Patho - Lect 1: Pain

What is pain?

An unpleasant sensation - Discomfort caused by stimulation of pain receptors.

What are these causes of:

• Inflammation

• Infection

• Ischemia and tissue necrosis

• Stretching of tissue

• Stretching of tendons, ligaments, joint capsule

• Chemicals

• Burns

• Muscle spasm

Causes of Pain

What type of pain:

• From skin (cutaneous)

• Muscle/Bone

• Conducted by sensory fibers

Somatic pain

What type of pain:

• Originates in organs

• Conducted by sympathetic fibers

• May be acute or chronic

Visceral pain

Pain Pathways

__ - are free sensory nerve endings.

Nociceptors (pain receptors)

What aspect of pain is this:

• Level of stimulation required to elicit a pain response

• Subjective but can be compared from day to day in person

Pain threshold

What aspect of pain is this:

• Ability to cope with pain

• Degree of pain, intensity, or duration

• May be increased by endorphin release

• May be reduced because of fatigue or stress

• Varies among people in different situations

Pain tolerance

Which type of afferent pain fibers:

• Transmit impulses very rapidly

• Acute pain (sudden, sharp, localized)

Myelinated A delta fibers

Which type of afferent pain fibers:

• Transmit impulses slowly

• Chronic pain (diffuse, dull, burning, or aching sensation)

Unmyelinated C fibers

Pain Pathways

• Area of skin innervated by a specific spinal nerve

• Somatosensory cortex → “mapped”

  • Corresponds to source of pain stimuli

Dermatome

Pain Pathways

• Involuntary muscle contraction away from pain source - withdrawal

• Involuntary muscle contraction to guard against movement - protect

Reflex response

Which tract of Pain Pathways:

• Fast impulses; acute pain

Neospinothalamic tract

Which tract of Pain Pathways:

• Slow impulses; chronic, dull pain

Paleospinothalamic tract

Pain Pathways

Spinothalamic tracts connect with __.

reticular formation of brain.

Pain Pathways

Somatic sensory area in the __ located in the parietal lobe.

→ Perception and localization of sensation

cerebral cortex

Pain Pathways

Hypothalamus and limbic system are __.

emotional factors.

Which part of Pain Pathways:

• Reticular formation in the pons and medulla

• Awareness of incoming brain stimuli

Reticular activating system (RAS)

Which theory:

• Control systems, “gates” built into normal pain pathways

• Can modify pain stimuli conduction and transmission in the spinal cord and brain

• Carry tactile information

Gate control theory

The Gate Control Theory is based on the presence of neurons for transmission and __ the transmission cells.

other cells that could inhibit

Gate Control Theory

__ - Pain impulses transmitted from periphery to brain.

Gates open

Gate Control Theory

__ - Reduces or modifies the passage of pain impulses.

Gates closed

Which Pain Control:

• Impulses from temperature receptors close gates

Application of ice

Pain Control

__ - is a therapeutic intervention that increases sensory stimulation at a site, blocking pain transmission.

Transcutaneous electrical nerve stimulation (TENS)

Which Pain Control:

• Secreted by interneurons of the CNS (endogenous)

• Block conduction of pain impulses to the CNS

• Resemble morphine - enkephalins, dynorphins, beta - lipoproteins

Opiate-like chemicals (opioids)

What does the O in OPQRST stands for?

O → Onset - how/when did it start?

What does the P in OPQRST stands for?

P → Provocation - what makes it worse?

What does the Q in OPQRST stands for?

Q → Quality - describe the pain

What does the R in OPQRST stands for?

R → Radiates - arm, leg, or local?

What does the S in OPQRST stands for?

S → Severity - 1 to 10, sleep?

What does the T in OPQRST stands for?

T → Time - how long, also is it constant?

Young Children and Pain

__ - respond physiologically

Ex: tachycardia, increased blood pressure, facial expressions

Infants

Young Children and Pain

Range of behavior - __

eating, playing, sobbing, crying

Which type of pain:

• Source may be difficult to determine

• Pain may be perceived at site distant from source

  • Characteristic of visceral damage in the abdominal organs

  • Heart attack or ischemia in the heart

Referred Pain

Which type of pain:

• Can follow an amputation (pain, itching, tingling)

• Usually does not respond to common pain therapies, may resolve within week to months

• Usually in adults, phenomenon not fully understood

Phantom Pain

Which type of pain:

• Usually sudden and severe, short term

• May be localized or generalized

Acute Pain

Which type of pain:

• Occurs over extended time; may be recurrent

• Often perceived to be generalized

Chronic Pain

PAIN: Types and Causes

__ - caused by dysfunction or damage to the brain or spinal cord.

Central pain

PAIN: Types and Causes

__ - caused by trauma or disease involving the peripheral nerves.

Neuropathic pain

PAIN: Types and Causes

__ - results from a profound, sudden loss of blood flow to an organ or tissue.

Ischemic pain

PAIN: Types and Causes

__ - caused by advance of the disease; pain associated with treatment; result of coexisting disease.

Cancer-related pain

Which method of managing pain:

• Adjuncts to analgesic therapy

• Promote rest and relaxation

• May reduce dosage requirements for analgesic

Sedatives and antianxiety drugs

Which method of managing pain:

• May occur in cancer

• Stepwise fashion to reduce pain

• Tolerance to narcotics develops over time

  • Increase dose requirement

  • New drug may be required

Chronic and increasing pain

Which method of managing pain:

• Patients administer medication, as needed.

• Patient-controlled analgesia (PCA) - IV

• Lessens overall consumption of narcotics

Severe pain

Which method of managing pain:

• Cannot be controlled with medication

• Surgical intervention is a choice

Intractable pain - Unbearable

Anesthesia

__ - injected or applied to skin or mucous membranes.

Local anesthesia

Anesthesia

__ - blocks pain from legs or abdomen.

Spinal or regional anesthesia

Anesthesia

__ - Patient can respond to commands. Relatively unaware of procedure, no discomfort.

Neuroleptanesthesia (twilight)

Anesthesia

__ - causes loss of consciousness (gas or injection).

General anesthesia