THE PLANTAR REFLEX - RePub

confirmed by Walshe (1914). His is another classical study inspired by
Sherrington, and it can now be recommended without the cautionary note
'not free from insular prejudices' (Jelliffe and White, 1923).
In one important aspect, however, Walshe's findings were different
from those of his French colleagues. Marie and Foix regarded the upgoing
toe as the minimal response of the shortening synergy. Accordingly, they
stated that the Babinski sign could occur without other reflex phenomena
in the leg. Walshe, on the other hand, found that contraction of the
hamstring muscles (semitendinosus and semimembranosus) constituted
the minimal response or 'motor focus' of the flexion reflex, and that the
threshold for activation of the extensor hallucis longus was always
higher. Walshe explains the difference by pointing out that early contraction
of the hamstring muscles is often noticeable only by palpation of the
tendons and may easily be overlooked; this was also observed by Munch­
Petersen (1902). Visual information alone can be misleading, because the
extensor hallucis longus muscle is almost unopposed by gravity; the same
applies to the musculus tensor fasciae latae. The important inference was
therefore that the Babinski sign was never obtained without contraction of
other limb flexors. Forty-two years later, Walshe (1956) could still assert
that he had never seen an isolated 'extensor response'! In contrast, a
downward response of the toes may very well be the only reflex movement.
Opposition from Babinski and others
Babinski did not at first react favourably to the idea that the normal
downward response of the roes had nothing to do with the flexion reflex of
the leg, whereas the upgoing toe sign was part of this synergy - all this
conflicted with his concept of the 'transformation' of the flexion reflex. He
contested the 'simple' nature of the normal response with the argument
that it could be evoked from the thigh or abdomen in some patients
(Babinski, 1904 a, b), but it was later shown that this phenomenon is part
of a pathological extensor synergy, including the (anatomical) toe flexors
(see p. 36). Initially, Babinski had to oppose only van Gehuchten, a
dialogue complicated by unrelated issues (van Gehuchten, 1904; Babinski,
1904 b), but when the other arguments were put forward by Marie and
Foix (1912, 1913) and Walshe (1914), he became more or less reconciled to
these ideas (Babinski, 1915 a, 1922). Babinski admitted in these studies
that there were strong ties between 'his' sign and the flexion reflex of the
lower limbs, but on the other hand he persistently maintained that these
ties were not indissoluble. His arguments are summarized below, together
with later objections.
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