Overview of Cranial Nerves

• Cranial nerves are 12 nerve pairs originating from the brain, essential for sensory and motor functions in the head and neck.

Olfactory Nerve (CN I)

• Controls the sense of smell and carries sensory information from nasal receptors to the brain.

Optic Nerve (CN II)

• Primarily controls vision and carries sensory information from the retina to the brain.

Oculomotor Nerve (CN III)

• Controls most eye movements, pupil constriction, lens shaping for focus, and upper eyelid elevation.

Trochlear Nerve (CN IV)

• Controls the superior oblique muscle for downward and inward eye movements.

Trigeminal Nerve (CN V)

• Largest cranial nerve and serves sensory and motor functions; provides sensory information from the face and controls chewing muscles.

Abducens Nerve (CN VI)

• Primarily controls the lateral rectus muscle, responsible for outward eye movement.

Facial Nerve (CN VII)

• Controls facial expressions, taste from the anterior two-thirds of the tongue, and tear and saliva production.

Vestibulocochlear Nerve (CN VIII)

• Has two parts: the vestibular nerve(balance) and cochlear nerve (hearing); transmits sensory information for balance and sound perception.

Glossopharyngeal Nerve (CN IX)

• Controls taste sensation from the posterior one-third of the tongue, swallowing, and monitoring blood pressure and blood gas levels.

Vagus Nerve (CN X)

• Provides parasympathetic innervation to organs; monitors and regulates digestive system functions, speech, and swallowing.

Accessory Nerve (CN XI)

• Controls head and shoulder movements and aids in swallowing.

Hypoglossal Nerve (CN XII)

• Controls tongue muscles, essential for speech and swallowing.

Meningitis

• Meningitis is the inflammation of the meninges, which are membranes protecting the brain and spinal cord.
• Viral meningitis results from a virus causing inflammation of the meninges.
• Bacterial meningitis results from a bacterial infection, such as otitis media, pneumonia, or sinusitis, infecting the meninges.
• Symptoms include excruciating constant headache, nuchal rigidity (stiff neck), photophobia, fever/chills, nausea and vomiting, and altered LOC.
• Positive Kernig’s sign is resistance and pain with leg extension from a flexed position.
• Positive Brudzinski’s sign is knee and hip flexion occurring with deliberate neck flexion.
• Additional symptoms include hyperreactive DTRs, tachycardia, seizures, red macular rash (meningococcal meningitis), and restlessness and irritability.
• Diagnosis involves spinal sampling of cerebrospinal fluid (CSF); cloudy CSF and decreased glucose indicate bacterial meningitis.
• Complications include increased intracranial pressure (ICP), Syndrome of Inappropriate Antidiuretic Hormone (SIADH), and septic emboli.
• Increased ICP poses the greatest risk, potentially leading to brain herniation and death.
• Neurological assessments, including cranial nerve evaluations, should be performed at least every 4 hours.
• Monitor for early neurological changes, such as decreased level of consciousness and Cushing’s triad (severe hypertension, widened pulse pressure, and bradycardia).

Brain Injury (Closed Head Injury)

• Traumatic brain injury (TBI) is a sudden, physcial damage to the brain and falls are the most common cause
• TBIs can be closed or penetrating.
• Males are more affected than females

Simple TBI

• Simple TBIs, also known as mild TBIs or concussions, are the less severe form of traumatic brain injuries.
• Often result from a blow, jolt, or bump to the head, causing a brief alteration in consciousness, confusion, or amnesia for a short period.
• Symptoms may be mild and transient, including headache, dizziness, and nausea.
• Imaging tests like CT scans or MRIs typically appear normal.
• Most individuals with simple TBIs recover within days to weeks with rest and limited physical and cognitive activity.

Complex TBI

• Complex TBIs, also known as moderate or severe TBIs, are more severe and involve significant damage to the brain.
• Often result from more substantial trauma, such as a car accident, fall from a height, or gunshot wound to the head.
• Symptoms are severe and can include prolonged loss of consciousness, memory deficits, and neurological impairments.
• Imaging tests may show structural brain damage, bleeding, or visible injuries.
• Recovery from complex TBIs can be challenging and lengthy and often requires intensive medical and rehabilitative care.

Concussion

• A concussion is a mild traumatic brain injury caused by a blow or jolt to the head or body, leading to temporary changes in brain function.
• May involve symptoms such as confusion, memory problems, headache, dizziness, and a range of other physical, cognitive, and emotional issues.

Risk Factors for Concussions

• Participation in contact sports increases the risk of concussions due to the physical nature of these activities.
• Falls are a common cause of concussions, especially in young children and older adults.
• Motor vehicle, motorcycle, and bicycle accidents can result in head trauma and concussions.
• Military personnel deployed in combat zones are at risk of concussions due to exposure to explosive blasts.
• Recreational activities can lead to concussions if there's a head injury.
• Being a victim of physical assault can result in head trauma and concussion.
• Individuals with a history of concussions are at a higher risk for future concussions.
• Young children, adolescents, and young adults are more prone to concussions, and males are generally at a higher risk than females.
• Occupations such as construction work or military service may have a higher risk of head injuries and concussions.
• Individuals with pre-existing medical conditions or those taking medications that affect blood clotting or brain function may be more susceptible to concussions.

Coup Injury

• A coup injury occurs at the site of the impact.
• When the head is struck by an external force, the brain can move inside the skull, and the side of the brain directly opposite the point of impact can hit the inside of the skull.
• Causes injury to the brain tissue at the point of impact.

Contrecoup Injury

• A contrecoup injury occurs on the side of the brain opposite the site of impact.
• When the head is struck and comes to a sudden stop, the brain, which is suspended in cerebrospinal fluid, may continue to move inside the skull and hit the opposite side of the skull.
• Can cause injury to the brain tissue on the side opposite the point of impact.
• Both coup and contrecoup injuries can result in damage to the brain, including bruising, bleeding, and swelling.

Diffuse Axonal Injury (DAI)

• Diffuse axonal injury (DAI) is a severe and often devastating form of traumatic brain injury (TBI) characterized by widespread damage to the brain's axons.
• DAI typically results from rapid acceleration or deceleration of the head, as seen in high-speed car accidents, falls, or shaken baby syndrome.
• Involves widespread injury and is often associated with a more severe and complex clinical course.
• Occurs when the brain experiences rotational forces or shearing forces during trauma, causing the axons to stretch and tear, leading to injury.
• Can occur without visible signs of head trauma on the outside.
• Common symptoms include loss of consciousness, confusion, memory deficits, and changes in consciousness.
• Treatment involves managing symptoms and providing supportive care, which may include interventions to control intracranial pressure and prevent secondary brain damage.
• Rehabilitation includes physical therapy, occupational therapy, speech therapy, and neuropsychological interventions.
• Promoting safety measures reduces the risk of head injuries e.g wearing seatbelts, using child safety seats, wearing helmets when engaging in high- risk activities, and practicing safe driving habits.

Penetrating Brain Injury

A penetrating brain injury occurs when an object penetrates the skull and enters the brain tissue.

• Result from a direct impact or intrusion through the skull.
• Typically involves surgical intervention to remove the foreign object and repair damaged brain tissue.

Skull Fracture

• A skull fracture a break or crack in one or more bones of the skull.
• Different types include linear fractures, depressed fractures, and basilar fractures
• Caused by direct head trauma.
• Symptoms may include pain at the fracture site, swelling, bruising, bleeding from the ear or nose, and neurological symptoms if there is associated brain injury.
• Raccoon eyes is bruising or discoloration around both eyes and occurs when blood from a facial bone fracture collects in the tissues around the eyes
• Battle's sign is bruising or discoloration over the mastoid process behind the ear.
• Halo Sign (CSF Leak): Place a few drops of the fluid on a sterile surface (e.g., gauze). If CSF is present, it will spread outward, creating a halo effect around a central bloodstain.

Blast Brain Injury

• Blast-induced neurotrauma, occurs as a result of exposure to high-intensity shockwaves generated by explosions.
• Caused by sudden changes in pressure from a blast wave that affect the brain, leading to various forms of brain injury
• This may include primary blast injury (direct impact of the shockwave on the brain), secondary blast injury (injury caused by flying debris), or tertiary blast injury (physical trauma from being thrown by the blast).

Neurological Assessments

• Neurological assessments are clinical examinations performed to evaluate the functioning of the nervous system, as well as detect neurological disorders.
• They encompass a range of tests and observations to assess cognitive, motor, sensory, and reflex functions.

Mental Status Examination

• Includes orientation, concentration and memory, and language and speech

Cranial Nerve Examination

• A detailed evaluation of the 12 cranial nerves to assess sensory and motor functions related to vision, hearing, taste, facial movements, and other functions.

Motor Function

• Asses muscle strength and coordination

Sensory Function

• Asses light touch, vibration and proprioception, pain and temperature, and tactile localization

Reflexes

• Asses deep tendon reflexes, superficial reflexes, and pathological reflexes

Coordination and Balance

• Asses fine motor coordination and determines a patient's ability to maintain balance with eyes closed.

• Meningeal Signs: Assessing for signs of meningeal irritation, which can be indicative of conditions like meningitis.

Special Tests

Pupillary Examination: (PERRLA) Evaluating the size, shape, and reactivity of the pupils, which can provide information about the functioning of the cranial nerves and brainstem.

• Glasgow Coma Scale (GCS) assess the severity of brain injury.
• The Sport Concussion Assessment Tool, or SCAT, is a standardized tool used to assess and evaluate concussions in athletes.

Brain Injury Test/Treatment

• The assessment and treatment of brain injuries depend on the type, severity, and cause of the injury.

Assessment/Diagnostics

• Assess the patient's vital signs.
• Conduct a Glasgow Coma Scale (GCS) assessment.
• Use Diagnostic imaging techniques to assess abnormalities.
• A comprehensive neurological examination.
• Intracranial Pressure (ICP) Monitoring.
• Cerebral Angiography.
• Neuropsychological Testing.

Treatment

• Control intracranial pressure (ICP) with medications, head elevation, and ensuring proper oxygenation and blood pressure control.
• Medication to control seizures, reduce ICP, and manage pain.
• Rehabilitation services, including physical therapy, occupational therapy, and speech therapy.
• Providing psychological counseling and support.
• Preventative measures and lifestyle modifications to prevent further brain injuries
• Frequent follow-up appointments and monitoring.

Glasgow Coma Scale (GCS)

• The Glasgow Coma Scale (GCS) asses the severity of brain injury
• Assesses three areas: eye opening, verbal repsonse, and motor response
• Lowest GCS 3, highest 15
• Less than 8 = intubate
• Use as series of scores, compared over time
• The lower the GCS the more required cares must be performed for the patient.

Eye Repsonse

• 4 points (E4): The patient opens their eyes spontaneously.
• 3 points (E3): The patient opens their eyes in response to verbal stimuli.
• 2 points (E2): The patient opens their eyes in response to pain or physical stimuli.
• 1 point (E1): The patient's eyes do not open, regardless of the stimulus.
• 1 point (E0): The patient's eyes remain closed due to physical injury or other factors.

Verbal Response

• 5 points (V5): The patient is oriented.
• 4 points (V4): The patient is confused but can provide some meaningful responses.
• 3 points (V3): The patient speaks inappropriately
• 2 points (V2): The patient only emits incomprehensible sounds.
• 1 point (V1): The patient does not make any verbal response.
• 1 point (V0): The patient is unable to produce sounds due to injury or other factors.

Motor Response

• 6 points (M6): The patient obeys commands.
• 5 points (M5): The patient localizes painful stimuli.
• 4 points (M4): The patient withdraws from painful stimuli but does not localize it.
• 3 points (M3): The patient exhibits abnormal flexion (decorticate posturing) in response to pain.
• 2 points (M2): The patient displays abnormal extension (decerebrate posturing) in response to pain.
• 1 point (M1): The patient does not exhibit any motor response to pain.
• 1 point (M0): The patient is unable to move due to injury or other factors.
• The total GCS score is calculated by summing the points from each of the three components (E + V + M), with scores ranging from 3 (deep coma) to 15 (fully alert and oriented).

Epidural Hematoma

• An epidural hematoma is the accumulation of blood between the skull and the dura mater, the outermost layer of the meninges and is typically the result of head trauma.
• Common symptoms include alternating periods of alertness and unconsciousness, sever headache, vomiting, seizure, pupil distortions, Cushing’s triad.
• The rupture of arteries leads to the rapid blood accumulation in the epidural space.
• As the hematoma grows it exerts pressure on the brain which can lead to neurological symptoms and increased intracranial pressure (ICP).
• Mass Effect compreses the brain, affecting its function and causing various neurological deficits.
• May expand and compresses the brain, it can lead to local cerebral edema and, in some cases, ischemia to the surrounding brain tissue.
• Surgical Intervention is crucial to remove the accumulated blood, repair the damaged blood vessels, and relieve the pressure on the brain.

Subdural Hematoma

• A subdural hematoma is the accumulation of blood between the layers of the meninges.
• Usually due to tearing of bridging veins in subdural space
• Typically occurs as a result of head trauma or injury
• Slow bleeding, but blood can accumulate over time.
• The presence of blood in the subdural space can trigger an inflammatory response.
• Neurological Impairments: compression of brain tissue, increased ICP, and inflammation can lead to a range of neurological symptoms, including headache, altered mental status, confusion, motor and sensory deficits.
• Can be acute or chronic
• Large, acute SDH require craniotomy, burr hole to evacuate blood and small SDH may be slowly reabsorbed by brain

Intracranial Pressure (ICP)

• Increased intracranial pressure (ICP) refers to elevated pressure within the cranial vault, the rigid space that contains the brain and cerebrospinal fluid (CSF).
• Elevated ICP can cause a range of neurological symptoms and, if left untreated, can result in brain damage or even death.
• Symptoms include level of consciousness changes, headache, visual changes (diplopia), irritability, nausea/vomiting, pupil changes, vital sign changes (Cushing’s Triad), and ineffective thermoregulation.

Causes of ICP

• Cerebral Blood Volume (CBV): increase in cerebral blood volume, either due to an increase in systemic blood pressure or dilated blood vessels in the brain.
• Cerebral Spinal Fluid (CSF): Imbalances in the production, circulation, or absorption of CSF.
• Brain Swelling (Edema): brain edema caused by trauma, tumors, infections, or inflammation.
• Mass Effect: physical presence of a mass, such as a tumor, hematoma, or abscess.
• Vasodilation: Blood vessels in the brain can dilate
• Obstruction of CSF Flow: Conditions that obstruct the flow of CSF within the brain's ventricles or subarachnoid space
• Hydrocephalus: buildup of excess CSF within the brain's ventricles.
• Brain Herniation: displacement of brain tissue from its normal position within the cranial vault

ICP Treatment

• Surgical Decompression.
• Medications: Osmotic diuretics, such as mannitol.
• Hyperventilation: Controlled hyperventilation can help reduce ICP.
• Elevating the Head.
• Controlling Blood Pressure.

Cushing’s Triad

• Cushing's triad is a clinical indication of increased intracranial pressure (ICP).
• The triad consists of three main components:
  • Hypertension (Increased Blood Pressure)
  • Bradycardia (Slow Heart Rate)
  • Irregular Respirations
• The nurse should administer mannitol 25%, an osmotic diuretic that promotes diuresis to treat cerebral edema.

Cerebral Perfusion Pressure (CPP)

• Cerebral perfusion pressure (CPP) is dependent on mean arterial pressure (MAP) and ICP

  • CPP=MAP–ICP
  • CPP=MAP−(ICP+CVP) if CVP is being directly monitored.

• If pressure autoregulation is disrupted, cerebral blood flow and ICP altered

• Mechanisms that INCREASE ICP:

  • Cytotoxic cerebral edema: reduced oxygen
  • Compression of jugular vein with tracheostomy ties or tight cervical collars

• Mechanisms that DECREASE ICP:

  • External drainage of CSF via catheter
  • Lower blood pressure
  • Hypertonic IV
  • Low carbon dioxide
  • Vasoconstrict cerebral arteries
  • Removing brain tissue (lobectomy)
  • Decompressive craniectomy

Surgical Interventions for ICP

• Craniotomy: is a surgical procedure that involves the temporary removal of a section of the skull (bone flap) to access and treat the brain.
• Cranioplasty: a surgical procedure performed to repair a defect or replace a missing segment of the skull.
• Burr Hole: small openings made in the skull using a specialized drill for various reasons, including draining blood or relieving pressure.

Posturing

• Posturing refers to specific abnormal body movements and positions that can be observed in individuals with elevated ICP.

Decorticate Posturing

• Decorticate posturing is characterized by abnormal flexion of the upper limbs (arms) and extension of the lower limbs (legs).
• Decorticate posturing suggests damage to the cerebral hemispheres or the corticospinal tracts in the brain and indicates a significant neurological problem.

Decerebrate Posturing

• Decerebrate posturing involves the rigid extension of all four limbs.
• Decerebrate posturing suggests that the damage or pressure on the brain is located lower in the brainstem and indicates a more critical neurological condition.

Cerebrovascular Circulation & Metabolism

• Brain Metabolism consumes 20% of oxygen and glucose for energy. Brain cells are not capable of anaerobic metabolism and hypoglycemia and hypoxia affect brain functioning and can mimic strokes.
• R and L vertebral arteries feed posterior brain Internal and external carotids
• Internal carotid serves the brain’s anterior and middle cerebral arteries; anterior cerebral artery to frontal lobe, and middle cerebral artery to the lateral cortex, 80% of brain’s tissue
• Circle of Willis provides collateral circulation and is a common site for aneurysms

Stroke

• Two types of strokes: Ischemic (85%) or Hemorrhagic (15%)
• Ischemic strokes are thrombus or embolus that leads to cerebral infarction
• Hemorrhagic Strokes ruptures a cerebral artery
• Transient ischemic attack (TIA) is an ischemic injury, “mini-stroke” which has a disruption of cerebral circulation lasting less than 24 hours with no permanent injury, but can warn of future attacks

Ischemic Stroke

• Thrombotic Stroke occurs when a blood clot (thrombus) forms within an artery in the brain, blocking blood flow to that region.
• Embolic Stroke occurs when a blood clot or embolus forms in another part of the body and travels through the bloodstream until it becomes lodged in a smaller artery within the brain, blocking blood flow.
• Common risk factors include: High blood pressure (hypertension), atherosclerosis, diabetes, smoking, high cholesterol, atrial fibrillation, heart disease, obesity, and family history of stroke
• Symptoms of an ischemic stroke include: weakness or numbness, difficulty speaking or slurred speech, confusion, visual disturbances, severe headache, trouble with coordination and balance, and dizziness or loss of consciousness
• Treatment is time-sensitive and includes:
  • Intravenous Thrombolytic Therapy (tPA) which can help dissolve the clot
  • Mechanical Thrombectomy using a catheter to remove the clot directly
  • Antiplatelet Medications such as aspirin or clopidogrel
  • Anticoagulants

Ischemic Damage

• Cerebral ischemia may develop gradually
• Neurons in core area of ischemia suffer irreversible infarction within minutes
• Ischemic penumbra: perimeter of ischemic zone where less perfusion is present but not irreversible damage, so rapid reperfusion is critical to recover cells
• Cerebral edema may develop in the area causing further damage
• Lacunar infarct is small infarcts in the brain due to occlusion of tiny blood vessels

Hemorrhagic Stroke

• Hemorrhagic stroke results from bleeding into the brain tissues, ventricles, or subarachnoid space and can be caused by hypertension, an aneurysm, or an arteriovenous malformation.
• Sudden, severe headache is an expected initial manifestation.
• Hematoma and clot form and may expand in first 24 hours.
• Intracerebral Hemorrhage (ICH) occurs with a blood vessel within the brain itself ruptures.
• Subarachnoid Hemorrhage (SAH) is characterized by bleeding into the space between the arachnoid membrane; commonly caused by the rupture of an aneurysm. Trauma, bleeding disorders, or vascular malformations can also lead to SAH.
• Common risk factors include: High blood pressure (hypertension), aneurysms, arteriovenous malformations (AVMs), blood clotting disorders, head trauma, illicit drug use, and use of anticoagulant medications
• Symptoms often include:
  • Severe headache (often described as "the worst headache of my life")
  • Nausea and vomiting
  • Altered consciousness
  • Weakness or numbness
  • Seizures
  • Visual disturbances
  • Difficulty speaking or slurred speech
• Treatment is time-sensitive:
  • Surgical Intervention to repair damaged blood vessels or remove aneurysms
  • Endovascular Procedures using catheters and coils to treat aneurysms
  • Blood Pressure Management is crucial in preventing recurrent bleeding.
  • Close Monitoring and Supportive Care.

Risk Factor of Stroke

• Hypertension (HTN)
• Hyperlipidemia
• Diabetes
• Smoking
• Obesity
• Lack of exercise
• Atrial fibrillation
• Oral contraceptives
• Excess alcohol
• Family history
• Age 55+
• Gender - Male risk is greater than female
• Ethnicity - African American risk is greater than Caucasian
• Sickle cell disease
• History of transient ischemic attack (TIA)
• Amyloid accumulation

Signs and Symptoms (Stroke)

• Ischemic and hemorrhagic strokes present with similar signs
• Middle cerebral artery most common stroke location with presents as speech, motor, sensory deficits; neurological deficits on one side of body, Slurred speech, loss of gag reflex, facial droop, Hemiparesis, hemiparalysis, loss of sensation,and vision loss
• Some patients have disorientation, confusion
• Subarachnoid hemorrhage (SAH) presents as sudden onset (“worst headache ever,” “thunderclap headache”)
• Vertebrobasilar insufficiency (VBI) Ischemia of vertebrobasilar circulation causing dizziness, vertigo, headache

BE FAST Stroke Assessment

• B: Balance: Check the person's balance.
• E: Eyes: Ask the person to check their vision.
• F: Face: Ask the person to smile.
• A: Arms: Ask the person to raise both arms
• S: Speech: Ask the person to repeat a simple phrase.
• T: Time: Time is critical in stroke care, so call emergency services immediately It is crucial to rule out other pathologies that may present similar to stroke, and remember that hypoglycemia mimics stroke symptoms.
• In acute phase CT scans without contrast are used, Treatment will be based on whether the stroke is ischemic or hemorrhagic
• CT scan with dye may allow visualization of ischemia
• Use Magnetic resonance angiography (MRA) to distinguish between ischemic and hemorrhagic stroke
• Use Transcranial Doppler
• Use National Institutes of Health Stroke Scale (NIHSS)

Ischemic Stroke Treatment

• Tissue plasminogen activator (tPA) is a clot-dissolving medication that helps to break down blood clots in the brain's blood vessels:
  • Is administered intravenously within 4.5 hours of symptom onset
  • Is not for all stroke patients and carries a risk of bleeding
• Thrombectomy – Patient Evaluation: uses neuroimaging (often with CT or MRI scans) to confirm the presence and location of the blood clot
  • Is most effective when performed within 6-24 hours from symptom onset
  • Uses real-time imaging to guide the insertion of a catheter into the affected blood vessel
  • Catheter is advanced through a large artery up to the site of the blood clot in the brain to have the clot be captured or physically removed using specialized devices
  • Patient's must be observed in an intensive care unit or stroke unit to monitor neurological status
• TIME IS BRAIN!

Hemorrhagic Stroke Treatment

• Emergency Medical Care is needed to ensure the patient's airway is clear and stabilize vital signs.
• Patients with these strokes may need Emergency Neurosurgery to evacuate the hematoma or to repair the ruptured blood vessel.
• Blood Pressure has to undergo controlled management to prevent re-bleeding.