Accurate Education – Acute Pain: Initial Post-Injury

Goals

There are four primary goals in the management of acute post-injury pain:

(1) Reduce the severity and duration of the acute post-injury pain

(2) Reduce the risk of the acute post-injury pain from becoming chronic

(3) Enhance the individual’s coping skill relative to living with pain

(4) Facilitate improved engagement in daily activities and reduce functional impairment.

Considerations in the Management of Acute Post-Injury Pain

After one suffers significant trauma resulting in injury or injuries, it is common and expected to experience pain.  How effectively that pain is initially treated is very important because poorly controlled pain after an acute injury substantially increases the risk of that pain becoming chronic, defined as pain greater than 3 months duration. Therefore, a primary consideration when treating acute pain is to assess the likelihood of the painful condition becoming chronic. When circumstances suggest an increased risk for chronification of pain, a more aggressive treatment regimen should be engaged with emphasis on a multi-modal approach (See: Avoiding Transition to Chronic Pain).

When this risk is low, a more simple, less complex treatment plan may be engaged although whenever feasible steps to reduce the chronification of pain should be included. This education section emphasizes the components of the simple, less complex treatment plan for acute post-injury pain in patients estimated to be at low risk for chronification of their pain.

Acute Post-Injury Pain Management – Overview

In addition to contributing to the chronification of pain and impairment of quality of life, poorly controlled acute post-injury pain is associated with increased complications of pain including anxiety and depression along with the use of multiple medications and their potential side effects. So, how well one addresses their acute pain after an injury may be one of the most important influences on their future quality of life.

Reearch has taught us that the preferred means of reducing post-injury pain is to engage a comprehensive, multi-modal approach. A multi-modal approach can be defined as the use of more than one therapeutic approach including different pharmacological classes of analgesic medications targeting different receptors in various pain pathways with the goal of improving analgesia while reducing individual class-related side effects. It has been said that “a good multi-modal protocol is a checklist rather than a recipe,” one that allows for flexibility in the individual components based on the patient’s comorbidities, allergies and other medications.

Post-injury pain can be nociceptive (derived from damaged tissues), neuropathic (nerve based), mixed or psychogenic, depending on the patient and the injury. As such, medications from different classes may be required for successful pain reduction while at the same time reducing reliance on opioids and limiting the evolution of chronic pain.

A comprehensive approach for treating post-injury pain is a neccesity for obtaining the best outcome, one that includes not only reduced pain and suffering but also restoration of quality and enjoyment of life and a return to functionality. Engaging a comprehensive approach requires not just the use of physical treatments performed on someone or the use of analgesics and prescription medications. It should also include lifestyle changes for long-term therapeutic effectiveness. It is important to engage in regular stretching and relaxation exercises as well as strengthening exercises for maintaining good posture.

A nutritional approach must be included to support and enhance tissue healing through eating an appropriate diet and the use of nutriceutical supplements. Finally, the psyche of an injured individual must be supported to avoid or treat the stress, anxiety and depression that commonly accompany significant injury.

This educational section reviews evidence-based information from current research directed at treating acute post-injury pain. Considerations directed at reducing the risk and/or severity of developing chronic pain after an injury is deferred to another educational section (See: Avoiding Transition to Chronic Pain). Much of the information in this section is based on studies that evaluate post-surgical pain which does differ somewhat from post-trauma pain but shares many important considerations. The study of post-surgical pain has an advantage in that these studies may allow for control subject testing, providing more accurate study conclusions.

Its important to remember that pain is a multi-dimensional emotional and sensory experience and different patients respond to pain very differently based on physiologic and psychologic factors as well as the context in which the pain is experienced. For example, perhaps the greatest difference between post-surgical and post-injury pain is that the first is usually a planned and controlled trauma while post-injury pain is neither of these. As such, post-injury pain is potentially more subject to acute physical and emotional stress related to the circumstances surrounding the injury. Since stress is a worsening influence for pain it is especially important to emphasize stress and anxiety management related to post-injury pain.

Conditions That Contribute to the Severity and Duration of Post-Injury Pain

Aside from the nature and severity of the injury itself, there are other variables that contribute to pain after an injury.

(1) The Presence of Pain Before an Acute Injury

The presence of pain priory to injury, especially chronic pain, is a factor that contributes to both acute as well as chronic post-injury pain. There is evidence that the effectiveness of management of pre-injury pain may impact the severity of acute post-injury pain.

Additionally, certain pre-existing chronic pain conditions are more likely to be associated with increased post-injury pain including chronic migraine headaches, chronic neck or low back pain, knee arthritis, fibromyalgia, chronic pancreatitis, chronic regional pain syndrome (CRPS) and other conditions. These conditions are all associated with neuropathic pain and/or peripheral sensitization and central sensitization (see below).

 (A) Neuropathic pain

Neuropathic pain, which is based on dysfunctional or dysregulated nerves, is generally experienced as burning, electric shocking or shooting in nature. A dominant component of chronic pain, neuropathic pain can also occur acutely as a component of post-injury pain.

(See: Neuropathic Pain)

(B) Central and Peripheral Sensitization

Central and peripheral sensitization are conditions associated with many common chronic pain syndromes including chronic low back pain, neck pain and whiplash syndromes, arthritis, migraine headaches, irritable bowel syndrome (IBS), inflammatory bowel conditions and many other conditions.

Sensitization of the central nervous system (brain and spinal cord) and peripheral nervous system (outside the brain and spinal cord) are common conditions that are characterized by changes in nerves including pain receptors, nerve junctions and nerve pathways in the spine and brain that occur over time with continued pain. This sensitization results in the magnification of pain experiences where what should be a mild pain is experienced as moderate or severe pain or where sensations that are  not normally painful become painful.

Patients with central and peripheral sensitization are much more likely to experience increased severity of pain after an injury, even with those injuries that are not normally considered likely to be associated with significant pain. In turn, these patients are more vulnerable for having their acute pain becoming chronic. Patients with central and peripheral sensitization can be identified and treatment should be initiated ASAP after an acute injury to reduce the  severity of their acute post-injury pain as well as reduce the likelihood and severity of transition to chronic pain.

(See: Central Sensitization)

(2) Nutritional Status

An important variable that impacts the severity of post-injury pain is the nutritional status of the patient at the time of injury and in the post-injury time period. Vitamin and other nutritional deficiencies may contribute to poor or prolonged healing and enhance pain.

Additionally, studies suggest that diet and nutrition-based supplements reduce post-injury pain by promoting healing and reducing  inflammation. While inflammation is a natural process that is important in the healing of damaged tissue, it can also lead to problems when dysregulated and prolonged. Patients with increased systemic inflammation and oxidative stress (see below) associated with certain medical conditions and unhealthy diets are more at risk for increased post-injury pain.

(3)  Oxidative Stress

“Oxidative stress” is an imbalance in the body where there are excessive “oxidants” and insufficient “antioxidants.” Oxidants are chemically active agents such as free radicals and Reactive Oxidizing Species (ROS) acquired from the diet, produced in the body or encountered in the environment. Antioxidants are chemically active agents that are also obtained from the diet or produced by the body and include CoQ-10, vitamins C and E, and curcumin. Antioxidants neutralize oxidants to help prevent the tissue damage and caused by oxidants.

Lifestyles, stress, and environmental factors that may cause excessive free radical formation and oxidative stress include:

(1) Psychological stress

(2) Air pollution.

(3) Cigarette smoke

(4) Alcohol use

(5) Toxins

(6) High blood sugar levels

(7) High intake of polyunsaturated fatty acids

(8) Radiation, including excessive sunbathing.

Oxidative stress is capable of inducing harmful changes, particularly to the central nervous system ,and has been shown to play an important role in many mechanisms involved in pain modulation and central sensitization. Elevated spinal levels of oxidants (ROS and nitric oxide) can alter pain pathways and lead to the hyperexcitability of both the peripheral and central nervous system contributing to peripheral and central sensitization and the maintenance of pain symptoms.

The overabundance of oxidants associated with oxidative stress causes damage to cells, tissue and biomolecules, (lipids, proteins and nucleic acids including RNA & DNA). In addition to enhancing pain, these damages contribute to aging and chronic diseases including chronic inflammation, arthritis, atherosclerosis, cancer, diabetes, heart diseases and stroke. Maintaining a heathy diet and lifestyle, including exercise, are the best measures one can take to reduce oxidative stress and limit the evolution of pain.

(See: Oxidative Stress)

(4) Psychological and Psychiatric States

A patient’s psychological state, both before and after an injury, is a significant factor in predicting risk for increased post-injury pain. Psychological conditions that predispose to increased post-injury pain include depression, anxiety, PTSD and pain catastrophizing. Pain “catastrophizing” is a process where patients experience their symptoms out of proportion to the nature of their condition. It is often based on underlying fears related to previous experience which can be effectively treated with education and counseling including cognitive behavior therapy. It is very important to treat these underlying conditions to limit the severity and  duration of acute post-injury pain.

Treatment to Reduce the Severity and Duration of Acute Post-Injury Pain

Medication Management

Analgesics – Non-Opioid

Over-the-counter (OTC) Analgesic Medications

Treating acute pain can be relatively straight forward. Pain medicines  (analgesics) are likely the first step to obtain immediate relief. The usual initial analgesic is an over-the-counter (OTC) medication such as acetaminophen (Tylenol) or a non-steroid anti-inflammatory drug (NSAID) such as ibuprofen (Advil) or naproxen (Naprosyn). A prescription NSAID such as meloxicam (Mobic) may be prescribed. These medications are useful for mild to moderately severe pain.

Acetaminophen (Tylenol)

Acetaminophen is perhaps the safest of the OTC analgesics with its toxicity limited to excessive dosing. Its effectiveness is generally limited to mild pain but it offers this benefit with little risk of side effects compared with the NSAIDs which are contraindicated in those with gastric ulcers and bronchial asthma, pregnant women, nursing mothers, and children amongst others.

Up until recently, the mechanism by which acetaminophen works as an analgesic was largely unknown and poorly understood. It is now known that its pain benefits comes from the actions of its metabolites, p-aminophenol, which crosses the blood-brain barrier and gets metabolized by fatty acid amide hydrolase (FAAH) to  N-acylphenolamine (AM404). AM404 acts on the transient receptor potential vanilloid 1 (TRPV1) and cannabinoid 1 (CB1) receptors in the brain and spinal cord which provide analgesia. Additionally, AM404 suppresses NF-kB activation of microglia, immune cells responsible for nerve pain and central sensitization which contribute to the chronification of acute to chronic pain.

In short, while acetaminophen may provide only weak analgesic benefit directly, it may offer a long term benefit by suppressing the transition of acute to chronic pain.

NSAIDs

It has been reported that NSAIDs may slow or impair bone healing in the setting of bone fractures or surgery. Although isolated clinical investigations have provided limited evidence to withhold NSAIDs during fracture treatment, current research does not support the need to avoid NSAIDs because of fears about bone healing. Current guidelines for managing acute pain include the use of NSAIDs for mild to moderate pain in cases of bone injury.

While NSAIDs alone may often be sufficient to provide adequate pain relief, the addition of acetaminophen (Tylenol) will enhance the benefit from NSAIDs and reduce the need for opioids. Currently there are over-the-counter products that combine these two agents in one pill.

Adjunctive Medications

As part of the multi-modal approach, adjunctive pain medications may be prescribed to supplement  primary analgesics (NSAIDs and/or opioids) to provide synergistic benefits for improving pain and to allow for reduced dosing of primary analgesic medications.  These adjunctive pain medications are also commonly used independently to reduce pain. Neuromodulators and muscle relaxers are two common classes of adjunctive medications used in acute pain management.

Neuromodular Medications
“Neuromodulator” medications are those that act directly or indirectly on nerves to reduce nerve pain such as sciatica or neuropathy. Nerve pain is generally perceived as burning, electric, tingling or sharp and is often experienced as a pain referred from one location to another. Examples of neuromodulators include gabapentin (Neurontin), pregabalin (Lyrica), topiramate (Topamax), milnacaprin (Savella), duloxetine (Cymbalta), venlafaxine (Effexor), amitryptiline (Elavil), doxepin and others. These medications are usually tolerated well, especially when initially prescribed at low doses followed by slowly increasing the dose as tolerated. Because these medications reduce pain by different mechanisms than opioids, they can be very successful in reducing pain when used synergistically with opioids.

Many of the neuromodular medications that can be used to facilitate acute pain control are also helpful in reducing anxiety, improving sleep and possibly reducing opioid analgesic tolerance and centralization of pain. The most common of these prescription medications include gabapentin (Neurontin) and pregabalin (Lyrica).

(see Gabapenten and Lyrica)

Duloxetine (Cymbalta) is a medication that was initially prescribed to manage anxiety and depression but has been found to also be effective for nerve pain. It works on pain pathways that descend from the brain down the spinal cord to inhibit pain signalling ascending up to the brain and to conscious awareness. These descending pathways are implicated in the chronification of pain as well as the sensitization process that contributes to the severity of the pain experience.

See: Duloxetine (Cymbalta)

Nutriceutical Neuromodulator Supplements

There are a number of over-the-counter (OTC) supplements that have evidence for benefit in treating nerve pain and central sensitization. The use of these supplements is safe and round out a multi-modal approach to controlling acute pain. These analgesic supplements include palmitoylethanolamide (PEA), lipoic acid, acetyl L-carnitine and cannabidiol (CBD) among others.
See: Central Sensitization

Muscle Relaxers

Medications typically prescribed for muscle tightness, spasm and spasticity such as baclofen and tizanidine (Zanaflex) can also be helpful in reducing muscle pain. Another potent muscle relaxer, orphenadrine (Norflex, Norgesic  and  Orphengesic Forte), is an anti-cholinergic drug that is an analgesic used to treat painful muscle tightness and spasms. Due to its central nervous system (CNS) and peripheral actions, orphenadrine is useful for pain of many causes, including pain from radiculopathy, muscles, and headaches.

Analgesics – Opioids

The use of opioids may prove necessary to treat severe pain when initial medications above are ineffective or not tolerated. Due to current concerns regarding the “opioid epidemic” and recent research evaluating the tendency for opioids taken for acute pain to become chronically prescribed, the use of opioids for acute pain needs to be directed carefully by the prescribing physician. It is strongly recommended that patients should use the lowest effective dose of opioids for the shortest period possible. Additionally, the use of extended release opioids are generally avoided in the acute management of pain, in part because they may have a higher rate of abuse and diversion, and because they may contribute to the chronification of opioid use.

The use of opioids for acute pain in general should be initiated with short-acting opioids such as tramadol (Ultram) or hydrocodone (Norco). Codeine, which is about 15% as potent an analgesic as hydrocodone or oral morphine, may sometimes be considered for mild to moderate pain but it is frequently not tolerated due to its common side effect of nausea. Dihydrocodeine, which is a little more potent than codeine, may also be considered but is prescribed less frequently.

See: Opioids

An important consideration in the choice of which opioid to use for acute post-injury pain is presence of nerve pain and the degree of risk the patient may have for transitioning from acute to chronic post-injury pain. Patients with nerve pain or those at high risk for transitioning may benefit from the use of opioids with secondary mechanisms of action in addition to their basic action at the mu-opioid receptor which is shared by all opioids. These opioids include those with activity on the descending pain pathways (tramadol and tapentadol) and those with NMDA antagonism (levorphanol and methadone). These secondary actions provide greater benefit for nerve pain and may reduce the transition of acute to chronic pain.

See: Transitioning from Acute to Chronic Post-Injury Pain

Tramadol (Ultram)
Tramadol is frequently the first opioid prescribed for mild to moderate pain and it has the advantage of offering potentially more benefit for nerve pain compared with many other opioids due to its secondary activity on the descending pain pathways.  It has the disadvantage of being subject to genetic variants in which a patient may be unlikely to experience analgesic benefit (7% of Caucasians, about 1% of Orientals) or may have enhanced benefit with the potential for more side effects (about 2% of people).

Hydrocodone (Norco)
Hydrocodone is commonly prescribed for acute pain and is generally well-tolerated, offering the usual side effects of opioids including sedation, nausea, altered mentation and constipation. Hydrocodone offers no secondary mechanism of action for analgesic benefit. Short acting formulations of hydrocodone also contain acetaminophen (Tylenol) which provides a synergistic benefit for pain. The presence of acetaminophen however offers the potential for liver toxicity if taken in excessive amounts (>3000 mg/day).  Oral forms of hydrocodone have an analgesic potency equivalent to oral forms of morphine where 10 mgs of hydrocodone offers the same benefit for pain as does 10 mgs of morphine.

Oxycodone (Percocet and Prolate)
Another opioid sometimes used for managing acute pain is oxycodone, commonly in formulations also containing acetaminophen (Tylenol) such as Percocet (with 325 mg acetaminophen/tablet) and Prolate (with 300 mg acetaminophen/tablet). Prolate is a newer formulation with slightly less acetaminophen that offers the advantage of providing a slightly greater buffer against accidental acetaminophen toxicity. Like hydrocodone, oxycodone offers no secondary mechanism of action for analgesic benefit.

Oxycodone is 50% more potent than hydrocodone and oral morphine and is generally reserved for moderate to severe pain. While all opioids have the potential to trigger abuse and addiction, some physicians believe oxycodone to be somewhat more prone to abuse than tramadol or hydrocodone. Additionally, oxycodone may be more likely to develop analgesic tolerance more quickly than tramadol or hydrocodone. Analgesic tolerance is when the analgesic benefit provided by oxycodone slowly weakens over time, thus requiring stronger doses to achieve the same benefit. Analgesic tolerance to oxycodone typically takes months to years to develop.

See: Opioid Tolerance

Levorphanol

Levorphanol is an opioid with special characteristics including potent NMDA antagonism that makes it a particularly attractive choice for acute post-injury pain management, especially in those at risk for transitioning to chronic pain. While appropriate for use on an as-needed basis, it offers a longer half-life compared with usual short-acting opioids including hydrocodone, oxycodone and hydromorphone.

 See: Levorphanol

Newer Opioids

There are two opioids that are relatively new – buprenorphine (Butrans and Belbuca) and tapentadol (Nucynta). Each of these opioids offer unique advantages over traditional opioids in the management of acute pain, including the potential for greater benefit for nerve pain and for limiting the transition of acute to chronic pain.

Buprenorphine (Butrans and Belbuca)
Buprenorphine is an opioid that is considered to be a partial opiate agonist which imparts special properties not shared by traditional opioids. It has the advantage of providing up to 12 hours of analgesic benefit per dose in the case of Belbuca, a film strip that is applied to the inside cheek. In the case of Butrans, buprenorphine is formulated as a topical skin patch that can be worn for 7 days while providing consistent analgesic benefit 24 hours/day.

Additionally, buprenorphine offers greater benefit for nerve pain and it develops tolerance very slowly compared with most traditional opioids. Most importantly, it imparts no significant respiratory depression as a side effect which makes buprenorphine the safest opioid for avoiding accidental overdose.  Buprenorphine is a preferred opioid for patients who are elderly or for those with sleep apnea or prescribed other sedating medications.

Some physicians believe that because of buprenorphine’s special properties it should be preferentially considered for early or initial use in acute pain if initial management with usual short-acting opioids is ineffective, not tolerated or less safe compared with buprenorphine.

See: Buprenorphine for Pain

Tapentadol (Nucynta)
Tapentadol is a unique opioid that offers analgesic benefit based on two mechanisms of action. First, it acts on the same mu-opioid receptor in common with all opioids to provide analgesia. Additionally, it acts on the descending pain pathways in the central nervous system that provides greater secondary benefit for nerve pain compared with traditional opioids.

Because of tapentadol’s secondary  mechanism of action, it also offers less respiratory depression than comparable analgesic doses of other opioids with the exception of buprenorphine. This makes tapentadol potentially safer to use in patients with sleep apnea and for avoiding accidental overdose.

More potent than tramadol, tapentadol has analgesic potency in a comparable range to oxycodone when prescribed at usual, typical doses. Tapentadol offers fewer side effects at equipotent doses compared with other opioids with  slower development of tolerance and it also offers less risk for abuse.

See:  Tapentadol (Nucynta)

Physiotherapy Treatments to Reduce Acute Post-Injury Pain

The most common sources of post-injury pain are muscle, tendons and ligaments. Muscle pain arises from both the muscle  tissue itself as well as the fibrous tissue encapsulating muscle, the fascia, together referred to as myofascial pain. Myofascial pain syndrome (MPS) is the most common cause of back and neck pain, both acute post-injury pain  as well as chronic back and neck pain. Because myofascial pain is so pervasive, it is important to understand myofascial pain to provide context to understanding the various treatments recommended here.

Myofascial Pain

Myofascial pain is characterized by the presence of painful trigger points in muscles as well as muscle spasm and tightness, reduced range of motion and weakness. It can be caused by trauma or overuse of muscles and is associated frequently with cervial or lumbar spine injuries as well as extremity or joint injuries, especially shoulders.

See: Myofascial Pain

MPS starts as a localized central area of muscle contraction but evolves to include the development of myofascial trigger points (MTrP). MTrPs are taut bands of muscle that are tender to palpation but over time may evolve into sources of spontaneous pain that mo longer require triggering by palpation or movement to generate pain. Furthermore, MTrPs can develop patterns of referred pain, in which the pain can be felt distant to the MTrP itself. In fact, the referral pain patterns of some MTrPs can mimic radicular pain such as sciatica which can lead to inaccurate diagnoses and treatment. The main objective in the treatment of MPS is to resolve the spasm, reduce the pain, and inactivate the trigger points.

See: Trigger Points Therapy

Within a few weeks of developing myofascial pain, peripheral and central sensitization can develop, inducing spread of the perceived pain to larger areas than the original area of perceived pain. Furthermore, myofascial pain and MTrPs can lead to the development of peripheral and central sensitization, in which the myofascial pain becomes magnified in severity and more easily elicited with simple touch or otherwise by stimulation that would normally be considered only slightly painful.

See:Central Sensitization

Non-invasive Physiotherapy Treatments

Non-invasive treatment modalities to reduce acute post-injury pain include transcutaneous electrical stimulation, therapeutic ultrasound, manual therapy including various massage techniques and heat packs. Preferred invasive treatment methods include dry needling, local anesthetics, and botulinum injections (Botox).

Heat Therapy and Application of Hot Packs
See: Heat and Cold Therapy

The therapeutic application of heat to injured tissues with the use of hot packs or soaks is as old as time and continues to be a recommended treatment. It decreases joint stiffness and promotes muscle relaxation. Hot packs cause dilation of blood vessels in superficial tissues but may reflexly also enhance blood circulation in the deeper tissues (including improved oxygenation and nutrient delivery). This increased blood flow enhances tissue healing by delivering nutrients needed for tissue repair and removing toxins associated with the injury and repair process.

Hot packs are generally coupled with therapeutic ultrasound to provide synergistic benefit. In a 2015 study, the authors evaluated the treatment sequence of hot packs followed by therapeutic ultrasound or vice versa, therapeutic ultrasound followed by hot packs.

The results of the study revealed that the application of hot packs followed by therapeutic ultrasound provides a greater beneficial effect for pain. The authors theorized that increasing blood circulation in the trigger points with the hot packs allowed for the therapeutic ultrasound to be more effective because of increased tissue density induced by the increased blood flow.

Transcutaneous Electrical Stimulation

Therapeutic Ultrasound Therapy

Therapeutic ultrasound is a non-invasive, painless treatment that can be engaged to promote healing and decrease pain by providing deep heating to soft tissue to improve blood flow to tendons, muscle and other tissue. It reduces muscle spasm and potentially accelerates the healing of muscle and tendon injuries. It also has a micromassage effect which enables the movement of interstitial fluid in the tissues to help reduce swelling.

Therapeutic ultrasound for treating trigger points has been used clinically for years and is well supported by clinical experience. An early 2007 study demonstrated therapeutic ultrasound significantly reduced the short-term pain pressure sensitivity of myofascial trigger points an average 44.1% from a trigger point within the trapezius muscle after a 5-min therapeutic treatment with ultrasound. A 2018 study showed therapeutic ultrasound to be an important deep-heating treatment for myofascial pain and muscle spasms as well as for improving psychological state.

To engage therapeutic ultrasound a hand-held transducer is applied to the treatment area with a gel and moved in a circular motion over the injured or painful area with treatment sessions lasting from 5-20 minutes.

Preventing Pain Related to Surgery – Enhanced Recovery After Surgery (ERAS)

1. Enhanced Recovery After Surgery: A Review. – PubMed – NCBI – 2017
2. Pain management within an enhanced recovery program after thoracic surgery – 2018
3. Optimizing pain management to facilitate Enhanced Recovery After Surgery pathways. – PubMed – NCBI – 2015