Pain Types and Viscerogenic Pain Patterns
IASP Definition of Pain
The International Association for the Study of Pain (IASP) defines pain as “an unpleasant sensory and emotional experience associated with, or resembling that associated with, actual or potential tissue damage”.
This definition includes six key notes for further context, acknowledging advances in pain understanding.
Importance of Pain Assessment
Thorough pain assessment is crucial for optimal physical therapy patient management.
Pain is often the primary symptom for patients seeking physical therapy services.
Examination and evaluation of pain are key in the physical therapy interview.
Pain assessment is the basis for a multidisciplinary pain management approach, essential in addressing the opioid crisis.
Pain is recognized as the “fifth vital sign,” alongside blood pressure, temperature, pulse, and respiration.
Physical therapists are responsible for investigating pain sources and understanding pain types.
Pain Patterns and Systemic Disease
Recognizing pain patterns characteristic of systemic disease is vital for screening.
Understanding referred pain from diseased organs aids therapists in identifying suspicious patterns.
Common sites of referred pain include the chest, back, shoulder, scapula, pelvis, hip, groin, and sacroiliac (SI) joint.
Differentiating pain from cancer versus psychogenic or emotional sources is crucial.
Conversion symptoms, symptom magnification, and illness behavior are important considerations.
Mechanisms of Referred Visceral Pain
Neuroanatomical bases of visceral pain are less understood than somatic pain.
Current understanding relies on knowledge of the somatic (nonvisceral) system.
Peripheral visceral neurotransmission occurs via afferent fibers projecting to the central nervous system (CNS) through autonomic nerves.
Afferent supply to internal organs runs close to blood vessels, similar to the sympathetic nervous system.
Increased nociceptive input from an inflamed organ can sensitize neurons receiving convergent input from an unaffected organ.
Viscerosensory Pathways
Viscerosensory fibers ascend the anterolateral system to the thalamus, projecting to various brain regions.
These regions poorly encode the origin of visceral pain due to low receptor density, overlapping receptive fields, and extensive convergence.
The cortex struggles to distinguish the exact origin of pain messages from the gut.
A variety of gastrointestinal (GI) sensations, like hunger, satiety, and pain, are conveyed to the CNS via afferent nerves with specialized endings.
Embryologic Development
Pain is referred to the site where the organ was located during fetal development.
Organs form early in fetal development, with nerves persisting in original locations.
The chest is embryologically part of the gut, explaining referred abdominal pain from intrathoracic organ pathology (viscero-visceral reflex).
For example, pneumonia or pleuritis can refer pain to the abdomen.
Fetal Development Examples
The pericardium around the heart is formed from gut tissue, explaining referred abdominal pain from myocardial infarction or pericarditis.
The ear and kidney share the same shape and embryologic tissue, forming simultaneously.
Anomalies of the ear may indicate similar changes in the kidney on the same side.
Clinical Implications of Embryology
Understanding fetal embryology helps recognize red flag signs and symptoms of visceral origin.
Knowledge of anatomy, innervation, and neurophysiology improves identification of potential structures involved.
Multisegmental Innervation
Multisegmental innervation is another mechanism explaining viscerogenic pain patterns.
The autonomic nervous system (ANS) has sympathetic and parasympathetic divisions with multisegmental innervations to the viscera.
Referred visceral pain to somatic tissues occurs due to overlapping segmental projections of spinal afferent neurons to the spinal dorsal horn (visceral-organ cross-sensitization).
Clinical Evidence of Multisegmental Innervation
Treatment of one visceral area with overlapping segmental projections can relieve pain in all affected organ systems.
Conversely, relief is not obtained until all involved visceral systems are treated in cases without overlapping segments.
Cardiac pain serves as a model: pain can occur in any structure innervated by C3 to T4 (jaw, neck, upper trapezius, shoulder, arm).
Cardiac and diaphragmatic pain is often experienced in the shoulder because the C5 spinal segment supplies the heart, respiratory diaphragm, and shoulder.
Direct Pressure and Shared Pathways
Direct pressure and shared pathways explain visceral pain referral to the soma.
Inflammation, infection, or obstruction of organs near the respiratory diaphragm can cause referred pain.
Impingement of the central diaphragm can refer pain to the shoulder, while peripheral impingement refers pain to costal margins and/or lumbar region.
Neural Ganglions and Plexuses
Ganglions from each neural system gather and share information through the cord to the plexuses.
Visceral organs are innervated through the ANS. Nerve plexuses control local responses.
Plexuses originate in the neck, thorax, diaphragm, and abdomen, supplied by parasympathetic fibers from the vagus and pelvic splanchnic nerves.
Ganglia collect information from parasympathetic and sympathetic fibers; plexuses provide local control.
Organ Proximity and Referred Pain
The lower portion of the heart contacts the center of the diaphragm.
The spleen is tucked under the dome of the diaphragm on the left.
Kidneys and pancreas are close to the diaphragm.
Central Diaphragm and the Phrenic Nerve
Inflammation, infection, or obstruction of the pancreas can put pressure on the central diaphragm.
The phrenic nerve (C3-C5) innervates the central zone of the diaphragm, pericardium, gallbladder, and pancreas.
Impairment of these viscera can present with signs and symptoms in somatic areas supplied by C3-C5 (e.g., shoulder).
Pain Patterns and Nerve Pathways
Disorders affecting the pancreas can mimic heart, gallbladder, or midback/scapular/shoulder problems.
Pancreatic disease typically presents as left epigastric pain, but referred pain to the shoulder or back occurs.
Peritonitis or gallbladder inflammation can irritate phrenic endings in the diaphragmatic peritoneum, causing referred shoulder pain.
Structures adjacent to the diaphragm in utero can also refer pain.
Case Example: NSAIDs and Visceral Pain
A 72-year-old woman with a history of prescription and OTC medications (Feldene, Vioxx, Ativan, Glucosamine, Ibuprofen, Furosemide) reports constant right shoulder pain and burning behind her armpit.
The therapist suspects that the combination of Feldene and Ibuprofen along with long-term use of Vioxx may be problematic.
Retroperitoneal bleeding from a peptic ulcer can cause referred pain to the back or right shoulder/upper trapezius.
Side effects of NSAIDs can include fatigue, anxiety, fluid retention, and bleeding.
Peritoneal bleeding may irritate the diaphragm through direct pressure resulting in significant changes in blood pressure and pulse requiring immediate attention.
Assessment of Pain and Symptoms
Information from the interview and examinatio
Comprehensive Pain Assessment
Considerations: Culture, pain perceptions, intensity, ethnic groups, medication history(nonprescription, therapies),functional status & psychosocial -spiritual factors are all key components of a comprehensive pain assessment
The clients perception of pain is a critical factor in an interview and should be carried out in a non judgment manner.
Pain assessment in Older Adults
Therapists should take reports of pain from older patients very serious and real, not discount symptoms as aging, or affected by cognitive disturbances.
Joint pain is very Health prevalent in older adults and population continues to age.
Reasons patients avoid giving an accurate assessment: Concerns, perceived by others, fear, avoidance or medical settings, medical actions, cost. etc.
*Communication & pain assessment made difficult due to sensory & cognitive impairments in older individuals( Glasses and ear aids are very helpful )Verbal & Facial comments during painful movements indicate cognitive impairments
Pain assessment in YOung CHild
Do not underestimate a Childs questions as they should still be able to use pain rating scales ( explain carefully ).
FPS- R ( faces pain scale - revised) used with similar measures, avoids gender, age & racial biases.
Words such as " Hurt rather the pain understood by 3yr Olds & Owie or Ouchie by Childs to described substitudes.
PT rely on Childs behavior (lack of cooperation, withdrawal, eating patterns).
Pain assessment Record Form
A useful Tool used to complete pain History & receive a pain Pattern Description
Can record onset of pain , If accident occurred, additional symtoms.
Numeric Rating Scale Instructions 0-10 Pain value, Pain-free and worst possible pain value described.
Characteristics of Pain
This is important to identify to the clients description & the Physical Theraist for assessment related to Sources of Pain:
Theses Characteristics is Location, Description of sensation , Frequency, Duration,pattern Aggravating / Relieving factors
Follow up Question include does pain worsen from MORNING to Evening
Pain Types
Most Effective diagnosis will define Syndrome, address the causes of pain rather then sources.
Classification by Anatomic Distrubtion, quality, intesity & look at sources of pain in pain types ( table 3:3)
Cutaneous Sourcess of Pain
Cutaneous includes somatic structure, the pain is well realized and can be pointed too.
Types of Somatic Pain. - Deep somatic, samatoviscerlal, Samato emotional -Also known as psychosomatic, & vice versa
Superficial somatic structures include the skin, superficial fasciae, tendon sheaths, etc. while Dee
Somatoemotional sources of pain occur when emotional or psychologic distress produces physical symptoms, which cause functional disturbanc.