Hi, and welcome to this review of neuropathic pain! Today, we’ll be discussing the causes and types of neuropathic pain, how it is evaluated, and what treatment options are available.
Neuropathic pain is defined by the International Association for the Study of Pain (IASP) as “pain caused by a lesion or disease of the somatosensory system”. The somatosensory system is connected to our perception of touch, pressure, pain, and other similar attributes. Neuropathic pain can originate in various places depending on what disease you have. It can appear in the central nervous system if you have multiple sclerosis, or in the peripheral nervous system if you have diabetes.
There are many reasons that patients may develop neuropathic pain. However, on a cellular level, one explanation is that an increased release of certain neurotransmitters which signal pain, combined with an impaired ability of the nerves to regulate these signals, leads to the sensation of pain originating from the affected region.
Additionally, in the spinal cord, the area which interprets painful signals is rearranged, with corresponding changes in neurotransmitters and loss of normally functioning cell bodies; these alterations result in the perception of pain even in the absence of external stimulation. In the brain, the ability to block pain can be lost following an injury such as stroke or trauma. Over time, further cellular damage occurs and the sense of pain persists. Pain may be visceral, caused by injuries to internal organs, or it may be somatic pain, involving muscles, skin, bones, and joints. Either way, neuropathic pain is chronic, so it does not occur rapidly or resolve quickly.
Examples of neuropathic pain include:
- post herpetic (or post-shingles) neuralgia
- complex regional pain syndrome
- components of cancer pain
- phantom limb pain
- entrapment neuropathy (such as carpal tunnel syndrome)
- peripheral neuropathy (or widespread nerve damage)
There can be many causes of neuropathic pain. Side effects of certain medications can cause neuropathy, as well as a damaged or injured nerve or a nerve placed under pressure. Diseases of the nervous system and vascular disorders can also affect the nerves.
When diagnosing neuropathic pain, it’s important to evaluate how intense the pain is. There are several pain assessment tools that can be used, and they generally differ from the traditional pain scale of 0-10, in that nurses search for the quality of the pain the patient is experiencing. Some examples of the types of assessments used might be the Leeds assessment of neuropathic symptoms and signs (LANSS); Douleur neuropathic pain, which has four questions; and the neuropathic pain questionnaire (NPQ). All of these scales are similar in that they attempt to assess the quality and characteristics of the neuropathic pain the patient is experiencing. All have had rigorous validation, and have proven to be quite effective in the assessment of neuropathic pain.
Treatment options for neuropathic pain depend on the causes and the types of pain the patient is experiencing. Medications are the mainstay. If possible, treating the underlying cause of the pain can have benefits too. For instance, in a patient with diabetes, tight glycemic control may diminish their neuropathic pain. There are some “off label” treatments, meaning treatments that are not indicated or approved for neuropathic pain, but have proven to be effective. Examples include tricyclic antidepressants, such as amitriptyline, nortriptyline, and desipramine. Selective serotonin reuptake inhibitors, like paroxetine and citalopram, and other antidepressants, such as venlafaxine and bupropion have been used in some patients. Heart arrhythmia medications such as lidocaine are also used to treat neuropathic pain.
Ok, before we go, let’s look at a couple of review questions:
1. Which of the following does NOT describe neuropathic pain?
- It is chronic
- It can be visceral
- It is acute
- It can be somatic
The correct answer is C! Neuropathic pain is chronic, not acute.
2. How is neuropathic pain usually evaluated?
- A 0-10 pain scale
- Evaluation of pain quality and characteristics
- A physical examination
- Using a reflex hammer
The correct answer is B! Instead of a pain scale, the nurse will evaluate the characteristics of the pain, usually via a patient-completed questionnaire.
That’s all for this review! Thanks for watching, and happy studying!