Neurologic Systems Pathopharmocology

These flashcards cover important vocabulary and concepts related to the neurologic system, pathophysiology, and pharmacology as discussed in the lecture.

CNS (Central Nervous System)

Consists of the brain and spinal cord; responsible for processing and transmitting neural information.

Peripheral Nervous System (PNS)

Carries messages to and from the CNS; includes somatic and autonomic nervous systems.

Somatic Nervous System

Controls voluntary muscles and transmits sensory information to the CNS.

Autonomic Nervous System

Controls involuntary bodily functions and is divided into sympathetic and parasympathetic systems.

Meninges

Protective membranes covering the brain and spinal cord; includes dura mater, arachnoid mater, and pia mater.

Cerebral Edema

Increase in tissue volume due to abnormal fluid accumulation; can increase intracranial pressure.

Excitotoxicity

Injury to neurons caused by overstimulation of excitatory amino acid receptors, particularly glutamate.

Diencephalon

Part of the brain comprising the thalamus, hypothalamus, and pineal gland; involved in regulating consciousness, homeostasis, and hormone secretion.

Intracranial Pressure (ICP)

Pressure inside the skull; normal range is 0-15 mmHg; increases can lead to neurological issues.

Cushing’s Triad

Set of symptoms indicating increased intracranial pressure: hypertension, bradycardia, and irregular respiration.

Glial Cells (Neuroglia)

Supporting cells of the CNS, including astrocytes, oligodendrocytes, microglia, and ependymal cells.

Neurotransmitter

Chemical messengers in the nervous system that transmit signals across a synapse.

Membrane Potential

The difference in voltage across a cell membrane, crucial for the generation of action potentials in neurons.

Cerebral Cortex

The outer layer of the brain responsible for higher-level functions, including sensation, voluntary motor control, and cognitive processes.

Basal Ganglia

A group of subcortical nuclei responsible for motor control, coordination, and the execution of movement patterns.

Brainstem

Composed of the midbrain, pons, and medulla; regulates life-sustaining functions such as respiration, heart rate, and sleep cycles.

Cerebellum

Located at the back of the brain; is essential for maintaining balance, posture, and smooth motor coordination.

Limbic System

Includes structures like the hippocampus and amygdala; involved in emotional response, motivation, and memory formation.

Astrocytes

The most numerous glial cells; they provide structural support, maintain the blood-brain barrier, and regulate ion concentrations.

Oligodendrocytes

Glial cells responsible for forming the myelin sheath around axons within the Central Nervous System.

Microglia

Phagocytic cells that act as the immune system of the CNS, removing debris and responding to inflammation.

Ependymal Cells

Cells that line the ventricles of the brain and the central canal of the spinal cord; they produce and circulate cerebrospinal fluid (CSF).

Neuron Structure

Consists of the cell body (soma), dendrites (signal reception), axon (signal transmission), and synapse (junction for communication).

Saltatory Conduction

The rapid jumping of an action potential from one Node of Ranvier to the next in myelinated axons.

Na⁺/K⁺ ATPase Pump

An active transport mechanism that pumps three $Na^{+}$ ions out and two $K^{+}$ ions in to maintain testing membrane potential.

Action Potential Ions

$Na^{+}$ influx leads to depolarization; $K^{+}$ efflux leads to repolarization; $Ca^{2+}$ influx triggers the exocytosis of neurotransmitters.

Glutamate vs. GABA

Glutamate is the primary excitatory neurotransmitter; GABA is the primary inhibitory neurotransmitter in the CNS.

Ionotropic vs. Metabotropic Receptors

Ionotropic receptors are direct ligand-gated ion channels (fast); metabotropic receptors use G-proteins and second messengers (slow/prolonged).

Reticular Activating System (RAS)

A network in the brainstem that serves as the controller for arousal, wakefulness, and consciousness.

Levels of Altered Mental Status

Includes being confused (disoriented), delirious (hallucinations), lethargic (drowsy), obtunded (slow response), stuporous (arousal only by vigorous stimuli), and comatose (unarousable).

Decorticate vs. Decerebrate Posturing

Decorticate involves flexion toward the core (injury above the brainstem); decerebrate involves extension (more severe, indicating brainstem injury).

Monroe-Kellie Hypothesis

The principle that the sum of the volumes of brain tissue, blood, and CSF is constant; an increase in one must result in a decrease in the others or ICP will rise.

Cerebral Perfusion Pressure (CPP)

Calculated as $CPP = MAP - ICP$; it represents the pressure required to move blood through the cerebral circulation.

Mannitol (Osmitrol)

An osmotic diuretic used clinically to reduce intracranial pressure by pulling fluid from brain tissue into the blood vessels.

Vasogenic vs. Cytotoxic Edema

Vasogenic edema is extracellular fluid accumulation due to a leaky BBB; cytotoxic edema is intracellular swelling due to the failure of ATP-dependent pumps.

Hydrocephalus Types

Communicating hydrocephalus occurs from impaired CSF absorption; non-communicating (obstructive) hydrocephalus occurs from a blockage within the ventricular system.

Stroke Risk Factors (Modifiable vs. Non-modifiable)

Includes non-modifiable (age, gender, race, heredity) and modifiable factors; hypertension is the most significant modifiable risk factor.

Ischemic vs. Hemorrhagic Stroke

Ischemic stroke: Obstruction of blood flow (thrombus/embolus); Hemorrhagic stroke: Bleeding into brain tissue due to vessel rupture.

Thrombotic vs. Embolic Ischemic Stroke

Thrombotic: Clot forms locally at the site of atherosclerosis; Embolic: Clot travels from another part of the body (e.g., heart) and lodges in a cerebral vessel.

Transient Ischemic Attack (TIA)

A temporary episode of neurologic dysfunction caused by focal brain ischemia without permanent infarction; serves as a warning sign for future stroke.

Ischemic Penumbra

The area of viable but marginally perfused brain tissue surrounding the central core of an infarction; salvageable with timely treatment.

Tissue Plasminogen Activator (tPA)

A thrombolytic agent that dissolves clots by converting plasminogen to plasmin; must be administered within a narrow 3-4.5 hour window.

tPA Contraindications and Risks

Contraindicated in conditions with high bleeding risk (e.g., recent surgery, active bleed, high BP); primary risk is intracranial hemorrhage.

Arteriovenous Malformation (AVM)

A congenital tangle of abnormal arteries and veins without a capillary bed, leading to impaired perfusion and high risk of rupture/hemorrhage.

Post-Stroke Disabilities

Can include motor deficits (hemiparesis), speech disorders (aphasia/dysarthria), and sensory/cognitive impairments; depends on location and extent of damage.

Primary vs. Secondary Seizure Disorders

Primary (epilepsy): Idiopathic or genetic origin; Secondary: Resulting from an underlying cause like trauma, fever, electrolyte imbalance, or stroke.

Focal vs. Generalized Seizures

Focal (Partial): Originates in one hemisphere; Generalized: Involves both hemispheres from onset and usually results in loss of consciousness.

Antiepileptic Drug (AED) Mechanisms

Suppress seizures by: 1. Blocking sodium channels ($Na^{+}$), 2. Blocking calcium channels ($Ca^{2+}$), or 3. Enhancing inhibitory effects of GABA.

AED Safety and Nursing Considerations

Side effects include CNS depression and potential fetal harm; strict adherence is required to prevent status epilepticus.

Status Epilepticus

Continuous seizure activity for >5-30 minutes or repeated seizures without recovery; medical emergency due to extreme metabolic demand and hypoxia.

Parkinson’s Disease Pathophysiology

Caused by the progressive depletion of dopamine in the substantia nigra and basal ganglia, leading to impaired motor control.

Primary vs. Secondary Parkinsonism

Primary: Idiopathic Parkinson’s disease; Secondary/Drug-induced: Result of brain trauma, infections, or side effects from medications like antipsychotics.

Cardinal Motor Signs of Parkinson’s

1. Tremor (rest tremor), 2. Rigidity (muscle stiffness), 3. Bradykinesia (slowness of movement).

Parkinson’s Non-motor Symptoms

Includes autonomic dysfunction (e.g., orthostatic hypotension), depression, sleep disturbances, and cognitive changes/dementia.

Carbidopa–Levodopa (Sinemet) Mechanism

Levodopa is converted to dopamine in the brain; Carbidopa prevents the peripheral breakdown of levodopa, increasing its availability to the CNS.

Parkinson’s Drug Adverse Effects

Common effects include orthostatic hypotension, hallucinations, and dyskinesias (involuntary movements).

Multiple Sclerosis (MS) Pathophysiology

An autoimmune demyelinating disease where T-cell–mediated inflammation targets the CNS myelin, leading to plaques and disrupted nerve conduction.

MS Subtypes

Includes Relapsing-remitting (most common), Secondary-progressive, Primary-progressive, and Progressive-relapsing.

Natalizumab (Tysabri) Nursing Priority

Monitor for Progressive Multifocal Leukoencephalopathy (PML), a rare but fatal brain infection.

Mitoxantrone Nursing Priority

Monitor for cardiotoxicity and potential development of leukemia due to its cytotoxic nature.

Amyotrophic Lateral Sclerosis (ALS)

A degenerative disease of both upper and lower motor neurons resulting in progressive muscle weakness and paralysis; cognition tipically remains intact.

ALS Major Morbidity Causes

Respiratory failure and aspiration pneumonia are the leading causes of death.

Huntington’s Disease Genetics and Pathophysiology

An autosomal dominant disorder; excessive dopamine and loss of GABAergic neurons lead to chorea (hyperkinesis) and dementia.

Alzheimer’s Disease Pathology

Characterized by the accumulation of extracellular amyloid plaques, intracellular neurofibrillary tangles, and significant brain atrophy.

Donepezil and Rivastigmine Mechanism

Cholinesterase inhibitors that prevent the breakdown of acetylcholine, aiming to improve cognitive function in Alzheimer’s.

Lecanemab Risks

Indicated only for early Alzheimer’s; major risks include ARIA (Amyloid-Related Imaging Abnormalities), such as cerebral edema and hemorrhage.

Primary vs. Secondary Brain Injury

Primary: Immediate injury at the time of impact (e.g., concussion); Secondary: Progressive damage following the initial event (e.g., edema, ischemia, increased ICP).

Epidural vs. Subdural Hematoma

Epidural: Arterial bleed between dura and skull (rapid onset); Subdural: Venous bleed between dura and arachnoid (can be acute, subacute, or chronic).

Diffuse Axonal Injury (DAI)

Widespread damage to axons caused by shearing forces during acceleration/deceleration injuries; leads to severe neurologic impairment.

Bacterial Meningitis Signs

Classic triad of headache, fever, and nuchal rigidity; positive Kernig’s sign (pain with knee extension) and Brudzinski’s sign (neck flexion causes hip flexion).

Bacterial Meningitis CSF Findings

Cloudy appearance, elevated protein, decreased glucose level, and high WBC (neutrophil) count.

Primary vs. Metastatic Brain Tumors

Primary: Originates within the brain tissue or meninges; Metastatic: Spreads to the brain from other parts of the body (e.g., lung, breast).

Dermatome

A specific area of skin innervated by sensory fibers from a single spinal nerve; clinically used to assess the level of spinal cord or nerve root damage.

UMN vs. LMN Injury Findings

UMN damage: spasticity, hyperreflexia, and positive Babinski. LMN damage: flaccid paralysis, hyporeflexia, fasciculations, and muscle atrophy.

Spinal Cord Injury (SCI) Common Causes

Include motor vehicle accidents (MVA), falls, violence (e.g., gunshot wounds), and recreational/sports injuries.

Spinal Shock Progression

Early: Flaccid paralysis and areflexia (temporary loss of reflex activity). Late: Return of reflex activity with potential hyperreflexia and spasticity.

Autonomic Dysreflexia (Risk and Nature)

A medical emergency occurring in patients with injuries at T6 or above; triggered by noxious stimuli (like a full bladder) below the level of injury.

Autonomic Dysreflexia Hallmark Manifestations

Severe hypertension and pounding headache with flushing above the injury; bradycardia and pale, cold skin (vasoconstriction) below the level of injury.

Degenerative Disc Disease: Bulging vs. Herniated

Bulging: The annulus remains intact but the disc protrudes into the canal. Herniated: The nucleus pulposus breaks through the annulus fibrosis to compress nerves.

Radiculopathy

A condition caused by the compression of a spinal nerve root, typically manifesting as pain, numbness, or weakness in the corresponding dermatome.

Trigeminal Neuralgia (CN V)

Severe, paroxysmal facial pain triggered by chewing, touch, or temperature changes; effectively treated by anti-seizure drugs to stabilize nerve membranes.

Bell’s Palsy (CN VII)

Acute, usually unilateral facial paralysis linked to viral inflammation of the 7th cranial nerve; management must prioritize eye protection due to inability to close the eyelid.

Guillain–Barré Syndrome (GBS)

A postinfectious, autoimmune demyelinating polyneuropathy causing ascending muscle weakness; can involve the autonomic system leading to BP instability.

Myasthenia Gravis (MG) Pathophysiology

Chronic autoimmune disorder where antibodies block or destroy acetylcholine receptors at the neuromuscular junction, causing fluctuating weakness.

MG Management and Myasthenic Crisis

Acetocholinesterase inhibitors improve symptoms by keeping ACh available. Myasthenic crisis is a life-threatening exacerbation (often triggered by infection) that compromises breathing.