Definition: SNRIs block the reabsorption (reuptake) of the neurotransmitters serotonin and norepinephrine in the brain.
Common SNRIs include:
Venlafaxine
Desvenlafaxine
Duloxetine
SNRIs are also utilized to treat anxiety disorders.
Both serotonin and norepinephrine are crucial in the transmission of pain.
Implication: Drugs used to treat depression may also positively modulate pain sensation.
Neurological Disorders
Tetanus
Tetanus is a disease caused by the bacterium Clostridium tetani affecting the nervous and muscular systems.
Transmission: Bacteria enter through contaminated puncture wounds or animal bites.
Mechanism: The bacteria thrive in low-oxygen environments, leading to the death of tissues and multiplication of the bacteria.
The released neurotoxin impacts the motor neurons, resulting in:
Loss of inhibition signals to muscles.
Outcome: Excessive muscle contraction, prolonged spastic paralysis, and potentially death.
Vaccination with a modified tetanus toxin provides active immunity against the effects of the toxin and the bacteria.
Meninges and Cerebrospinal Fluid (CSF)
Meninges
The brain and spinal cord are covered by the meninges, consisting of three layers:
Pia Mater: Innermost layer, delicate and tight-fitting, contains blood vessels that nourish nerve tissue.
Arachnoid: Middle layer, lace-like membrane.
Dura Mater: Tough fibrous outer layer, protecting the CNS from mechanical damage.
Subdural Space: Located between dura mater and arachnoid.
Subarachnoid Space: Found between arachnoid and pia mater.
Ventricles and CSF
The brain has several cavities called ventricles, which connect to other brain sections through passageways.
The central canal of the spinal cord is connected to the most inferior ventricle.
Cerebrospinal Fluid (CSF):
Fills the cavities and acts as a shock absorber and protector for CNS tissues.
Transports nutrients (primarily proteins and carbohydrates).
Production: Formed continuously at a rate of 450extml (15 ounces) per day.
Volume: Typically, 150extml is present at any time in a normal adult.
Reabsorbed into blood vessels via arachnoid villi.
Neurological Diagnostic Tests
Common Tests and Their Purposes
Diagnosis of neurological disorders often requires specific tests.
Arteriography (Cerebral Angiography):
Involves inserting a catheter into an artery.
A dye is injected to visualize cerebral blood vessels via X-rays.
Can detect conditions like aneurysm, hemorrhage, cerebrovascular accidents, arteriosclerosis, and tumors.
Glasgow Coma Scale:
Assessment tool to evaluate level of consciousness.
Assesses eye movement, verbal response, and motor response.
Important for paramedics to report on patient condition during transport.
Computed Tomography (CT) Scan:
Series of X-rays to create a 3D image of the brain.
Useful for identifying tumors, bleeding, clots, and brain edema.
Takes about 15 minutes, may require contrast materials for clearer images.
Electroencephalography (EEG):
Measures electrical activity in the brain.
Can detect abnormalities such as epilepsy and sleep disorders but not intellectual disabilities unless linked to seizures.
Includes newer technologies like ambulatory EEG monitor for continuous monitoring.
Electromyography (EMG) and Nerve Conduction Studies (NCS):
EMG records electrical activity in muscles; NCS measures speed of nerve conduction.
Helps diagnose conditions like radiculopathy, ALS, and carpal tunnel syndrome.
Genetic Testing:
Can identify certain neurological disorders, including spina bifida, using amniocentesis or CVS.
Lumbar Puncture:
Involves CSF removal for examination, indicated in suspected infections or hemorrhages.
Magnetic Resonance Imaging (MRI):
1977 technology using magnets to generate images.
Preferred for imaging the brain/spine if no metal implants are present.
Enhancements include MRA for blood flow imaging.
Myelography:
Injects contrast material into spinal space; viewed with fluoroscopy.
Used for irregularities in the spinal cord, lessened in usage due to MRI.
Positron Emission Tomography (PET) Scan:
Visualizes physiologic performance using radiolabeled agents.
Particularly useful for evaluating and staging malignancies.
Ultrasound Imaging:
High-frequency sound waves to obtain internal images, useful for diagnosing various conditions.
Neurosonography specifically analyzes blood flow to diagnose strokes and tumors.
X-Rays:
Commonly part of neurological assessments to view skeletal structures and potential abnormalities like fractures.
Alzheimer's Disease
Overview
Definition: Progressive degenerative disease affecting brain function, leading to impaired memory, thinking, and behavior.
Statistics: Approximately 6.7 million Americans reported having Alzheimer's in 2023, estimated to rise to 13.8 million by 2060 among those aged 65 and older.
Impact: Seventh leading cause of death in the US, with around 122,000 annual deaths attributed to the disease.
Signs and Symptoms
Gradual memory loss
Decline in routine task performance
Impairment in judgment
Disorientation
Personality changes
Difficulty in learning
Loss of language skills
Results in inability to care for oneself over time
Etiology
Exact cause is currently unknown.
Suspected causes include:
Genetic predisposition
Infectious agents (slow virus)
Environmental toxins
Immunological changes
The disease manifests as the extinction of certain brain cells, characterized by the presence of amyloid plaques and neurofibrillary tangles in affected brains.
Family history can increase risk; multiple first-degree relatives amplify this risk.
No cure currently exists; research aims to prevent nerve cell death and ensure neuroprotection.
Management and Care
Managing symptoms through medication, improving sleep, treating anxiety and depression, and promoting a structured environment is crucial.
Lifestyle changes: Physical exercise, healthy nutrition, social interactions, and cardiovascular health control are recommended.
Support for caretakers is vital given the disease's impact on daily living.
Average disease course ranges from 2 to 10 years, potentially extending up to 20 years.
Diagnosis
Typically includes taking a patient history, memory and problem-solving tests, lab and blood tests to check for beta-amyloid levels, urine tests, CSF analysis via spinal tap, and brain imaging scans (CT, MRI, PET).
Preventative Measures
Steps to potentially reduce Alzheimer’s risk:
Regular exercise
Balanced diet
Injury protection for the head
Strong social connections
Control over cardiovascular risk factors
Staying mentally active
Warning Signs
Key warning signs published by Alzheimer's Association include:
Memory loss disrupting daily life
Problems with planning or solving problems
Difficulty with familiar tasks
Confusion with time or space
Trouble understanding visual images and relationships