THE PLANTAR REFLEX - RePub

esult in disappearance of the Babinski sign, while it did abolish plantar flexion of the toes
in normal subjects. Marinesco and Noica (191)) repeated Babinski"s experiment in a
healthy volunteer, and found selective loss of distal power and of the ankle jerk. The
hyperexcitability of the flexion reflex after ischaemia - providing the efferents are not
blocked- was later attributed to a specific effect on afferent nerve fibres from the skin, with
a reverse change in tendon reflexes and tone (Gilliatt, 1952).
It is more difficult to explain why the reflex in the flexor muscles of the toes -provided
this is still remnant in patients - recovers earlier from ischaemia than the response in irs
more proximal antagonists. Marie and Foix (1912), who confirmed this finding, assumed
that the muscles of the sole had a better vascular supply. Landau and Clare (1959)
implicated mechanical compression of the lateral popliteal nerve against the head of the
fibula, buc Babinski probably applied the bandage more proximally. Whatever its explanation,
the difference in sensitivity to ischaemia between the normal and pathological plantar
response does not detract from the identity of the Babinski sign with the flexion reflex. The
dissociation only indicates that the normal response may still emerge under some circumstances.
c) Upgoing toe without flexion reflex of the leg
Whereas the two preceding categories were advanced by Babinski as instances of an
exaggerated flexion reflex without dorsiflexion of the hallux, he also observed the reverse,
if only by applying light stimuli. In this respect, Babinski was supported by Marie & Foix
(1912, 1913), and not by them alone. Bing (1915) found that proximal reflex phenomena
accompanied the upgoing toe sign in most patients with spinal lesions, but only exceptionally
in cerebral disease. The occurrence of an isolated Babinski response was subsequently
mentioned by Fulton and Keller (1932), Szapiro (1958) and also by Scholten (1964, 1965),
who came to the surprising conclusion that only this constitutes the real Babinski sign,
quite separate from the sign described by Babinski. Guillain and Dubois (1914) published
the case history of a young woman with infantile hemiplegia in whom an upgoing toe
phenomenon could be evoked from as far rosrrally as the ipsilateral face, while "the defence
reflexes were nil'. In this last patient, the flexion reflex was probably masked by the
concomitant spasticity of the extensor muscles in the leg - the extensor hallucis longus is
the only physiological flexor muscle able to overpower its antagonists (Walshe, 1923 ).
This explanation, however, probably does not account for all reported instances of an
isolated Babinski sign. Walshe (1914) comends that in such cases a barely palpable
contraction of the hamstring muscles or a just visible twitch of the musculus tensor fasciae
latae has been overlooked. Although this follows from one of the most detailed studies on
the subject, at this stage it must remain an open question whether this explanation is
universally applicable (it will be referred to again in Chapter IV). That the recruitment
order of muscles taking part in the flexion reflex could vary from one patient ro another
was stressed by Bersot (1917- 1919), and by DimitrijeviC and Nathan (1968).
Some authors, apparently quite unaware of the physiological discussions
about the toe muscles, continued to connect the upgoing toe phenomenon
to extensor synergies of the lower limb (Meyers, 1920; Armenise, 1924;
Tournay, 1926; Salomon, 1921), or the normal plantar response to the
flexion reflex (Goldflam, 1908; Waggoner and Ferguson, 1930; Yakovlev
and Farrell, 1941; Morgenthaler, 1948).
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