Neurologic Disorders Overview

Neurologic Disorders Study Notes

Learning Objectives

  • Differentiate seizure types and pathophysiology

  • Consider the pharmacology of various anticonvulsant medications

  • Identify mechanisms in neurodegenerative diseases

  • Compare and contrast various neurodegenerative disorders

  • Describe prototype medications

  • Prioritize nursing care, safety, and red flags

Brain Structure – Functional Anatomy

  • Lobes:

    • Frontal Lobe:

    • Functions: Executive function, speech.

    • Temporal Lobe:

    • Functions: Memory, emotion.

    • Note: Affected in seizures and Alzheimer's Disease (AD).

    • Parietal Lobe:

    • Functions: Sensory processing.

    • Occipital Lobe:

    • Functions: Vision.

    • Basal Ganglia:

    • Role: Important for movement control.

    • Note: Affected in Parkinson’s disease.

    • Brainstem and Reticular Activating System:

    • Functions: Alertness and consciousness.

Seizure Pathophysiology

  • Definition of Seizures:

    • Abnormal or uncontrolled neuronal discharges in the brain.

    • Often due to foci of neural activity.

  • Foci:

    • Damaged area of the brain responsible for abnormal neuronal firing.

  • Imbalance in Neurotransmitters:

    • High glutamate (excitatory) and low GABA (inhibitory) contribute to seizures.

  • Consequences:

    • Affects consciousness, motor activity, and sensation.

    • Seizures are usually a symptom of another underlying disorder.

Seizure Types

  • Focal Seizures:

    • Localized to one area of the brain.

    • Patients often stay aware during the seizure.

  • Generalized Seizures:

    • Foci spread to the entire brain, resulting in loss of consciousness.

    • Types include:

    • Tonic-Clonic Seizures:

      • Characterized by a clonic phase followed by an ictal phase.

    • Absence Seizures:

Epilepsy vs Isolated Seizures

  • Epilepsy:

    • Defined as two or more unprovoked seizures.

  • Acute Causes of Seizures:

    • Fever (common in children).

    • Trauma.

    • Alcohol withdrawal.

    • Hypoglycemia.

    • Common Seizure Triggers:

    • Missed doses of seizure medications.

    • Sleep deprivation.

    • Stress.

    • Flashing lights.

    • Electrolyte imbalances.

Dangers of Seizures

  • Risks:

    • Risk for injury.

    • Aspiration risk.

    • Hypoxia and apnea.

    • Long-term neurological damage.

    • Postictal confusion and paralysis.

    • Importance of protecting from asphyxiation.

  • Status Epilepticus:

    • Defined as a seizure lasting longer than 30 minutes.

    • Requires treatment of seizures lasting more than 5 minutes to prevent cerebral edema or hypoxia.

    • Pathophysiology:

      • Increased metabolic demand leads to acidosis, brain injury, and hypoxia.

    • Goals of Treatment:

      • Maintain ventilation.

      • Correct underlying causes.

      • Terminate seizure with medications.

Seizure Management

  • Management Strategies:

    • Depends on seizure type.

    • “One-time events”: Treat seizure and observe for future events.

    • Recurrent seizures:

      • Medications.

      • Surgical interventions.

      • Medication management includes prophylaxis and rescue medications such as benzodiazepines.

      • Surgical interventions may involve video EEG (VEEG) to map areas with foci and ablation procedures.

Benzodiazepines

  • Mode of Action:

    • Potentiate GABA in the brain, increasing inhibition of neurons.

  • Uses:

    • Rescue medication to stop active seizures.

    • Management of alcohol withdrawal.

  • Prototype Drug:

    • Lorazepam (Ativan).

    • Other examples: Diazepam, Midazolam.

  • Important Considerations:

    • Monitor for respiratory depression, hypotension, and oversedation.

Barbiturates

  • Prototype Drug:

    • Phenobarbital (Luminal).

  • Mode of Action:

    • Modify the action of GABA, resulting in sedative effects.

  • Primary Use:

    • Control of status epilepticus.

    • Rarely used due to severe side effects.

  • Adverse Effects:

    • Dependence and addiction.

    • Drowsiness and oversedation.

    • Potential liver and kidney damage, laryngospasm, and vitamin deficiencies.

Hydantoins: Sodium Channel Blockers

  • Prototype Drug:

    • Phenytoin (Dilantin).

    • Other example: Fosphenytoin.

  • Mode of Action:

    • Sodium channel blockers prevent neuronal excitability.

  • Nursing Considerations:

    • Very narrow therapeutic range; monitor drug levels closely.

  • Side Effects:

    • Ataxia, gingival hyperplasia.

    • Monitor CBC for blood dyscrasias and assess liver and kidney function.

Other Seizure Medications

  • Valproate (Valproic Acid):

    • Mechanism: Desensitizes sodium channels.

    • Effective for a wide range of seizures, but hepatotoxic.

    • Side effects: CNS depression, vertigo, ataxia, visual disturbances.

  • Carbamazepine (Tegretol):

    • Monitor for blood dyscrasias.

  • Levetiracetam (Keppra):

    • Widely used for seizure prophylaxis, fewer side effects and interactions.

Considerations for Seizure Management

  • Important to monitor plasma drug levels closely.

  • Promoting patient adherence to medication regimens is critical.

  • Risks associated with medication discontinuation include rebound seizures and increased suicidal ideations.

  • Pregnancy and Seizures:

    • Many medications are dangerous for fetal health, but seizures also pose risks to the baby.

    • Valproic acid is highly teratogenic, associated with neural tube defects and cleft palate.

    • Phenytoin and phenobarbital require careful evaluation of risks versus benefits.

Neurodegenerative Diseases

  • Overview:

    • Neurodegenerative disorders are chronic and progressive diseases affecting the nervous system.

    • Commonly affect motor function, cognition, or both.

    • Currently no cure; focus on treatment includes symptom relief, preserving function, and improving quality of life.

  • Examples of Disorders:

    • Parkinson’s disease

    • Alzheimer’s disease

    • Multiple sclerosis

    • Lewy-Body dementia

    • Frontotemporal dementia

Parkinson’s Pathophysiology

  • Location:

    • Substantia nigra in the basal ganglia.

  • Imbalance:

    • Shortage of dopamine, responsible for initiating movement.

    • Excess acetylcholine inhibits movement.

  • Pathophysiology of Parkinson’s Disease:

    • Acetylcholine dominance causes characteristic motor symptoms.

    • The disease is progressive and currently has no cure.

  • Medication Management Strategies:

    • Increase dopamine levels and inhibit acetylcholine activity using drugs like Levodopa/Carbidopa and anticholinergics.

Parkinson’s Symptoms

  • Motor Control Symptoms:

    • Tremors, rigidity, bradykinesia.

    • Increased fall risk and difficulties with eating.

  • Non-Motor Symptoms:

    • Sleep disturbances, constipation, drooling, and depression.

Levodopa/Carbidopa

  • Components:

    • Levodopa: Crosses the blood-brain barrier as dopamine.

    • Carbidopa: Prevents premature breakdown of levodopa, allowing higher levels to reach the CNS.

  • Considerations:

    • Gold standard for early treatment; timing of administration is crucial.

“Wearing Off” and Dyskinesias

  • “Wearing Off”:

    • Refers to when medications stop being effective during the day, causing “off periods” with symptoms such as freezing and bradykinesia.

  • Dyskinesias:

    • Occur during “on periods” when medications are working effectively.

  • Considerations:

    • Timing of doses is very important; adjustments may be required.

Anticholinergics (Benztropine)

  • Prototype Drug:

    • Benztropine.

  • Uses:

    • Reduces tremors and rigidity in Parkinson’s.

  • Nursing Considerations:

    • Assess for anticholinergic effects: dry mouth, constipation, photophobia, urinary retention.

    • Caution in elderly due to potential confusion and fall risk.

Alzheimer’s Disease Overview

  • Prevalence:

    • Leading cause of dementia in 70% of all cases.

  • Symptoms:

    • Progressive cognitive decline, memory loss, confusion affecting cognition and behavior.

  • Changes to the Brain:

    • Cerebral atrophy (brain shrinkage).

    • Decrease in acetylcholine affecting the hippocampus and cerebral cortex.

    • Presence of amyloid plaques and tau tangles associated with cerebral inflammation.

Medication Management for Alzheimer’s Disease

  • Current Treatment Status:

    • No completely effective treatments exist, but options can slightly slow progression.

  • Cholinesterase Inhibitors:

    • Increase acetylcholine in the CNS.

    • Prototype drug: Donepezil; other drugs include Rivastigmine.

    • Side effects: Cholinergic effects such as bradycardia, drooling, tearing, syncope, and diarrhea.

    • Atropine: Antidote for overdosage.

Memantine (Namenda)

  • Mechanism of Action:

    • Regulates glutamate levels; used for moderate to severe Alzheimer's disease.

  • Effects:

    • May slow progression slightly.

    • Adjuvant medications also used to manage Alzheimer's symptoms include atypical antipsychotics, anxiolytics, and mood stabilizers.

Other Types of Dementia

  • Lewy-Body Dementia:

    • Characterized by the presence of Lewy bodies in neurons, displaying Parkinsonian symptoms and hallucinations.

    • Many medications are ineffective or exacerbate symptoms.

  • Vascular Dementia:

    • Results from impaired blood flow to the brain.

  • Frontal-Temporal Dementia:

    • Early age onset dementia, a rare and familial degenerative disease that is irreversible and progressive.

Multiple Sclerosis Pathophysiology

  • Definition:

    • Autoimmune attack on myelin in the central nervous system (CNS).

    • Autoantibodies target and destroy myelin and axons.

  • Diagnosis:

    • Based on plaques observed on MRI and lumbar puncture findings.

  • Disease Course:

    • Varies widely:

    • Relapsing-Remitting:

      • Flares followed by partial or full recovery (most common at 85%).

    • Other forms progressively worsen with little to no relapsing.

Multiple Sclerosis Symptoms

  • Associated Symptoms:

    • Fatigue, heat sensitivity, neuropathic pain, spasticity, impaired cognitive function, balance and gait issues, bowel and bladder dysfunction, sexual dysfunction, dizziness, vertigo, visual impairment, and slurred speech.

Medication Management of MS

  • Treatment Goals:

    • Treat flares early and reduce severity and frequency of flares.

    • Preserve intact neurological function.

  • Short-term Treatment of Flares:

    • Steroids: Prednisone, hydrocortisone.

  • Long-term Management:

    • Interferons, glatiramer acetate, and new biologics under development.

Amyotrophic Lateral Sclerosis (ALS)

  • Definition:

    • Motor neuron degenerative disease with no cognitive impairment.

  • Symptoms:

    • Progressive muscle paralysis leading to respiratory failure, weakness, atrophy, and spasticity.

  • Treatment:

    • No cure; Riluzole may provide modest life extension.

Guillan-Barre Syndrome

  • Pathophysiology:

    • Demyelination in the peripheral nervous system (PNS) post-viral infection.

    • Autoantibodies result in ascending paralysis.

    • Symptoms are usually reversible, but relapses can occur.

  • Treatment Options:

    • IVIG, plasmapheresis.

    • Importance of monitoring respiratory status and autonomic dysfunction.

Myasthenia Gravis

  • Definition:

    • Autoimmune condition characterized by autoantibodies to acetylcholine receptors at the neuromuscular junction.

  • Symptoms:

    • Weakness leading to paralysis, with a danger of respiratory paralysis.

  • Treatment:

    • Pyridostigmine (an acetylcholinesterase inhibitor) to reverse effects.

    • Cholinergic effects, along with IVIG and steroids, may be required.

    • Respiratory support may be necessary in a myasthenia crisis.

Knowledge Check 1: Autoimmune Disorders

  • Characteristics Comparison:

    • Clinical Characteristics:

    • Presence of autoantibodies, risk for respiratory failure, untreated paralysis, treatment with IVIG, potential for permanent neurological damage, and neuromuscular junction impact.

  • Disorders Analyzed: 1. Multiple Sclerosis 2. Myasthenia Gravis 3. Guillan-Barre Syndrome

Knowledge Check 2: Neurocognitive Disorders

  • Clinical Characteristics:

    • Progressive memory loss, affects motor movement, tremors/muscle rigidity, spasticity or flaccid paralysis, severe neurological decline, cognition impact, leads to respiratory failure.

  • Disorders Analyzed: 1. Alzheimer’s Disease 2. Parkinson’s Disease 3. Amyotrophic Lateral Sclerosis (ALS)

Knowledge Check 3: Antiseizure Medications

  • Clinical Properties:

    • Severe sedation potential, best for stopping status epilepticus, daily for seizure prophylaxis, unsafe for pregnancy long-term, potential rebound seizures from discontinuation, need for regular lab value monitoring.

  • Medications Analyzed: 1. Diazepam 2. Phenytoin 3. Phenobarbital 4. Valproic Acid

Final Reflection Questions

  • Which topic from the lecture felt the most complex or unfamiliar?

  • Which neurological disorder would be most challenging to care for as a nurse?

  • How might you support a patient who is cognitively intact but losing physical function, such as with ALS?

References

  • Adams, M., Holland, N., & Urban, C. (2020). Pharmacology for Nurses: A Pathophysiologic Approach. 6th Ed. Pearson.

  • Huether, S., McCance, K, & Brashers, V. (2020). Understanding Pathophysiology. Elsevier.