Back Pain

Patients presenting with back pain following trivial or unrecalled trauma are considered here, along with a variety of nontraumatic etiologies. This chapter does not include spinal cord injuries or fractures of the spine.

COMMON CAUSES OF BACK PAIN

Musculoligamentous strain or sprain^*
Ruptured or herniated intervertebral disk^*
Osteoarthritis of the spine^*
Renal or ureteral colic^*
Pleural-based posterior pneumonitis^*
Pleurodynia^*
Rib fracture^*

LESS COMMON CAUSES OF BACK PAIN NOT TO BE MISSED

Pneumothorax^*
Leaking abdominal aortic aneurysm^*
Aortic dissection^*
Pulmonary embolism^*
Pyelonephritis^*

OTHER CAUSES OF BACK PAIN

Herpes zoster^*
Pancreatitis
Cholecystitis
Penetrating duodenal ulcer
Malignancy^*
Metabolic bone disease^*
Spinal stenosis^*
Vertebral osteomyelitis^*
Epidural abscess

HISTORICAL FEATURES

Historical features that may be helpful in the differentiation of the various causes of back pain include the following:

Musculoskeletal pain usually begins suddenly and in clear relation to physical exertion (e.g., bending, lifting, climbing), is not pleuritic, and is reproduced by activities or maneuvers that stress the particular area.
The sudden onset of back or thoracic discomfort made worse by inspiration and
associated with shortness of breath suggests pleurodynia, pneumothorax, or pulmonary embolism; these diagnoses must be excluded in all such patients. Pleuralbased pneumonia is also suggested by these symptoms, and many such patients also report fever, chills, cough, and sputum production. Predisposing factors for the development of thromboembolic disease should be investigated, and if present, the possibility of pulmonary embolism should be considered. It is important to note that, since the kidney normally descends during inspiration, patients with pyelonephritis, perinephric abscess, or renal or ureteral colic frequently report a pleuritic component to their discomfort.
A prior history of dysuria, frequency, fever, and chills further suggests the diagnosis of pyelonephritis. Back pain that radiates or is vaguely referred to the lower abdomen, testicle, or labia is commonly noted in patients with ureteral colic.
Herpes zoster (shingles), when involving the thoracic or lumbar spinal nerve roots, may produce a number of puzzling back symptoms, even before the development of any rash. Patients may complain of a severe, often lancinating pain, usually beginning in the back and radiating anteriorly, frequently along the course of a rib. Patients without an initial rash will, within several days, develop first erythema and papules, and eventually typical vesicles in the affected distribution.

Frequently, considerable confusion occurs as to whether a patient’s pain is truly pleuritic in nature. If so, a number of diagnostic possibilities gain importance. Much of the thoracic and periscapular musculature is involved in deep inspiration; certainly, such muscle groups, if injured or inflamed, will produce discomfort during inspiration and may prompt a designation of such pain as “pleuritic.” Such a designation, although technically correct, is diagnostically misleading unless efforts are made to separate pulmonary from extrapulmonary etiologies of pleuritic pain. In addition, most activities requiring some degree of minimal effort, such as sitting up or bending over, are preceded by an inspiratory effort; this fact becomes extremely important both historically and during the examination of the patient in differentiating movement- or posture-related muscular pain from potentially more significant causes of genuine pulmonary, pleuritic discomfort.

PHYSICAL EXAMINATION

Pain that can be reproduced or increases during quiet, slow inspiration should be considered pulmonary (and occasionally renal) unless proved otherwise.
Local tenderness with palpation and coarse crepitus auscultated on inspiration over a rib suggests rib fracture.
In the patient with pneumothorax, breath sounds may be normal, reduced, or absent.

Tenderness with percussion over the renal area suggests pyelonephritis, perinephric abscess, or renal or ureteral colic.

Table 45-1 Symptoms and Signs of Lower Back Disk Herniation

Interspace	Nerve	Pain/Paresthesia	Motor Loss	Sensory Loss	Reflex Loss
L3-4	L4	Anterior thigh, inner shin	Quadriceps	Anteromedial thigh down to inner shin	Knee jerk
L4-5	L5	Outer side of back of thigh, outer calf, dorsum of foot to first toe	Extensor hallucis longus	Outer side of calf and first toe	None
L5-S1	S1	Back of thigh to foot and lateral toes	Gastrocnemius	Outer side of calf, lateral foot and toes	Ankle jerk

Rales may be appreciated in patients with pneumonitis, pleurodynia, and pulmonary embolism; evidence of consolidation suggests pneumonia. A pleural friction rub may be heard in patients with any of these complaints.
Calf tenderness or swelling should be sought and if present, in association with pleuritic back pain, makes the diagnosis of pulmonary embolism likely. It is important to remember, however, that calf swelling or tenderness is noted in no more than 40% of patients with pulmonary embolism.
A rash may indicate herpes zoster infection, although, as noted, symptoms may precede the rash by several days. Skin hypersensitivity along the suspected dermatome or a subjective difference in sensitivity when sides are compared is suggestive of this diagnosis. In patients with evolving herpes zoster, initial erythema is followed by the development of typical papules and vesicles.
Localized muscle spasm and occasional tenderness are found in patients with muscular injury, sprain, and disk injury.
If lower extremity reflexes are focally and unilaterally absent or decreased, potentially serious root injury is suggested, and subspecialty consultation should be considered. Abnormalities of sensation may be determined and may provide evidence for a specific nerve root syndrome as well (Table 45-1). Passive straight-leg raising with the knee extended places traction on the lumbosacral roots and may increase back discomfort in patients with root compression syndromes. The specificity of the straight-leg-raising test is enhanced if the lumbosacral discomfort occurs on the side opposite the raised leg (the so-called crossed-leg-raising test).
A careful abdominal examination should be performed to exclude primary abdominal disorders associated with referred discomfort to the back (see Chapter 26).

DIAGNOSTIC TESTS

Chest X-Ray

An upright, end-expiratory chest x-ray excludes the diagnosis of pneumothorax. Aortic widening, as well as evidence of consolidation, will be noted in patients with thoracic aortic dissection and lobar pneumonitis, respectively.

Lumbosacral Spine X-Rays

Indications for lumbosacral spine x-rays include

Significant motor vehicle or industrial accidents or other trauma
Those with neurological deficits
Extremes of age
Those with significant comorbities such as prostate cancer

In the older patient with major back complaints, it is important to demonstrate radiologically normal bony architecture and thus exclude malignant or severe degenerative processes involving the spine.

Chest CT Angiogram/VQ Scan

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