Specificity

By | February 28, 2015

This CAT Scan showing an enlarged appendix is highly specific for appendicitis but comes at the expense of a moderately large dose of radiation. "CAT scan demonstrating acute appendicitis" by James Heilman, MD - Own work. Licensed under CC BY-SA 3.0 via Wikimedia Commons - http://commons.wikimedia.org/wiki/File:CAT_scan_demonstrating_acute_appendicitis.jpg#mediaviewer/File:CAT_scan_demonstrating_acute_appendicitis.jpg

This CAT Scan showing an enlarged appendix is highly specific for appendicitis but comes at the expense of a moderately large dose of radiation.
“CAT scan demonstrating acute appendicitis” by James Heilman, MD – Own work. Licensed under CC BY-SA 3.0 via Wikimedia Commons – http://commons.wikimedia.org/wiki/File:CAT_scan_demonstrating_acute_appendicitis.jpg#mediaviewer/File:CAT_scan_demonstrating_acute_appendicitis.jpg

The converse of sensitivity, which is a measure of the frequency of false negatives is specificity, which is a measure of the frequency of false positives or Type I errors. The mathematical definition is the percentage of people without the disease in question who in fact have a negative test. A real world example can be seen in the evaluation of a teenage patient who goes to his doctor complaining of two days of worsening right lower quadrant abdominal pain. The patient is running a low-grade fever and has lost his appetite. The physician exams the patient’s abdomen and finds moderate tenderness confined to the right lower quadrant. On the basis of this test (palpation of the abdomen) the doctor makes the provisional diagnosis of appendicitis and sends the patient to the hospital for confirmatory testing and surgical treatment. He did this because in combination with the history abdominal palpation is a relatively sensitive test for appendicitis[1], but it is not very specific[2]. Upon arrival in the ER the physician on duty repeats the physical exam and orders blood work and a CAT Scan of the abdomen. Why did the ER physician order the CAT Scan? He ordered it because is fairly specific[3] and an unnecessary operation can thereby be avoided. The CAT Scan was not done in the first doctor’s office because he didn’t have a machine and wanted confirmatory blood tests before subjecting the patient to such a high dose of radiation. One of the most vexing examples we see at Schlesinger Pain Centers is in the screening blood tests that we do looking for rheumatologic conditions in some of our patients. Very often we will get back a positive Rheumatoid Factor or ANA (antinuclear antibody) test as the only abnormality in the panel. While a positive result increases the likelihood of disease neither test has the specificity to allow us to go further. But this is still not the whole story. In the next blog we will look at the effect of different patient populations on the usefulness of these tests.

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[1] Most people with the disease will have an abnormal exam.

[2] There are a number of other inflammatory conditions of the intestines that can mimic appendicitis upon abdominal palpation.

[3] People who do not have appendicitis are likely to have a negative exam, at least with regards to the appendix. Other abnormalities may be found in small intestine, colon kidneys or ureters.

Sensitivity

By | February 27, 2015

Sometimes a simple stethoscope is the appropriate first test, despite its low sensitivity and specificity. "Stethoscope-2" by this version: Sonarpulse. origenal:Huji - modified version made by myself of image:Stethoscope-2.jpg. Licensed under Public Domain via Wikimedia Commons - http://commons.wikimedia.org/wiki/File:Stethoscope-2.png#mediaviewer/File:Stethoscope-2.png

Sometimes a simple stethoscope is the appropriate first test, despite its low sensitivity and specificity.
“Stethoscope-2” by this version: Sonarpulse. origenal:Huji – modified version made by myself of image:Stethoscope-2.jpg. Licensed under Public Domain via Wikimedia Commons – http://commons.wikimedia.org/wiki/File:Stethoscope-2.png#mediaviewer/File:Stethoscope-2.png

As we have said above the majority of the complexity in medical decision-making results from the uncertainty of our information. The first type of uncertainty that we will deal with is the problem of false negatives or Type II errors, which is the possibility that someone with a negative test for a disease may actually have it. Sensitivity is defined as the percentage of patients with a disease who will test positive for it. In general the higher the sensitivity of a test the better because it reduces the uncertainty attached to a diagnosis. Why might a doctor use a test with lower sensitivity? Convenience, cost and invasiveness (or possible injury to the patient) are all competing concerns. Perhaps a concrete example will help to clarify this point. Let us assume that you have been feeling poorly and that you go to your doctor. You complain of fever and a cough productive of yellow sputum. Your physician is likely to listen to your chest with his stethoscope to evaluate the possibility of pneumonia. Auscultation with a stethoscope is a test with relatively low sensitivity, probably 50% or less. A chest X-ray has a much higher sensitivity especially for small areas of pneumonia, but most doctors don’t have an X-ray machine in their office and an X-ray exposes the patient to a small but measurable amount of radiation. At Schlesinger Pain Centers we see this problem with MRIs, which may miss small discs. Tomorrow we will look at the topic of specificity and the other major type of error contributing to the uncertainty of laboratory test.

The Mystery of Medical Management: Why Is Everything My Doctor Says So Complicated

By | February 26, 2015

I have not yet resorted to a ouija board in the elucidation of medical diagnoses and the formulation of treatment plans, despite what some of my patients may say!

I have not yet resorted to a ouija board in the elucidation of medical diagnoses and the formulation of treatment plans, despite what some of my patients may say!

Medical management is complicated at the outset by two mutually incompatible mandates imposed by our society. Most patients approach their physician in a spirit of subordination, seeing him as an expert able to weigh competing pieces of information and make a decision that they themselves are incapable of, much as a child might approach a parent. In direct opposition to this is the expectation of society that the patient will make an informed decision about his or her own care. At Schlesinger Pain Centers I try as much as possible to explain the pieces of information upon which I base my decisions as well as the degree of uncertainty attached to each piece. The next slight of hand is to explain the competing forms of treatment, the plethora of possible treatment plans, the several supposed sequelae and their effects on the patient. Very often the patients are incapable of assimilating all of this information and make their decisions on which of the possible outcomes they fear most. In the following blogs we will introduce the concepts of sensitivity, specificity and predictive value and show how they are used to arrive at a working diagnosis and then later suing the principles of game theory demonstrate several ways of evaluating the merits of competing treatment plans.

Two New Series of Blogs

By | February 25, 2015

I suffer from writer's block as commonly as any author, especially when coming to the end of a log series of blogs.

I suffer from writer’s block as commonly as any author, especially when coming to the end of a log series of blogs.

As a regular blogger I suffer from writer’s block, like any other author. The problem becomes especially severe as I come to the end of a long series of blogs and am at a loss to come up with a new topic. I am afraid that topics that interest me such as the psychological problems caused by the long periods of retirement facing most Americans today are either of little interest to others or inappropriate for the blog section of a pain clinic website. The other day it came to me. Why not write about the discussions that come up most often in the examination and treatment rooms of Schlesinger Pain Centers? There are two topics that continually occupy the greatest portion of my time. The first is the peculiar nature of medical decision-making especially as it relates to uncertainty in diagnosis and treatment outcomes. The other is surgery for back and neck pain. I hope that these topics will be as interesting to you as they are to me.

Back Rehabilitation – An Overview

By | February 24, 2015

In order to guarantee strength and comfort in all of the positions that you normally assume it may be necessary to assume some positions you never anticipated.

In order to guarantee strength and comfort in all of the positions that you normally assume it may be necessary to assume some positions you never anticipated such as this beautiful example of a Cobra Pose.

We have spent a great deal of time discussing the individual component parts of our back rehabilitation program. In today’s blog I will finally attempt to put all of the pieces together and show you how the program is implemented.

When a patient comes to see us for the first time at Schlesinger Pain Centers we always include a brief discussion of rehabilitation, because whatever the problem there are always structural or functional weaknesses in the back that have lead up to the problem. Left uncorrected these weaknesses will result in a recurrence of the problem, usually in less than 2 years. Whether the condition causing the pain is related to a bulging disc, arthritic condition or a malalignment of the spine we know that the patients invariably have tight paraspinal muscles, tight gluts and tight hamstrings all of which tend to increase the lumbar lordosis and pull the spine out of alignment. In addition these tight muscles are invariably weak and unable to resist the stresses and strains of daily life or mild exercise. All of these things need to be corrected if the patient is to have an optimal chance at rehabilitation. But how do we begin?

Step 0:            Relieve the pain. Whether the treatment is an anti-inflammatory agent, injection therapy or even surgery, it must be done before rehab starts. I have never been able to succeed at rehabilitation if the patient has more than a little pain. This phase of treatment is self-limited. Once the pain is gone all medications and injections are discontinued.

Step 1:             Spinal Distraction Therapy. For most patients this will be done on an inversion table at 30-45 degrees for 10 minutes once or twice a day. This phase of therapy will continue forever, but the first two weeks seem to be the most important because two weeks of pain free inversion are generally necessary before the patient advances to the next step.

Step 2:             Yoga Therapy. Whether done in a physical therapy office or a yoga studio restoring normal spine flexibility is essential to prevent further injuries and prepare the patient for the next step. We generally suggest that the patient practice yoga for a minimum of 10 minutes a day on their own and attend at least 1 private or group class per week. Like Step 1, Step 2 continues forever, but the first two weeks are again critical, because 2 weeks of pain free yoga therapy are generally necessary before starting strength exercises.

Step 3:             Strength Training. Most patients start this phase of rehabilitation in a physical therapy office, but like the previous two steps, strength training should be a part of the patient’s life forever and at some point the transition to a gym or health club will be necessary. Again we recommend that the patient devote a minimum of 10 minutes a day on their own and attend at least one group class or one hour a week with a personal trainer.

These are the minimums. Patients who are interested in having a healthy back as opposed to merely the absence of pain will invariably do more, incorporating other disciplines such as aerobics, Pilates and massage. Your back is like everything else in life. You get out what you put in.

Surgery in the Setting of Back Rehabilitation

By | February 23, 2015

Some people may need surgery before back rehabilitation can be successful in restoring full health.

Some people may need surgery before back rehabilitation can be successful in restoring full health.

Surgery and back rehabilitation are rarely discussed in the same setting but this is in my opinion a mistake. We at Schlesinger Pain Centers know from past experience that 50% of our patients will need surgery at one time or another. We know that past success of conservative management is not an absolute predictor of current or future success. Furthermore we know that if pain becomes limiting either in rehab or activities of daily living a more invasive approach involving injection therapy or surgery will be necessary. Factors that increase the likelihood of surgical intervention are unremitting leg pain and malalignment of the spine. Finally, one should not think of a choice between back rehabilitation and surgery, but rather as the fact that some people may need surgery before back rehabilitation can be successful in restoring full health.

My Favorite Back Exercises

By | February 22, 2015

If you can do bridges like this, 3 sets of 10 reps, I would wager that you have no significant back problems

If you can do bridges like this, 3 sets of 10 reps, I would wager that you have no significant back problems

Despite all of the prior disclaimers, here is a short list of my favorite back exercises. As with the yoga positions listed above, they are not all appropriate for my patients here at Schlesinger Pain Centers and I do not do all of these exercises every day, but will probably hit them all in the course of a week. My current workout includes about 15 minutes of back exercises daily.

 

On the Value of a Good Teacher

By | February 21, 2015

While Nika is actually a very pretty girl there are times when she sounds more like a drill sergeant than ...

While Nika is actually a very pretty girl there are times when she sounds more like a drill sergeant than …

Experience is the best teacher. Much of what I have learned about back rehabilitation I have learned directly from my patients and even more importantly from my own experience. Exercise is difficult to study scientifically, because form is so important. If you take a simple exercise like crunches and modify it slightly, lets say by putting in a small twist at the end, you actually get a completely different exercise. In one case you work primarily the rectus abdominis muscles and in the second case you are working the transversus abdominis and the obliques. I have been working with Nika Eshetu who owns Atomic Pilates in North Hollywood for about a year now. While some of our work is done on the Reformer and the Cadillac, most of it is relatively simple floor work. Nika gives me exercises to do in class so that she can measure my progress, but just as importantly so that she can identify weakness and correct my form. When I first attempt one of her exercises I invariably modify it, or perhaps degrade the form would be a better way of putting it, usually by doing something as simple as turning my feet out slightly. This makes the exercise easier, usually by allowing me to use muscles, which are already strong rather that strengthen weak ones. I am usually unaware of these modifications until Nika points them out to me. By the end each session I am usually able to feel what Nika wants and am able to attempt the exercises on my own during the coming week. It is possible that my patients at Schlesinger Pain Centers are better athletes than I am, but it is extremely likely that they would also benefit from the professional supervision of a good teacher in their rehabilitation and exercise regimes.

Getting Serious About Back Exercises

By | February 20, 2015

Giving this guy a list of back exercises without proper supervision is an accident waiting to happen.

Giving this guy a list of back exercises without proper supervision is an accident waiting to happen.

I am often asked, almost casually, at the end of an office visit at Schlesinger Pain Centers if I could give the patient a few simple exercises to do for their back. In fact this series of blogs is a response to that seemingly simple question. In the beginning I would try to give them my top 5 back exercises off the top of my head. Some patients would then have the temerity to ask that I write them down and provide a few pictures. This would then lead to a lengthy discussion of back rehabilitation, which would make me late for my next patient. To make matters worse virtually none the patients would follow through on our conversation. Then one day my nurse, Melissa pulled me aside and warned me that despite my best intentions what I was doing was not only counterproductive, but perhaps even dangerous. She told me that I couldn’t teach the patients the proper form of these exercises in 5 minutes and that most of them were in such poor physical condition that it was potentially dangerous for them to attempt these exercises without the supervision of a physical therapist or personal trainer. This is now the policy in the office. If a patient asks us about back exercises they are given a link to the website, a prescription for physical therapy and information about exercise classes offered by the City of Burbank.

My Favorite Yoga Positions

By | February 19, 2015

Yoga for back health starts with forward folds and sun  salutations.  There is no end.  In fact I have found that the more strength work I do the more yoga I want to do.

Yoga for back health starts with forward folds and sun salutations. There is no end. In fact I have found that the more strength work I do the more yoga I want to do.

My favorite yoga poses include forward folds, cat, cow, cobras, bridgeslow lunges spine rotations, side bends, warrior I, warrior II and of course downward dog. I do not use all of these positions every day and there are many other positions that I mix in to my daily 30 minute workouts. As I have said many times before it is important to have a good teacher that can correct your form, monitor your progress and help prevent injuries. While we no longer offer in house yoga classes here at Schlesinger Pain Centers we work with some of the best yoga instructors in Los Angeles. Private and group classes can usually be arranged that fit into your schedule.