Neurologic System Overview

Neurologic System Study Notes

Learning Outcomes

  • Describe the normal structures and functions of the nervous system

  • Identify the effects of aging on the nervous system

  • List data to collect when caring for a patient with a disorder of the nervous system

  • Identify tests used to diagnose disorders of the nervous system

  • Plan nursing care for patients undergoing each of the diagnostic tests for disorders of the nervous system

  • Describe common therapeutic measures that are used for patients with disorders of the nervous system

Structure of the Neurologic System

  • The neurologic system is divided into two main divisions:
      - Central Nervous System (CNS)
        - Composed of the brain and spinal cord
      - Peripheral Nervous System (PNS)
        - Includes all nerves outside the CNS, including those of the Autonomic Nervous System (ANS)
        - Functions through electrical impulses

Neurons

  • Neurons are the fundamental units of the nervous system, classified based on their function:
      - Afferent Neurons (Sensory)
        - A = Affect or sense; they transmit sensory information from sensory receptors to the CNS.
      - Efferent Neurons (Motor)
        - E = Effect or action; they transmit signals from the CNS to effectors (muscles and glands).
      - Interneurons (Relay Neurons)
        - Located entirely within the CNS and connect afferent and efferent neurons.

Synapses

  • Synapse: The small gap between neurons where communication occurs.
      - Converts electrical impulses into chemical signals.
      - One-way transmission; information flows in one direction.
      - Many medications interact at the synaptic level.

Spinal Cord

  • Functions:
      - Transmits impulses to and from the brain.

  • Anatomy:
      - Nerves attach to the spinal cord via roots.
      - Surrounded by protective meninges and circulating Cerebrospinal Fluid (CSF).

Spinal Nerve Supplies

  • Cervical Nerves:
      - C1: Head and neck
      - C2: Diaphragm
      - C3: Deltoids, Biceps
      - C4: Wrist Extensors
      - C5: Triceps
      - C6: Hand

  • Thoracic Nerves:
      - T1 to T12: Involved with upper body and chest muscles

  • Lumbar Nerves:
      - L1 to L5: Involved with leg muscles

  • Sacral and Coccygeal Nerves:
      - S1 to S5: Bowel, bladder, and sexual functions
      - Coccygeal nerves (Co): innervate coccyx region

Reflexes

  • Reflexes: Fast, involuntary responses to stimuli.
      - Types:
        - Stretch Reflex: Involves muscle stretch responses
        - Flexor Reflex: Involves flexion to withdrawal from stimuli

Brain Anatomy

  • The brain consists of four main areas:
      - Cerebrum: Divided into the frontal, parietal, occipital, and temporal lobes.
      - Diencephalon: Comprising the thalamus and hypothalamus.
      - Brainstem: Includes the midbrain, pons, and medulla oblongata.
      - Cerebellum: Coordinates movement and balance.

Cranial Nerves

  • There are 12 pairs of cranial nerves, each with specific functions:
      - 1. Olfactory: Smell
      - 2. Optic: Visual acuity
      - 3. Oculomotor: Eye movement and pupil constriction
      - 4. Trochlear: Eye movement
      - 5. Trigeminal: Facial sensations and chewing
      - 6. Abducens: Eye movement
      - 7. Facial: Facial muscle movement; taste
      - 8. Auditory (Vestibulocochlear): Hearing and balance
      - 9. Glossopharyngeal: Taste and swallowing
      - 10. Vagus: Controls functions of the heart, lungs, and digestive tract
      - 11. Accessory: Shoulder shrug
      - 12. Hypoglossal: Tongue movement

Autonomic Nervous System (ANS)

  • Divisions:
      - Sympathetic Nervous System:
        - Uses norepinephrine and epinephrine.
        - Prepares the body for fight or flight response.
        - Increases:
          - Heart rate
          - Respiratory rate
          - Blood pressure
          - Pupil dilation
        - Decreases digestion.
      - Parasympathetic Nervous System:
        - Uses acetylcholine.
        - Encourages rest and digest processes.
        - Increases digestion.
        - Decreases:
          - Heart rate
          - Respiratory rate
          - Blood pressure
          - Pupil dilation
          - Urine production

Effects of Aging on the Nervous System

  • Aging can lead to several changes:
      - Decreased blood flow to the brain
      - Decreased postural stability
      - Deposition of lipofuscin pigment in nerve cells and amyloid in blood vessels
      - Decreased acetylcholine and loss of dendrite connections
      - Decrease in dopamine levels
      - Increased instances of syncope (fainting)
      - Decreased mental function, cognition, reasoning, and judgment
      - Altered short-term memory
      - Decreased motor function and changes in sleep patterns
      - Increased likelihood of accidents and falls

Neurological Examination

  • Assessment strategies:
      - Establish current neurological function
      - Detect changes/alterations in neurological status
      - Rapid detection and intervention are critical, especially for conditions like paresis (muscle weakness) and dysphagia (difficulty swallowing).

  • Elements of assessment include:
      - Health history
      - Physical examination
      - Glasgow Coma Scale (GCS) for assessing consciousness
      - Mental status evaluation
      - Evaluation for abnormalities (e.g., posture, aphasia)

Glasgow Coma Scale (GCS)

  • Eye Opening Response:
      - 4. Spontaneous
      - 3. To speech
      - 2. To pain
      - 1. No response

  • Verbal Response:
      - 5. Oriented
      - 4. Confused
      - 3. Inappropriate words
      - 2. Incomprehensible sounds
      - 1. No response

  • Motor Response:
      - 6. Obeys commands
      - 5. Localizes pain
      - 4. Withdraws from pain
      - 3. Abnormal flexion
      - 2. Abnormal extension
      - 1. No response

Assessment for Conditions

  • Facial Drooping:
      - Subjective data collection
      - Physical exam focusing on orientation, comprehension, and speech
      - Limb paralysis awareness
      - Vital sign assessment
      - Safety precautions in place

  • Paresis and Dysphagia: Same assessments as above, aiming for early detection and intervention.

Diagnostic Testing

  • Tests used to diagnose neurologic disorders:
      - Lumbar Puncture: Analyzing CSF
      - X-ray: Imaging bone structure
      - Computed Tomography (CT): Cross-sectional imaging of the brain
      - Magnetic Resonance Imaging (MRI): Imaging to assess soft tissues
      - Angiogram: Visualizes blood vessels
      - Myelogram: Special X-rays to visualize spinal cavity
      - Electroencephalogram (EEG): Measures electrical activity in the brain

Supportive Nursing Care

  • Nursing actions to support patients include:
      - Assistance with positioning and ambulation
      - Monitoring for sensory loss, including paresthesia
      - Physical therapist referral for mobility support
      - Ensuring proper body alignment, using splints and footboards to prevent contractures and foot drop
      - Assessment and assistance with Activities of Daily Living (ADL)
      - Communication assessments for conditions like dysarthria, expressive and receptive aphasia
      - Nutrition assessments and family assessments to determine support needs.