CorrectCare

Dr. Scott’s Case File: A Questionable Complaint of Back Pain

By Sir Scott Savage, DO, FACEP, KtB, CCHP

The Case
Thursday, 5:30 p.m.
Inmate Health Services, State Prison
Exam Room 3
Case 200 – 401

It had already been a full day, and Dr. Scott was looking forward to finishing this last case and going home. He reviewed the information on the manila chart: Andrew Paxton*, 36 years old, had been incarcerated just over one year. He complained of low back pain for three days. There was no known injury or other significant medical history. Flipping back a few pages, Dr. Scott noted Mr. Paxton did have a seven-year history of cocaine abuse but no intravenous drug use. He also was listed as having depression, but without suicide attempt.

History
Mr. Paxton entered the room with a right-sided limp and sat in the exam chair slowly and with a short wince. Without prompting, he said, “Doc, my back is killing me.”

He then went on to relate a history of a gradual onset of constant dull low back pain, radiating occasionally to the right buttocks. He had no history of incontinence, fever, weight loss, constipation or urinary problems. The pain was worse when bending forward, and he complained of having difficulty getting in and out of his top bunk.

Physical Exam
On examination, the vital signs were normal. The patient sat stiffly upright. On his right sitting straight leg-raising test, he complained of low back pain radiating to the right buttocks, but not elsewhere. He kept his leg extended for seven seconds after the physician released the leg. The left sitting straight leg-raising test was normal, and the patient kept his leg extended two seconds after this leg was released. On the supine straight leg-raising test, the patient had back pain radiating to the knees bilaterally at 10 degrees of elevation.

His sensory exam was normal to light touch, and his motor exam was normal. Deep tendon reflexes were equal on both sides. Examination of the back showed no fasciculation, skin changes or atrophy. He had no pain to palpation or rotation of the hips bilaterally. Axial loading of approximately 10 pounds of pressure increased the patient’s low back pain. Passive shoulder and pelvis rotation both increased his pain. The rest of the exam was normal.

Upon leaving the office, the patient was noted to rise quickly and smoothly, and he had spontaneous twisting without gait abnormalities.

Discussion
This case is actually a composite of two similar patients I recently saw in one day. Back pain is a common problem. In the corrections setting there are added concerns for work avoidance, privilege seeking and drug seeking. A large portion of the inmate population has a history of intravenous drug abuse. In this subsegment of inmates, there is a special concern for transverse myelitis.

Fortunately, this patient did not have a fever, recent drug abuse or focal neurological symptoms. The patient’s relatively young age of 36, his normal vital signs and his lack of constitutional symptoms abate the concern for most referred diseases.

Even in the absence of neurological findings, care should always be taken to consider emergent conditions such as abdominal aortic aneurysm, retroceocal appendicitis and, in females, ectopic pregnancy.

Early in the interview, it is useful to try to classify the disease process into one of four major categories: referred, radicular, mechanical or psychogenic. Commonly, patients will have a mixture of categories, but usually one predominates.

Referred Pain
Referred pain usually has evidence of a remote organ system involvement, commonly from the genitourinary system or gastrointestinal system, but any system can be involved. A rapid review of systems can be useful. Specific red flags for serious disease are:
1. Age > 50 years
2. Fever
3. Night sweats
4. Unexplained weight loss
5. Incontinence
6. Chronic constipation

Reviewing vital signs also is paramount. If any red flags are present, then further history and examination are indicated. Labs may include a complete blood count, erythrocyte sedimentation rate and serum creatinine. Plain film radiographs also may be indicated. Rarely, bone scans, computerized tomography, electromyography with nerve conduction studies or magnetic resonance imaging may be indicated.

This patient did not have symptoms of serious underlying disease.

Radicular Pain
Radicular (nerve root) pain is usually sharp, burning and radiates below the knee. Neurological findings are sometimes present, and herald more serious disease. Saddle anesthesia and incontinence are particularly worrisome.

A common misconception concerns the straight leg-raising test, which is used to confirm radicular pain. Actually, the test is positive only if there is pain below the knee with greater than 60 degrees of elevation. Patients with short hamstring syndrome will have discomfort limited to the length of this muscle when it is stretched, and elevation below 60 degrees does not stretch the nerve root. Thus, only pain below the knee and pain and with more than 60 degrees of stretching is considered positive.

The patient in this case did not have a positive straight leg-raising test.

Mechanical Pain
Mechanical pain is common, and keys to diagnosing it include a dull, aching pain that is localized to the back or radiates only to the buttocks. It is usually worse with movement. There is often, but not always, a history of recent trauma or exertion.

This patient had a mechanical component to his pain.

Psychogenic Pain
Psychogenic pain is difficult to diagnose. Findings often include recent psychological stressors, desire for special privileges, inconsistent exam findings or non-anatomic findings.

This patient had interesting findings. First, he entered the office with a limp, but left without one. Second, on the sitting leg-raising test, he left his leg extended several seconds on both sides. This maneuver causes a great deal of stress on the back muscles, and patients with mechanical pain will drop their legs or at least complain of pain when the leg is released. The fact that this patient was able to voluntarily keep his leg extended was not consistent with severe back pain. Note that this does not mean he had no pain at all, but it does indicate milder disease.

Likewise, although the patient complained of pain with even mild passive straight leg-raising, he had no pain when he had the same test done when he was sitting at a 90 degree angle.

‘Nonorganic’ Physical Signs
The rest of the exam lists Waddell’s signs. If four or more of these signs are present, then the patient can be considered to have a significant psychological component of disease.
1. Pain to very light touch
2. Low back pain to mild axial loading of the head
3. Pain with passive rotation of the pelvis
4. Pain with passive rotation of the shoulder
5. Non-anatomic pain distribution
6. Inconsistent response to lying and standing straight leg-raising tests
7. Non-anatomic sensory deficit
8. Give-way or cogwheel motor weakness

This patient was positive for four signs.

Having Waddell’s signs does not mean the patient is feigning his symptoms. Diagnosing a psychological component of back pain also can mean unconscious conversion of stress into physical symptoms, fear by the patient that he will be inadequately treated or even an attempt to please an authority figure. There is no clinically reliable method of differentiating these processes on a single exam. Likewise, the presence of a psychological component of disease does not in any way rule out the possibility of any of the other types of back pain.

To sum up the remainder of the patient encounter…

Diagnostic tests: none

Final diagnosis: mechanical and psychological low back pain

Treatment: ibuprofen 600 mg po tid for seven days, light duty restriction with no sports for three days, reexamination in three days, McKinsey exercise instructions given

Follow-up: The patient filed a grievance for not receiving a permanent bottom bunk restriction. Independent review found that this was not indicated for this patient.

— About the author: Sir Scott Savage, DO, FACEP, KtB, CCHP, is assistant medical director for the Ohio Department of Rehabilitation and Corrections. To contact him, send an e-mail to ssavage4@columbus.rr.com. Savage presented on this subject as part of a broader discussion of malingering at the 2004 National Conference on Correctional Health Care. To obtain a recording of that session (no. 123), titled “Malingering: Recognition and Coping With Inmates,” please visit Nationwide Recording Service at www.nrstaping.com/ncchc.

[This article first appeared in the Winter 2005 issue of CorrectCare.]