science

Referred pain

Referred pain is a science topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand Referred pain rather than just read about it. In short: Referred pain, also called reflective pain, is pain perceived at a location other than the site of the painful stimulus. An example is the case of angina pectoris brought on by a myocardial infarction (heart attack), where pain is often felt in the left side of the neck, left shoulder, and back rather than in the thorax (chest), the site of the injury.

Key takeaways

Referred pain belongs to science; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Referred pain to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Referred pain from memory before moving on to harder problems.

Reference excerpt

Referred pain, also called reflective pain, is pain perceived at a location other than the site of the painful stimulus. An example is the case of angina pectoris brought on by a myocardial infarction (heart attack), where pain is often felt in the left side of the neck, left shoulder, and back rather than in the thorax (chest), the site of the injury. The International Association for the Study of Pain has not officially defined the term; hence, several authors have defined it differently. Referred pain has been described since the late 1880s. Despite an increasing amount of literature on the subject, the biological mechanism of referred pain is unknown, although there are several hypotheses. Radiating pain is slightly different from referred pain; for example, the pain related to a myocardial infarction could either be referred or radiating pain from the chest. Referred pain is when the pain is located away from or adjacent to the organ involved; for instance, when a person has pain only in their jaw or left arm, but not in the chest. Radiating pain would have an origin, where the patient can perceive pain, but the pain also spreads ("radiates") out from this origin point to cause the pain to be perceived in a wider area in addition.

Characteristics The size of referred pain is related to the intensity and duration of ongoing/evoked pain. Temporal summation is a potent mechanism for generation of referred muscle pain. Central hyperexcitability is important for the extent of referred pain. Patients with chronic musculoskeletal pains have enlarged referred pain areas to experimental stimuli. The proximal spread of referred muscle pain is seen in patients with chronic musculoskeletal pain and very seldom is it seen in healthy individuals. Modality-specific somatosensory changes occur in referred areas, which emphasize the importance of using a multimodal sensory test regime for assessment. Referred pain is often experienced on the same side of the body as the source, but not always.

Mechanism There are several proposed mechanisms for referred pain. Currently there is no definitive consensus regarding which is correct. The cardiac general visceral sensory pain fibers follow the sympathetics back to the spinal cord and have their cell bodies located in thoracic dorsal root ganglia 1-4(5). As a general rule, in the thorax and abdomen, general visceral afferent (GVA) pain fibers follow sympathetic fibers back to the same spinal cord segments that gave rise to the preganglionic sympathetic fibers. The central nervous system (CNS) perceives pain from the heart as coming from the somatic portion of the body supplied by the thoracic spinal cord segments 1-4(5). Classically the pain associated with a myocardial infarction is located in the mid or left side of the chest where the heart is actually located. The pain can radiate to the left side of the jaw and into the left arm. Myocardial infarction can rarely present as referred pain and this usually occurs in people with diabetes or older age. Also, the dermatomes of this region of the body wall and upper limb have their neuronal cell bodies in the same dorsal root ganglia (T1-5) and synapse in the same second order neurons in the spinal cord segments (T1-5) as the general visceral sensory fibers from the heart. The CNS does not clearly discern whether the pain is coming from the body wall or from the viscera, but it perceives the pain as coming from somewhere on the body wall, i.e. substernal pain, left arm/hand pain, jaw pain.

Convergent-projection This represents one of the earliest theories on the subject of referred pain. It is based on the work of W.A. Sturge and J. Ross from 1888 and later TC Ruch in 1961. Convergent projection proposes that afferent nerve fibers from tissues converge onto the same spinal neuron, and explains why referred pain is believed to be segmented in much the same way as the spinal cord. Additionally, experimental evidence shows that when local pain (pain at the site of stimulation) is intensified the referred pain is intensified as well. Criticism of this model arises from its inability to explain why there is a delay between the onset of referred pain after local pain stimulation. Experimental evidence also shows that referred pain is often unidirectional. For example, stimulated local pain in the anterior tibial muscle causes referred pain in the ventral portion of the ankle; however referred pain moving in the opposite direction has not been shown experimentally. Lastly, the threshold for the local pain stimulation and the referred pain stimulation are different, but according to this model they should both be the same.

Convergence-facilitation Convergence facilitation was conceived in 1893 by J MacKenzie based on the ideas of Sturge and Ross. He believed that the internal organs were insensitive to stimuli. Furthermore, he believed that non-nociceptive afferent inputs to the spinal cord created what he termed "an irritable focus". This focus caused some stimuli to be perceived as referred pain. However, his ideas did not gain widespread acceptance from critics due to its dismissal of visceral pain. Recently this idea has regained some credibility under a new term, central sensitization. Central sensitization occurs when neurons in the spinal cord's dorsal horn or brainstem become more responsive after repeated stimulation by peripheral neurons, so that weaker signals can trigger them. The delay in appearance of referred pain shown in laboratory experiments can be explained due to the time required to create the central sensitization.

Axon-reflex Axon reflex suggests that the afferent fiber is bifurcated before connecting to the dorsal horn. Bifurcated fibers do exist in muscle, skin, and intervertebral discs. Yet these particular neurons are rare and are not representative of the whole body. Axon-Reflex also does not explain the time delay before the appearance of referred pain, threshold differences for stimulating local and referred pain, and somatosensory sensibility changes in the area of referred pain.

… excerpt ends here. Continue reading the full article.

Illustrations

Worked examples

Example 1 — a first encounter with Referred pain

Start with the simplest possible case. Write down what Referred pain claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In science, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Referred pain before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Referred pain ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Referred pain

In research: Referred pain appears in science research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses Referred pain in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: Referred pain is common in secondary-school and first-year university syllabi. It links to neighbouring topics Pain, Symptoms and signs: Cardiac, so understanding it makes those chapters shorter.
In everyday life: Look for Referred pain outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

Ask Teacher Smith questions about this articleOpens your AI tutor with a question about “Referred pain” →

Affiliate

Preply — study more efficiently by working with a personal tutor. 50% off.

How to study Referred pain in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Referred pain means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain Referred pain out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Referred pain in simple terms?

Why does Referred pain matter?

Because it connects several science ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Referred pain?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Referred pain.