From the Guidelines
Paresis refers to a partial weakness or mild paralysis of muscles, often resulting from damage to the nervous system, and during an ischemic stroke, blood flow to a part of the brain is blocked by a clot or narrowed blood vessel, depriving brain cells of oxygen and nutrients, leading to a cascade of events that can cause paresis on the opposite side of the body. The mechanism of paresis in ischemic stroke involves the blockage of blood flow to a part of the brain, which triggers a cascade of events: neurons cannot maintain their energy metabolism, leading to failure of ion pumps, membrane depolarization, and release of excitatory neurotransmitters like glutamate 1. Excessive glutamate causes calcium influx into cells, activating destructive enzymes that damage cellular structures. Within minutes, brain cells in the core of the affected area die, while those in the surrounding "penumbra" region remain at risk but potentially salvageable.
Key Points
- The location of the stroke determines which body functions are affected - strokes in motor pathways often cause paresis on the opposite side of the body 1.
- Treatment focuses on rapid restoration of blood flow, ideally within 4.5 hours for intravenous thrombolysis with alteplase (0.9 mg/kg, maximum 90 mg, with 10% given as bolus and remainder over 60 minutes) or up to 24 hours for mechanical thrombectomy in eligible patients 1.
- Early recognition of stroke symptoms using the FAST method (Face drooping, Arm weakness, Speech difficulties, Time to call emergency services) is crucial for timely intervention and better outcomes 1.
- The use of anticoagulants and antiplatelet agents should be delayed for 24 hours after treatment with rtPA 1.
Recommendations
- Intravenous fibrinolytic therapy is recommended in the setting of early ischemic changes on CT, regardless of their extent (Class I; Level of Evidence A) 1.
- A noninvasive intracranial vascular study is strongly recommended during the initial imaging evaluation of the acute stroke patient if either intra-arterial fibrinolysis or mechanical thrombectomy is contemplated for management but should not delay intravenous rtPA if indicated (Class I; Level of Evidence A) 1.
From the Research
Mechanism of Paresis
- Paresis is a condition characterized by partial paralysis or weakness of a limb or limbs, often resulting from damage to the brain or spinal cord.
- In the context of ischemic stroke, paresis occurs due to the loss of blood supply to the brain tissue, leading to irreversible damage if blood flow is not restored quickly 2.
- The mechanism of paresis in ischemic stroke involves the disruption of normal brain function, including motor control, due to the lack of oxygen and nutrients to the affected brain tissue.
Ischemic Stroke
- Ischemic stroke accounts for approximately 85% of all strokes and is a major cause of mortality and morbidity worldwide 3, 4.
- The pathogenesis of ischemic stroke is similar to myocardial infarction, involving the loss of blood supply to the tissue, which can result in irreversible damage if blood flow is not restored quickly 2.
- During an ischemic stroke, the brain tissue is damaged due to the lack of oxygen and nutrients, leading to progressive, irreversible loss of brain tissue if therapy is not started promptly 2, 5.
- Reperfusion therapy, including intravenous tissue plasminogen activator (tPA) and/or endovascular thrombectomy, is a mainstay of acute stroke management, aiming to restore blood flow to the affected brain tissue and minimize damage 3, 6.