THE PLANTAR REFLEX - RePub

Of the 12 patients without evidence of foot weakness, impairment of
skilled movements could still be demonstrated in eight. Six of these eight
patients had discrete proximal weakness, two had no loss of power at all.
In the whole group of 50 patients with a unilateral upgoing toe sign,
only four remained who showed neither weakness nor loss of skill. All
relevant findings in these exceptional patients are listed in table XVIII. To
find in all four the relatively rare sign of hallux dorsiflexion on contralateral
hip flexion against resistance is statistically highly significant (occurrence
in the whole group 22%, the Fisher test gives p = 0.001). Because
this phenomenon was also found on the control side of other patients,
(table XVI) it can hardly explain in itself why a Babinski sign occurs in the
absence of demonstrable motor deficit in the foot.
In summary, 92% of the patients with a unilateral Babinski sign showed
some motor deficit in the foot, 16% having a disturbance of rapid
movements alone.
Increased tendon reflexes
Hyperactivity of tendon jerks came second in the list of motor abnormalities
found in conjunction with a Babinski sign: 74%. There was no
correlation (either positive or negative) with the presence of other
pathological signs: table XIX, A, shows that the distribution of the other
signs in patients with symmetrical tendon jerks is quite comparable to that
in the group of 50 patients as a whole (Fisher test: differences not significant).
Table XVI shows that asymmetry usually involved various reflexes at
the same time. The ankle jerk was rarely increased alone (10%), and not
preferentially in cases with a purely distal motor deficit: of the seven
patients with motor impairment in the foot only, all or most tendon
reflexes were exaggerated in four, only the ankle jerk in one, and in two
patients the tendon jerks were symmetrical. The jerks elicited from the
adductor and biceps femoris muscles rarely gave extra information, and
obtaining the latter was sometimes a little awkward. These findings imply
that hyperreflexia usually involves all leg muscles, with little segmental
specificity or differentiation between (physiological) flexor and extensor
muscles.
Exaggerated flexion reflex in proximal muscles
By definition the flexion reflex is more active on the side of a unilateral
Babinski response, as the extensor hallucis longus muscle is recruited into
the synergy. One of the principal questions in this chapter was how often
this also involved increased reflex activity in proximal flexor muscles.
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