Alteration of the brain

Alterations of the Brain and Nervous System

Traumatic Brain Injury (TBI)

• What it is: TBI happens when an outside force changes how the brain works.

• How common: About 1.7 million people in the U.S. get a TBI each year.

• Common Causes:

  • Falls

  • Car accidents

  • Sports injuries

• Types of Damage:

  • Primary Injury: This is the immediate damage from the direct hit, affecting a small area (focal) or a large area (diffuse) of the brain.

  • Secondary Injury: This damage develops later due to the body's response, like swelling and inflammation in the brain.

• How it's measured: We use the Glasgow Coma Scale (GCS).

  • Purpose: It checks a person's eye opening, verbal response, and movement to figure out how severe the TBI is.

  • Severity Scores:

    • Mild: GCS between 13 and 15

    • Moderate: GCS between 9 and 12

    • Severe: GCS between 3 and 8

Focal and Diffuse Brain Injuries

Focal Brain Injuries

• What they are: Injuries that affect only a specific part of the brain due to a direct hit.

• How they happen:

  • Closed Trauma: The skull stays intact, but there might be bruising (contusions) or blood clots (hematomas) inside.

  • Open Trauma: The skull is broken or pierced, and the brain's protective covering (dura) is breached, like with a penetrating injury.

• Common Blood Clots (Hematomas):

  • Epidural Hematoma: Bleeding from an artery, often more serious due to faster blood loss.

  • Subdural Hematoma: Bleeding from a vein, usually slower.

• Coup and Contrecoup Injuries: A "coup" injury happens at the exact spot of impact. A "contrecoup" injury happens on the opposite side of the brain when the brain bounces against the skull.

Diffuse Brain Injuries

• What they are: Widespread damage across many brain areas, usually from the head moving rapidly back and forth (acceleration-deceleration).

• Types:

  • Concussion: A temporary disruption of brain function with no obvious damage on imaging scans.

  • Diffuse Axonal Injury (DAI): Tiny tears or damage to the brain's nerve fibers (axons) across different parts of the brain.

  • Subarachnoid Hemorrhage (SAH): Bleeding into the space around the brain where cerebrospinal fluid (CSF) flows.

• Long-term Effects: DAI and SAH can cause lasting problems with thinking, memory, and other brain functions.

Secondary Brain Injury and Management

• Reasons for Secondary Injury: Damage that develops after the initial injury.

  • Body-wide Factors: Low blood pressure (hypotension), lack of oxygen (hypoxia), reduced blood flow (ischemia), low red blood cells (anemia), too much or too little carbon dioxide (hypercapnia, hypocapnia)—all these badly affect blood flow to the brain.

  • Cellular Responses: Inflammation, brain swelling (cerebral edema), increased pressure inside the skull (intracranial pressure), over-excitement of brain cells (excitotoxicity), oxidative stress, and damage to the protective blood-brain barrier.

• Outcome: These processes harm brain cells, eventually leading to their death through problems with energy production, too much calcium inside cells, and programmed cell death (apoptosis).

• How to manage it:

  • Main Goals: Prevent oxygen deprivation, maintain stable blood flow and pressure to the brain, control pressure inside the skull, and protect brain cells.

  • Treatment Methods: Balancing body fluids and electrolytes, regulating body temperature, providing breathing support, ensuring early nutrition, and performing prompt surgeries (e.g., draining blood clots).

Spinal Cord Injury (SCI)

• What it is: A primary SCI is direct damage to the spinal cord due to trauma, which can be complete or partial. This can include:

  • A jarring injury (concussion)

  • Bruising (contusion)

  • Squeezing (compression)

  • A cut (laceration)

  • Being cut across (transection)

• Effects: How severe the injury is determines how much movement, sensation, and automatic body functions (like bladder control) are lost below the injured spot.

• Injury Stages: The primary injury causes immediate tissue damage. A secondary injury then develops over days to weeks, involving inflammation, swelling, lack of blood flow, oxidative stress, and cell death, which makes recovery harder.

Spinal Shock and Neurogenic Shock

• Spinal Shock: This is the immediate reaction to an SCI. All reflexes and movement below the injury are lost for several days. Later, muscles might become stiff (spasticity) and reflexes overactive (hyperreflexia).

• Neurogenic Shock: This happens with injuries in the neck (cervical) or upper chest (upper thoracic) area. It leads to:

  • Widening of blood vessels (vasodilation)

  • Low blood pressure (hypotension)

  • Slow heart rate (bradycardia)

  • Problems regulating body temperature.

• Symptoms of Spinal Shock: Limp paralysis, no feeling, absent reflexes.

• Neurogenic Shock Symptoms: Low blood pressure and a slow heart rate.

• Autonomic Dysreflexia: A serious and life-threatening problem that can happen with injuries above the T6 level.

Autonomic Hyperreflexia: Causes, Symptoms, and Emergency Management

• What it is: This condition occurs in people with spinal cord injuries at or above the T6 level. It happens because the brain loses its ability to control exaggerated reflex responses from the sympathetic nervous system below the injury.

• What can trigger it: Most often, it's caused by a full bladder or impacted bowels, but skin irritation or pain below the injury can also set it off.

• Symptoms:

  • Very high blood pressure, appearing suddenly

  • A severe, throbbing headache

  • Redness or flushing of the skin

  • Sweating above the level of injury

  • Stuffy nose

  • Slow heart rate (bradycardia)

• What to do immediately:

  • Find and remove whatever is causing the irritation (the triggering stimulus).

  • Raise the person's head.

  • Give blood pressure-lowering medications if needed, to prevent severe issues like stroke or seizures.

Low Back Pain (LBP)

• What it is: Pain in the lower part of the back that might spread down into the thighs.

• How common: Very common; about 80% of people will experience it at some point.

• Causes: Strained muscles, sprained ligaments, inflammation.

• Things that increase risk: Repeated heavy lifting, being overweight, smoking.

Degenerative Joint Disease and Spondylolysis

• What these are: This group of conditions includes spondylolysis, which is a flaw or fracture in a part of the vertebra (spinal bone), often at the L5 level.

• Complications: Spondylolysis can cause the vertebra to slip forward (spondylolisthesis), leading to pain and instability, especially in athletes and older adults.

Disk Herniation and Spinal Stenosis

• Disk Herniation: This happens when the soft, jelly-like center of a spinal disk (nucleus pulposus) pushes out through a tear, pressing on nearby spinal nerves, commonly at L4-L5 or L5-S1. This causes radiating pain.

• Spinal Stenosis: This is a narrowing of the spinal canal, which squeezes the nerves and causes pain, numbness, and weakness.

Herniated Intervertebral Disk: How it happens and where it's common

• What happens: A spinal disk ruptures when its soft center pushes out through a tear in its tough outer ring.

• Result: The material that pushes out presses on or irritates spinal nerve roots, causing inflammation and nerve pain (radiculitis).

• Most frequent spots: Most common in the lower back (lumbosacral disks) at levels L4-L5 and L5-S1. Sometimes in the neck (cervical disks) at C5-C6 and C6-C7.

• Symptoms: Pain that travels along the path of the affected nerve (radicular pain), often involving the sciatic nerve in lower back herniations. Also includes numbness, tingling, weakness, and weaker reflexes. Pain usually gets worse when you strain, cough, or sneeze.

• Treatment: Most herniated disks get better with simple treatments: physical therapy, pain relievers, and changing activities. Surgery (like removing part of the disk or fusing vertebrae) is considered if symptoms are severe, nerves are significantly damaged, or conservative treatments fail.

Neurology: Seizure Disorders and Epilepsy

• What seizures are: These are sudden, brief disturbances in the brain's electrical activity, caused by abnormal and excessive firing of brain cells.

• What epilepsy is: This condition involves having recurrent seizures without an obvious cause. The definition includes having two or more seizures more than 24 hours apart.

• Things that can trigger seizures: Metabolic problems, genetic factors, brain infections, brain tumors, head injury, alcohol or drug withdrawal, and toxins.

• How seizures are classified:

  • By where they start: focal (one area) or generalized (widespread)

  • By awareness: aware (person is conscious) or impaired (person is unconscious or confused)

  • By movement: motor (involving movements) or nonmotor (not involving movements).

• Examples:

  • Focal Seizures: Can look like tonic-clonic (stiffening and jerking), myoclonic (muscle jerks), or absence (staring spells) seizures, but they start in one area of the brain.

  • Generalized Seizures: Affect the whole brain from the start, like tonic-clonic, atonic (loss of muscle tone), or epileptic spasms.

Epilepsy: How it develops and its stages

• Causes: It results from genetic changes and environmental factors that upset the balance between signals that excite and inhibit brain cells. This leads to abnormal communication between cells, changes in how receptors and ion channels work, and the formation of networks of overactive neurons that can trigger seizures.

• Seizure Stages:

  • Prodroma: Early, vague symptoms like anxiety or depression that might appear hours to days before a seizure.

  • Aura: A specific sensory or visual warning sign that occurs just before a seizure begins.

  • Ictus: The actual seizure event, characterized by movements like stiffening (tonic) and jerking (clonic).

  • Postictal state: The period right after a seizure, often involving confusion, headache, and fatigue.

• Status Epilepticus: This is a medical emergency where seizures last longer than 5 minutes or repeat without the person recovering in between. This is dangerous because it can lead to brain oxygen deprivation, brain cell damage, and even death. It needs immediate treatment to prevent lasting harm.

Cerebrovascular Disorders: An Overview

• What it is: Cerebrovascular disease (CVD) refers to any problem with the blood vessels in the brain that causes either a lack of blood flow (ischemia) or bleeding (hemorrhage).

• Main Risk Factors: High blood pressure, smoking, diabetes, irregular heartbeat (atrial fibrillation), high cholesterol, obesity, not being active, and a family history of these problems. Managing these factors can greatly reduce the chance of having a stroke or having another one.

• Transient Ischemic Attacks (TIAs): These are brief episodes of brain dysfunction caused by a temporary blockage of blood flow to the brain. Symptoms usually last less than 24 hours. TIAs are a warning sign of a higher risk for future strokes, so they require urgent medical attention.

Ischemic Stroke and Hemorrhagic Stroke

• Ischemic Stroke:

  • Cause: Occurs when a blood vessel in the brain is blocked by a blood clot (thrombus or embolus) or due to very low blood flow.

  • Outcome: This blockage leads to a lack of oxygen and nutrients, causing brain tissue damage and death.

  • Symptoms: Depend on which brain artery is affected. Common signs include weakness on one side of the body (hemiparesis), numbness, confusion, and difficulty speaking. Quick treatment (within $3-4.5$ hours) with clot-busting drugs (thrombolytics) can restore blood flow and reduce brain damage.

• Hemorrhagic Stroke:

  • Cause: Happens when a blood vessel in the brain ruptures, causing bleeding into the brain tissue or the space around the brain.

  • Symptoms: Often include a sudden, severe headache, nausea, vomiting, sudden neurological problems, and decreased awareness or consciousness.

  • Treatment Focus: Stopping the bleeding, lowering pressure inside the skull, and preventing further problems.

Intracranial Aneurysm and Subarachnoid Hemorrhage

• Intracranial Aneurysms: These are weak spots in brain arteries that bulge out, often found where vessels branch.

  • Types: The most common type is a saccular (berry) aneurysm, often linked to weak vessel walls and high blood pressure.

• Symptoms if it ruptures: Sudden, excruciating headache (often described as the "worst headache of my life"), nausea, vomiting, stiff neck, sensitivity to light (photophobia), and changes in consciousness. Signs of irritation of the brain's membranes and neurological problems may also occur.

• Vasospasm: A complication where brain arteries constrict days after the rupture, which can cause new neurological problems. Treatment involves stabilizing the patient, controlling blood pressure, preventing the aneurysm from bleeding again, and managing pressure inside the skull. Surgical options include clipping the aneurysm or filling it with coils (endovascular coiling).

Vascular Malformations

• Arteriovenous Malformations (AVMs): These are abnormal tangles of blood vessels present from birth, where arteries connect directly to veins without the normal tiny capillaries in between. This leads to twisted, enlarged vessels.

• Signs and Symptoms: Can cause chronic headaches, seizures (in about half of cases), and problems related to bleeding in the brain.

• Diagnosis: Doctors use imaging tests like MRI or CT angiography. Clinical findings, such as a whooshing sound (systolic bruit) heard over the head, can also suggest an AVM.

• Treatment Options: Depending on their size, location, and risk, treatments include surgical removal, blocking the vessels with injected material (endovascular embolization), focused radiation (stereotactic radiosurgery), or just watching it closely.

Headaches

Primary Headache Syndromes

• Migraine: More common in women, often starting in teenage years. Caused by activation of nerves around the head and brain wave changes. Results in one-sided, throbbing headaches with nausea and sensitivity to light. Treatments include triptans and CGRP antagonists.

• Cluster Headache: Mainly affects men between 20 and 50. Causes very severe, stabbing pain on one side of the head, occurring in

Summary and Key Takeaways

• TBI ranges from mild concussions to severe injuries; key focus on preventing secondary injury and maintaining cerebral perfusion.

• Spinal cord injuries involve primary damage and secondary inflammation; clinical importance of monitoring spinal shock and autonomic dysreflexia.

• Degenerative spine disorders lead to radicular pain; treatment approaches encompass both conservative and surgical options.

• Seizure disorders require comprehensive knowledge of seizure types and phases for appropriate management.

• Rapid diagnosis and intervention are critical in cerebrovascular diseases to reduce morbidity and mortality, highlighting the urgency of care.

Questions and Discussion

Here are the answers to your questions, based on the provided notes:

1. Differentiate clinical signs of focal vs. diffuse TBI:

   • Focal Brain Injuries result from direct impact to a specific brain area and typically cause localized symptoms related to that area. These can include contusions and hematomas (epidural and subdural). Clinical signs would depend on the specific region affected (e.g., motor deficits if motor cortex is involved, visual disturbances if occipital lobe is affected).

   • Diffuse Brain Injuries involve widespread damage across brain areas, usually from acceleration-deceleration forces. This includes concussions (transient brain dysfunction without visible imaging changes) and Diffuse Axonal Injury (DAI) (microscopic axonal shearing damage). Clinical signs are often more global, such as widespread cognitive and neurologic deficits, and altered consciousness.

2. Manage a patient presenting with autonomic hyperreflexia symptoms:
   Autonomic hyperreflexia is a life-threatening complication occurring in spinal cord injuries above T6, triggered by stimuli like bladder distension or bowel impaction. Immediate management involves:

   • Identifying and removing the triggering stimulus (e.g., catheterizing a distended bladder, disimpacting the bowel).

   • Elevating the head of the patient.

   • Administering antihypertensive medications if necessary to prevent complications such as stroke or seizures.

3. Discuss treatment differences between ischemic and hemorrhagic strokes:

   • Ischemic Stroke is caused by an arterial obstruction (thrombus, embolus, or hypoperfusion) leading to brain tissue infarction. Treatment focuses on restoring perfusion, often with thrombolytics if administered within $3-4.5$ hours of symptom onset.

   • Hemorrhagic Stroke is caused by the rupture of brain vessels, leading to bleeding into brain tissue or the subarachnoid space. Management focuses on controlling bleeding, reducing intracranial pressure, and preventing complications. For intracranial aneurysms causing subarachnoid hemorrhage, surgical options like clipping or endovascular coiling may be used to prevent rebleeding.

4. Examine how seizure types impact antiseizure medication choices:
   The notes classify seizures by origin (focal or generalized), awareness (aware or impaired), and motor activity (motor or nonmotor). Examples include focal seizures (which can manifest as tonic-clonic, myoclonic, or absence features) and generalized seizures (e.g., tonic-clonic, atonic, epileptic spasms). While the notes do not detail specific medication choices for each type, the classification itself implies that antiseizure medication selection is highly individualized and based on the specific seizure type and underlying epileptogenic mechanisms present in a patient to ensure effective control and minimize side effects. Status epilepticus, defined as continuous seizures lasting more than 5 minutes or repeated seizures without recovery, requires immediate treatment to prevent cerebral hypoxia and neuronal injury.

5. Strategies for preventing recurrent cerebrovascular events:
   Preventing recurrent cerebrovascular events primarily involves aggressive management and control of key risk factors. These include:

   • Controlling hypertension.

   • Quitting smoking.

   • Managing diabetes.

   • Treating atrial fibrillation.

   • Lowering high cholesterol.

   • Addressing obesity.

   • Increasing physical activity.

   • Additionally, transient ischemic attacks (TIAs) are a warning sign, and urgent evaluation and management are required for patients experiencing TIAs to reduce the risk of future strokes.

• Manage a patient presenting with autonomic hyperreflexia symptoms.

• Discuss treatment differences between ischemic and hemorrhagic strokes.

• Examine how seizure types impact antiseizure medication choices.

• Strategies for preventing recurrent cerebrovascular events.

Chapter 18 Objectives