Subarachnoid Hemorrhage Overview

Subarachnoid Hemorrhage (SAH)

• A subarachnoid hemorrhage occurs when cerebral vessels, primarily from the Circle of Willis, rupture and bleed into the subarachnoid space.
• Can also lead to intraventricular hemorrhage when blood seeps into the ventricles.

Causes of Subarachnoid Hemorrhage

• Traumatic Causes:

  • Blunt force trauma (e.g., hit with a bat).
  • Penetrating trauma (e.g., stab wounds).

• Non-Traumatic Causes:

  • Aneurysmal:
    • Types include:
      • Saccular (berry) aneurysms: Asymmetric outpouching of a vessel.
      • Giant saccular aneurysms: Greater than 2.5 cm.
      • Fusiform aneurysms: Symmetrical dilation of the vessel.
      • Pseudoaneurysms: Vessel dissection creating a false appearance of an aneurysm.
      • Mycotic aneurysms: Caused by infectious material.

Risk Factors for Aneurysm Formation

• Increased Stress on Vessel Walls:

  • Hypertension: Major contributor to weakening of vessels.
  • Sympathomimetic drugs: Cocaine and methamphetamine increase stress.
  • Smoking and ethanol consumption contribute to vessel wall stress.
  • Oral contraceptives and pregnancy can influence blood vessel integrity.

• Genetic Connective Tissue Defects:

  • Marfan syndrome: Deficiency of fibrillin affecting vessel elasticity.
  • Ehlers-Danlos syndrome: Deficiency of collagen impacting the tunica media.
  • Polycystic kidney disease: Leads to defects in polycystin proteins in vessel walls.

• Fibromuscular Dysplasia:

  • Abnormal growth of smooth muscle, making vessels susceptible to dilations.

Triggers for Aneurysm Rupture

• Acute rise in blood pressure due to stressors such as pain or anger can precipitate a rupture.

Common Sites for Aneurysm Formation

• Anterior Communicating Artery: Most common site (30% of cases).
• Posterior Communicating Artery: Second most common (25%).
• MCA Bifurcation: Thirdmost common (20%).
• Internal Carotid Artery Terminus: Accounts for 7.5%.
• Basilar Tip: 7% occurrence.
• Anterior Cerebral Artery: 4% incidence.
• PICA: 3.5% occurrence.

Clinical Features and Treatment

• Subarachnoid Space: Located between the pia mater and arachnoid mater, where blood accumulates during SAH.
• Managing SAH involves monitoring and potentially surgical intervention to prevent complications.

Arteriovenous Malformation (AVM)

• A common cause of non-traumatic SAH, particularly in children and adolescents.
• AVMs bypass capillary beds, leading to direct connections between arteries and veins, increasing the risk of rupture.

Important Notes

• Recognize the difference between types of aneurysms and the associated risk factors for each.
• Understand the significance of vessel stressors and genetic factors in the pathology of subarachnoid hemorrhage.### Subarachnoid Hemorrhage Overview
• Aneurysm rupture leads to blood accumulation in the subarachnoid space.
• Blood may extend into ventricles causing complications.

Cerebrospinal Fluid (CSF) Flow

• CSF flows from lateral ventricles to the third ventricle, then to the fourth ventricle.
• Obstruction from blood clots in the cerebral aqueduct can lead to hydrocephalus.

Types of Hydrocephalus

• Obstructive Hydrocephalus: Results from blockages (e.g., blood clots obstructing CSF flow).
• Communicating Hydrocephalus: Caused by impaired CSF absorption due to obstructed arachnoid granulations.

Clinical Features

• Worst Headache of Life: Characterized as a thunderclap headache.
• Meningeal Signs:
  • Photophobia (sensitivity to light).
  • Nuchal rigidity (stiff neck).
  • Positive Kernig's and Brudzinski's signs.

Increased Intracranial Pressure (ICP)

• Elevated ICP occurs from blood accumulation leading to various symptoms:
  • Headache, nausea, vomiting.
  • Cranial nerve deficits (e.g., blown pupil).
  • Abnormal posturing (decorticate, decerebrate).
  • Cushing's triad: hypertension, bradycardia, irregular respirations.

Focal Deficits

• Depending on the affected vessel (e.g., anterior communicating artery, MCA), patients can develop stroke-like symptoms.

Hunt and Hess Score

• Used to assess mortality risk based on clinical presentation:
  • Score of 1: Asymptomatic or mild symptoms.
  • Score of 2: Moderate headache with nuchal rigidity and cranial nerve deficits.
  • Score of 3: Lethargy with focal deficits.
  • Score of 4: Stupor or early posturing signs.
  • Score of 5: Comatose state or severe posturing.

Diagnostic Approach

• Non-Contrast CT Scan: Identifies classic patterns of subarachnoid hemorrhage and possible hydrocephalus.
• Modified Fischer Score: Assesses risk of vasospasm based on CT findings, with grading based on hemorrhage thickness and ventricular involvement.

Angiographic Imaging

• CT Angiogram: Identifies ruptured aneurysms and distinguishes from conditions like RCVS.
• Digital Subtraction Angiogram (DSA): Gold standard for direct vascular imaging; can also be therapeutic (e.g., coiling aneurysms).

Lumbar Puncture

• Can confirm subarachnoid hemorrhage by detecting blood in CSF.
• Presence of xanthochromia indicates prior hemorrhage.

Differential Diagnosis

• Investigate potential causes of aneurysms:
  • Hypertension, trauma, drug use, genetic conditions.
  • Imaging (e.g., renal ultrasound) aids in diagnosing underlying issues.

Treatment Protocol

• Emergency Management: Focus on airway, breathing, and circulation due to potential respiratory compromise from ICP.
• Continuous monitoring is essential for neurological status and management of increased ICP.### Airway Management in Neurological Emergencies
• GCS less than eight indicates potential airway protection issues due to large bleeds or high intracranial pressure (ICP).
• Hypoxic patients may require escalating oxygen measures: nasal cannula, rebreather, high-flow, or CPAP before intubation.
• Intubation is critical in managing severe hypoxia or unstable patients to ensure airway protection.

Modes of Ventilation

• Continuous Mechanical Ventilation (CMV) allows for controlled ventilation settings, including tidal volume, respiratory rate, FIO2 (oxygen concentration), and PEEP (positive end-expiratory pressure).
• Adaptive Support Ventilation (ASV) adjusts ventilation based on patient demand, supporting spontaneous breaths and closed-loop alternative to traditional ventilation methods.

Blood Pressure Management

• Maintaining systolic blood pressure less than 160 mmHg is critical to prevent ongoing bleeding in subarachnoid hemorrhage.
• Key medications for blood pressure control:
  • Nicardipine (calcium channel blocker, vasodilator).
  • Labetalol (alpha and beta blocker).
  • Hydralazine (vasodilator).
  • Enalapril (ACE inhibitor, requires normal renal function).

External Ventricular Drain (EVD) Indications

• Use EVD for patients with high Hunt-Hess scores (indicating severity) or intraventricular hemorrhage (IVH) to prevent obstructive hydrocephalus.
• EVD reduces ICP by draining CSF and blood, decreasing ventricle size.
• In cases of clotting in the EVD, intraventricular tPA (tissue plasminogen activator) can be administered to dissolve clots and restore drainage.

Monitoring and Managing Intracranial Pressure (ICP)

• ICP should be monitored using the EVD; target ICP is less than 20 mmHg.
• Sustained pressures above this indicate a potential crisis; factors like coughing and pain can temporarily elevate ICP.
• Key interventions include maintaining head position, elevating the head of the bed, and managing hyperventilation cautiously.
• Mannitol and hypertonic saline can be used to reduce ICP by drawing water from brain cells.

Aneurysmal Treatment: Clipping vs. Coiling

• Aneurysm management using coiling or clipping must occur within the first 24 hours.
• Factors influencing the choice:
  • Age (coiling preferred for older patients).
  • Neck size of the aneurysm (smaller neck favors coiling).
  • Hemodynamic stability (stable patients are better suited for clipping).
  • Location of the aneurysm (coiling is ideal for vertebral basilar vessels, clipping for ACA, MCA, ICA terminus).

Complications After Aneurysmal Treatment

• Rebleeding poses a 70% mortality risk, most critical within the first 48 hours.
• Temporary stabilization involves administering medications like aminocaproic acid and tranexamic acid for clot stabilization, alongside platelet transfusion if counts drop.

Vasospasm and Delayed Cerebral Ischemia

• Vasospasm is a significant complication post-subarachnoid hemorrhage due to inflammatory mediators discharged from vessel rupture.
• This leads to vessel narrowing within the Circle of Willis, reducing cerebral blood flow and risking ischemia that may result in infarction if untreated.

Subarachnoid Hemorrhage (SAH)

• Occurs when cerebral vessels rupture, primarily from the Circle of Willis, causing bleeding into the subarachnoid space.
• Blood can seep into the ventricles, potentially leading to intraventricular hemorrhage.

Causes

• Traumatic Causes: Include blunt force and penetrating trauma.
• Non-Traumatic Causes: Most commonly due to aneurysms, which can be:
  • Saccular (berry): Asymmetric outpouching of a vessel.
  • Giant saccular: Larger than 2.5 cm.
  • Fusiform: Symmetrical vessel dilation.
  • Pseudoaneurysms: Result from vessel dissection.
  • Mycotic aneurysms: Caused by infections.

Risk Factors for Aneurysm Formation

• Vessel Wall Stressors:
  • Hypertension: Can weaken vessel walls.
  • Drugs: Cocaine and methamphetamine increase vessel stress.
  • Lifestyle: Smoking, ethanol, oral contraceptives, and pregnancy contribute to vessel integrity.
• Genetic Conditions:
  • Marfan syndrome: Deficiency of fibrillin impacts vessel elasticity.
  • Ehlers-Danlos syndrome: Deficiency of collagen affects blood vessel structure.
  • Polycystic kidney disease: Leads to vascular defects.
• Fibromuscular Dysplasia: Abnormal smooth muscle growth affecting vessel stability.

Triggers for Aneurysm Rupture

• Acute blood pressure spikes due to stressors like pain or anger can precipitate a rupture.

Common Sites for Aneurysms

• Anterior Communicating Artery: Most common site (30% of cases).
• Posterior Communicating Artery: Second most common (25%).
• MCA Bifurcation: Thirdmost common (20%).
• Other sites: Internal Carotid Terminus (7.5%), Basilar Tip (7%), Anterior Cerebral Artery (4%), PICA (3.5%).

Clinical Features and Treatment

• Blood accumulates in the subarachnoid space, prompting monitoring and potential surgical intervention to avert complications.

Arteriovenous Malformation (AVM)

• Common non-traumatic SAH cause, especially in children and adolescents.
• AVMs bypass capillary beds, creating direct artery-to-vein connections, increasing rupture risk.

Hydrocephalus

• Cerebrospinal Fluid (CSF) Pathway: Flows from lateral to third, then to fourth ventricle.
• Obstruction: Blood clots can block CSF flow, resulting in hydrocephalus.
• Types:
  • Obstructive Hydrocephalus: Caused by blockages.
  • Communicating Hydrocephalus: Due to impaired CSF absorption.

Key Symptoms

• Headache: Described as the “worst headache of life.”
• Meningeal Signs: Include photophobia, nuchal rigidity, and positive Kernig's/Brudzinski's signs.

Increased Intracranial Pressure (ICP)

• Symptoms include headache, nausea, vomiting, cranial nerve deficits, abnormal posturing, and Cushing's triad (hypertension, bradycardia, irregular respirations).

Focal Neurological Deficits

• Stroke-like symptoms can occur depending on the vessel affected by the hemorrhage.

Hunt and Hess Score

• Assesses mortality risk and clinical presentation severity, ranging from asymptomatic (score 1) to comatose (score 5).

Diagnostic Approach

• Non-Contrast CT Scan: Identifies SAH patterns and hydrocephalus.
• Modified Fischer Score: Evaluates vasospasm risk based on hemorrhage thickness on CT.

Angiographic Imaging

• CT Angiogram: Detects ruptured aneurysms.
• Digital Subtraction Angiogram (DSA): Gold standard for vascular imaging, can be therapeutic.

Lumbar Puncture

• Confirms SAH by detecting blood in CSF; xanthochromia indicates prior hemorrhage.

Differential Diagnosis

• Consider causes such as hypertension, trauma, drug use, and genetic conditions; imaging aids in underlying diagnosis.

Treatment Protocol

• Focus on airway, breathing, and circulation during emergency management due to ICP risks.
• Continuous neurological monitoring is crucial for ICP management.

Airway Management

• GCS less than eight suggests potential airway protection issues; escalating oxygen measures may be necessary.

Ventilation Modes

• Continuous Mechanical Ventilation (CMV) allows controlled settings.
• Adaptive Support Ventilation (ASV) adjusts to patient demand, supporting spontaneous breaths.

Blood Pressure Management

• Keeping systolic blood pressure below 160 mmHg is essential to limit bleeding risk.
• Key medications include Nicardipine, Labetalol, Hydralazine, and Enalapril.

External Ventricular Drain (EVD) Indications

• EVD is indicated for severe Hunt-Hess scores or intraventricular hemorrhage, reducing ICP by draining fluid.

Monitoring ICP

• Target ICP is less than 20 mmHg; sustained pressures require intervention. Mannitol and hypertonic saline can be used to reduce ICP.

Aneurysm Treatment: Clipping vs. Coiling

• Treatment should occur within 24 hours, with coiling preferred for older patients and smaller neck aneurysms; location influences choice.

Complications After Treatment

• Rebleeding is critical within the first 48 hours, with stabilization treatments including clotting medications and platelet transfusion.

Vasospasm and Delayed Cerebral Ischemia

• Develops from inflammatory mediators following SAH, leading to vessel narrowing and reduced cerebral blood flow risk.

Subarachnoid Hemorrhage (SAH)

• Occurs when cerebral vessels rupture, primarily from the Circle of Willis, causing bleeding into the subarachnoid space.
• Blood can seep into the ventricles, potentially leading to intraventricular hemorrhage.

Causes

• Traumatic Causes: Include blunt force and penetrating trauma.
• Non-Traumatic Causes: Most commonly due to aneurysms, which can be:
  • Saccular (berry): Asymmetric outpouching of a vessel.
  • Giant saccular: Larger than 2.5 cm.
  • Fusiform: Symmetrical vessel dilation.
  • Pseudoaneurysms: Result from vessel dissection.
  • Mycotic aneurysms: Caused by infections.

Risk Factors for Aneurysm Formation

• Vessel Wall Stressors:
  • Hypertension: Can weaken vessel walls.
  • Drugs: Cocaine and methamphetamine increase vessel stress.
  • Lifestyle: Smoking, ethanol, oral contraceptives, and pregnancy contribute to vessel integrity.
• Genetic Conditions:
  • Marfan syndrome: Deficiency of fibrillin impacts vessel elasticity.
  • Ehlers-Danlos syndrome: Deficiency of collagen affects blood vessel structure.
  • Polycystic kidney disease: Leads to vascular defects.
• Fibromuscular Dysplasia: Abnormal smooth muscle growth affecting vessel stability.

Triggers for Aneurysm Rupture

• Acute blood pressure spikes due to stressors like pain or anger can precipitate a rupture.

Common Sites for Aneurysms

• Anterior Communicating Artery: Most common site (30% of cases).
• Posterior Communicating Artery: Second most common (25%).
• MCA Bifurcation: Thirdmost common (20%).
• Other sites: Internal Carotid Terminus (7.5%), Basilar Tip (7%), Anterior Cerebral Artery (4%), PICA (3.5%).

Clinical Features and Treatment

• Blood accumulates in the subarachnoid space, prompting monitoring and potential surgical intervention to avert complications.

Arteriovenous Malformation (AVM)

• Common non-traumatic SAH cause, especially in children and adolescents.
• AVMs bypass capillary beds, creating direct artery-to-vein connections, increasing rupture risk.

Hydrocephalus

• Cerebrospinal Fluid (CSF) Pathway: Flows from lateral to third, then to fourth ventricle.
• Obstruction: Blood clots can block CSF flow, resulting in hydrocephalus.
• Types:
  • Obstructive Hydrocephalus: Caused by blockages.
  • Communicating Hydrocephalus: Due to impaired CSF absorption.

Key Symptoms

• Headache: Described as the “worst headache of life.”
• Meningeal Signs: Include photophobia, nuchal rigidity, and positive Kernig's/Brudzinski's signs.

Increased Intracranial Pressure (ICP)

• Symptoms include headache, nausea, vomiting, cranial nerve deficits, abnormal posturing, and Cushing's triad (hypertension, bradycardia, irregular respirations).

Focal Neurological Deficits

• Stroke-like symptoms can occur depending on the vessel affected by the hemorrhage.

Hunt and Hess Score

• Assesses mortality risk and clinical presentation severity, ranging from asymptomatic (score 1) to comatose (score 5).

Diagnostic Approach

• Non-Contrast CT Scan: Identifies SAH patterns and hydrocephalus.
• Modified Fischer Score: Evaluates vasospasm risk based on hemorrhage thickness on CT.

Angiographic Imaging

• CT Angiogram: Detects ruptured aneurysms.
• Digital Subtraction Angiogram (DSA): Gold standard for vascular imaging, can be therapeutic.

Lumbar Puncture

• Confirms SAH by detecting blood in CSF; xanthochromia indicates prior hemorrhage.

Differential Diagnosis

• Consider causes such as hypertension, trauma, drug use, and genetic conditions; imaging aids in underlying diagnosis.

Treatment Protocol

• Focus on airway, breathing, and circulation during emergency management due to ICP risks.
• Continuous neurological monitoring is crucial for ICP management.

Airway Management

• GCS less than eight suggests potential airway protection issues; escalating oxygen measures may be necessary.

Ventilation Modes

• Continuous Mechanical Ventilation (CMV) allows controlled settings.
• Adaptive Support Ventilation (ASV) adjusts to patient demand, supporting spontaneous breaths.

Blood Pressure Management

• Keeping systolic blood pressure below 160 mmHg is essential to limit bleeding risk.
• Key medications include Nicardipine, Labetalol, Hydralazine, and Enalapril.

External Ventricular Drain (EVD) Indications

• EVD is indicated for severe Hunt-Hess scores or intraventricular hemorrhage, reducing ICP by draining fluid.

Monitoring ICP

• Target ICP is less than 20 mmHg; sustained pressures require intervention. Mannitol and hypertonic saline can be used to reduce ICP.

Aneurysm Treatment: Clipping vs. Coiling

• Treatment should occur within 24 hours, with coiling preferred for older patients and smaller neck aneurysms; location influences choice.

Complications After Treatment

• Rebleeding is critical within the first 48 hours, with stabilization treatments including clotting medications and platelet transfusion.

Vasospasm and Delayed Cerebral Ischemia

• Develops from inflammatory mediators following SAH, leading to vessel narrowing and reduced cerebral blood flow risk.

Subarachnoid Hemorrhage (SAH)

• Occurs when cerebral vessels rupture, primarily from the Circle of Willis, causing bleeding into the subarachnoid space.
• Blood can seep into the ventricles, potentially leading to intraventricular hemorrhage.

Causes

• Traumatic Causes: Include blunt force and penetrating trauma.
• Non-Traumatic Causes: Most commonly due to aneurysms, which can be:
  • Saccular (berry): Asymmetric outpouching of a vessel.
  • Giant saccular: Larger than 2.5 cm.
  • Fusiform: Symmetrical vessel dilation.
  • Pseudoaneurysms: Result from vessel dissection.
  • Mycotic aneurysms: Caused by infections.

Risk Factors for Aneurysm Formation

• Vessel Wall Stressors:
  • Hypertension: Can weaken vessel walls.
  • Drugs: Cocaine and methamphetamine increase vessel stress.
  • Lifestyle: Smoking, ethanol, oral contraceptives, and pregnancy contribute to vessel integrity.
• Genetic Conditions:
  • Marfan syndrome: Deficiency of fibrillin impacts vessel elasticity.
  • Ehlers-Danlos syndrome: Deficiency of collagen affects blood vessel structure.
  • Polycystic kidney disease: Leads to vascular defects.
• Fibromuscular Dysplasia: Abnormal smooth muscle growth affecting vessel stability.

Triggers for Aneurysm Rupture

• Acute blood pressure spikes due to stressors like pain or anger can precipitate a rupture.

Common Sites for Aneurysms

• Anterior Communicating Artery: Most common site (30% of cases).
• Posterior Communicating Artery: Second most common (25%).
• MCA Bifurcation: Thirdmost common (20%).
• Other sites: Internal Carotid Terminus (7.5%), Basilar Tip (7%), Anterior Cerebral Artery (4%), PICA (3.5%).

Clinical Features and Treatment

• Blood accumulates in the subarachnoid space, prompting monitoring and potential surgical intervention to avert complications.

Arteriovenous Malformation (AVM)

• Common non-traumatic SAH cause, especially in children and adolescents.
• AVMs bypass capillary beds, creating direct artery-to-vein connections, increasing rupture risk.

Hydrocephalus

• Cerebrospinal Fluid (CSF) Pathway: Flows from lateral to third, then to fourth ventricle.
• Obstruction: Blood clots can block CSF flow, resulting in hydrocephalus.
• Types:
  • Obstructive Hydrocephalus: Caused by blockages.
  • Communicating Hydrocephalus: Due to impaired CSF absorption.

Key Symptoms

• Headache: Described as the “worst headache of life.”
• Meningeal Signs: Include photophobia, nuchal rigidity, and positive Kernig's/Brudzinski's signs.

Increased Intracranial Pressure (ICP)

• Symptoms include headache, nausea, vomiting, cranial nerve deficits, abnormal posturing, and Cushing's triad (hypertension, bradycardia, irregular respirations).

Focal Neurological Deficits

• Stroke-like symptoms can occur depending on the vessel affected by the hemorrhage.

Hunt and Hess Score

• Assesses mortality risk and clinical presentation severity, ranging from asymptomatic (score 1) to comatose (score 5).

Diagnostic Approach

• Non-Contrast CT Scan: Identifies SAH patterns and hydrocephalus.
• Modified Fischer Score: Evaluates vasospasm risk based on hemorrhage thickness on CT.

Angiographic Imaging

• CT Angiogram: Detects ruptured aneurysms.
• Digital Subtraction Angiogram (DSA): Gold standard for vascular imaging, can be therapeutic.

Lumbar Puncture

• Confirms SAH by detecting blood in CSF; xanthochromia indicates prior hemorrhage.

Differential Diagnosis

• Consider causes such as hypertension, trauma, drug use, and genetic conditions; imaging aids in underlying diagnosis.

Treatment Protocol

• Focus on airway, breathing, and circulation during emergency management due to ICP risks.
• Continuous neurological monitoring is crucial for ICP management.

Airway Management

• GCS less than eight suggests potential airway protection issues; escalating oxygen measures may be necessary.

Ventilation Modes

• Continuous Mechanical Ventilation (CMV) allows controlled settings.
• Adaptive Support Ventilation (ASV) adjusts to patient demand, supporting spontaneous breaths.

Blood Pressure Management

• Keeping systolic blood pressure below 160 mmHg is essential to limit bleeding risk.
• Key medications include Nicardipine, Labetalol, Hydralazine, and Enalapril.

External Ventricular Drain (EVD) Indications

• EVD is indicated for severe Hunt-Hess scores or intraventricular hemorrhage, reducing ICP by draining fluid.

Monitoring ICP

• Target ICP is less than 20 mmHg; sustained pressures require intervention. Mannitol and hypertonic saline can be used to reduce ICP.

Aneurysm Treatment: Clipping vs. Coiling

• Treatment should occur within 24 hours, with coiling preferred for older patients and smaller neck aneurysms; location influences choice.

Complications After Treatment

• Rebleeding is critical within the first 48 hours, with stabilization treatments including clotting medications and platelet transfusion.

Vasospasm and Delayed Cerebral Ischemia

• Develops from inflammatory mediators following SAH, leading to vessel narrowing and reduced cerebral blood flow risk.

Subarachnoid Hemorrhage (SAH)

• Occurs when cerebral vessels rupture, primarily from the Circle of Willis, causing bleeding into the subarachnoid space.
• Blood can seep into the ventricles, potentially leading to intraventricular hemorrhage.

Causes

• Traumatic Causes: Include blunt force and penetrating trauma.
• Non-Traumatic Causes: Most commonly due to aneurysms, which can be:
  • Saccular (berry): Asymmetric outpouching of a vessel.
  • Giant saccular: Larger than 2.5 cm.
  • Fusiform: Symmetrical vessel dilation.
  • Pseudoaneurysms: Result from vessel dissection.
  • Mycotic aneurysms: Caused by infections.

Risk Factors for Aneurysm Formation

• Vessel Wall Stressors:
  • Hypertension: Can weaken vessel walls.
  • Drugs: Cocaine and methamphetamine increase vessel stress.
  • Lifestyle: Smoking, ethanol, oral contraceptives, and pregnancy contribute to vessel integrity.
• Genetic Conditions:
  • Marfan syndrome: Deficiency of fibrillin impacts vessel elasticity.
  • Ehlers-Danlos syndrome: Deficiency of collagen affects blood vessel structure.
  • Polycystic kidney disease: Leads to vascular defects.
• Fibromuscular Dysplasia: Abnormal smooth muscle growth affecting vessel stability.

Triggers for Aneurysm Rupture

• Acute blood pressure spikes due to stressors like pain or anger can precipitate a rupture.

Common Sites for Aneurysms

• Anterior Communicating Artery: Most common site (30% of cases).
• Posterior Communicating Artery: Second most common (25%).
• MCA Bifurcation: Thirdmost common (20%).
• Other sites: Internal Carotid Terminus (7.5%), Basilar Tip (7%), Anterior Cerebral Artery (4%), PICA (3.5%).

Clinical Features and Treatment

• Blood accumulates in the subarachnoid space, prompting monitoring and potential surgical intervention to avert complications.

Arteriovenous Malformation (AVM)

• Common non-traumatic SAH cause, especially in children and adolescents.
• AVMs bypass capillary beds, creating direct artery-to-vein connections, increasing rupture risk.

Hydrocephalus

• Cerebrospinal Fluid (CSF) Pathway: Flows from lateral to third, then to fourth ventricle.
• Obstruction: Blood clots can block CSF flow, resulting in hydrocephalus.
• Types:
  • Obstructive Hydrocephalus: Caused by blockages.
  • Communicating Hydrocephalus: Due to impaired CSF absorption.

Key Symptoms

• Headache: Described as the “worst headache of life.”
• Meningeal Signs: Include photophobia, nuchal rigidity, and positive Kernig's/Brudzinski's signs.

Increased Intracranial Pressure (ICP)

• Symptoms include headache, nausea, vomiting, cranial nerve deficits, abnormal posturing, and Cushing's triad (hypertension, bradycardia, irregular respirations).

Focal Neurological Deficits

• Stroke-like symptoms can occur depending on the vessel affected by the hemorrhage.

Hunt and Hess Score

• Assesses mortality risk and clinical presentation severity, ranging from asymptomatic (score 1) to comatose (score 5).

Diagnostic Approach

• Non-Contrast CT Scan: Identifies SAH patterns and hydrocephalus.
• Modified Fischer Score: Evaluates vasospasm risk based on hemorrhage thickness on CT.

Angiographic Imaging

• CT Angiogram: Detects ruptured aneurysms.
• Digital Subtraction Angiogram (DSA): Gold standard for vascular imaging, can be therapeutic.

Lumbar Puncture

• Confirms SAH by detecting blood in CSF; xanthochromia indicates prior hemorrhage.

Differential Diagnosis

• Consider causes such as hypertension, trauma, drug use, and genetic conditions; imaging aids in underlying diagnosis.

Treatment Protocol

• Focus on airway, breathing, and circulation during emergency management due to ICP risks.
• Continuous neurological monitoring is crucial for ICP management.

Airway Management

• GCS less than eight suggests potential airway protection issues; escalating oxygen measures may be necessary.

Ventilation Modes

• Continuous Mechanical Ventilation (CMV) allows controlled settings.
• Adaptive Support Ventilation (ASV) adjusts to patient demand, supporting spontaneous breaths.

Blood Pressure Management

• Keeping systolic blood pressure below 160 mmHg is essential to limit bleeding risk.
• Key medications include Nicardipine, Labetalol, Hydralazine, and Enalapril.

External Ventricular Drain (EVD) Indications

• EVD is indicated for severe Hunt-Hess scores or intraventricular hemorrhage, reducing ICP by draining fluid.

Monitoring ICP

• Target ICP is less than 20 mmHg; sustained pressures require intervention. Mannitol and hypertonic saline can be used to reduce ICP.

Aneurysm Treatment: Clipping vs. Coiling

• Treatment should occur within 24 hours, with coiling preferred for older patients and smaller neck aneurysms; location influences choice.

Complications After Treatment

• Rebleeding is critical within the first 48 hours, with stabilization treatments including clotting medications and platelet transfusion.

Vasospasm and Delayed Cerebral Ischemia

• Develops from inflammatory mediators following SAH, leading to vessel narrowing and reduced cerebral blood flow risk.

Subarachnoid Hemorrhage (SAH)

• Occurs when cerebral vessels rupture, primarily from the Circle of Willis, causing bleeding into the subarachnoid space.
• Blood can seep into the ventricles, potentially leading to intraventricular hemorrhage.

Causes

• Traumatic Causes: Include blunt force and penetrating trauma.
• Non-Traumatic Causes: Most commonly due to aneurysms, which can be:
  • Saccular (berry): Asymmetric outpouching of a vessel.
  • Giant saccular: Larger than 2.5 cm.
  • Fusiform: Symmetrical vessel dilation.
  • Pseudoaneurysms: Result from vessel dissection.
  • Mycotic aneurysms: Caused by infections.

Risk Factors for Aneurysm Formation

• Vessel Wall Stressors:
  • Hypertension: Can weaken vessel walls.
  • Drugs: Cocaine and methamphetamine increase vessel stress.
  • Lifestyle: Smoking, ethanol, oral contraceptives, and pregnancy contribute to vessel integrity.
• Genetic Conditions:
  • Marfan syndrome: Deficiency of fibrillin impacts vessel elasticity.
  • Ehlers-Danlos syndrome: Deficiency of collagen affects blood vessel structure.
  • Polycystic kidney disease: Leads to vascular defects.
• Fibromuscular Dysplasia: Abnormal smooth muscle growth affecting vessel stability.

Triggers for Aneurysm Rupture

• Acute blood pressure spikes due to stressors like pain or anger can precipitate a rupture.

Common Sites for Aneurysms

• Anterior Communicating Artery: Most common site (30% of cases).
• Posterior Communicating Artery: Second most common (25%).
• MCA Bifurcation: Thirdmost common (20%).
• Other sites: Internal Carotid Terminus (7.5%), Basilar Tip (7%), Anterior Cerebral Artery (4%), PICA (3.5%).

Clinical Features and Treatment

• Blood accumulates in the subarachnoid space, prompting monitoring and potential surgical intervention to avert complications.

Arteriovenous Malformation (AVM)

• Common non-traumatic SAH cause, especially in children and adolescents.
• AVMs bypass capillary beds, creating direct artery-to-vein connections, increasing rupture risk.

Hydrocephalus

• Cerebrospinal Fluid (CSF) Pathway: Flows from lateral to third, then to fourth ventricle.
• Obstruction: Blood clots can block CSF flow, resulting in hydrocephalus.
• Types:
  • Obstructive Hydrocephalus: Caused by blockages.
  • Communicating Hydrocephalus: Due to impaired CSF absorption.

Key Symptoms

• Headache: Described as the “worst headache of life.”
• Meningeal Signs: Include photophobia, nuchal rigidity, and positive Kernig's/Brudzinski's signs.

Increased Intracranial Pressure (ICP)

• Symptoms include headache, nausea, vomiting, cranial nerve deficits, abnormal posturing, and Cushing's triad (hypertension, bradycardia, irregular respirations).

Focal Neurological Deficits

• Stroke-like symptoms can occur depending on the vessel affected by the hemorrhage.

Hunt and Hess Score

• Assesses mortality risk and clinical presentation severity, ranging from asymptomatic (score 1) to comatose (score 5).

Diagnostic Approach

• Non-Contrast CT Scan: Identifies SAH patterns and hydrocephalus.
• Modified Fischer Score: Evaluates vasospasm risk based on hemorrhage thickness on CT.

Angiographic Imaging

• CT Angiogram: Detects ruptured aneurysms.
• Digital Subtraction Angiogram (DSA): Gold standard for vascular imaging, can be therapeutic.

Lumbar Puncture

• Confirms SAH by detecting blood in CSF; xanthochromia indicates prior hemorrhage.

Differential Diagnosis

• Consider causes such as hypertension, trauma, drug use, and genetic conditions; imaging aids in underlying diagnosis.

Treatment Protocol

• Focus on airway, breathing, and circulation during emergency management due to ICP risks.
• Continuous neurological monitoring is crucial for ICP management.

Airway Management

• GCS less than eight suggests potential airway protection issues; escalating oxygen measures may be necessary.

Ventilation Modes

• Continuous Mechanical Ventilation (CMV) allows controlled settings.
• Adaptive Support Ventilation (ASV) adjusts to patient demand, supporting spontaneous breaths.

Blood Pressure Management

• Keeping systolic blood pressure below 160 mmHg is essential to limit bleeding risk.
• Key medications include Nicardipine, Labetalol, Hydralazine, and Enalapril.

External Ventricular Drain (EVD) Indications

• EVD is indicated for severe Hunt-Hess scores or intraventricular hemorrhage, reducing ICP by draining fluid.

Monitoring ICP

• Target ICP is less than 20 mmHg; sustained pressures require intervention. Mannitol and hypertonic saline can be used to reduce ICP.

Aneurysm Treatment: Clipping vs. Coiling

• Treatment should occur within 24 hours, with coiling preferred for older patients and smaller neck aneurysms; location influences choice.

Complications After Treatment

• Rebleeding is critical within the first 48 hours, with stabilization treatments including clotting medications and platelet transfusion.

Vasospasm and Delayed Cerebral Ischemia

• Develops from inflammatory mediators following SAH, leading to vessel narrowing and reduced cerebral blood flow risk.