Tuesday, November 26, 2013

Managing Chronic Post-Surgical Pain Syndromes

sharma-obesity-surgery3Chronic post-surgical pain (CPSP) at the surgery site can occur in up to one out of five patients undergoing surgery – particularly in those with surgery of the chest wall, breast, total joint replacements and iliac crest bone harvest. It can, however, occur after any type of surgery including minor procedures.

This problem and possible management strategies for the non-pain specialist are now reviewed in a paper by my colleagues Saifee Rashiq and Bruce Dick from the University of Alberta, in a paper published in the Canadian Journal of Anaesthesiology.

The consequences of CPSP on the patients is severe with staggering economic implications and powerful negative effects on the quality of life. CPSP also places a a significant burden on chronic pain treatment services.

Increased incidence of CPSP is seen in associated with younger age, obesity and female sex as well as certain psychological characteristics (anxiety, depression, stress, and catastrophizing).

Other risk factors include, “Capacity overload” in the six months prior to surgery (having had more to deal with in the psychological sense than the subject thought (s)he could handle) and/or  the presence of two or more indicators suggestive of stress (sleep disorder, exhaustibility/exhaustion, frightening thoughts, dizziness, tachycardia, feeling of being misunderstood, trembling hands, or taking sedatives or sleeping pills).

In addition, severe acute or chronic pain (even when unrelated to the surgical site) prior to surgery appears to be a predisposing factor.

Emerging evidence shows that the syndrome is not simply a consequence of local nerve injury but rather involves higher cognitive functions that influence events at the spinal cord by powerful descending control mechanisms.

Thus, CPSP is increasingly seen as a “multisystem illness that transcends the operative field and includes, most importantly, the patient’s psychological state and social circumstances“.

Based on their findings, the authors argue for better pain control prior to surgery as well as the use of regional anesthetic techniques, infiltration of local anesthetic, or preoperative use of gabapentin under special circumstances.

However, they also note that the ability of other known interrupters of afferent nociceptive transmission-commonly used to reduce CPSP when administered at the time of surgery remain currently unproven.

Given that obesity is a risk factor for this syndrome and many obese patients present with pre-surgical pain, clinicians working with this population should be aware of this problem and counsel patients accordingly.

If you have experienced this problem, I’d like to hear about it.

@DrSharma
Sudbury, ON

ResearchBlogging.orgRashiq S, & Dick BD (2013). Post-surgical pain syndromes: a review for the non-pain specialist. Canadian journal of anaesthesia = Journal canadien d’anesthesie PMID: 24185829

 

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Monday, November 25, 2013

BMI Does Not Affect Outcomes in Knee-Replacement Surgery

sharma-obesity-knee-arthtoplasty2One of the most pervasive “myths” amongst orthopaedic surgeons is that higher BMI is a contraindication to knee-replacement surgery.

Regular readers, however, will perhaps previous posts on this issue, suggesting that BMI is largely irrelevant in terms of outcomes and benefits for obese patients requiring knee replacements.

This previous finding is further supported by a new paper by David Murray and colleagues from The University of Oxford, UK, published in KNEE.

The researchers prospectively examined the impact of BMI on failure rate and clinical outcomes of 2,438 unicompartmental knee replacements in 378 patients with a BMI less than 25, 856 patients with a BMI 25 to 30, 712 patients with a BMI 30 to 35, 286 patients with a BMI 35 to 40, 126 patients with a BMI 40 to 45 and 80 patients with BMI greater than 45.

At a mean follow-up of 5 years (range 1–12 years) there was no significant difference in the Objective American Knee Society Score between BMI groups.

Although there was a slight trend to decreasing post-operative function scores with increasing BMI, patients with higher BMI had lower scores prior to surgery. Thus, overall higher BMIs were associated with a greater change in functional scores.

Thus, this study, further confirms the notion that obese individual have as much (if not more) to benefit from knee replacement surgery with little evidence that initial BMI adversely affects outcomes.

For clinicians this finding means that there is little evidence to deny knee replacement surgery to individuals with higher BMI levels or require that these patients lose weight prior to surgery.

If you have experience (positive or negative) with knee replacement surgery in overweight and obese patients, I’d like to hear from you.

@DrSharma
Edmonton, AB

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Wednesday, July 4, 2012

Obesity: I Feel The Pain!

Regular readers will appreciate the importance that I have given to pain both as a driver and consequence of weight gain as well as a barrier to treatment.

Just how closely obesity and pain are associated is now documented by Arthur Stone and Joan Broderick from Stony Brook University, NY, in a paper just published in OBESITY.

This study is based on a Gallup ‘poll’ of 1,062,271 randomly selected US individuals surveyed between 2008 through 2010.

BMI and pain yesterday were reliably associated (even when adjusted for a wide range of demographic variables): the overweight group reported 20% higher rates of pain than Low-Normal group, 68% higher for Obese I group, 136% higher for Obese II group, and 254% higher for Obese III group.

All of the tests of association between the pain conditions and BMI groups were significant, with the strongest association for the knee and leg condition.

The association held for both men and women but in women, the trend to more pain as BMI increases was steeper than in men.

The association between BMI and pain increases moving from the younger categories to the older categories; for those in the Obese III group, the odds ratio for the youngest group is 1.72 compared with a ratio of 3.79 for those in the highest age group.

As the authors note,

“The association is robust and holds after controlling for several pain conditions and across gender and age. The increasing BMI-pain association with older ages suggests a developmental process that, along with metabolic hypotheses, calls out for investigation.”

Despite the possible limitations due to the nature of the survey (telephone, self-reported height and weight and pain levels, etc.), the relationship between higher weight and pain is striking.

Assessing for pain (the 2nd ‘M’ or ‘Mechanical’) should be routine part of any exam for obesity and may have to be tackled in any obesity management program.

AMS
Edmonton, Alberta

ResearchBlogging.orgStone AA, & Broderick JE (2012). Obesity and pain are associated in the United States. Obesity (Silver Spring, Md.), 20 (7), 1491-5 PMID: 22262163

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Saturday, June 25, 2011

Medical Barriers: Chronic Pain Conditions

Today’s post is another excerpt from “Best Weight: A Practical Guide to Office-Based Weight Management“, recently published by the Canadian Obesity Network.

This guide is meant for health professionals dealing with obese clients and is NOT a self-management tool or weight-loss program. However, I assume that even general readers may find some of this material of interest.

CHRONIC PAIN CONDITIONS

Any condition that leads to chronic pain can contribute to obesity by increasing physiological and psychological stress. Pain also makes exercise more difficult to undertake and enjoy.

Osteoarthritis and Back Pain

Obesity is commonly associated with musculoskeletal pain and osteoarthritis, resulting in functional and motor limitations. Obese patients usually move more slowly, are less flexible and feel pain when performing tasks at floor level. There is a strong association between knee osteoarthritis and obesity. Degenerative arthritis resulting from chronic trauma associated with excess body weight develops primarily in weight-bearing joints such as the knee and ankle. However osteoarthritis can also be seen in non-weight-bearing joints, suggesting a systemic inflammatory response. Excess body weight is also closely related to lower back pain. Both static and compressive loading may damage the integrity of intervertebral discs. Increased biomechanical force can also cause muscle sprain and ligament strain.Sleep disorders are very prevalent among obese people. Obstructive sleep apnea is the most common disorder, but disturbed sleep may also be due to primary insomnia, or insomnia secondary to medications, medical or psychiatric disorders.

The presence of significant pain can promote immobility, leading to loss of muscle mass and reduced cardiopulmonary fitness. This can precipitate psychological and metabolic changes that promote further weight gain.

Patients with painful joints may benefit from water-based (non-weight-bearing) exercise and may require pain management before embarking on a weight-loss program. Obese patients requiring joint-replacement surgery are generally advised to lose weight (often in unrealistic amounts) before surgery, but this is very difficult if they are already partially immobilized by pain.

To complicate matters further, most commercial gyms are ill-equipped to handle the needs of obese clients, many of whom cannot go from lying down on the floor to standing up without assistance. Step classes and aerobics classes are in many cases ill-advised, and exercise machines and weight benches are not usually designed for obese users.

Fibromyalgia

Obesity is often associated with fibromyalgia, a common disorder characterized by fatigue, pain, stiffness in the trunk and extremities and a number of specific tender points. Fibromyalgia is more common in women than in men and is frequently accompanied by sleep disorders. Treatment of fibromyalgia may increase a patient’s ability to be physically active, and exercise has been shown to reduce the severity of fibromyalgia symptoms over time. As with severe osteoarthritis, starting with joint-sparing exercises may be prudent.

© Copyright 2010 by Dr. Arya M. Sharma and Dr. Yoni Freedhoff. All rights reserved.

The opinions in this book are those of the authors and do not represent those of the Canadian Obesity Network.

Members of the Canadian Obesity Network can download Best Weight for free.

Best Weight is also available at Amazon and Barnes & Nobles (part of the proceeds from all sales go to support the Canadian Obesity Network)

If you have already read Best Weight, please take a few minutes to leave a review on the Amazon or Barnes & Nobles website.

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Thursday, March 31, 2011

Bariatric Surgery For Migraines?

Among the many aches and pains commonly associated with excess weight, the increased prevalence and severity of migraines in patients with obesity is perhaps the least well known.

Not only do migraines appear to be more common in patients with excess weight but there is also evidence that people with severe obesity are likely to have more severe migraines than individuals with normal weight.

There are a number of plausible psychological and physiological mechanisms that could explain this relationship. The former include the finding that pathological pain processing, catastrophising and sensitivity has been associated with excess weight. The latter is supported by recent evidence that pro-inflammatory molecules that are increased in obese individuals can act as pain mediators in neurovascular inflammation.

These finding certainly raise the question whether weight loss can reduce the frequency and/or intensity of migraines.

This question was now addressed by Dale Bond and colleagues from Providence, Rhode Island, in a paper just published in NEUROLOGY.

The researchers prospectively assessed 24 patients (88% female, BMI 47) who had migraine according to the ID-Migraine screener before and 6 months after bariatric surgery.

Post-surgical weight loss was associated with a significant reduction in number of headache days from 11 to 7 in the 90 days preceding each assessment. Patients, who lost the most weight, also had the greatest odds of experiencing a more than 50% reduction in headache days. Furthermore, the number of patients reporting moderate to severe disability due to migraines decreased from 12 (50.0%) before surgery to 3 (12.5%) after surgery. While patients also reported significant improvement in depression (average PHQ-9 scores reduced from 8.8 to 4.3), the changes in mood were not predictive of the improvements in migraines.

This study certainly supports the hypothesis that migraine frequency and severity in severely obese patients reduces with surgical weight loss.

On the other hand, before jumping to overly enthusiastic conclusions, it may be prudent to note that this study did not assess or discuss the possibility that the lifestyle changes associated with surgery may simply have reduced exposure to many of the nutritional and lifestyle triggers of migraines (e.g. certain foods such as fruits, onions, chocolate, nuts, cheese, sugar, caffeine, alcohol or red wine as well as stress or physical exertion).

I guess it would take a prospective trial with careful assessment of these migraine triggers (or at least a control group of weight-stable patients who make the same dietary and lifestyle changes) to determine how much of this finding is explained by weight loss rather than simply by lifestyle change following surgery.

Nevertheless, I do wonder if any of my readers have observed similar changes in headache frequencies with changes in body weight or environmental triggers unrelated to weight loss.

AMS
Edmonton, Alberta

Bond DS, Vithiananthan S, Nash JM, Thomas JG, & Wing RR (2011). Improvement of migraine headaches in severely obese patients after bariatric surgery. Neurology, 76 (13), 1135-8 PMID: 21444898

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In The News

Diabetics in most need of bariatric surgery, university study finds

Oct. 18, 2013 – Ottawa Citizen: "Encouraging more men to consider bariatric surgery is also important, since it's the best treatment and can stop diabetic patients from needing insulin, said Dr. Arya Sharma, chair in obesity research and management at the University of Alberta." Read article

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