What are the differences between Acute and Chronic Pain

Pain is a complex phenomenon to study, understand and treat. It is a personal experience with a multidimensional character influenced by biological, psychological and social factors. Pain is an unpleasant sensory and emotional response to a stimulus associated with actual or potential tissue damage [1]. The difference between acute pain and chronic pain lies in a pathophysiological rather than temporal criterion [2]. There is a misconception that the difference between these two types of pain is the length of time spent in pain. When considering pain and time, we could say that there are three types of pain: acute pain, persistent pain and chronic pain.

What are the types of pain

 Acute pain is a consequence of tissue damage. It is an adaptive response that has a sudden onset and typically lasts only for a short time. It can usually be clearly linked to a specific event, injury or illness. With acute pain, tissue damage is expected, which means there will be signs and symptoms of inflammation, localised increase in temperature, etc. Acute pain is not just temporally limited pain that often resolves on its own. It is an important subject for further research as acute pain may transition into more damaging and debilitating chronic pain. Postoperative pain is a prevalent form of acute pain and must be recognised as a global public health challenge. [3] This type of pain may be severe, impede rehabilitation and is often under-treated.

• Pain may also be a recurrent problem, consisting of pain episodes interspersed with pain-free periods. We call this persistent pain. Persistent pain is pain with tissue damage or inflammation due to a chronic disease that continues over time. Some examples of persistent pain include patients with chronic rheumatologic illness such as rheumatoid arthritis. These patients suffer from recurrent tissue damage. This recurrent tissue damage is “new”, but it is constantly happening, so patients are in constant pain.
• Finally, we have chronic pain. Chronic pain usually happens without tissue damage. It may be due to a previous lesion or disease. However, healing has already completed and there is no longer any damage. Chronic pain with no previous damage is very common [4]. Chronic pain is no longer an adaptative response. As the healing process has already finished, a certain period of time has been set before pain is referred to as chronic to try to distinguish between acute and chronic pain. This is where the misconception mentioned above comes from. Chronic pain is the term used for pain that lasts more than several months (three to six months, certainly longer than it takes for “normal healing” to be established). The prevalence of chronic pain in the adult population increases with age [5]. Approximately two in every three people over the age of 65 report some form of chronic pain, with the most common types being low back or neck pain, musculoskeletal pain, joint pain and neuropathic pain. Chronic pain with no previous damage is very common [4]. Nevertheless, patients can feel different types of pain at the same time [6].

While the normal aging process does not necessarily guarantee that chronic pain symptoms will develop, elderly individuals are far more likely to develop painful conditions such as osteoarthritis, diabetic neuropathy, post-herpetic neuralgia and lower back pain [6]. It is not uncommon to find that an elderly person suffers from various chronic pain syndromes [6] or that they do not know how to (or cannot) explain what is happening to them. And, again, they do feel pain. When chronic pain is no longer an adaptative response, it becomes a burden. This burden on those who suffer from chronic or persistent pain is much heavier than we might first imagine [7].

Pain Treatment

It is important to differentiate the type of pain being targeted, as treatment strategies and evidence are different for each. Here we give some pointers. The management of all types of pain should be multifactorial and comprehensive rather than focused on only one treatment modality [8]. Acute pain is often far more complex – and treating it far more important – than previously thought. Chronic pain is associated with aberrant pain signal processing and interpretation and, as such, is much more challenging to treat. [3]

Patient Education and Psychosocial Support [9]

Although an initial medical assessment is crucial to identify any organic contributory factors and gain the patient’s trust, a psychosocial assessment is also essential to evaluate the role of psychological and socioeconomic factors, especially when we are targeting persistent or chronic pain syndromes [8].

Non-Invasive Therapies

Nonpharmacologic techniques should also be an integral component of patients’ pain management, especially with chronic pain patients (e.g. transcranial direct-current stimulation (T-DCS) or transcutaneous electrical nerve stimulation (TENS)). These techniques also allow patients to take lower doses of medication and give them more control over the situation. Physical therapy plays a key role in managing acute and persistent pain. It plays a lesser role in managing chronic pain, for which occupational therapy is better.

In addition, distraction has emerged as a viable method for reducing acute pain. It has not been extensively studied but appears to be more effective in paediatric patients than in adults.

References:

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