focal neurologic syndrome. Annually, there are around 5.5 million people died worldwide along and 44 million disability-adjusted life-years lost due to stroke. (1,2) In the United Kingdom, stroke has contributed in no small number of sudden deaths and permanent disabilities. With the occurrence every 3.5 minutes, stroke accounts for the hospitalisation of over 220 people per day. (3,4) Parallel to the growing elderly population worldwide, the prevalence of stroke is expected to increase by 9 million people per year since advanced age contributes to the increased stroke incidence. (1) These devastating data encourages further studies in promoting early risk prevention and prompt management on stroke are demanded to reduce mortality and morbidity of vulnerable patient groups.
Discussion
Based on the aetiologies of stroke, stroke is divided into two major groups: ischaemic stroke and haemorrhagic stroke. Differentiating stroke between the two groups could be done using such modalities as MRI and CT scan. (5) Correct and proper diagnosis between the two is crucial as the two groups are caused by different risk factors and lead to different outcomes which may vary their prognosis and treatment in clinical settings.
Ischaemic Stroke
Ischaemic strokes occur when the arterial blood flow to the brain is obstructed and results in hypoperfusion of brain tissue, or in rarer cases, caused by an impeded venous blood flow which results in a stasis that impairs diffusion process in the capillary. (6)
Ischaemic stroke is a multifactorial vascular event with various risk factors. Advanced age, gender, and ethnicity such as blacks are non-modifiable risk factors of ischaemic stroke. (5,7) Despite the possibility to occur in foetal stages, 95% of stroke occurs in people aged above 45 years with 60% of them occur at the age of over 65. (7) Men excluding the elderly and youngsters have approximately 19% higher risk of stroke which is potentially caused by hormonal differences among genders. However, hormonal therapy in postmenopausal women is reported not to reduce the risk of cardiovascular events. (5,7)
Meanwhile, modifiable risk factors of stroke could be obtained from underlying medical conditions and lifestyle/behaviours. Hypertension, metabolic disorders such as diabetes mellitus and hyperlipidaemia, underlying vascular problems such as atrial fibrillation, coronary heart disease (CHD), left ventricular hypertrophy (LVH); haemostatic disorder such as excessive von Willebrand factor level (vWF), polymorphism which leads to increased fibrinogen level; homocysteine elevation, and elevated serum lipoprotein(a) level. Lifestyle modification such as recession of smoking, obesity, increase physical activity, healthy diet which is rich in potassium, calcium, vegetables and fruits, fish, and antioxidants, along with avoiding alcohol drink also lower the risk of ischaemic stroke.(5,7)
Although the predisposing factors of ischaemic stroke subtypes might be similar to one another, their outcomes which could be depicted in neurological function, mortality, and quality of life post-stroke events differ significantly.
Classification and Prognosis of Ischaemic Strokes
There have been efforts in classifying ischaemic stroke. American Heart Association, constructed a classification system based on the aetiology according to a multicentre trial called TOAST in 2015. In this classification system, ischaemic stroke is grouped to large artery atherosclerosis, small artery occlusion, cardioembolism, other demonstrated cause, and cryptogenic cause. (8) Furthermore, another classification known as Oxfordshire or Bamford’s classification categorises ischaemic stroke accordingly to its clinical findings, such as total anterior circulation infarct (TACI), partial anterior circulation infarct (PACI), lacunar infarct (LACI), and posterior circulation infarct (POCI). (2)
The application of these systems has different implications in clinical settings. TOAST classification might ease the clinical decision making in treating stroke accordingly to its aetiologies whereas Bamford’s classification aims aids in diagnosis while pointing possible occlusion for further medical intervention and prognosis prediction. This paper focuses more on Bamford’s classification.
Total Anterior Circulation Infarct (TACI)
TACI is diagnosed when a patient comes with higher cerebral dysfunction, homonymous visual field defect, and ipsilateral motor and/or sensory deficit in at least two sites of the face, arm, and leg. (2,6) With the case fatality rate of 58.1% within one-month post-stroke, TACI remains the ischaemic stroke with the deadliest fatality rate. (9) Besides, approximately 32% of the survivors are dependent functionally (mRS 0-2), and only 3% of them are functionally independent (mRS 3-5) 1-year post-TACI; signifying the fatality of TACI despite its low recurrence. (2,9)
Partial Anterior Circulation Infarct (PACI)
Meanwhile, PACI manifests only two out of three TACI syndromes. (2) Thus, it has lesser fatality rate (12.2%) and lighter functional dependency than TACI one month after stroke event, enabling 48% of post-PACI patients to be independent functionally and 29% functionally dependent. However, PACI usually recurs early throughout one year of survival, doubling the risk of recurrent stroke in the first six months. (2,9)
Posterior Circulation Infarct (POCI)
POCI happens when the damage occurs in the posterior circulation area, such as cerebellum and brainstem. Thus, any of such clinical symptoms as cerebellar ataxia, isolated homonymous visual field defect, ipsilateral cranial nerve palsy along with the contralateral motor and sensory deficit might be found in patients manifesting POCI. Affecting different functional brain area, POCI allows 52% independency in neurological function with 20% of both functional dependency (9) and fatality rate at the first 30 days along with a high risk of recurrence throughout the year. (2)
Lacunar Infarct (LACI)
Diagnosis of LACI is established when at least one of these symptoms, such as a pure motor or sensory stroke, dysarthria, and ataxia, is apparent. These subcortical disturbances occur when there are occlusions in small penetrating branches of the cerebral arteries. (6) Contributing with the lowest recurrence rate of ischaemic stroke, LACI accounts for the lowest 30-days fatality risk among all ischaemic stroke (5.1%), with possibilities of 12% and 78% of functional dependency and independency post-stroke event. (2,9)
Haemorrhagic Stroke
Haemorrhagic stroke is a sudden neurological loss caused by blood vessel rupture and results in the damage around brain area compressed by the bleeding. This stroke is classified based on the bleeding location, intracerebral haemorrhage (ICH) and subarachnoid haemorrhage (SAH). (6)
Such modifiable factors as hypertension, cigarette smoking, and excessive alcohol intake remain to be the major modifiable predisposing factors for both subtypes of haemorrhagic stroke. (10,11) These conditions are also supported by increasing age, male, Asian ethnicity which enhance the risk of hypertension along with the use of antiplatelet and anticoagulant agents in ICH. (10) Meanwhile, the incidence of SAH is lesser than other strokes for its common cause comes from underlying conditions such as aneurysms (underlying connective tissue or angiogenesis disorders), cerebral arteriovenous malformations and brain tumours. (5)
Outcomes of Haemorrhagic Stroke
Anatomically, ICH occurs when there is bleeding in brain parenchyma, damaging basal ganglia/thalamus, lobar, or cerebellum/brainstem. ICH is often characterised by diminishing consciousness, vomiting, and other focal neurological deficits such as paralysis and apraxia. (5) The case fatality rate of ICH reaches approximately 30% at the first 30-days and increases to 39% six-months post-ICH. These numbers are followed by 28% of functional dependency and chance of 33% functional independence among the survivors. (9)
Meanwhile, subarachnoid haemorrhage signifies the bleeding surrounding the brain. Thus, such symptoms as headaches, loss of consciousness, epileptic seizures, and focal neurological deficits depending on the sites (e.g., cranial nerve palsy) could be found in emergency conditions. (5) SAH has a higher fatality rate among other types of stroke, account for 40% of 30-days fatality risk and 46% fatality rate after 6 months. Notwithstanding that nearly half of SAH cases result in death, survivors usually have relatively good neurological functions with the chance to be independent functionally around 46% and only 8% for being functionally dependent. (9)
Acute Specialised Management of Stroke and Its Evident Benefits
Traditionally, stroke was taken care in Accident and Emergency Department before being sent to acute stroke units, other medical units, or stroke rehabilitation. Nonetheless, the traditional approach in managing stroke is gradually replaced by the centralisation of acute stroke services into high-volume stroke units, Hyperacute Stroke Unit (HASU) and Acute Stroke Unit (ASU) throughout the United Kingdom. This centralisation is even advocated by the updated National Clinical Guideline for Stroke 2016 in the admission of all patients with suspected stroke to HASU for the first 72hours, followed by further care in ASU. (4)
Underlying this recommendation is the 2013 Cochrane review (Stroke Unit Trialists’ Collaboration), which emphasise the significantly satisfactory quality of life one-year post-stroke event in patients receiving organised in-patient care in specialised stroke units. Specifically, the implementation of acute stroke unit in hospitals has been proven to significantly reduce the case-fatality rate by OR 0.78, mortality rate after one year with the OR of 0.81, and functional dependency by OR 0.79 while maintaining the cost-effectiveness of service delivery. (4,12)
Specialist Stroke Assessment
Acute stroke unit utilises a team of multi-professional consisting of physiotherapies, occupational therapies, speech and language therapist, clinical psychologist/neuropsychologist, dietitian, nurse, and consultant stroke physician. This specialist stroke team work together in providing comprehensive and multidisciplinary approaches in diagnosing and managing stroke. (3,4)
Moreover, this specialist team monitors and recognises signs of regression in early stages to avoid further deterioration in admitted patients, and assists early rehabilitation initiation in stroke in-patients. (4)
Rapid Diagnosis and Acute Brain Imaging
Stroke units are required to have easy radiography access since imaging is essential in diagnosing stroke immediately. The current target of performing brain imaging for diagnostic purposes is within 1 hour after arrival in the hospital. Diagnosis of stroke using imaging is also useful for further therapy decisions, for example in assessing the eligibility of a patient to undergo thrombolysis, making immediate imaging of stroke cost-effective in clinical settings. Imaging modalities, in ischaemic stroke, includes not only CT scan and MRI, but also CT angiogram to assess the eligibility of endovascular therapy. (4)
Unlike other stroke subtypes, such modalities as cerebrospinal fluid spectrophotometry and lumbar puncture could be used to confirm the existence of SAH, especially when CT brain scan shows negative stroke result. (4)
Management of Stroke
Acute management of stroke differs each stroke subtypes. For ischaemic stroke, recanalization and reperfusion are essential in preventing further neuronal damages and mortality. Thus, such interventions as intravenous thrombolysis and endovascular therapy such as intra-arterial clot extraction using mechanical thrombectomy, are highly recommended to be performed immediately.
Intravenous Thrombolysis (IVT)
Since the introduction of thrombolysis in the treatment of stroke several decades ago, intravenous thrombolysis has remained as a significant treatment in handling ischaemia. Thrombolytic drugs such as tissue plasminogen activator (tPA) in alteplase should be administered immediately post-stroke event. (4) The last IST-3 trial has proven the benefit of IVT up until 6 hours after ischaemic stroke onset. (13)
Nevertheless, it should be taken into account that thrombolysis does not reduce overall mortality since it has the potential to induce haemorrhagic transformation of stroke. However, thrombolysis is proven to reduce morbidity. Approaches have been made to solve this complication. One of them is proposed by the ENCHANTED study which suggests lowering tPA dose to abbreviate the risk of haemorrhagic stroke, which gives simultaneously lower impact on reducing mortality and morbidity of ischaemic stroke, the prior reason in giving patients this thrombolytic agent. (4)
Mechanical thrombectomy (MT)
Mechanical thrombectomy is a new recommendation of stroke intervention in the updated National Clinical Guideline for Stroke. MT should be considered in patients with contraindication of intravenous thrombolysis, occlusion in proximal intracranial large vessels including those in the posterior circulation. (4)
MT is a tricky procedure which requires advanced imaging and prompt intervention in a short period. Long procedural duration leads to devastating complications such as vessel or nerve injuries and emboli to new territories. (14) Thus, MT is only recommended to be performed in large vessel occlusions so far, since the previous 2012 Cochrane review in internal carotid artery (ICA) occlusion, where IVT is proven to be inferior in tackling large occlusions. (15)
Meanwhile, management for haemorrhagic stroke focuses on reversing the bleeding and prohibit further damages. Haemorrhagic-reversal therapy such as intravenous vitamin K, idarucizumab, prothrombin complex should be given to patients accordingly to their underlying treatment-associated ICH. When hypertension is the underlying cause of haemorrhagic, acute blood pressure-lowering therapy is performed immediately. Appropriate reference for surgical interventions should be promptly conducted in treating haemorrhagic stroke. (4)
Monitoring and Preventing Complications
Stroke patients are prone to further neurological deterioration, infection, metabolic disorders, pulmonary embolism (PE), deep-vein thrombosis (DVT) and cardiovascular diseases. Thus, close monitoring of the patient’s glycaemic status, blood pressure, oxygen saturation, temperature, heart rate, and rhythm are crucial. (4) In regards to DVT, intermittent pneumatic compression has been proven to be effective in reducing DVT and mortality post-stroke incidence. (3)
Moreover, considering that stroke patients are at risk of having dehydration and malnutrition, comprehensive assessment in patient’s swallowing ability should be performed within 4 hours after arrival to the hospital to determine the most appropriate route of administering nutrition and hydration. Patients who are found to be dysphagia should be fed using nasogastric tube within 24 hours or alternative fluid therapy. (3,4)
Rehabilitation and Palliative Care Services
Early initiation of rehabilitation is encouraged to be performed once patients are stable although patients are still under the care of the stroke specialist team. Rehabilitation aims to support patients to recover from disabilities that they obtained from strokes. As each patient usually has different needs, rehabilitation is personalised, and every patient should be involved in deciding their rehabilitative goals since the very beginning. (3,4)
As patients come with different severity and needs, stroke specialist team is demanded to expertise various stroke care, including minimising pain and improving quality of life in patients with bad prognosis. Furthermore, integrating palliative care and stroke unit care in earlier stages is reported to benefit in enhancing patients care. (4)
Conclusion
Stroke is a growing cerebrovascular disorder which could be differentiated into ischaemic and haemorrhagic strokes. Each stroke subtype has different risk factors. Overall, such non-modifiable factors such as increasing age, male, and ethnicity along with hypertension, smoking, and excessive alcohol consumption continue to be the significant risk factors which predispose people to stroke. Underlying cardiovascular and metabolic disorders seem to impact the occurrence of ischaemic stroke than haemorrhagic stroke subtypes. In regards to its prognosis, TACI accounts for the highest fatality rate and neurofunctional disabilities amount all types of strokes. Following TACI are SAH, ICH, POCI, PACI, and LACI with the lowest case-fatality rate.
Furthermore, the centralisation of stroke service into Hyperacute Stroke Unit (HASU) has enabled the delivery of a cost-effective, comprehensive, and specialised stroke care. These services include rapid assessments by specialist stroke team, acute brain imaging, specialised stroke management, monitoring, rehabilitation, and palliative care. Involving multisectoral professionals, HASU demonstrates a satisfactory reduction in patients’ fatality rate and neurological dependency.