The site of pain in this patient presentation is the lower legs (below the knee), with the exception of lumbar disc herniation, in which the pain either is limited to the back of the thigh or traverses down to the lower leg and foot. The differentials are displayed as unilateral causes on the right side of this clinical mind map, and bilateral causes on the left side of this clinical mind map. The reason for this type of organization is that unilateral and bilateral causes differ on a pathophysiologic basis. The diagnostic task becomes easy if a clinician is clear early on in the diagnostic process in terms of the type of pathology. Often patients offer information about the location or uni/bi-laterality of the pain as a part of their chief complaint. For example, a patient is more likely to say “my right leg hurts,” or “my legs hurt,” as opposed to “there is leg pain.”
Unilateral and bilateral differentials for leg pain are further subdivided into acute versus chronic causes. Asking about the duration of pain further helps narrow the differentials under consideration. The acuteness or chronicity of pain must be kept in mind. A patient with shin splints or chronic exertional compartment syndrome (CECS) may bring up an episode of acute pain which lasted for some time period and then resolved upon the cessation of exercise. However, when prompted, the patient may say that this problem has been bothersome for quite some time. In this case, each individual episode can be described as acute pain, but the disease process tends to be chronic. For this reason, shin splints and CECS are included in the category of bilateral chronic leg pain, although each individual episode of pain may be acute.
To address urgent/emergent situations, risk factors must be taken into consideration in addition to vital signs and the patient’s appearance. This consideration of risk factors is because life-threatening conditions associated with leg pain (pulmonary embolism, and acute arterial occlusion) do not always present with acute decompensation in hemodynamic status, and because the pain is so subjective, the patient’s appearance of distress may not always be proportional to the degree of the underlying pathology. Therefore, gathering and reviewing information about risk factors early on in the evaluation process helps a clinician calibrate the index of suspicion about life-threatening conditions.
It is particularly important for a clinician to understand exactly where the pain is because the differentials change dramatically based upon the exact location of the pain. Keeping disease presentation or illness scripts in mind, a clinician can readily conclude that a patient with chronic bilateral thigh pain is not likely to be suffering from deep vein thrombosis, and that lumbar disc herniation is most likely not a cause of right calf pain.
Information about the quality and character of pain is another feature that sets this clinical mind map apart from some of the other pain-related clinical mind maps because the differentials of leg pain are often quite distinguishable from one another based upon the quality and character of the pain. The prototypical presentation for acute lumbar disc herniation is sharp, shooting pain, whereas patients with rhabdomyolysis often have dull achy pain.