Diagnosing Stroke

Stroke Diagnosis and Testing

• Immediate measurement of blood sugar levels is crucial to rule out hypoglycemia, which can mimic stroke symptoms like unilateral paralysis.
• Imaging tests are essential for stroke diagnosis, with CT and MRI as the primary methods for detecting brain issues.
• CT scans effectively identify most hemorrhagic strokes but may miss certain subarachnoid hemorrhages.
• If CT fails to identify a stroke, a spinal tap can be performed to check for blood indicative of a subarachnoid hemorrhage.
• Ischemic strokes can also be detected by CT and MRI, though they might not show clear results until several hours after symptoms onset.
• Additional imaging techniques include:
  • Magnetic Resonance Angiography (MRA)
  • CT Angiography (CTA)
  • Cerebral Angiography
• Cerebral Angiography involves catheter insertion into the groin and injecting contrast dye into brain arteries, but it's more invasive than CT angiography.
• CT angiography is preferred due to its less invasive procedure—contrast is injected into a vein in the arm instead of an artery.
• Diffusion-weighted MRI identifies damaged brain tissue, aiding in diagnosing and differentiating between transient ischemic attacks and ischemic strokes, though its availability may be limited.

Assessing Stroke Cause and Severity

• Tests aim to identify underlying issues that might contribute to a stroke, including heart infections, low blood oxygen levels, and dehydration.
• Urinalysis may be performed to check for cocaine usage.
• Swallowing ability is rapidly evaluated upon stroke suspicion, often using x-rays with a radiopaque contrast agent like barium.
• Patients with swallowing difficulties are advised to avoid oral intake, except for necessary medications, until improvement is noted.
• A standardized assessment is utilized to evaluate stroke severity and recovery, covering:
  • Level of consciousness
  • Response to questions
  • Ability to follow simple commands
  • Visual function
  • Arm and leg movements
  • Speech capabilities.

Ischemic Stroke

• Represents around 87% of all stroke cases, indicating its prevalence.
• Resulting from a blockage in a brain blood vessel, which limits blood and oxygen supply to the brain.
• Primary Causes:
  • Thrombosis: Formation of a blood clot within a brain artery.
  • Embolism: A clot or plaque fragment dislodges from another location and travels to the brain.
• Symptoms:
  • Sudden weakness or numbness, typically affecting one side of the body (face, arm, leg).
  • Abrupt confusion or difficulty in speech.
  • Immediate vision problems in one or both eyes.
  • Unexpected severe headache without a known cause.
  • Sudden imbalance or coordination loss.
• Treatment Options:
  • Thrombolytic therapy (tPA): Aimed at dissolving clots.
  • Anticoagulants: Medications designed to inhibit new clot development.
  • Antiplatelet agents: Help to prevent platelet clumping.
  • Endovascular therapy: Involves techniques to physically remove the blood clot.

Hemorrhagic Stroke

• Comprises about 13% of all strokes, showcasing less frequency compared to ischemic strokes.
• Occurs when a blood vessel ruptures, leading to bleeding within the brain.
• Primary Causes:
  • Hypertension: Elevated blood pressure that can weaken vessel walls, leading to rupture.
  • Aneurysms: Sections of the artery wall that are weak and susceptible to rupture.
  • Arteriovenous malformations (AVMs): Abnormal artery-vein connections that can compromise vascular integrity.
  • Cerebral amyloid angiopathy: A condition where amyloid protein accumulates in blood vessel walls, increasing rupture risk.
• Symptoms:
  • Intense, sudden headache is often the first symptom.
  • Accompanied by nausea and vomiting.
  • Changes in consciousness or confusion may occur.
  • Possible occurrences of seizures.
  • Weakness or numbness appearing similar to ischemic stroke symptoms.
• Treatment Approaches:
  • Surgical clipping/coiling: Techniques used to seal off the ruptured vessel.
  • Endovascular embolization: Minimally invasive procedure to halt bleeding.
  • Drug therapies to manage blood pressure, pain relief, and seizure control.
  • Rehabilitation efforts to aid recovery and restore function.

Neurological Deficits

• Stroke can lead to diverse neurological deficits based on the affected brain regions and the extent of damage.
• Affected functions may include motor skills, sensory perception, cognitive abilities, language and communication, visual processing, and swallowing.
• Common deficits encompass:
  • Weakness or paralysis of limbs
  • Loss or impairment of sensory functions
  • Language impairments known as aphasia
  • Dysphagia, indicating difficulty in swallowing
  • Visual field deficits impacting sight
  • Cognitive impairments affecting attention, memory, and processing speed

Hemiparesis

• Hemiparesis is a prevalent neurological deficit following a stroke.
• It involves weakness or paralysis on one side of the body, potentially affecting the face, arm, or leg.
• Types include:
  • Hemiplegia: characterized by total paralysis on one side of the body.
  • Hemiparesis: marked by partial weakness on one side of the body.
• Nursing interventions aimed at managing hemiparesis include:
  • Implementing range of motion exercises to mitigate the risk of contractures.
  • Conducting strengthening exercises to enhance motor function.
  • Utilizing compensatory strategies to accommodate any remaining weakness.
  • Managing pain to address discomfort associated with hemiparesis.

Aphasia

• Aphasia is a language disorder that arises from stroke-related brain damage.
• It manifests as difficulties in understanding spoken language, articulating thoughts, and in reading and writing.
• Types of aphasia include:
  • Broca's aphasia: characterized by struggles to form grammatically correct sentences.
  • Wernicke's aphasia: involves challenges in comprehending spoken words and in forming coherent sentences.
  • Global aphasia: indicates profound language impairment affecting all language abilities.
• Nursing interventions for patients with aphasia consist of:
  • Supporting alternative communication methods (like gestures or writing) to facilitate interaction.
  • Encouraging the use of preferred communication styles.
  • Providing emotional reassurance and support during communication.
  • Collaborating with speech-language pathologists to establish tailored communication strategies.

Cerebral Edema

• Defined as excess fluid in the brain that raises intracranial pressure (ICP).
• Common causes include traumatic brain injury, infections like meningitis and encephalitis, tumors, stroke, and hypoxia.
• Consequences involve increased ICP, compression of brain structures, displacement of brain tissue, and potential brain herniation.

Brain Herniation

• Involves displacement of brain tissue through openings in the skull or dura mater.
• Types of herniation:
  • Subfalcine: tissue moves under the falx cerebri.
  • Transtentorial: tissue shifts through the tentorial notch.
  • Uncal: tissue compresses the brainstem after moving through the tentorial notch.
• Significant effects include compression of the brainstem and cranial nerves, which can lead to respiratory failure, cardiac instability, and even death.

Increased ICP

• ICP is considered elevated when above 20-25 mmHg.
• Causes include cerebral edema, hydrocephalus, brain tumors, traumatic brain injury, and infections like meningitis and encephalitis.
• Elevated ICP effects include brain compression, decreased cerebral blood flow, increased risk of brain herniation, respiratory failure, and cardiac instability.

Monitoring Techniques

• Invasive methods for measuring ICP:
  • Intraventricular catheter: provides direct ICP measurement from the ventricles.
  • Intraparenchymal catheter: measures ICP from within brain tissue.
  • Subdural catheter: assesses ICP beneath the dura mater.
• Non-invasive techniques include:
  • Transcranial Doppler ultrasound: evaluates cerebral blood flow velocity.
  • Optic nerve sheath diameter measurement: estimates ICP by assessing optic nerve swelling.
  • Electroencephalography (EEG): monitors brain activity to detect changes indicative of increased ICP.

Cerebral Edema

• Abnormal fluid accumulation in the brain increases intracranial pressure (ICP).
• Common causes include traumatic brain injury, infections like meningitis and encephalitis, tumors, and strokes.
• Results in compression of brain tissue and blood vessels, disrupting normal brain function.
• Heightened risk for brain herniation occurs due to increased pressure.

Brain Herniation

• Describes the displacement of brain tissue through openings in the skull or fractures.
• Types include:
  • Subfalcine herniation: Cingulate gyrus moves beneath the falx cerebri.
  • Transtentorial herniation: Uncus or hippocampus shifts through the tentorial notch.
  • Foramen magnum herniation: Cerebellar tonsils displace through the foramen magnum.
• Leads to compression of vital structures, which can cause respiratory and cardiac failure, potentially resulting in death.

Increased Intracranial Pressure (ICT)

• Normal ICT ranges from 7-15 mmHg.
• Increased ICT can be caused by cerebral edema, hemorrhage, tumor growth, or infection.
• Symptoms include:
  • Headaches and vomiting.
  • Papilledema, indicated by optic disc swelling.
  • Decreased consciousness.
  • Potential for brain herniation.

Monitoring Techniques

• Invasive monitoring:
  • Intraventricular catheter provides direct measurement of ICT.
  • Subdural or epidural sensors offer indirect measurement.
• Non-invasive monitoring:
  • Transcranial Doppler ultrasonography assesses blood flow velocity.
  • Near-infrared spectroscopy evaluates cerebral oxygenation.
  • CT or MRI scans visualize brain structures and identify edema.
• Clinical monitoring:
  • Glasgow Coma Scale (GCS) is used to assess the level of consciousness.
  • Pupillary response evaluation checks brainstem function.

Symptoms of Head Injury

• Symptoms can resemble those of a minor head injury but can be more severe.
• Initial symptoms often include a period of unconsciousness at the moment of impact, with variable duration.
• Upon awakening, individuals may exhibit drowsiness, confusion, restlessness, agitation, vomiting, or seizures.
• Impairments in balance and coordination may occur, depending on affected brain regions.

Brain Function and Injury Effects

• Damage to specific brain areas can lead to long-term issues in thinking, emotional control, movement, sensation, speech, vision, hearing, and memory.
• Clear fluid or blood may drain from the nose or ears if a skull base fracture exists.

Intracranial Pressure (ICP)

• Brain injuries can result in bleeding or swelling, known as cerebral edema, increasing intracranial pressure.
• The skull's rigid structure prevents expansion, causing even minor bleeding or swelling to significantly raise intracranial pressure.
• Elevated ICP hampers blood flow to the brain, leading to dysfunction and symptoms.

Early Signs of Increased ICP

• Initial symptoms of increased ICP include worsening headaches, impaired thinking, decreased consciousness, and vomiting.
• As ICP rises, the person may become unresponsive, and pupil dilation may occur.

Risks of Herniation and Serious Outcomes

• Within one to two days post-injury, elevated pressure may cause brain herniation, where brain tissue protrudes abnormally.
• Herniation poses severe risks such as coma or death, especially if it compresses the brain stem, which regulates vital functions like heart rate and breathing.
• High ICP can lead to the cessation of blood flow in the brain, potentially resulting in brain death.

Diagnosing stroke involves ruling out other conditions that mimic stroke symptoms. Blood sugar level is checked to exclude hypoglycemia, and CT or MRI scans are used to detect hemorrhagic strokes.