Stroke: current concepts in diagnosis and intraarterial (minimal invasive) therapy

<WRAP center round box 60%> Topic 1 - Team T - Nashwa Shaik Monica Yadav Tariq Saif Syed Dhanush Kumar Mudupur

Introduction

When a person accidentally bruises his thumb with a knife or bruises his toe on the edge of anything sharp, he may bleed for a while. Eventually, the bleeding stops on its own. The stunning ability of blood to remain as the liquid within the blood vessels but to turn into solid and patch holes in the same vessels in case they are torn being the reason behind it! Although this superpower of blood can save lives during injuries in accidents or during childbirth, it could be devastating to cause a catastrophe of stroke! Just like, a heart attack threatens a heart, a stroke threatens a brain. It’s basically, a problem with blood vessels. Most strokes are painless, while the symptoms being a paralyzed arm or leg for example, which are not apparently related to the brain. The catastrophe doesn’t take too long to make itself obvious when a slice of the brain is deprived of oxygen. It attacks out of the blue! One could experience an inability to speak all of a sudden, or a dish could crash from a hand that could no longer grasp, or one could lose consciousness. Well, it strikes its victims like the wind, violently without a warning. Or maybe it does?! It has most probably been there for years in the making, in an environment of high blood pressure, obesity, high cholesterol, and diabetes which are highly responsible for the wear and tear of the blood vessels. All these conditions intensify the risks of suffering either a blockage or a rupture of a brain artery.[10]

Statistically speaking:(according to WHO)[4]

  • 15 million people suffer strokes worldwide each year. Among these, 5 million dies, and another 5 million are permanently disabled.
  • High blood pressure contributes to more than 12.7 million strokes worldwide.
  • Europe averages approximately 650,000 stroke deaths each year.

Summary

Stroke is a sudden and unexpected beginning of a focal neurological sign in consequence of an event related to blood vessels persisting around 24 hours. The first 24-hour duration of stroke event is referred to as an “Acute stroke”. Stroke can be categorized into either ischemic, which is a result of thrombosis or embolism and hemorrhagic, a result of aneurysm or blood vessel rupture.

The blockage of a cerebral artery leads to diminished flow in the blood to the brain and thus ischemia. If the intensity of the ischemia is severe, this would further lead to infarction within few minutes. Infarction is basically a cellular death and the cells here are the nerve cells. Therefore, it causes irreparable and irreversible harm and destruction to the affected part of the brain called “core of the infarct”. Although the tissue surrounding the infarct is affected, it may be possible for it to recover functionally once the blood flow to it is restored. This condition is referred to as “Ischemic Penumbra”. The first three hours from the occurrence of occlusion are crucial in most of the patients as the ischemic penumbra is capable of treatment, while in some patients this condition lasts for 12 hours and hence called “therapeutic window”. Thus, appropriate diagnosis and identification of the patients are decisive and critical in the effectiveness of interventions.

Vascular recanalization and supportive care following imaging remain as two foremost strategies for the efficient management of acute stroke. In a hemorrhagic stroke, the differential diagnosis plays a crucial role. Recovery of perfusion and or blood flow restoration is a principal strategy in therapy. Nevertheless, recombinant tissue plasminogen activator (rt-PA), aspirin, a little better than placebo, remains not so productive. Rehabilitation and general care are employed at present for the therapy.

Evacuation or clearance of hematoma especially in the cerebellum and supratentorial regions exceeding 3 cm, the treatments employed currently for the patients with a hemorrhagic stroke despite the trails failed to demonstrate efficacies. Endovascular intervention or surgical intervention is imperative if the hemorrhage is caused due to aneurysm rupture to prevent bleeding again.

Although there was an enhancement in care, the consequences after stroke persist to be a serious issue. About 50-70 % of stroke victims those that survive an ischemic attack may retrieve functionality around three months after its onset; around twenty percent of the victims may require institutional care. Accurate and differential diagnosis, quick and proper treatment, advances in access to well efficient therapeutic options, and rehabilitation services play crucial roles to lessen the disabilities and prevent suffering in future sufferings in a society consisting of higher aging citizens.

Here, we review the anatomical aspects of the human nervous system, blood vessels concerning the nervous system, and the pathophysiological aspects when affected by stroke, its identification (FAST rule), its diagnosis, and therapeutic options such as intra-arterial and minimally invasive therapies, etc.

Chapter 1

Anatomy

1.1 Brain

The brain is an organ that governs the whole human body and contains approximately 100 billion neurons. Information from our sensory organs like eyes, ears, nose, tongue, and skin is being processed by the neurons. The brain which is considered to be the central processing unit of the human body consumes over 20% of the oxygen and blood in the body.

The Brain

Interestingly an adult brain only weighs about 3 pounds which is about 2% of the total body weight still brain has the capacity of processing a large amount of data and can perform at most a thousand different operations per second. The information which is being received by the sense of sight, smell, touch, taste, and hearing is being stored in our memory and things like emotions, intelligence, and creativity are also a part of brain functionality.

The Brain is a central organ of the nervous system which consists of:

  • The central nervous system consists of the brain and spinal cord.
  • The peripheral nervous system consists of spinal nerves and cranial nerves.

1.2 Parts of the brain:

The brain consists of three main parts: Cerebrum, Cerebellum, and Brainstem.

Cerebrum: It is considered to be the largest part of the brain with the right and left hemispheres. Functions like reasoning & judgment, problem-solving, emotions, vision, and hearing are performed by the cerebrum.

Cerebellum: Cerebellum makes up to only 10% of the brain mass and positioned under the cerebrum and above the brain stem which is responsible for functions like balance, posture of the body, coordination, and voluntary movements.

Brainstem: The connection between the spinal cord and the cerebrum and cerebellum is being established by the brainstem. It also performs involuntary and automatic functions such as breathing, digestion, sneezing, coughing, and heart rate.

Anatomy of brain

1.3 The hemispheres: Right and left

The cerebrum is significantly divided into two halves, Right hemisphere and left hemisphere. Corpus callosum is the fiber connecting the hemispheres and transmitting information between them. Each hemisphere is responsible for the control of the opposite side of the body. For example, if a stroke occurs on the left side of the brain, the right arm or leg may become weak or paralyzed.

Hemispheres of the brain

The Cerebral hemisphere is the mirror image of each other but performing different types of functions. Meanwhile, the left hemisphere is known for controlling speech, language, comprehension, and writing whereas the right hemisphere controls artistic and creative skills.

1.4 Lobes of the brain:

The hemisphere has distinct functions, each hemisphere has been divided into four lobes namely: Frontal, temporal, parietal, and occipital.

Lobes of the brain

There are no individual functions of the lobes. Moreover, the complex relationships between the four lobes and the hemisphere are the reason for the functions performed.

1.4.1 Functions of the lobes:

  1. Frontal lobe: It is the front face of the brain which is responsible for cognitive function and control of voluntary activity or movement, personality, behavior & emotions.
  2. Parietal lobe: Processes information such as temperature, movement, touch, taste, language, sensory and memory operation.
  3. Occipital: Primarily responsible for vision.
  4. Temporal: Responsible for memories, sound, sight, touch, and organization.

Language: For speech and understanding of the language there are two areas in the left hemisphere namely:

  1. Broca’s area: Speaking and writing
  2. Wernicke’s area: Understanding language

There are two areas performing language-related functions and based on the symptoms shown by the body the damage is being determined. If Broca’s area is being damaged the body can feel difficulty moving the tongue or facial muscles to produce the sounds of speech called Broca’s aphasia. Any damage to the Wernicke’s area causes Wernicke’s aphasia, In this condition, a person can make speech sounds but having difficulty understanding speech being unaware of their mistakes.

1.5 Cortex:

Cortex is the surface of the cerebrum composed of folds of grey matter and contains 16 billion neurons specifically arranged in the layer for functionality. The nerve cells give the cortex a grey colour hence called grey matter. Beneath the cortex is the white matter in which the nerve fibers are present which interconnects the brain.

Cortex

The capacity of the neurons increases with the area of foldings in the cortex which results in higher functionality. The fold is called a gyrus and the groove between folds is called the sulcus.

1.6 Nervous Tissue:

The nervous system is divided anatomically into the Central nervous system and the Peripheral nervous system.

1.6.1 Central nervous system: The central nervous system consists of the brain and the spinal cord. The nervous tissue of the system consists of only the three meninges (dura mater, arachnoid membrane, and pia mater). Due to the absence of connective tissue, the CNS tissue has a very soft jelly-like consistency. The two main classes of the cells of the nervous tissue are nerve cells-neurons and supporting cells-glia.

Neurons: A majority of neurons are generated before birth, the stem cells give rise to a small number of new neurons throughout the lifetime of a human being. The addition of permanent neuron might be necessary for the maintenance of some parts of the CNS, neurons should last a lifetime and are not mitotically active.

Neuron structure

The key points in understanding the function of a neuron are:

  1. The shape of the neuron and its processes
  2. The chemicals used by the neuron to communicate with the other neurons(neurotransmitters)
  3. How the neuron may react to the neurotransmitters sent by other neurons.

Neurons have long processes, the processes are being divided into different groups, dendrites, and axons. The receptive surface of the neuron consists of dendrites, neurons have several primary dendrites emerging from the perikaryon. Primarily dendrites can divide into secondary and tertiary dendrites, dendrites can have small mushroom-shaped appendages called spines. Every neuron has only one axon emerging from the perikaryon or close to the trunks of primary dendrites. The point of origin of the axion is known as axion hillock. The axon is considered to be the ‘transmitting’ process of the neuron.

1.6.2 Transmitters: The neurotransmitter could either excite or inhibit the postsynaptic neuron.The prominent excitatory transmitter in the CNS is L-glutamate and a prominent inhibitory transmitter in the CNS is GABA(gamma-aminobutyric acid). Other main transmitters are dopamine, serotonin, acetylcholine, noradrenaline, and glycine. Each neuron uses only one of the main transmitters.

1.6.3 Receptors: These are a multitude of receptors that are sensitive to one particular neurotransmitter. Different receptors possess different response properties. The reaction of the neuron to the neurotransmitter released on to its plasma membrane is determined by the types of Receptors expressed by the neuron.

1.6.4 Glia: The CNS tissue contains non-neuronal supporting cells-Neuroglia

  1. Astrocytes: Also known as astroglia are star-shaped cells and their processes are in contact with a blood vessel. Astrocytes that provide mechanical and metabolic support to the neurons also participate in the maintenance of the composition of the extracellular fluid.
  2. Oligodendrocytes: As known as oligoglia have shorter processes, they form the myelin sheath around axons in the CNS and are functional homolog of peripheral Schwann cells.
  3. Microglia: These are small cells with complex shapes. Microglia are in contrast to neurons and the other types of glial cells. They are desired from the same cell line which also gives rise to monocytes.

1.6.5 Peripheral Nerves: Every nerve fibers consist of an axon and its nerve sheath, Each axon is surrounded by a sheath of Schwann cells. Every individual Schwann cell can surround the axon for several hundred micrometers and can surround up to 30 separate axons. In myelinated nerve fibers, Schwann cells surround this axon with several double layers of the cell membrane.

Myelination

1.6.6 Types of fibers:

  1. Type A fibers(myelinated): These fibers are 4-20 µm in diameter and conduct impulses at high velocities of 15-120m per second Ex: motor fibers, sensory fibers.
  2. Type B fibers(myelinated): These fibers are 1-4µm in diameter and conduct impulses at the velocity of 3-14m per second. Ex: Preganglionic autonomic fibers.
  3. Type C fibers (unmyelinated): These fibers are 0.2-1µm in diameter and conduct impulses at velocities ranging from 0.2 to 2 m per second.Ex: Autonomic and sensory fibers.

1.6.7 Ganglia: Ganglia are the aggregations of the nerve cells outside the CNS. Individual ganglion cells are surrounded by a single layer of flattened satellite cells. The neurons in cranial nerve and dorsal root ganglia are pseudounipolar and have a T-shaped process. The arms of the T are branches of the neurite connecting the ganglion cell with the CNS and the periphery. As both branches function as an actively conducting axon that transmits information from periphery to the central nervous system.

1.7 Deep structures of the brain:

Deep structures of the brain

Pituitary gland: It is called as the ‘master gland’. It is a small organ located in a small pocket of bone at the skull base known as sella turcica. The pituitary gland is controlled by the hypothalamus and functions in hormone production.

The pineal glandbelongs to the endocrine system located in the groove between the two hemispheres. This gland produces several important hormones like serotonin-influences sexual development sleep-wake cycles.

Hypothalamus: It is neutrally and chemically connected to the pituitary gland and is responsible for regulating thirst, hunger, response to pain, sexual satisfaction, etc. The main function of the hypothalamus is the maintenance of the body’s “homeostasis”.

Thalamus: Acts as a communication gateway for all sensory information of the cerebral cortex and has a significant role in pain, temperature sensation, and touch.

Hippocampus: Memory formation, organization, and storage are some of the main functions of the hippocampus. Memory sorting as well as sending and receiving memories out to the different regions of the cerebral hemisphere so that it can be retrieved when necessary.

1.8 SKULL:

The hard bony structure which is meant to protect the brain from injury is called the skull. A set of bones being fused along suture lines includes frontal, parietal(2), temporal(2), sphenoid, occipital, and ethmoid. The face structure is formed by 14 pairs of bones which include the maxilla, zygoma, nasal, palatine, lacrimal, inferior nasal conchae, mandible, and vomer.

Skull

1.8.1 Meninges: The three membranes that line the skull and vertebral canal and enclose the brain and spinal cord namely:

  1. Dura mater: It is a strong and thick membrane that lines the inside of the skull. It consists of two layers the periosteal and meningeal dura. Little folds or compartments are created by the dura. The two dural folds are the falx and tentorium. The falx separates the right and left hemisphere and the tentorium separates the cerebrum and cerebellum.
  2. Arachnoid mater: It is a thin, web-like membrane covering the entire brain. The space between the dura and arachnoid membrane is subdural space.
  3. Pia mater: Surrounds and huges the surface of the brain following the folds and grooves. The space between arachnoid and pia is called subarachnoid space. The cerebrospinal fluid baths and cushions the brain in the subarachnoid space.

1.9 Cranial Nerves:

The cranial nerves are the 12 pairs of nerves that can be seen on the bottom surface of the brain. Some of these nerves are responsible for bringing information from sensory organs to the brain. Other cranial nerves are being connected to different glands or internal organs such as the heart and lungs.

Functions of cranial nerves

Chapter 2- Main aspects of the disease

2.1 Blood Flow to the Brain

The brain is to the body what a CPU (Central Processing Unit) is to the computer but, superior and sophisticated by manifold. The structure of the blood vessel causing blood flow is a very complex and efficient mechanism. The blood supply of the brain is divided into two systems, the Anterior system, and the Posterior system.

2.1.1 Let us start from the heart:

Fig 1. Arteries arising from the aortic arch

The Aorta is the main artery that carries blood away from the heart to all the parts of the body. The aortic arch is a bend between the ascending and descending aorta. The ascending aorta traversing to the brain has three branches. The first branch is the Brachiocephalic artery which gives rise to the Right subclavian artery and the Right common carotid artery. The aortic arch itself divides into the left subclavian artery and the left common carotid artery which function as the second and third branches arising from the heart to the brain. These three branches continue further to form the two systems of the brain blood supply.

2.1.2 Posterior System:

Fig. 2 Anterior and posterior circulation of the brain

The posterior system arises from the subclavian artery which gives rise to two branches named Vertebral artery that travel upwards towards the cranial cavity. The vertebral artery will pierce through the Dura and Meninges and reach the subarachnoid space. These arteries will lie on the anterior surface of the Medulla Oblongata. The vertebral artery which is in two branches merges into one at the border of the Medulla Oblongata and Pons (Pontomedullary junction) and continues as the Basilar artery. The Intracranial branches of Vertebral artery are:

  • Posterior spinal artery
  • Anterior spinal artery
  • Posterior inferior cerebellar artery (PICA)
  • Medullary and meningeal branches

The posterior spinal artery and anterior spinal artery mainly supply to the spinal cord, while the anterior spinal artery supplies the median part of the medulla oblongata as well. The PICA is the biggest branch of cerebral arteries and it gets its name as it supplies to the inferior and posterior region of the cerebellum. In some people, the posterior spinal arteries originate from PICA rather than directly from the Vertebral artery. The two vertebral arteries unite at the lower border of the pons to form the basilar artery which further branches into Anterior inferior cerebellar artery which arises at the lower border of pons and will supply the anterior and inferior surface of the cerebellum, Labyrinthine artery which supplies to the inner ear, Pontine branches are numerous slender branches which are of two types. The first type is the Paramedian arteries which will supply the median area of the Pons. The long and short circumflex artery supplies to the lateral surface of the Pons and moves to the posterior surface of the Pons and supplies the posterior surface, Superior cerebellar artery is one single artery without any bifurcation which supplies to the superior border of pons where it winds posteriorly and the superior surface of the cerebellum. There are also two terminal posterior cerebral branches that diverge at upper border of pons which supply the midbrain through cortical branches. The Basilar artery terminates by dividing into its terminal branches at the midbrain, called Posterior cerebral arteries. The Posterior cerebral artery splits into Cortical branches and Sensual branches. Cortical branches supply to then Cortex and Sensual branches supply to the deeper structures within the brain such as parts of the Thalamus, parts of the Lentiform nucleus.

2.1.3. Anterior System:

The anterior system starts from the common carotid artery. It gives two branches, the internal carotid and the external carotid artery at Corotid sinus. The internal carotid artery will enter the cranial cavity through the carotid canal and the temporal bone and from there the internal carotid artery will supply the whole anterior circulation. Branches of the Internal carotid artery:

  • Posterior communicating artery- The left and the right posterior communicating artery connects three cerebral arteries on the respective sides. Posteriorly it connects to the posterior cerebral artery, establishing communication between both the systems.
  • Anterior choroidal artery- Supplies the choroid plexus of lateral ventricle
  • Anterior cerebral artery- Deep branches supply internal capsule and basal ganglia. Cortical artery will move medially and anteriorly and supply the medial surface through orbital, frontal and parietal branches.
  • Middle cerebral artery- Middle cerebral artery moves laterally, moving outwards towards the lateral surface of the hemisphere. Gives upward and downward branches, supplying whole lateral surface of the brain except for areas supplied by anterior cerebral artery and by posterior cerebral artery through temporal, frontal, and parietal branches along with perforating branches which supply the internal capsule and part of basal nuclei.
  • Ophthalmic artery- It is the first branch of the internal carotid artery. It traverses through the optic canal, entering the orbit. It supplies to the orbit of the eye and to some structures of the face, nose, and meninges.

2.1.4. Circle of Willis:

Circle of Willis is an arterial ring situated at the base of the brain and is completed by the anterior communicating artery and two posterior communicating arteries, thereby connecting the anterior and posterior supply. It is the meeting point of the left and right internal carotid arteries, left and right anterior cerebral arteries, left and right posterior cerebral arteries left and right posterior communicating arteries, basilar artery, anterior communicating artery.

Fig.3 Circle of Willis

The Circle of Willis functions as a backup system for blood flow between the arteries involved when the blood supply in one of the regions supplied by these arteries is reduced, maintaining the equilibrium between blood flow to the right and left hemispheres. The blood flows through the midline of brain to supply when there is a low pressure created by the occlusion or blockage of the arteries involved.

2.2 Main functional regions of the Brain

From thinking, feeling, breathing to walking our every action is a coordinated effort that is orchestrated by the brain. The left and right brain hemispheres are known to control different aspects, the right hemisphere is known to be more creative while co-ordinating activities like imagination, arts, rhythm, etc., and the left is known to be analytical as it is connected to logic, mathematics, facts and so on (ref Fig1.3). The brain is divided into regions that control specific actions. The functions of different parts of the brain are discussed in chapter 1. The cortical functional areas such as motocortex, sensory cortex, visual cortex, Broca's area, Wernicke's area, and their functions are discussed here. These regions are situated in the cortex of the brain. (ref Fig 1.4) Motocortex: The motor strip present in the cortex control the voluntary movements. It is categorized into 3 areas,

  • Primary motor cortex: The nerve impulses required for the control of execution of movement are generated here
  • Premotor cortex: It is responsible for some aspects such as sensory and spatial guidance for movement and planning of movement.
  • Supplementary motor area: Responsible for the coordination between the two sides of the body, planning of movement and the sequence of movement.
  • There are additional structures which control motor functions:
  • Posterior parietal cortex: Guides spatial reasoning, attention and planned movements.
  • Dorsolateral prefrontal cortex: Important for working memory, abstract reasoning, cognitive flexibility- ability to switch between topics and thinking about multiple concepts simultaneously.

Sensory cortex: Receiving and processing the five sensations sight, touch, smell, hearing, and taste.

  • Somatosensory cortex: The centre that receives all the sensory information from your body through the motor cells related to specific parts.
  • Gustatory cortex: Responsible for the perception of taste and is present in the postcentral gyrus.
  • Olfactory cortex: Responsible for the sense of smell located in the uncus, found along the ventral surface of the temporal lobe.
  • Visual cortex: Located in the occipital lobe and is responsible for vision.
  • Auditory cortex: Part of the temporal lobe, responsible for hearing.

Association areas: Other than the sensory and motor areas, the brain has other areas that are responsible to control and coordinate its functions. The association areas will pool in the incoming sensory information and form a connection between motor and sensory areas.

  • Wernicke’s area: The posterior section of the cerebral hemisphere on the dominant hemisphere (mostly left), is linked with speech along with the Broca's area. Wernicke's area is associated with understanding language
  • prefrontal association complex: A region of the brain located in the frontal lobe that is involved in abstract thought and planning of actions
  • Broca’s area: A region in the frontal lobe of the dominant hemisphere (mostly left) with functions linked to speech production, mainly speaking and writing.

Cortical homunculus

Fig 4. Motor and sensory homunculus

The cortical homunculus is a neurological map that corresponds to the areas and proportions of the brain which control and co-ordinate various activities. The more surface area shown in the cortical homunculus the more co-ordination and association of the brain involved.

2.3 Effect of stroke on functioning of the body

Effect of a stroke on different organs depends on the location and the degree to which brain tissue is affected. It is important to note that since one side of the brain controls the opposite side of the body, a stroke affecting in one hemisphere will affect the functions of the side of the body it co-ordinates. Hence a stroke occurring on the left side of the body will cause paralysis in the right side of the body and affect other functions and vice versa however, both of them will cause memory loss. Effects of a left-sided stroke:

  • Anomia: Inability to recall names of everyday objects.
  • Aphasia: Problems in speaking and understanding a language. Depending on whether you have trouble speaking aloud, reading, writing or listening, the problem of aphasia can affect the ability to speak, read, write, listen, deal with numbers, understand speech or written words, think of words when talking or writing.
  • Apraxia (motor apraxia): Inability to move even with a normal function of muscles and senses.
  • Verbal apraxia: Inability to coordinate the movement of the mouth to form sounds or words

Effects of a right-sided stroke:

  • Agnosia: Inability to recognise voices, faces, places and objects.
  • Anomia: Inability to recall names of everyday objects.
  • Attention span: Inability to focus on a conversation or task for a long amount of time.
  • Denial: Patients deny that they had a stroke and in some cases deny that the paralysed hand or leg belongs to them
  • Neglect: Ignoring the left side of your body or environment
  • Perseveration: Difficulty in following instructions, repeating the same answers even when the question is changed
  • Visual or spacial problems: Inability to judge distance, size, rate of motion of an object.

Affect on different organ systems of the body:

Respiratory system:

  • Pneumonia: Eating and swallowing are affected when there is damage to the area of the brain that controls these actions. This is dysphagia and improves along with time. However, when dysphagia occurs the food that is not directed to the oesophagus can be directed to the airway and settle in the lungs, causing infections and pneumonia.
  • A stroke that takes place in the brain stem causes breathing problems. This type of stroke can result in death or coma.

Nervous system:

  • The nervous system sends signals back and forth in order to control the whole body. These messages are not received properly when the brain is damaged.
  • The patient may feel more pain or loss of sensation in some cases.
  • Loss of vision on one side or parts, processing issues where the brain does not get the right information from the eyes, problems in moving the eyes are caused when the part of the brain that controls vision undergoes a stroke.
  • Foot drop is a common type of weakness that occurs in case of a stroke.

Circulatory system: A stroke is an existing circulatory system issue which can lead to a second stroke or a heart attack. High blood pressure, high cholesterol levels and diabetes must be regulated.

Muscular system:

  • Hemiparesis: One-sided weakness of the body depending on the affected hemisphere
  • Spasticity: The muscles become stiff and unusually tight.
  • Dysphagia: Eating and swallowing are affected, thus affecting the movement of food to the oesophagus
  • Hemiplegia: One-sided paralysis of the body
  • Foot drop: It is the difficulty to lift the front part of the foot. This type of paralysis forces the patient to drag their foot or to bend their knee in order to lift it up
  • Balance problems: Depending on the area affected, balancing and coordination while walking and doing other activities are affected.

Digestive system and Urinary system They are affected similarly, loss of control of bowel function and loss of control of bladder occur. Fig 5. Effect of a stroke on the body

2.4 Symptoms of a stroke

Stroke shows varied symptoms on our bodies like the clinical terms discussed - anomia, aphrasia, apraxia, agnosia, dysphagia, hemiparesis, spasticity of muscles, hemiplegia etc. A good knowledge of the symptoms that occur during stroke helps in early diagnosis and therapy which can help reduce the risk of stroke. To summarise the symptoms discussed, these are some of the symptoms that are easy to spot:

  • Sudden weakness or numbness in the face, legs or arms especially on one side of the body.
  • Sudden confusion, troubled in understanding speech and speaking.
  • Sudden impairment in vision in one or both eyes.
  • Sudden trouble walking, experiencing dizziness, loss of coordination or balance.
  • Sudden headache-causing severe headache with no known reason.

But the most widely known mnemonic to spot the symptoms of a stroke is F.A.S.T it stands for

F: Face drooping Ask the person to smile. Check if the person's smile is uneven. Does the person have a sensation on both sides of his/her face?
A: Arm weakness Ask the person to raise both arms. Is one arm drifting downward? Is one of the arm weak or numb?
S: Speech difficulty Ask the person to repeat a simple sentence. Is the person finding it hard to speak or understand? Is his/her speech slurred?
T: Time to call an emergency service If the person shows any of these symptoms, even if the symptoms go away, call an emergency service

Chapter 3

Provision of medical care for stroke

3.1 Prevention of stroke

Factors of risk:

* Hypertension or high blood pressure is a key risk factor for stroke. Despite the immense accessibility of the medicines that treat high blood pressure, they were not used frequently.

Reasons:

  • Misinformation
  • Negative attitude towards the medications.[1][5]

In patients with excessive cholesterol, curtailing of lipids with statins helps in diminishing the risks of stroke by about 21% as demonstrated in a study.[2][3]

Atherosclerosis may be confronted with Endarterectomy, a surgical procedure. It may be impractical due to the involved risks and costs.[5]

Atrial fibrillation, a crucial reason for Ischemic stroke in the aged population can be managed by:

  • Aspirin
  • Warfarin
  • Pacemaker

Diabetes, smoking, alcohol can be controlled to lower the risk of stroke.

Prevention of stroke plays a crucial role in countries where the care units are unfeasible, exorbitant, or unavailable.

3.1.2 How to prevent the onset of stroke?

Strategies:

  • Aspirin–> Highly beneficial, economical (18.1% risk reduction in contrast to placebo).
  • Dipyridamole –> suggested being a standard (37% risk reduction) [7]
  • Clopidogrel –> to lower the reoccurrence of ischemic stroke, in patients allergic to aspirin.[8]
  • Warfarin –> Lowers the risk by 70% for the reoccurrence of stroke in people with atrial fibrillation.[5]
  • Carotid endarterectomy –> Efficient in patients with at least 70% stenosis of the symptomatic carotid artery.[3]
  • Perindopril protection –> A medication for blood pressure demonstrated about 30% lowered recurrent stroke.[5][9]

3.2 Acute Therapy

3.2.1 Strategies for successful management of Acute Ischemic stroke:

  • Vascular recanalization strategies:
  • Antiplatelet agents
  • Thrombolysis

Thromboembolic occlusion of an intracranial artery is the key cause for most of the strokes. Hence, the restoration of blood flow to the ischemic area is a crucial therapeutic strategy. Ischemic Penumbra, the brain tissue that has the potential to recover, permits preliminary intervention in order to tackle the functional disability and neurological symptoms in the wake of the attack.

  • Oral aspirin
  • Intravenous rt-PA

The above two pharmaceuticals are currently recommended for the treatment of acute stroke.

Antiplatelet agents

Some studies indicate a decrease in the incidence of ischemic stroke with the administration of aspirin. However, they also demonstrated a ramp up in hemorrhagic strokes. Thus, the efficacy of aspirin for the treatment of acute stroke is not lucid yet.[5] Aspirin along with thrombolytics may ramp up bleeding. So, for patients suffering from a stroke that cannot be treated with thrombolysis only aspirin is currently recommended.

Benefits of acute aspirin treatment:

  • Low cost
  • Easy administration
  • Low risk of toxic effects

Side effects:

  • Abdominal pain
  • Peptic ulcerations

Thus, its wider usage is limited.

  • Clopidogrel can be an alternative to aspirin.
  • Warfarin, an anticoagulant is not as efficient as aspirin alone.

Nevertheless, no other antiplatelet agent is reported to be as effective as aspirin so far.[5]

Thrombolysis:

A study demonstrated the efficacy at three months after the intravenous administration of rt-PA within 3 hours of ischemic stroke onset. Thus, the rt-PA administration is FDA approved. However, its safety and efficacy in children are not yet proven.

Side effects: Bleeding from cuts, gums, wounds, injection sites, fever, and low blood pressure.[5]

No other thrombolytic agent is reported to be as effective as rt-PA so far.

Therapeutic window: Treatment within 3 hours from the stroke onset is called “Therapeutic window for acute stroke”. Earlier treatment plays a critical role. Some studies demonstrated that treatment within 4 hours from onset remains effective with no ramping up in the risk of hemorrhage.

3.2.2 Treatment options for acute hemorrhagic stroke

Hemorrhagic stroke is an extremely arduous kind of stroke to be treated and the strategies available to lower the disability and mortality are scanty. Recombinant Activated Factor VII to treat excessive bleeding in patients with hemophilia.

Upon consultation with a neurosurgeon and after a CT scan, the assessment is done based on the size and location of the hematoma. This determines the prognosis. Evacuation or clearance of hematoma especially in the cerebellum and supratentorial regions exceeding 3 cm, the treatments are employed currently for the patients with a hemorrhagic stroke despite the trails failed to demonstrate efficacies.

Re-bleeding may be a risk in patients with hemorrhagic stroke in case the surgery is delayed.

Antifibrinolytic agents may be beneficial in such cases as they reduce the risk of re-bleeding as they are associated with a lowered incidence of aneurysmal re-rupture. However, this doesn’t enhance the poor patient outcomes.[4][5]

3.3 Supportive care

As soon as a cerebral infarction occurs, the immediate goals would be

  • To restore and optimize the perfusion rate in the ischemic area
  • To control and monitor the potential intricacies related to strokes such as cerebral edema, hemorrhagic transformation, seizures, cardiovascular and pulmonary complications, fever, and hypertension.
  • To avoid issues like malnutrition, pressure sores, deep venous thrombosis, infections, aspiration pneumonia, and pulmonary embolism those are common in bedridden patients.
  • Provision of nutritious food.
  • Offering support to the paralyzed parts, to the airways, and assistance of ventilation to the troubled patients.
  • Antipyretics with no antiplatelet effect is to be used to treat fever as it is associated with poor outcome.
  • To reduce and control the sugar levels following stroke.
  • To monitor the swallowing function.
  • To monitor for cardiovascular diseases like myocardial infarction and arrhythmias.[4][5]

3.4 Major challenges in the management of stroke

  • Prehospital delays remain a major concern and a challenge concerning the management of stroke. The therapeutic window is significant in stroke victims.
  • Unavailability and lack of access to health services is a major challenge in developing countries.
  • Lack of knowledge of symptoms of stroke, its severity and the significance of calling the emergency services.
  • Lack of protocols specific to stroke, delays in diagnosis, less effective treatment availability, lack of access to rt-PA.
  • High instability of stroke during the acute phase. This needs close monitoring and prompt, immediate attention to complications.
  • Recanalization strategies employed and recommended currently have limited efficacy and cause harmful side effects in some cases.
  • The complexity of stroke pathobiology
  • Inflammation and interaction of the brain-immune system
  • Regeneration: Reorganization ability of brain, plasticity, and repair after an injury is much greater than previously thought.
  • Confounding factors, long-term outcome, and predictive modeling.[5]

References

[1] Bornstein, N.; Silvestrelli, G.; Caso, V. & Parnetti, L.“Arterial Hypertension and Stroke Prevention: An Update” Clinical and Experimental Hypertension, Informa UK Limited, 2006, 28, 317-326 https://doi.org/10.1080/10641960600549405

[2] Gascon, J. J.” Why hypertensive patients do not comply with the treatment: Results from a qualitative study” Family Practice, Oxford University Press (OUP), 2004, 21, 125-130 https://doi.org/10.1093/fampra/cmh202

[3] Amarenco, P.; Labreuche, J.; Lavalle}e, P. & Touboul, P.-J. ”Statins in Stroke Prevention and Carotid Atherosclerosis” Stroke, Ovid Technologies (Wolters Kluwer Health), 2004, 35, 2902-2909 https://doi.org/10.1161/01.STR.0000147965.52712.fa

[4] World Health Organization. The World Health Report 2002: Reducing risk, promoting healthy life. 2003. Geneva, Switzerland, The World Health Organization.

[5] Weely, S. & Leufkens, H. “Priority medicines for Europe and the world - A public health approach to innovation” ORPHAN Diseases, 2004, 95-100

[6] Strong, K.; Mathers, C. & Bonita, R. “Preventing stroke: saving lives around the world” The Lancet Neurology, Elsevier BV, 2007, 6, 182-187 https://doi.org/10.1016/S1474-4422(07)70031-5

[7] Diener, H.; Cunha, L.; Forbes, C.; Sivenius, J.; Smets, P. & Lowenthal, A. “European Stroke Prevention Study 2. Dipyridamole and acetylsalicylic acid in the secondary prevention of stroke” Journal of the Neurological Sciences, Elsevier BV, 1996, 143, 1-13 https://doi.org/10.1016/S0022-510X(96)00308-5

[8] “A randomised, blinded, trial of clopidogrel versus aspirin in patients at risk of ischaemic events” (CAPRIE).CAPRIE Steering Committee Lancet, Academic Press, 1996, 348, 1329-39

[9] Matchar, D. B.; Samsa, G. P. & Liu, S. “Cost-Effectiveness of Antiplatelet Agents in Secondary Stroke Prevention: The Limits of Certainty” Value in Health, Elsevier BV, 2005, 8, 572-580 https://doi.org/10.1111/j.1524-4733.2005.00050.x

[10]Marler, J. R.Stroke for dummies John Wiley & Sons, 2005.

aes20/stroke.txt · Last modified: 2020/05/25 15:16 by myadav
Back to top
CC Attribution-Share Alike 3.0 Unported
Driven by DokuWiki Recent changes RSS feed Valid CSS Valid XHTML 1.0