Symptom Finder - Low Back Pain
Low Back Pain
In cases of both acute and chronic low back pain, the physician’s main
consideration is to rule out a herniated disc once he or she has ruled out a fracture with plain films. Perform a straight leg raising test, look for
Lasègue sign (flexing the leg at both the hip and the knee and gradually straightening the leg), and check for a reduced ankle jerk (on the side of the pain) in L4–L5 and L5–S1 disc herniations. Also check for loss of pain and touch in the big toe (in L4–L5 disc herniations) and the lateral surface of the foot and little toe (in L5–S1 disc herniations). A foot drop or weakness of dorsiflexion of the big toe is a sign of L5 radiculopathy (or an L4–L5 disc herniation). In cases of chronic low back pain, measure the circumference of the calves and thighs because there is usually wasting on the side of the lesion.
A clinician will miss a disc herniation at L3–L4 or L2–L3 if he or she stops the examination at this point. Continue by performing a femoral
stretch test. With the patient stretched out in the prone position, raise the lower leg and flex it onto the thigh. At 100 degrees or less, the patient
resists further movement if an L3–L4 herniation is present. The knee jerk is diminished on the side of the lesion in most cases. In addition, there is often loss of sensation in the L3 or L4 dermatome.
No back examination is complete without examining for sacrospinalis (paraspinous) muscle spasm. With the patient standing in the “at ease”
position (relaxed with feet 12 inches apart), one should palpate the paraspinous muscles and compare one side with the other. Normally, they
should both feel doughy. When one is more tense than the other, a lumbosacral sprain or disc herniation is likely, although many other
pathologic conditions of the lumbosacral spine may also be the cause.
Anyway, significant spasm is a clear indication for a computed tomography (CT) or magnetic resonance imaging (MRI) scan of the lumbosacral spine. The physician should not forget to check for tenderness of the sacrosciatic notches. A rectal examination is important to check for
sphincter tone and control, which may be lost in a cauda equina syndrome. Many cases of low back pain are due to a short leg syndrome, so measure the leg length.
When there are no objective findings, it is necessary to look for malingering. Certain signs are a clear indication of this condition. First of
all, there is secondary gain (e.g., workman compensation). Next, if there is sensory loss, it is nondermatomal. Weakness and muscle wasting are also diffused. Ask the patient to bend over as far as he or she can. If there is malingering, he or she will not bend very far. Now hold onto the patient’s hips and ask him or her to rotate the shoulders right and left. If rotation is limited, the patient with low back pain is probably malingering because rotation of the spine is a function primarily of the thoracic spine. Now rotate the whole spine at the hip. If the patient says this duplicates the pain, he or she does not have back pathology. Many patients who are malingering are schooled in resisting the straight leg raising test and thus have a false-positive result; however, if the physician has them sit on the examination table with their legs dangling and creates a distraction, it is possible to straighten their legs without resistance if they are malingering.
In cases of both acute and chronic low back pain, the physician’s main
consideration is to rule out a herniated disc once he or she has ruled out a fracture with plain films. Perform a straight leg raising test, look for
Lasègue sign (flexing the leg at both the hip and the knee and gradually straightening the leg), and check for a reduced ankle jerk (on the side of the pain) in L4–L5 and L5–S1 disc herniations. Also check for loss of pain and touch in the big toe (in L4–L5 disc herniations) and the lateral surface of the foot and little toe (in L5–S1 disc herniations). A foot drop or weakness of dorsiflexion of the big toe is a sign of L5 radiculopathy (or an L4–L5 disc herniation). In cases of chronic low back pain, measure the circumference of the calves and thighs because there is usually wasting on the side of the lesion.
A clinician will miss a disc herniation at L3–L4 or L2–L3 if he or she stops the examination at this point. Continue by performing a femoral
stretch test. With the patient stretched out in the prone position, raise the lower leg and flex it onto the thigh. At 100 degrees or less, the patient
resists further movement if an L3–L4 herniation is present. The knee jerk is diminished on the side of the lesion in most cases. In addition, there is often loss of sensation in the L3 or L4 dermatome.
No back examination is complete without examining for sacrospinalis (paraspinous) muscle spasm. With the patient standing in the “at ease”
position (relaxed with feet 12 inches apart), one should palpate the paraspinous muscles and compare one side with the other. Normally, they
should both feel doughy. When one is more tense than the other, a lumbosacral sprain or disc herniation is likely, although many other
pathologic conditions of the lumbosacral spine may also be the cause.
Anyway, significant spasm is a clear indication for a computed tomography (CT) or magnetic resonance imaging (MRI) scan of the lumbosacral spine. The physician should not forget to check for tenderness of the sacrosciatic notches. A rectal examination is important to check for
sphincter tone and control, which may be lost in a cauda equina syndrome. Many cases of low back pain are due to a short leg syndrome, so measure the leg length.
When there are no objective findings, it is necessary to look for malingering. Certain signs are a clear indication of this condition. First of
all, there is secondary gain (e.g., workman compensation). Next, if there is sensory loss, it is nondermatomal. Weakness and muscle wasting are also diffused. Ask the patient to bend over as far as he or she can. If there is malingering, he or she will not bend very far. Now hold onto the patient’s hips and ask him or her to rotate the shoulders right and left. If rotation is limited, the patient with low back pain is probably malingering because rotation of the spine is a function primarily of the thoracic spine. Now rotate the whole spine at the hip. If the patient says this duplicates the pain, he or she does not have back pathology. Many patients who are malingering are schooled in resisting the straight leg raising test and thus have a false-positive result; however, if the physician has them sit on the examination table with their legs dangling and creates a distraction, it is possible to straighten their legs without resistance if they are malingering.
