Pain, the unpleasant feeling caused by a dysfunction of the human body, either due to injury or an underlying disease, is in fact a protective mechanism.
Usually, pain subsides when the painful stimulus ceases and when the healing of the injured tissue has been completed. However, in some cases the pain can persist, and this indicates chronic pain, like neuropathic pain, rheumatic diseases pain, idiopathic pain, and of course, cancer pain.
The form of pain varies and may be described as burning, shock-like, stab-like sensation, or as pins and needles. On the other hand, visceral pain, the pain due to an internal organ dysfunction, may be diffused and difficult to identify or even accompanied by other symptoms, such as nausea or vomiting.
The pain intensity is also difficult to determine because of the subjectivity of the emotion, and for this reason it is monitored by specific questionnaires completed by the patient himself (McGill scale).