Pain Definition and Types Overview

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Questions and Answers

What mechanism of action is primarily associated with Conventional TENS?

Vascular Dilatation Mechanism

Endogenous Opiate Theory

Gate Control with some Descending Inhibition (correct)

Neuromuscular Re-education

Which of the following accurately describes the pulse rate used in Motor (Low Rate) TENS?

Moderate pulse rate for best results

Variable pulse rate based on patient feedback

High pulse rate to achieve rapid muscle contractions

Low pulse rate to elicit a strong muscle twitch (correct)

What type of pain is not effectively treated using Conventional (High Rate) TENS according to the provided content?

Chronic Migraine (correct)

Post herpetic Neuralgia

Low Back Pain

Phantom Limb Pain

What is a primary advantage of using Motor (Low Rate) TENS?

Long-lasting effects after treatment ends Signup and view all the answers

What type of sensation should a subject experience with Hyperstimulation/Noxious TENS?

Noxious, pricking sensation Signup and view all the answers

Why might Hyperstimulation TENS have limited patient control?

The sensation elicited is typically unpleasant Signup and view all the answers

What is an important contraindication for the use of electrical stimulation therapies?

Pregnancy in certain areas Signup and view all the answers

Which type of TENS is indicated for improving stretching outcomes?

Conventional (High Rate) TENS Signup and view all the answers

What is the primary effect of higher beat frequencies (50-100 bps) during interferential stimulation?

Sensory stimulation Signup and view all the answers

What physiological mechanism does interferential therapy utilize to reduce pain?

Gate Control and Endogenous Opiate Signup and view all the answers

What was the result of the randomized controlled trial comparing home interferential therapy to sham units?

Reduced pain and swelling Signup and view all the answers

Which of the following conditions has interferential current shown effectiveness for, according to literature?

Urinary incontinence Signup and view all the answers

In the context of interferential stimulation, what does a low beat frequency (1-5 bps) primarily result in?

Motor stimulation Signup and view all the answers

Which study indicated interferential therapy's effectiveness in reducing post-traumatic edema and pain?

Hobler (1991) Signup and view all the answers

Which of the following statements about interferential therapy is incorrect?

It has significant literature support compared to other modalities. Signup and view all the answers

How long is the typical application time for interferential therapy?

20-30 minutes Signup and view all the answers

What is a key advantage of Interferential Current (IFC) in pain management?

It allows for lower utilization of pain medications. Signup and view all the answers

Which method describes the mechanism of action for premodulated interferential current?

It is based on generating a beat frequency by the intersection of two distinct wave trains. Signup and view all the answers

Which of the following conditions is NOT typically indicated for TENS or IFC use?

Chronic cardiac conditions Signup and view all the answers

What conclusion can be drawn regarding the clinical effectiveness of TENS and IFC therapies?

Both therapies have similar results for various pain dysfunctions. Signup and view all the answers

Which of the following is a contraindication for the application of TENS or IFC?

Use on the anterior neck in all patients Signup and view all the answers

How does descending inhibition affect pain perception?

It modulates pain messages through an inhibitory loop. Signup and view all the answers

Which fibers are primarily involved in the gate control theory of pain modulation?

A-beta fibers Signup and view all the answers

What is a characteristic of Transcutaneous Electric Nerve Stimulation (TENS)?

It produces analgesia using sensory level stimulation. Signup and view all the answers

What is a primary goal of pain modalities used in modulation?

To interfere with the normal process of pain message transmission. Signup and view all the answers

Which mode of application for TENS is most commonly used?

Conventional (sensory or high rate) Signup and view all the answers

What type of pain is associated with distinct tissue trauma and serves a biological function?

Acute pain Signup and view all the answers

Which type of afferent fibers transmits pain information rapidly and is heavily myelinated?

A-delta afferents Signup and view all the answers

Which of the following characterizes C polymodal nociceptive afferents?

Small, unmyelinated nerve fibers that transmit pain slowly Signup and view all the answers

What term describes pain that arises in a location different from the actual site of injury?

Referred pain Signup and view all the answers

What is the primary function of the Spinothalamic tracts in pain processing?

To transmit input to the thalamus and somatosensory cortex Signup and view all the answers

Which type of pain is categorized as having an uncertain link to tissue damage and may not serve a biological purpose?

Chronic pain Signup and view all the answers

What characterizes the sharp, stabbing sensations typically transmitted by cutaneous afferents?

Fast onset due to heavy myelination Signup and view all the answers

Which type of pain transmission is mainly mediated by C polymodal afferents and is often described as dull and aching?

Nociplastic pain Signup and view all the answers

What sensation should a subject feel when experiencing high beat frequencies during interferential stimulation?

A comfortable, sub-motor paraesthesia Signup and view all the answers

What is the typical pulse/phase duration associated with lower beat frequencies during interferential therapy?

Longer phase duration Signup and view all the answers

Which setting is used for channel 1 in the interferential current application?

Set carrier frequency Signup and view all the answers

What duration is typically recommended for interferential therapy sessions?

20-30 minutes, up to several hours Signup and view all the answers

Which research supports the effectiveness of interferential therapy for urinary incontinence?

Dougall (1985) Signup and view all the answers

What is a primary mechanism of action for interferential current?

Endogenous opiate release and gate control theory Signup and view all the answers

What outcome was observed in the randomized control trial comparing home interferential therapy to sham units?

Reduced pain and swelling, decreased pain meds Signup and view all the answers

Which of the following is NOT a condition shown to be effectively treated with interferential current?

Skin infections Signup and view all the answers

What was the main finding in the study conducted by Bergeron-Vezina et al. regarding pain perception in young subjects?

Pain perception and threshold were reduced. Signup and view all the answers

What was concluded from the systematic review of TENS for treating low back pain?

TENS shows no difference when used in comprehensive treatment plans. Signup and view all the answers

In the Cochrane database review concerning TENS and labor pain relief, what was noted about women using TENS?

They generally wanted to use TENS again in future labor. Signup and view all the answers

What was revealed about TENS’s effectiveness in treating fibromyalgia in the systematic review by Honda et al.?

TENS significantly reduced VAS scores. Signup and view all the answers

What effect did low-frequency TENS have on heart rate variability according to Stein et al.?

Reduced heart rate. Signup and view all the answers

According to Govil et al., what aspect of patient response was examined in relation to TENS in osteoarthritis?

Comparison of genotypes with different TENS frequencies. Signup and view all the answers

What was a key finding from the 2017 clinical trial by Shahoei regarding TENS in labor?

TENS significantly improved pain scores. Signup and view all the answers

What was observed about TENS and its impact on the sympathetic nervous system as noted by Okuyucu et al.?

TENS had an inhibitory effect on sympathetic skin response. Signup and view all the answers

What is the primary advantage of using Interferential Current (IFC) for pain management?

It provides fast-acting pain relief. Signup and view all the answers

Which condition is most appropriate for the use of IFC or TENS based on the given indications?

Post-operative pain Signup and view all the answers

Which statement about premodulated interferential current is true?

It may be better suited for motor level stimulation. Signup and view all the answers

Which outcome was observed regarding the IFC group on day 5?

Lower utilization of pain medications. Signup and view all the answers

What sensation should a subject experience during Motor (Low Rate) TENS?

Strong, rhythmic muscle contraction Signup and view all the answers

What is a characteristic pulse duration for Conventional TENS?

Short pulse duration Signup and view all the answers

Which advantage is associated with Hyperstimulation/Noxious TENS?

Offers fast acting relief Signup and view all the answers

What type of pain is likely treated effectively by Motor (Low Rate) TENS?

Referred pain Signup and view all the answers

What is a key characteristic of the pulse rate for Hyperstimulation/Noxious TENS?

Low pulse rate Signup and view all the answers

Which factors contribute to the effectiveness of Conventional TENS?

Low pulse duration and high pulse rate Signup and view all the answers

What is the expected effect of using Conventional TENS on pain medication utilization?

Decreases the use of pain medications Signup and view all the answers

What is the recommended application time for Motor (Low Rate) TENS?

30-60 minutes Signup and view all the answers

Study Notes

Pain Definition

Pain is broadly defined as an unpleasant sensory and emotional experience associated with actual or potential tissue damage or described in terms of such damage.

Types of Pain (Review)

Acute: Associated with distinct tissue trauma and serving a biologic function. Often nociceptive or neuropathic.
Chronic: May or may not be associated with tissue damage or trauma. Often nociplastic.
Referred: Painful sensation in a location other than the site of the biologic injury.

Basic Concepts for the Transmission of Pain

Cutaneous afferents (A-delta): Transmit sensory pain information rapidly. First response. Often sharp, stabbing, or pricking pain. Heavily myelinated.
C polymodal afferents: Transmit pain slowly. Often described as dull, aching, throbbing, or burning pain. Unmyelinated. 80-90% of pain transmission.
Visceral nociceptive afferents: Carry the message of referred pain.

C Polymodal Nociceptive Afferents

Small, unmyelinated nerve fibers.
Transmit information (action potentials) more slowly than A-delta fibers causing a slower onset after the stimulus.
Pain sensations are often longer lasting and less localized.
Responsive to multiple stimuli (mechanical, thermal, chemical).
Can be mediated by opiates.
May be sensitized and involved in hyperalgesia.

Spinal Pathways

Dorsal Horn Lamina 5 is responsible for a wide range of pain transmission.
Dorsal Horn Lamina 1 is responsible for non-specific nociception.
Spinothalamic tracts carry pain input to the thalamus and somatosensory cortex, as well as the reticular formation and limbic system.
Transmission of pain information can impact affect and emotion.

Modulation of Pain

Endogenous Opiate System reduces pain.
Descending Inhibition modulates pain messages.
Gate Control is a classic explanation for pain modulation where sensory input from A beta fibers can inhibit pain transmission through C fibers.

Endogenous Opiates

Pain perception can be altered endogenously when peptides (endorphins) bind to opiate receptors.
Endogenous peptides act similar to exogenous opiates.
Opiate receptors reduce the release of Substance P, thus reducing pain transmission.
These peptides circulate through the bloodstream to affect pain throughout the body.

Primary Endogenous Opiates

Beta Endorphin
Enkephalins
Serotonin

Endogenous Opiates (Nice to know)

Beta endorphin is released from the pituitary and hypothalamus into the circulatory and cerebrospinal fluid.
Enkephalins are a 5-amino acid peptide released from the adrenal gland and other organs, inhibiting action potentials and release of Substance P.
Serotonin is often considered part of this class of substance due to its effects on pain.

Descending Inhibition

General concept of pain control/modulation.
Pain messages can be modulated by descending neurons in the brain.
This influences pain perception, motor responses, and emotional aspects of pain.
This is now thought to influence the gate control method of pain modulation.

Gate Control

Sensory input from A beta fibers can inhibit pain transmission through C fibers.
This reduces overall pain sensation.

Pain Modalities

Techniques to interfere with normal pain processes in the body to modulate pain transmission.
- Gate Control Theory (with descending inhibition)
- Endogenous Opiate Theory

Electric Stimulation for Pain Modulation

Transcutaneous electrical nerve stimulation (TENS)
Interferential current therapy (IFC)

TENS

Sensory level stimulation to produce analgesia.
Low frequency device with three common application modes, including:
- Conventional
- Motor
- Noxious (hyperstimulation)

Review of Literature

Common problems plaguing physical agent literature comparisons:
- Type of pain treated
- Type of parameters used
- Type of electrode placement
- Type of measurement of pain or dysfunction
- Types of subjects

Conventional TENS

Shown to be effective in reducing low back pain, pancreatitis, post herpetic neuralgia, rheumatoid arthritis, pain during jaw exercises, phantom limb pain, and improving stretching outcomes.
Subjects should feel a comfortable sub-motor paraesthesia (buzzing/tingling).
Pulse duration should be short.
Rapid activation of sensory, afferent nerve fibers.
Electrodes placed around the pain site or related spinal segment.
Time: 30-60 minutes typical, up to all day.

Motor Low Rate TENS

Subject should feel a strong, rhythmic muscle contraction.
Pulse duration should be long.
Strength duration curve: must reach motor threshold.
Pulse rate should be low.
Electrodes should be placed at the pain site or at a segmentally related myotome.
Time: 40-60 minutes, typically up to several hours per day.

Hyperstimulation/Noxious TENS

Subject should feel a noxious, pricking sensation.
Pulse duration should be long.
Electrodes placed at the pain site (trigger or acupuncture point).
Time: Short bouts since stimulus is painful.

Advantages and Disadvantages of Hyperstimulation TENS

Advantages: fast acting relief, long lasting relief, wide location of relief, unlikely to accommodate
Disadvantages: skill/ease of application, lack of patient control, unpleasant to patient

TENS Effectiveness in Aging Patients

Evidence is mixed regarding the effectiveness of TENS as patients age.

TENS and Low Back Pain

Systematic review shows TENS consistently better than placebo in treating low back pain.
Treatment plans using TENS showed no significant difference in functional outcomes.

TENS and Labor Pain Relief

Cochrane database review (2009) shows no significant difference in pain scores, need for intervention, or length of labor between women using TENS and controls.

TENS and Fibromyalgia

Systematic review found TENS significantly reduced visual analog scale (VAS) scores.

TENS and Sympathetic Nervous System

Transcutaneous electrical nerve stimulation (TENS) at different frequencies can reduce heart rate variability. This is associated with a change in the balance between sympathetic and parasympathetic nervous systems.
TENS had an inhibitory effect on SSR.

Genetic Predisposition for TENS

Genotype influences how well patients respond to different TENS frequencies.

Further Implications for TENS

Possible applications to prevent post-operative nausea and vomiting.
Efficacy in reducing spasticity, constipation in children with lower urinary tract dysfunction, and improvement in voiding symptoms in those with dementia.

Interferential Current Therapy (IFC)

Combines two applied electric fields to produce a third distinct electric field.
Medium frequency stimulation, producing deeper pain relief.
Less impedance (resistance) compared to other methods.
Produced by two distinct current generators in the machine.

Beat Frequency

The outcome of combining two electrical fields with slightly different frequencies.
Values of the beat frequency depend on the difference between the frequencies of the two wave trains.

Frequency Difference

Frequency difference is created by using one current generator at a constant frequency and the other at a variable frequency.
Allows modulation of interferential current.
Higher beat frequencies are used for sensory stimulation.
Lower beat frequencies are used for motor stimulation.

Application of Interferential Stimulation

Quadripolar electrode set-up around the pain area.
Set channel 1 carrier frequency.
Channel 2 is set to produce a variable carrier frequency.
Depending on the desired outcome of treatment (paraesthesia/muscle contraction), frequency can be adjusted.
Treatment duration of 20-30 minutes, up to several hours per day depending on the specific need.

Literature Review (IFC)

Early work by Nemec (1948, 1950, 1959) laid the foundation of research into IFC.
Little literature compared IFC to other methods, such as TENS.
Early work focused on older equipment.

Brief Overview of Literature (various conditions)

Kloth (1982), Hobler (1991), and Snyder-Mackler et al. have supported IFC effectiveness in various painful conditions like post-traumatic edema, pain, and strengthening of muscles.
Some articles support IFC being effective in urinary incontinence, chronic back pain, and bone healing.

Home Interferential Therapy

Studies have shown home IFC to be effective in reducing pain, inflammation, and improving range of motion for various conditions.

Advantages of IFC

Pain relief is generally quick (within minutes), large, and deep. Often carries over to the following session.

Premodulated Interferential Current

Current generated by the intersection of two distinct wave trains.
Occurring at the level of the machine, not in the body. This is a single channel, bipolar electrode technique.
The rest of the principles of IFC still apply.

Indications for TENS/IFC

Indications: Acute trauma, post-operative pain, local inflammation, and painful treatments.

Contraindications for TENS/IFC

Application in certain anatomic locations
Transthoracically, transcerebrally, and abdominally use cautiously, especially in pregnant females.
Avoid application to the anterior neck.
Do not use on patients using demand cardiac pacemakers.
Use cautiously or avoid in patients with unknown pain origins.

Additional Precautions

Potential contact dermatitis is common with TENS users due to prolonged electrode use.

Review of Pain Modalities (Comparison)

A table outlining the comparison of various pain modalities.

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Description

Explore the concepts surrounding pain, including its definition, various types like acute, chronic, and referred pain. Understand the basics of pain transmission and the roles of different afferents in signaling pain. This quiz is essential for anyone studying basic pain mechanisms.