NURS 1250 Exam 3: Intracranial Regulation

• Lakeland Community College presents study notes for NURS 1250 Nursing Care of Adults, Exam 3, focusing on the concept of intracranial regulation and nervous system disorders.
• The outline is for Increased Intracranial Pressure and Traumatic Brain Injury

Cranial Bones

• The cranium houses and protects the brain.
• It is made up of several fused bones.
• The cranial structure is fixed and cannot expand.
• The cranium is composed of eight cranial bones: Frontal (1), Parietal (2), Temporal (2), Occipital (1), Sphenoid (1), and Ethmoid (1)

Meninges

• Meninges are the membranous coverings of the brain located immediately internal to the cranium.
• The meninges consist of the dura mater, arachnoid, and pia mater.

Cerebrospinal Fluid

• Cerebrospinal fluid is a clear, colorless, liquid-like blood plasma that fills the ventricles of the brain.
• It is composed of 99% water.
• Approximately 100-150 mL of cerebrospinal fluid are present.
• Cerebrospinal fluid is formed in the choroid plexuses.
• It cushions the brain and spinal cord.
• Cerebrospinal fluid provides nourishment to the brain.
• Cerebrospinal fluid acts as a waste removal system.

Monro-Kellie Hypothesis

• The Monro-Kellie hypothesis is also known as "The Box Theory of the Brain."
• The skull has limited space for expansion.
• The intracranial volume is approximately 1700 mL.
• Brain tissue volume is approximately 1400 grams.
• The components within the skull must exist in equilibrium.
• Increased intracranial pressure results in decreased blood flow to the brain.

Intracranial Pressure

• Intracranial pressure is the pressure exerted by the volume of intracranial contents within the cranial vault.
• Normal ICP is 5 – 15 mmHg.
• Treatment is required when ICP is greater than 20 mmHg.
• An ICP greater than 40 mmHg is life-threatening.

Mean Arterial Pressure

• Mean arterial pressure is the average pressure in the arteries during one cardiac cycle, ensuring blood flow to vital organs.
• The normal range for MAP is 70 – 100 mmHg.
• Perfusion can be impeded if outside of the normal range
• Hypertension is indicated by a MAP of greater than 105 mmHg.
• MAP can be calculated using the formula: MAP = (SBP + 2(DBP)) / 3

Cerebral Perfusion Pressure

• Cerebral perfusion pressure is the pressure needed to ensure adequate blood flow to the brain, maintaining oxygen and nutrient delivery.
• Cerebral blood flow depends on cerebral perfusion pressure.
• CPP depends upon ICP.

CPP Calculation and Values

• CPP = MAP - ICP
• Normal CPP is 60 – 70 mmHg.
• A CPP value of less than 50 can cause irreversible neurologic damage.

Increased Intracranial Pressure

• Increased Intracranial Pressure is commonly referred to as intracranial hypertension.
• It is the pressure within the craniospinal compartment.
• Intracranial components consist of brain parenchyma (approx. 80%), cerebrospinal fluid (approx. 10%), and blood (approx. 10%).

Increased ICP Overview

• ICP fluctuates throughout the day.
• Brief increases in ICP are not harmful; these can be caused by coughing, bending, sneezing, and straining
• Sustained increases in ICP are harmful
• Sustained ICP can be the result of hydrocephalus, brain tumor, hemorrhage, CNS infection, and traumatic brain injury.

Increased ICP Etiology

• Causes of increased ICP can include:
• Traumatic brain injury
• Cerebrovascular accident
• Brain tumors
• Hydrocephalus
• Meningitis or encephalitis

Traumatic Brain Injury

• Traumatic brain injury can lead to hematoma, cerebral edema, and tissue damage.
• Common causes of TBI include:
• Falls
• Motor vehicle accidents
• Sports injuries
• Assaults and violence

Cerebrovascular Accident: Ischemic Stroke

• Ischemic stroke refers to brain infarction.
• Types of ischemic stroke include:
• Large vessel occlusion (LVO)
• Cardioembolic stroke

Cerebrovascular Accident: Hemorrhagic Stroke

• Hemorrhagic stroke refers to bleeding in the brain.
• Types of hemorrhagic stroke include:
• Intra cerebral hemorrhage (ICH)
• Subarachnoid hemorrhage (SAH)

Brain Tumors

• Brain tumors are space-occupying lesions.
• Types of brain tumors include:
• Glioblastoma
• Meningioma

Hydrocephalus

• Hydrocephalus is an increased accumulation of CSF.
• Types of hydrocephalus include cases caused by:
• Congenital malformations
• Post-meningitis scarring
• History of head trauma

Meningitis or Encephalitis

• Meningitis or encephalitis are infections of the brain and meninges.
• Types of meningitis or encephalitis include:
• Bacterial meningitis
• Viral encephalitis

Cushing's Triad

• Cushing's Triad is a CNS ischemic response reflex.
• It is initiated by the hypothalamus of the brain.
• The three components of Cushing's Triad are:
• Bradypnea
• Bradycardia
• Hypertension

Recognize Cues: Early vs Late Stage of Increased ICP

• Early stage features of increased ICP typically include confusion/restlessness, mild to moderate headache, blurred vision, sluggish/unequal pupillary response, weakness, slight BP elevation, slightly irregular respiration, and mild/focal seizures.
• Late stage of increased ICP typically includes stupor/coma, severe headache that is unrelieved by medication, diplopia/tunneled vision, non-reactive/dilated pupillary response, decorticate/decerebrate motor function/posturing, Cushing's Triad vital signs, Cheyne Stokes respiration, and generalized or no response seizures.

Recognize Cues: Posturing

• Decorticate posturing indicates lesions above the brainstem and causes flexion of arms with adduction, extension of legs with internal rotation, and a stiff body with bent arms.
• Decerebrate posturing indicates lesions of the brainstem and causes extension of arms with hyper pronation, extension of legs with plantar flexion, and a rigid body with stretched arms and clenched jaws.

Screening Tests

• Screening tests consist of vital signs (Cushing's Triad), Glasgow Coma Scale (GCS), pupillary response, neurological examination, and CT or MRI scan.

Glasgow Coma Scale

• The Glasgow Coma Scale is a diagnostic tool for gauging the patient's level of consciousness.
• The scale assesses eye opening response, verbal response, and motor response.
• Eye opening responses can be rated as: Spontaneous (4 points), to verbal command (3 points), to pain (2 points), or no eye opening (1 point).
• Verbal responses can be rated as: Oriented (5 points), confused conversation (4 points), inappropriate responses (3 points), incomprehensible sounds (2 points), or no verbal response (1 point).
• Motor responses can be rated as: Obeys commands (6 points), purposeful movement to pain (5 points), withdraws from pain (4 points), abnormal flexion/decorticate posture (3 points), extensor/decerebrate posture (2 points), or no motor response (1 point).
• Interpretation is as follows: Minor brain injury = 13-15 points; Moderate brain injury = 9-12 points; Severe brain injury = 3-8 points.

Pupillary Response

• Pupillary response refers to how pupils react to light.
• Pupils constrict in bright and normal light, and dilate in dim light.

Cranial Nerve Examination

• Cranial nerve examinations consist of:
• I Olfactory (Smell)
• II Optic (Visual fields)
• III, IV, VI Oculomotor, Trochlear, Abducens (Eye movements)
• V Trigeminal (Facial sensation)
• VII Facial (Facial movements)
• VIII Auditory (Hearing)
• IX, X Glossopharyngeal, Vagus (Palate movement)
• XI Accessory (Shrugging shoulders)
• XII Hypoglossal (Tongue movement)

Screening Tests: CT Scan and MRI

• CT scans are useful in immediate post-injury care and can identify hemorrhage, bleeds in and around the brain, blood flow, brain tissue swelling, and skull fractures.
• MRI is useful in ongoing assessment and follow-up care and can detect microhemorrhage, bruising, gliosis (bruising), and atrophy.

Multimodal Treatment

• Treatments consist of Collaborative Actions, Pharmacotherapy and Surgical Intervention.

Collaborative Actions

• Collaborative actions consist of, Adequate oxygenation, Fluid management, Blood pressure control, Sedation, Positioning, Thermoregulation, Antiseizure Therapy and Stool Softeners.

Pharmacotherapy

• Mannitol is a commonly used osmotic diuretic.
• It decreases cerebral edema and increases cerebral perfusion.
• Mannitol elevates blood plasma osmolality.
• Mannitol begins to lower ICP in 15 minutes.
• Mannitol is administered as a 1.5-2 g/kg IV infusion, requiring a filter.

Surgical Intervention

Craniotomy

• Temporary removal of a section of the skull.

Craniectomy

• Permanent excision of a section of the skull.
• A cranioplasty is performed once swelling is resolved.

Ventriculostomy:

• CSF Diversion
• CSF removal 1-2 mL/min
• Passive gravitational drainage

Ventriculoperitoneal Shunt (VP Shunt):

• Surgical device used to treat hydrocephalus.
• Drainage of excess CSF from the brain into the peritoneal cavity.