The first point to determine in the investigation of any pain is its exact situation and extent. If these correspond to the peripheral distribution of a nerve, it shows that the cause of the pain is irritation either of the trunk of the nerve or of one of its visceral branches; in the latter case, the pain is known as 'referred.' The situation and extent of the pain may correspond to the anatomical distribution of a particular nerve-root, indicating irritation at a point nearer the spinal cord than the formation of individual peripheral nerves. Pain caused by irritation of sensory nerve-endings is felt in the area of irritation independently of the anatomical distribution of a nerve. For example, pressure upon the trunk of the ulnar nerve in the arm is felt as pain in the little and the ulnar side of the ring fingers; while the pain of a boil or an abscess is purely local. Pain of neurotic origin is distinguished by the absence of an adequate local cause and the want of correspondence with the anatomical distribution of sensory nerves.
<Callout type="tip" title="Identifying Local Causes">Tenderness associated with pain can indicate whether the source is local or not. For instance, when pain is complained of in the knee, and the joint is found free from all tenderness to pressure or from pain on movement, the cause of the pain is not in that joint.</Callout>
The manner in which tenderness is elicited greatly aids in diagnosis. If, for instance, the lightest contact causes pain, it indicates irritation of the cutaneous nerves, either local or referred; if the skin can be handled freely, perhaps pinched up, without causing pain, while pressure upon the deeper parts (muscles or bones) excites pain, it shows that the nerves of these deeper structures are affected. When the hyperesthesia of the tissues close under the skin is very intense, and they lie superficially, as for instance in the case of periostitis over the inner surface of the tibia, the gentlest pressure upon the skin is at once transmitted to the inflamed periosteum and causes pain; to make the distinction in such a case requires great care.
Another very useful and important method of testing hyperesthesia is to observe how the pain is affected by movement. Movement excites pain if the muscles used in the act are inflamed or are the seat of pain, or if parts put on the stretch or compressed by the movement are tender, or if the parts moved one upon another are sensitive. Where any particular movement is painful it is important to notice if the pain occurs equally whether the movement be active or passive. For example, if it is found that active abduction of the arm is painful, but that the arm can be put into the same position by the surgeon without causing pain, provided the patient's abductor muscles are kept relaxed, it shows that it is the contraction of the muscles, and not the movement or the position of the limb, that causes the pain.
Fascial and ligamentous pain is elicited by any movement that stretches the ligament or fascia, whether active or passive. Take such a case as is presented in lumbago. If, when the patient bends well forward, pain is excited, and is relieved by his rising into the vertical posture by contraction of the lumbar muscles, the seat of the pain is in the lumbar fascia and not in the muscle. But if in the flexed position of the spine there is no pain, but acute pain is caused by any attempt to extend the spine, it is clearly a case of lumbar myalgia.
In all joints there is a considerable range of movement in which no ligament is placed on the stretch, but during which the articular surfaces are in contact, and passing over each other with more or less pressure; hence, if such range of movement is painless it is a good indication that the joint surfaces themselves are not tender; while, on the other hand, if the smallest degree of passive movement is painful, it clearly shows that the interior of the articulation is tender. Similar principles find a somewhat different application in other situations, as, for example, in the bladder, where the pain of vesical calculus is specially caused by the contraction of the bladder on the stone, and is relieved by the passage of urine into the viscus with relaxation of the contraction and floating of the stone. In acute cystitis, on the other hand, the chief pain is produced by the contact of the urine with and stretching of the inflamed mucous surface, and by the contraction of the inflamed muscular tissue, and it is relieved after the act, to be again exacerbated as the urine accumulates.
By the character of the pain something may at times be learnt. The itching, burning, smarting pain of cutaneous and mucous inflammations, the deep boring and aching pain of bone inflammations, the shooting, lancinating pains of 'neuralgic' origin, or of those due to central lesions, and to pressure upon and partial destruction or inflammation of nerve-trunks, and the 'lightning-like' pains of locomotor ataxy are all illustrations of this fact. Parasthesia or anaesthesia with pain is most frequently due to central nervous lesions, but may be of purely local origin, as in the case of commencing gangrene.
When there is a history of severe or of long-continued pain, it should be noticed whether there is any evidence of the constitutional influence of the pain. Pain exerts a depressing influence upon the central nervous system, and when acute or very prolonged its ravages are always visible. If, therefore, the account of the pain given by the patient corresponds with the fades, it receives important corroboration. If, on the other hand, there is no correspondence between the two, and with cheerful face and healthy countenance a patient describes himself as in great suffering, or as having recently suffered severely and for a long time, it will convince the surgeon that the statement is exaggerated, or that the pain is functional. Such a fact may render important aid in diagnosis, and may usually be corroborated by finding that when the patient's attention is engaged he permits of pressure, manipulations, and movements which, when his attention is directed to the part, he would describe as 'distracting,' or 'intense,' or 'unbearable,' or some similar term. The correspondence of all the facts about a given pain is a point of great importance, and the absence of it often enables the surgeon to give an opinion in otherwise difficult cases of 'hysteria.'
<Callout type="important" title="Constitutional Influence">Pain can significantly affect the central nervous system. Long-term or severe pain may show visible signs of its impact on the patient's overall health.</Callout>
<Callout type="risk" title="Misdiagnosis Due to Functional Pain">Functional pain, often associated with psychological factors, can be misdiagnosed if not properly evaluated for constitutional influences and other symptoms.</Callout>
Key Takeaways
- Determine the exact location and extent of pain to identify its cause.
- Use tenderness, movement, and hyperesthesia tests to diagnose pain accurately.
- Consider constitutional influences on pain for a comprehensive diagnosis.
Practical Tips
- Always perform a thorough physical examination when assessing pain to rule out local causes before considering functional pain.
- Take note of the patient's overall health and demeanor; severe or long-term pain may indicate more than just a physical issue.
- Use movement tests to differentiate between muscle, ligament, and nerve-related pain.
Warnings & Risks
- Misdiagnosing pain as purely functional can lead to inadequate treatment and worsening of the patient's condition.
- Ignoring constitutional influences on pain can result in overlooking serious underlying issues.
- Overlooking local causes of pain may delay appropriate medical intervention.
Modern Application
While the techniques described in this chapter are rooted in historical practices, they still hold relevance for modern survival preparedness. Understanding how to accurately diagnose and triage pain is crucial in emergency situations where immediate care might be limited. The principles of identifying local versus functional pain can help prevent misdiagnosis and ensure that patients receive appropriate treatment.
Frequently Asked Questions
Q: How can I tell if a patient's pain is due to a local cause or functional pain?
You should look for signs such as tenderness, the effect of movement on pain, and whether the pain corresponds with the anatomical distribution of nerves. If there are no local causes evident and the pain seems to be affecting the patient’s overall health and demeanor, it may indicate functional pain.
Q: What should I do if a patient describes severe pain but appears healthy?
This could suggest that the pain is functional. You should consider the patient's history, perform a thorough examination, and possibly consult with other specialists to rule out any underlying issues before concluding it’s purely psychological.
Q: How can I use movement tests in diagnosing pain?
Movement tests can help differentiate between muscle, ligament, and nerve-related pain. For example, if a patient experiences pain during active abduction of the arm but not when the surgeon moves it passively, it suggests that the contraction of the muscles is causing the pain rather than the movement or position itself.