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CHAPTER 23
TRANSVERSE LESIONS OF THE LUMBAR CORD (EPICONUS AND CONUS)
These may still be of spastic type below the transection if the lesion is confined to the
lumbar segments. While the knee jerks are reduced or absent as a result of the involvement
of L2-L4 segments, the ankle jerks are present and may be exaggerated, including ankle
clonus. If 14 has escaped, the knee jerks may be present, though diminished, but plantar
stimulation may provoke withdrawal response, and Babinski's sign and its modifications
(Oppenheim, Gordon and Chaddock) are positive. In lesions also involving L5, knee
jerks and Babinski's sign are absent but ankle jerks are still positive and so are Rossolimo's
and Mendel-Bechterew's signs. However, not infrequently, traumatic lesions of the I2th
dorsal and the first two upper lumbar vertebrae result in destruction of the distal thoracic
and lumbosacral cord, resulting in areflexia and paralysis of lower motor neuron type.
This applies in particular to the epiconus syndrome affecting 14-82 segments.
With regard to the disturbances of bladder, bowels and sexual functions in these
distal lesions, see the chapter dealing with these functions. In the following, only the
paralysis of the muscular system, reflexes and sensory functions are discussed.
LI SEGMENT
The quadratus lumborum is still reduced in power and all muscles of the lower limbs are
paralysed, including cremasterics, iliopsoas and sartorius. The cremasteric reflex is
absent. Knee and ankle jerks are exaggerated and the pyramidal signs, as mentioned
above, may be present.
Sensory loss involves all areas of the lower limbs and extends to the groins and to the
back above the buttocks.
L2 SEGMENT
All distal abdominal muscles and cremasterics are intact and there is also some, although
reduced, function of iliopsoas and sartorius. Sometimes the sartorius may be the only
muscle present at this level and its contour is clearly visible underneath the skin on
voluntary contraction. There is also a flicker of the gracilis. The cremasteric reflex is
positive.
Sensory loss involves the lower limbs with the exception of the upper third of the
anterior aspect of the thighs.
L3 SEGMENT
There is better hip flexion, due to increased function of iliopsoas and sartorius, and the
adduction of the legs is also increased, due to action of the adductor longus, pectineus and
gracilis. The legs are outwards rotated. The function of the rectus femoris is reduced.
The knee jerks may be absent or greatly reduced.
Sensory function is present over two-thirds of the anterior aspect of the thighs,
otherwise there is a complete sensory loss over the lower limbs, including the saddle area.
