Lumbar
spine
The lumbar spine is another part of the anatomy which can be best
examined initially with the patient standing up. Exposure is important and the
back must be visible as far down as the natal cleft. The key to the examination
of the lumbar spine is a full examination of the lower limbs. Irritation of
nerves in the spine can mimic problems in the lower limb. Whenever you see a
patient with problems in the lower limb, keep in the back of your mind that this
problem could be referred from the spine.
Look
Skin
Look for hairy tufts and dimples at the base of the spine which may
indicate an underlying spina bifida.
Soft
tissue
Look at the muscles on each side of the spine. If they are very
prominent they may be in spasm.
Bone
The lumbar spine should have a smooth concavity (lumbar lordosis). Loss
of lordosis and flattening of the buttocks go with muscle spasm (Fig.
20.22).
Feel
Skin
Sensation. Test sensation in both legs. Sensory loss is most likely to
be detectable distally, so simply compare touch on the lateral and medial side
of both feet. If this is abnormal, then continue to a full neurological
examination. Test for any loss of sensation in the perineal area if the patient
complains of sudden onset of pain and numbness in both legs (caudaequina
syndrome).
Soft
tissue
Feel the muscles on each side of the spine for spasm.
Bone
Trace the line of the spine with your fingers, checking for scoliosis.
Feel
the spine of the L5 and the S1 vertebrae. A step between the two may indicate a
spondylolisthesis.
Move
Active
Flexion/extension. Place the tip of your thumb over the T12—L1
junction, and the tip of your index finger of the same hand over the lumbosacral
junction. Ask the patient to reach forward to try to touch their toes. Note the
distance that your thumb and tip of finger separate as the patient bends forward
(Fig. 20.23). This distance is a measure of lumbar flexibility.
Note
also how far the tips of the patient’s fingers can reach down their legs when
they bend forwards. The distance that they can reach is an indication of total
spinal flexibility combined with hip flexibility.
Most
patients cannot touch their toes, but some hypermobile patients can put the
palms of their hands on the floor. Flexibility depends on fitness, age, gender
and overall body mobility, and varies enormously between individuals.
Lateral
deviation. Ask the patient to slide first one hand and then the other down the
side of their thigh, bending laterally. The spine should bend smoothly from top
to bottom. Total mobility can be recorded by noting the distance that each hand
can move down the side of that thigh (Fig. 20.24).
Rotation.
Stand behind the patient and hold their pelvis still with both hands. Ask the
patient to twist round and look over their shoulder, first in one direction and
then the other. Note the angle that the shoulder girdle can form with the pelvis
(Fig. 20.24).
For
these last three tests record whether any of the manoeuvres are limited by pain,
and if so where.
The Lasegue or straight leg raise test. This test can be painful and so
should only be performed slowly while watching the patient’s face at all
times. The test should be abandoned if pain becomes severe. It is a test of
sciatic nerve irritability and relies on the fact that when the straight leg is
flexed fully at the hip the roots of the sciatic nerve move as much as 2 cm
through the vertebral foraminae. If the nerve is compressed and/or inflamed this
movement will cause pain.
Pick
up the leg least affected by the pain and gently bend the hip and the knee until
both joints are fully flexed. Note the range of movement of both hip and knee.
Gradually
straighten the knee, while allowing the hip to extend only as much as the
patient feels is necessary for
The
test should then be repeated with the opposite leg.
Resisted
Extensor hallucis longus is served purely by lumbar nerve root 5 (L5).
It can be tested by comparing resisted extension of the tip of the big toes.
Stand at the feet of the patient and press down on the big toenails of each
patient while asking them to resist this pressure. If one distal phalanx drops
into flexion easily compared with the other toe despite the best efforts of the
patient, there is likely to be an L5 lesion (Fig. 20.7).
Testing
for motor weakness
L5 is the commonest nerve root to he affected by a prolapsed
intervertebral disc and is the only nerve root which is completely responsible
for serving one muscle (the extensor hallucis longus) and so is easy to test.
The simplest test for compromise of L4 motor function is loss of the knee reflex
and weakness in the quadriceps (demonstrated in the section on ‘The knee’).
The ankle reflex is lost in S1 damage, but beware; it is commonly missing in
elderly patients even without nerve root damage.