THE PLANTAR REFLEX - RePub

surpnsmg to learn that the results were similar in patients with and
without a Babinski response.
Recording with needle electrodes from the extensor hallucis longus
muscle in patients with a Babinski sign was first applied by Kugelberg
(1948), and subsequently by Landau and Clare (1959). Landau and Clare
made a comprehensive study of the activity in various foot and leg muscles
during mechanical stimulation of the sole. They showed that the extensor
hallucis longus was silent in normal subjects, but that in patients with a
Babinski response this muscle was recruited into the flexion reflex synergy,
at the same threshold as the tibialis anterior and extensor digitorum
longus .
. . . or the extensor hallucis brevis?
The studies confirming the role of the extensor hallucis longus as the
effector of the Babinski response were contradicted by Kugelberg et al.
(1960). They reported reflex activity of this muscle in both normal and
pathological cases, following delivery of electrical stimuli to the plantar
surface (pulse trains of 30-40 ms duration). In contrast, the extensor
hallucis brevis was active in normal subjects only when the toes were
stimulated, and this muscle was never activated by plantar stimulation.
Grimby (1963 a) employed the same technique of stimulation (short
pulse trains, here 20 ms) and recording (needle electrodes) in a further
study of normal subjects. Again, reflex discharges in the extensor hallucis
longus were evoked from various parts of the plantar surface as well as
from the pad of the hallux, but in the extensor hallucis brevis only from
the latter site. It was inferred by Grimby that reflex action in the extensor
hallucis longus had little value as an index of disturbed function, and
subsequent studies (Grimby, 1963 b, 1965 a,b; Grimby et al., 1966) were
based solely upon activity in the extensor hallucis brevis (and its antagonist).
However, the results were complex, and no exact boundary could be
drawn between the electromyographic reflex patterns of patients with and
without a Babinski sign. To relate the electrically evoked discharges to the
toe response after conventional stimulation, the tracings were differentiated
not only into 'flexor' and 'extensor' patterns (Grimby, 1963 a), but also
into early and late parts (Grimby, 1965 a), and into degrees of contrast
between effects of hallux stimulation and of plantar stimulation (Grimby,
1965 b). Changes were not parallel in these respects, and the action of
different supraspinal mechanisms had to be invoked (Grimby, 1963 b,
1965 b).
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