Neuro

Neural Alterations

Overview

  • Discussion of various neurological conditions and disorders, such as congenital disorders, infections, traumatic injuries, and chronic degenerative diseases.

Congenital Disorders

Hydrocephalus ("Water Brain")

Pathophysiology
  • Definition: Hydrocephalus is characterized by the accumulation of excess cerebrospinal fluid (CSF) within the skull.
  • Effects: This leads to dilated ventricles, compressing the brain and blood vessels.
  • Causes: Can arise from several factors, including:
    • Increased production of CSF
    • Obstruction to CSF flow
    • Defective absorption of CSF by the bloodstream
  • Complication: Hydrocephalus can be fatal if untreated.
Clinical Manifestations
  • Infants:
    • Large head size
    • Bulging fontanelles
    • Irritability
    • Lethargy
    • High-pitched cry
    • Downward gaze (often referred to as "setting sun appearance")
  • Older children & adults:
    • Headaches (H/A)
    • Nausea/Vomiting (N/V)
    • Downward gaze
    • Issues with balance, gait, and coordination
    • Impairments in work or school performance
    • Personality, cognitive, and memory impairments

Spina Bifida ("Spine-Split")

Definition
  • Literally means the spine is split.
  • The spinal column fails to close completely, allowing the spinal cord to protrude.
  • Most common permanently disabling birth defect affecting spine, spinal cord, and brain.
  • In about 90% of cases, it leads to hydrocephalus due to resultant alterations in brain development.
Pathophysiology
  • Posterior spinous processes on the vertebrae do not fuse, which permits the meninges and spinal cord to herniate through the opening.
  • Causes:
    • Exact cause is a combination of genetic and environmental influences.
    • Associated with folic acid deficiency, which is linked to neural tube defects.
  • Most common during the first month of fetal development, typically in the lumbar area of the vertebrae.
  • Forms of Spina Bifida:
    • Vary in severity.
Types of Spina Bifida
1. Spina Bifida Occulta
  • The mildest and most common form.
  • Characterized by a small gap in one or more vertebrae.
  • Features:
    • No protrusion of spinal nerves and meninges.
    • Typically asymptomatic.
    • Landmark signs may include a dimple, birthmark, or tuft of hair over the site.
2. Spina Bifida Meningocele
  • Rare form that shares the same bony defects as spina bifida occulta.
  • Protruding meninges through the vertebral opening form a sac on the back.
  • Spine often develops normally with no neurological impairment.
  • Risk: Rupture or infection of the sac can lead to complications.
3. Spina Bifida Myelomeningocele
  • Most severe form, termed "open spina bifida".
  • The spinal canal remains open along several vertebrae in the lower and middle back.
  • Characteristics:
    • Meninges, spinal cord, spinal nerves, and CSF protrude through a large opening, forming a sac.
    • In many cases, the tissues and nerves are exposed, leading to a high risk of infections and neurological impairments, including paralysis, bowel and bladder issues, seizures, skin conditions, and latex allergies.
Complications
  • Physical and neurological impairments vary among individuals.
  • Commonly leads to some degree of paralysis, with many requiring wheelchair assistance.
  • Additional complications include:
    • Bowel & bladder dysfunction
    • Urinary tract infections (UTIs)
    • Skin breakdown (decubitus ulcers)
    • Hydrocephalus, seizures, and meningitis

Infectious Neurologic Disorders

Meningitis

Pathophysiology
  • Definition: Meningitis is the inflammation of the meninges, often triggered by infection or irritants.
  • Consequences include reduced blood flow to the brain, swelling of the meninges, and increased intracranial pressure (ICP).
  • Can be self-limiting (typically viral) or life-threatening (acute bacterial).
  • Common Causes:
    • Bacterial pathogens (e.g., Neisseria meningitides, Streptococcus pneumoniae)
    • Viral pathogens (e.g., Haemophilus influenzae, enterovirus, herpes)
Risk Factors
  • Age (under 5, 16-25, over 55)
  • Community living conditions (e.g., daycare)
  • Immunodeficiency (e.g., missing spleen)
  • Not receiving vaccinations
Clinical Manifestations
  • Sudden onset mimicking flu-like symptoms:
    • Fever, chills, malaise
    • Mental status changes (confusion, lethargy)
    • Nausea, vomiting
    • Photophobia
    • Severe headache
    • Neck stiffness (meningismus)
    • Tachycardia, tachypnea
  • Complications:
    • Vary based on causative agent; can cause seizures, cerebral edema, long-term neurological impairment, and potentially death.

Bacterial Meningitis

Emergency Conditions
  • Inflammation of meningeal tissues surrounding the CNS can result from bacterial entry through various routes.
  • Untreated bacterial meningitis can lead to a 100% fatality rate.
  • Symptoms and Signs:
    • Classic "triad": fever, nuchal rigidity, altered level of consciousness.
  • Signs for Diagnosis:
    • Positive Kernig's sign: inability to extend the leg while lying flat.
    • Positive Brudzinski's sign: involuntary flexion of legs when the neck is flexed.
Treatment
  • Requires immediate medical intervention including:
    • Bed rest
    • IV fluids
    • Antibiotics
    • Dexamethasone (steroid)
    • Antiseizure medications
    • Mannitol for ICP management
  • Confirmation via lumbar puncture for CSF examination following initial MRI assessment.

Encephalitis

  • Inflammation of the brain, often attributed to viral infections.
  • Symptoms include: fever, headache, nausea, confusion, seizures, or memory issues.
  • Diagnosis: Imaging studies (CT, MRI, PET) and treatment may involve symptomatic management and controlling underlying causes.

Traumatic Brain Injury

Types of TBI

  • Diffuse axonal injury
  • Concussion
  • Contusion
  • Epidural
  • Subarachnoid
  • Subdural hematoma
  • Combinations of injury mechanisms from violent impacts, falls, or penetration.
Pathophysiology
  • Caused by sudden violent impacts to the head (closed injury) or penetrating wounds (open injury).
  • Clinical manifestations vary based on the injury's location and severity, ranging from mild (brief altered consciousness) to severe (prolonged unconsciousness).
  • Main causes: Falls, motor vehicle accidents, penetration from objects, assaults.
Risk Factors
  • Male gender, young children (0–4 years), adolescents (15–19 years), older adults (75 years and above).
  • Athletes and military personnel face heightened risks.
  • Alcohol or drug use, lack of safety equipment contribute to injury severity.
Clinical Manifestations
  • Symptoms may appear suddenly or develop gradually:
    • Motor/sensory deficits
    • Impaired coordination
    • Hearing, smell,, taste, speech, or vision deficits
    • Changes in pupil size or asymmetrical facial features
    • Signs of increased ICP (headache, confusion, drowsiness)
Characteristics of TBI
  • Primary Injury: Direct impact causing brain tissue damage.
  • Secondary Injury: Complications often manifest as increased ICP leading to cerebral ischemia, cell death, and potential permanent brain damage.
  • Possible long-term complications include:
    • Cognitive changes, sensory/motor disruptions, risk of seizure disorders, and increased risks for neurodegenerative diseases.

Increased Intracranial Pressure (ICP)

Pathophysiology

  • A normal ICP is less than 20 mm Hg. Increasing ICP decreases cerebral perfusion pressure (CPP).
  • Causes include traumatic brain injury, hypertension, tumors, infections, hydrocephalus, and others.
  • Monro-Kellie Hypothesis: The cranial vault contains three main volumes (brain, blood, CSF); an increase in one must be compensated by a decrease in another.
Compensatory Mechanisms
  • Cushing’s reflex: A response to increased ICP leading to hypertension, irregular breathing, and bradycardia.
  • Autoregulation: Blood flow modulation by blood vessels to maintain CPP.
    • CPP must remain between 60 and 150 mm Hg, calculated as CPP = MAP - ICP.
  • Absence of autoregulation leads to hypoxia and ischemia of brain tissue, risking cell necrosis.
Early and Late Signs of Increased ICP
  • Early: Headache, projectile vomiting, amnesia, behavioral changes.
  • Late: Dilated, non-reactive pupils, unresponsiveness, abnormal motor posturing, and Cushing’s triad (hypertension, bradycardia, respiration irregularities).
Medical Emergency and Treatment
  • ICP increase requires immediate management to reverse the causes and restore blood flow.
    • Treatments may involve IV mannitol, hyperventilation, head elevation, or even craniotomy in severe cases.

Seizure Disorders

Overview

  • Defined by abnormal electrical activity in the brain, commonly characterized by a disruption in the balance of excitatory and inhibitory neural activities.
Terminology
  • Seizure: A temporary disruption in brain electrical activity.
  • Epilepsy: Recurrence of unpredictable seizures.
  • Convulsion: Refers specifically to tonic-clonic movements during seizures.
Types of Seizures
  • Focal Onset: Localized activity affecting one part of the brain.
    • Simple: Consciousness maintained, with unusual sensations.
    • Complex: Impaired consciousness, may include automatisms.
  • Generalized Onset: Affects both hemispheres, includes:
    • Tonic-Clonic: Loss of consciousness with combined muscle rigidity and jerking.
    • Absence Seizures: Brief lapses of consciousness.
Complications
  • Brain damage, physical trauma from falls, aspiration risks, potential for mood disorders, or tongue bites during seizures.
  • Status Epilepticus: A medical emergency characterized by seizures lasting more than 20 minutes or continuous seizures without recovery.

Chronic Degenerative Disorders

Multiple Sclerosis (MS)

Pathophysiology
  • An autoimmune condition leading to the demyelination of the brain's white matter, causing delayed nerve impulses and brain atrophy.
  • Prevalence: Most common disabling neurological disease among young adults, frequently diagnosed between the ages of 20-40, with a higher prevalence in women and Caucasians.
Clinical Manifestations
  • Visual problems, balance and coordination issues, speech difficulties, sensory changes, bowel and bladder complications.
  • Psychological symptoms may include fatigue, cognitive impairment, and unstable mood.

Parkinson’s Disease

Pathophysiology
  • Characterized by the progressive deterioration of the substantia nigra in the brain leading to dopamine deficiency.
  • Most common neurological disorder in the elderly, occurring more frequently in men.
Manifestations (TRAP)
  • Tremor: Prominent at rest; may include pill rolling.
  • Rigidity: Increased muscle resistance to passive motion.
  • Akinesia: Loss of voluntary movement.
  • Postural disturbances leading to falls.

Amyotrophic Lateral Sclerosis (ALS)

Pathophysiology
  • Involves degeneration of upper and lower motor neurons, leading to progressive muscle weakness and paralysis.
  • Prevalence: Typical onset between ages 55 and 75, with a male-to-female ratio of 2:1.
Clinical Manifestations
  • Muscle weakness and atrophy, dysphagia, dysarthria, and progressive flaccid paralysis.

Myasthenia Gravis

Pathophysiology
  • Autoimmune disorder leading to impaired acetylcholine receptor function at the neuromuscular junction.
  • Associated with thymus gland abnormalities.
Clinical Manifestations
  • Muscles controlling the eye, face, and throat are primarily affected, leading to ptosis and difficulty swallowing.

Huntington’s Disease

Pathophysiology
  • A hereditary condition causing progressive degeneration of the basal ganglia due to gene mutations.
  • Onset: Typically between ages 35-45.
Clinical Manifestations
  • Movement disorders, mood swings, cognitive decline, and emotional disturbances.

Alzheimer’s Disease

Pathophysiology
  • A chronic and progressive neurological disorder characterized by neurofibrillary tangles and amyloid plaques that lead to neuron death.
  • Risk Factors: Aging, genetics, and other health conditions.
Clinical Manifestations
  • Memory loss, confusion, difficulty with familiar tasks, and changes in mood and personality.

Brain Tumors

Overview

  • May be benign or malignant, potentially life-threatening, and often lead to elevated ICP.

Clinical Manifestations

  • Headaches, nausea/vomiting, visual disturbances, and neurological deficits vary based on tumor size and location.

These notes provide a comprehensive overview based on the transcript provided, detailing various neurological disorders, their pathophysiology, clinical manifestations, and complications. Each section is extensive, ensuring that students can grasp the critical aspects of neurological health and disease management.