neuro conditions

Neurological Conditions

Seizure Disorder

Overview

  • Seizures are brief episodes of abnormal electrical activity in the nerve cells of the brain cortex.

  • Seizures can manifest in various forms, involving:
      - Motor (e.g., convulsions)
      - Cognitive
      - Sensory components.

  • Seizure disorder is also known as "Epilepsy", characterized by chronic, recurrent seizures, which are defined as 2 or more unprovoked seizures.

Terminology

Definition of Seizure

  • Seizure: A brief episode of abnormal electrical activity in the nerve cells of the brain cortex.
      - Involves various manifestations including motor (convulsions), cognitive, or sensory responses.

  • Seizure Disorder (Epilepsy): A chronic condition characterized by recurrent unprovoked seizures.
      - Criteria for Diagnosis: No metabolic causes must be identified during a seizure.
      - Electroencephalographic (EEG) changes may occur with unorganized electrical activity.
      - Epidemiology: Affects approximately 0.5% of the US population.

Pathogenesis of Seizures

Etiology of Seizures

Primary (Idiopathic)

  • Some seizures arise with no identifiable cause.

Secondary

  • Caused by identifiable factors or conditions such as:
      - Brain injury (e.g., traumatic causes leading to hemorrhage)
      - Ischemic events (e.g., stroke causing low oxygen levels)
      - Toxic imbalances (e.g., electrolyte imbalances)
        - Drugs or metabolic issues causing low sugar, low sodium, low calcium, or low oxygen levels.

Etiology by Age Groups

  • Children:
      - Birth trauma (e.g., low oxygen)
      - Infections (notably meningitis)
      - Congenital abnormalities
      - High fevers (known as febrile seizures)

  • Middle Age:
      - Head trauma
      - Infections (meningitis)
      - Alcohol-related issues
      - Stimulants/medications

  • Elderly:
      - Brain tumors
      - Strokes

Pathogenesis

Seizure Focus

  • Seizure Focus: A group of abnormal neurons that spontaneously fire, causing seizures.
      - This area is typically affected by gliosis (changes to the glial cells).

  • Functions autonomously and emits excessive paroxysmal electrical discharges, which can recruit adjacent neurons to discharge and spread, either locally or globally.

Seizure Threshold Factors

  • Various factors can lower the seizure threshold, classified as:

Common Factors

  • Sleep deprivation

Occasional Factors

  • Barbiturate withdrawal

  • Alcohol withdrawal

  • Flashing lights (e.g., television flicker)

  • Use of certain drugs (epileptogenic drugs)

  • Systemic infections

  • Head injuries

  • Recreational drugs

  • Non-compliance with anti-epileptic drugs (AEDs)

  • Hormonal changes (e.g., menstruation)

  • Dehydration

  • Hyperventilation

  • Diet issues and missed meals

  • Specific reflex triggers (e.g., stress, intense exercise)

Electroencephalographique (EEG)

  • EEG: A diagnostic tool used to visualize brain activity.

Seizure Clinical Manifestations

Factors Influencing Symptoms

  • Manifestations depend on the location of the seizure focus and may include:
      - Various sensations and perceptions
      - Muscle movements
      - Altered consciousness.

Seizure Classification

  • Focal/Partial Seizures: Caused by focal irritations that are unilateral and may either remain focal or become generalized.

  • Generalized Seizures: These involve both sides of the brain.

Types of Seizures

Generalized Seizures

  • Tonic-Clonic Seizures (Grand Mal):
      - Characteristics include:
        - Salivation
        - Tongue biting
        - Incontinence
      - No recollection of the event (loss of memory).
      - Includes tonic phase (stiffening of the body for 10-20 seconds) and clonic phase (jerking extremities for 30-40 seconds).

Absence Seizures (Petit Mal)

  • Primarily occurs in children and typically outgrown by adolescence.

  • Characterized by:
      - Brief staring spells
      - Extremely short loss of consciousness
      - Can occur multiple times a day (up to 100 times).

Partial Seizures

  • Simple Partial Seizures:
      - No loss of consciousness
      - Duration typically less than 1 minute.
      - May involve simple motor or sensory phenomena.

  • Complex Partial Seizures:
      - Usually originate in the temporal lobe.
      - Characterized by:
        - Altered consciousness
        - Duration of 45-90 seconds
        - Initial phase of being motionless with a fixed gaze
        - Followed by automatism (repetitive, purposeless movements).
        - Usually followed by a brief period of confusion.

Phases of Seizures

  • Prodromal Phase: Signs or activities that precede the seizure.

  • Aural Phase: Sensory warnings recognized prior to onset.

  • Ictal Phase: Actual seizure episode.

  • Postictal Phase: Recovery phase following seizure activity.

Aura and Prodrome

Description

  • Aura/Prodrome is characterized by a subjective sense of an impending seizure and may include:
      - Symptoms such as anxiety, mood change, confusion.
      - Physical sensations (e.g., jerking movements, headache, fatigue) or sensory alterations (e.g., unusual odors or sounds).

Postictal Phase

  • Duration varies based on the severity of the seizure, the affected brain area, and frequency.

  • Common symptoms include:
      - Muscle fatigue
      - Lethargy.

Status Epilepticus

  • Continuous seizure activity lasting longer than 15 minutes, constituting a medical emergency.

  • Requires immediate treatment due to risks of cardiac and respiratory dysfunction, potential for permanent neurological injury, or even death.
      - Hyperthermia may occur with prolonged seizure activity.

Pharmacotherapy of Seizure Disorder

Antiepileptic Drugs (AEDs)

Goals of AED Therapy

  • To raise seizure threshold and reduce seizures while enabling patients to maintain a normal lifestyle.

  • Generally implemented for long-term management with a focus on balancing seizure control and adverse effects.

Mechanism of Action of AEDs

  1. Suppression of Sodium Influx:
       - Key role in generating action potentials.
       - Sodium channel blockers (e.g., phenytoin, carbamazepine) work by binding reversibly to sodium channels in their inactivated state, prolonging channel inactivation.

  2. Suppression of Calcium Influx:
       - Involves inhibition of calcium channels, similar effects as sodium blockers.
       

  3. Blocking Glutamate Receptors:
       - Glutamate is the main excitatory neurotransmitter, vital for neural development and activity.
       - Drugs (e.g., felbamate, topiramate) block glutamate's action at receptors.

  4. Potentiation of GABA:
       - GABA (gamma-aminobutyric acid) is the primary inhibitory neurotransmitter. AEDs (e.g., gabapentin) enhance GABA receptors to suppress seizure activity.

Traditional AEDs

  • Examples include:
      - Phenytoin (Dilantin)
      - Levetiracetam (Tegretol)
      - Phenobarbital (Solfoton)
      - Valproic acid (Depacon)
      - Ethosuximide (Zarontin)
      - Primidone (Mysilone)

  • Characteristics:
      - Well-established efficacy and extensive clinical experience.
      - Often associated with side effects, less safe in pregnancy compared to newer AEDs, but less expensive.

Newer AEDs

  • Examples include:
      - Gabapentin (Neurontin)
      - Pregabalin (Lyrica)
      - Felbamate (Felbatol)
      - Topiramate (Topamax)

  • Characteristics:
      - Well-established efficacy but less extensive clinical experience.
      - Limited drug interactions; safer in pregnancy than traditional AEDs; more expensive without health insurance.

Challenges with AEDs

  • Drug plasma levels must be monitored for safety and efficacy.

  • Patient compliance is critical for successful treatment; abrupt withdrawal may lead to seizures.

  • Increased risk of suicidal thoughts/actions.

Adverse Effects of AEDs

  • CNS Depression: Drowsiness, fatigue, cognitive changes (confusion).

  • Children may display hyperactivity, sleep disorders, and irritability.

  • GI Disturbances: Nausea, vomiting, etc.

  • Motor Disturbances: Abnormal movements and coordination issues.

Specific Medication: Phenytoin (Dilantin)

  • Most utilized AED for all forms of epilepsy except absence seizures.

  • Mechanism of Action: Inhibits hyperactive sodium channels; dosing is individualized and closely monitored via serum levels.

  • Adverse Effects: Include gingival hyperplasia, acne, hirsutism, and hypertrophy of subcutaneous tissue.

  • Considerations: Many drug interactions due to it being a cytochrome P450 inducer, potential teratogenic effects, and monitoring necessary for cardiovascular dysrhythmias when injected.

How the CYP450 enzyme functions

  • Located in the liver; involved in drug metabolism.

  • Inducers: Increase enzyme activity, leading to faster drug clearance.

  • Inhibitors: Decrease activity, slowing clearance and increasing drug levels.

Inflammatory and Infectious Conditions

Meningitis

Definition

  • Acute inflammation of the meninges of the brain and spinal cord caused by infections or penetrating wounds.

Etiology

  • Caused primarily by:
      - Bacterial infections: Streptococcus pneumoniae, Neisseria Meningitidis
      - Viral infections, notably Enteroviruses.

Risk Factors

  • High risk in:
      - Older adults, college students, prisoners.
      - Incidence has decreased in populations due to vaccinations (e.g., N. Meningitides in 11-12-year-olds due to vaccines).
      - Conditions predisposing to infections include: alcoholism, diabetes, or post-splenectomy situations.

Clinical Symptoms (Classic Triad)

  1. Fever

  2. Headache

  3. Stiff neck

Pathogenesis

  • Infection leads to:
      - Inflammatory responses and pus production
      - Increased cerebrospinal fluid (CSF) production
      - Rise in intracranial pressure (ICP).

Other Manifestations

  • Symptoms include headache, nausea with vomiting, photophobia, altered mental status, and potentially a skin rash.

  • Kernig and Brudzinski signs are clinical tests used to assess meningeal irritation.

Treatment

  • Aggressive antibiotic therapy upon suspicion, with broad-spectrum coverage:
      - Common agents: Ceftriaxone, Vancomycin, Acyclovir.

  • Steroid therapy and prophylaxis through vaccination for at-risk populations are also key interventions.

Encephalitis

Definition

  • Acute inflammation of the brain, primarily due to viral infections (e.g., West Nile virus, Herpes simplex).

Clinical Manifestations

  • Signs typically appear 2-3 days post-infection; symptoms may range from mild changes in mentation to coma, often accompanied by fever, headache, nausea, and seizures.

Pharmacotherapy

  • For viral encephalitis, Acyclovir is a common treatment to reduce mortality (less effective for preventing neurological complications).

Brain Abscess

Definition

  • Defined as an accumulation of pus within brain tissue, typically arising from local infections (e.g., otitis, dental, or sinus infections).

Symptoms and Diagnosis

  • Similar symptoms to meningitis and encephalitis:
      - Headaches, fever, nausea, vomiting, and signs of increased ICP.
      - Focal neurological signs reflect the affected brain area.

Conclusion

  • Focus on continuous monitoring and effective treatment strategies for seizures, meningitis, encephalitis, and brain abscesses is paramount to optimize patient outcomes.

  • Understanding the pathophysiology and clinical management of these neurological conditions is essential for health care practitioners, particularly in emergency and acute care settings.