Stroke Notes, types, Epidemiology, pathophysiology, symptoms, diagnosis.

 Stroke or brain attack is the sudden loss of neurological function caused by an interruption of the blood flow to the brain.

Who Definition:- 

Stroke is defined as rapidly developing clinical signs of focal or global disturbance of cerebral function with symptoms lasting  24 hours or longer or leading to death with no apparent cause other than of vascular origin. 

Epidemiology:-

• Stroke is the 3rd leading cause of death and the most common cause of disability among adults. 
• The incidence of stroke is about 1.25 times greater for males than females. 
• The incidence of stroke increases dramatically with age doubling in the decade after 65 years of age. 

Etiology:-

Atherosclerosis is a major contributory factor in Cerebrovascular disease. 

It is characterized by plaque formation with accumulation of lipids, fibrin, complex carbohydrates and calcium deposits on the arteries walls that leads to progressive narrowing of the blood vessels. 

Pathophysiology:-

• Interruption of blood flow for few minutes
• Complete cerebral circulatory arrest
• Irreversible cellular damage with a core area of focal infraction within minutes
• Excess release of neurotransmitters
• Disturbance in energy metabolism
• Inability of brain cells to produce energy
• Excessive influx of Ca 2+ causing pump failure
• Ischaemic stroke produce cerebral edema
• Increase in the intracranial pressure. 

Types of Stroke:-

They are 2main types of stroke

Ischaemic stroke:-

•  It is the most common type of stroke 80% of the strokes are ischaemic
• Ischaemic stroke are the result of a thrombus, embolism or conditions that produce low systemic perfusion pressure. 
• Lack of Cerebral flow --> No O2 and glucose to the brain, Disrupts cellular metabolism, injury and death of tissues. 

Haemorrhagic Stroke:- 

• It is usually due to abnormal bleeding into the extravascular areas of the brain which is usually due to rupture of a cerebral vessel or a trauma. 
• Haemorrhage --> increased intracranial pressure, injury to brain tissues, restriction of blood flow distally

Classification

Impairment (symptoms) direct impairment:-

Somatosensory deficit:- 

Sensation is frequently impaired, deficits are reported in 53% of the patients with stroke. Patient may also sometimes complain of abnormal sensation such as numbness, dyesthesia, hyperesthesia. 

Pain:- Haemorrhagic Or ischaemic stroke can result in severe headache or nech and face pain. Pain may also result from indirect impairment such as muscle imbalance and improper movement patterns. 

Visual deficits:- Homonymous hemianopsia, visual field defect occurs with lesions involving the optic radiation in IC or 1° visual cortex. It occurs in 26% of patients with stroke. 

Motor deficits:- During the early stages of stroke, flaccidity with no voluntary movement is common, this is replaced by development of spasticity, hyperreflexia and mass patterns of movement termed synergies. 

Speech and language disorders:- 

Aphasia 

1. Fluent ( Wernicke`s or receptive aphasia) 
2. Non fluent ( Broca's Or expressive aphasia) 
3. Global Aphasia. 

Dysphagia:- may sometimes lead to aspiration. 

Bladder and Bowel disturbances

Seizures occurs in small% of patients with stroke and are slightly more common in occlusive carotid disease

Indirect impairment includes:-

• Venous thromboembolism
• Skin breakdown
• Decreased flexibility
• Shoulder subluxation and pain
• Cardiac deconditioning
• Reflex sympathetic dystrophy seen in 12-25% of patients. 

Diagnosis of stroke:-

Includes general medical examination as well as neurological examination

• General -- Vital Signs
  
  
  
• Urinalysis -- to detect infection, diabetes, renal failure or dehydration. 
• Blood analysis -- ESR, blood count. 
• Blood chemistry profile -- indicates serum electrolytes levels 
• Thyroid function tests:- Accelerated Atherosclerosis can result from hypothyroidism. 
• Full cardiac evaluation:- ECG to detect arrhythmia 
• Lumbar puncture:- used to diagnose subarachnoid haemorrhage 
• CT scan used to detect stroke in subacute stage. 
• MRI is more sensitive in the diagnosis of acute stroke. 
• PET scan identify areas of tissues where ischaemia is reversible. 
• Cerebral Angiography:- used when surgery is considered. 

Medical Management:-

• In case of lack of O2 - O2 is delivered via mask or nasal cannula to reestablish and oxygenation. 
• Maintain adequate blood pressure - Hypotension or extreme hypertension is treated. 
• Maintain sufficient cardiac output
• Restore/ Maintain fluid and electrolyte balance
• Maintain blood glucose levels
• Control seizures and infection
• Control intracranial pressure
• Maintain integrity of skin and joints. 

Pharmacological intervention:-

Anticoagulant therapy Heparin, reduce the risk of recurring clots. 

Antiplatelet therapy Asprin.