I have to admit that I kind of hate talking about pain management. Pain is one of those things that your patients can’t show you visibly (at least most of the time). It doesn’t show up in lab results. Treatment of pain is based on subjective report. So, as a nurse practitioner it can be difficult for me to make decisions about managing pain for my patients. Then, toss into the mix that our nation is facing an opioid crisis, the fact that I’ve been duped a few times into writing narcotic prescriptions for addicts and I’m not sure what to do next or where to draw the line.
Over the next several weeks, we’re exploring the topic of pain management here on MidlevelU. Today, let’s explore the very first step in treatment of pain.
As nurse practitioners and physician assistants we’ve been taught that pain is “whatever the patient says it is”. Or, you might choose to go by Urban Dictionary’s definition that “pain is what happens when you step on a Lego brick”. In the clinical setting though, we need to dig a little deeper and define pain more specifically. The very first thing you must do in managing pain is to classify it – determine what kind of pain the patient is experiencing. This will help you guide your course of therapy and may even give you ammo for your “opioids probably won’t actually help you” conversation.
Pain can be classified based on timing (chronic vs. acute), cause (cancer vs. non-cancer) and mechanism. Today, let’s look at classifying pain based on mechanism – essentially this can be distilled down to three groups- nociceptive pain, neuropathic pain and mixed pain.
To conceptualize nociceptive pain, think about the above Urban Dictionary definition – stepping on a Lego. Nociceptive pain occurs in response to a stimulus (basically an injury). It tends to be localized and characterized by descriptions like stabbing, sharp, throbbing, dull or achy and is typically worse with movement. Nociceptive pain may be associated with obvious tissue injury, illness or inflammation. Nociceptive pain can itself be divided into two subcategories, somatic and visceral.
Somatic pain is cutaneous or musculoskeletal in nature and can therefore be can be superficial or deep. For example, it may be felt in the skin (think the Lego example), muscle tissue or joints (think twisting an ankle related to stepping on the Lego). Examples of somatic pain include a sprained ankle, osteoarthritis, or a laceration.
Visceral pain originates with internal organs and smooth muscle. Examples of visceral pain include conditions like appendicitis, IBS, or pancreatitis. Visceral pain is more likely to be dull and achy or cramping than sharp. It may also be referred and more difficult to localize than somatic pain.
Neuropathic pain originates from damage to nerves. It is not well localized. Neuropathic pain can be described as burning, shooting, and/or accompanied by numbness or tingling. Tissue injury may not be obvious with neuropathic pain as this type of pain is caused by nerve injury or abnormal nerve firing. Neuropathic pain can further be classified as peripheral or central.
Central Neuropathic Pain
Central neuropathic pain is the result of injury or dysfunction of the central nervous system. This is seen in patients with spinal cord injuries or post-stroke.
Peripheral Neuropathic Pain
Peripheral neuropathic pain is the result of injury or dysfunction of peripheral nerves such as in diabetic neuropathy or carpal tunnel syndrome.
Pain can contain components of both nociceptive and neuropathic etiology. An example of mixed pain might be low back pain with radiculopathy.
If you’re one for simplification, here’s a quick reference.
Classifying pain helps to make decisions related to management, treatment and prescribing which we’ll discuss in subsequent posts.