THE PLANTAR REFLEX - RePub

p. 132). The fact that both abnormalities disappeared together in these cases
also goes some way to dispel the possibility that the general population
might harbour many Babinski signs without motor deficit, patients
presenting at hospital being biased towards weakness. Moreover, in a
recent survey of 808 elderly subjects at home, Broe et al. (1975) found a
completed stroke in 7.3%, upgoing roe signs plus hyperreflexia without
definite diagnosis in 1.6%, and isolated Babinski signs in only 1.0%
(bilateral in half).
The next most frequent sign accompanying the Babinski response was
increase of tendon reflexes (7 4% ). However, hyperreflexia was not only
absent in a quarter of the 50 patients with a unilateral Babinski sign, it also
persisted in two cases where the upgoing toe sign and motor impairment of
the foot disappeared simultaneously. In other words, the Babinski response
and increase of tendon jerks occur regularly without one another. Hence
one is not entitled to expect a Babinski sign on the strength of increased
tendon jerks alone (cases 6 and 8, table XX). All other signs were found in
half the patients at most and could be attributed even less to the same part
of the lesion as the Babinski response.
Within the pyramidal syndrome, only impairment of skilled foot
movements is so intimately related to occurrence of the Babinski sign that
these two pathological features can be assumed to result from disturbance
of identical or similar pyramidal fibres, i.e. fibres having the same termination.
Proximal versus distal motor deficit
One patient who 'lacked' a Babinski sign (case 7, table XX) showed
weakness of hip and knee flexion (MRC 4) and reduced abdominal reflexes,
but power and skill in the foot were normal. In retrospect the absence of the
Babinski response is therefore not very surprising. It has even been questioned
if the pyramidal system is concerned with proximal movements at all. For
monkeys, Tower (1940) concluded from her experiments (medullary pyramidotomies)
that the corticospinal system was almost exclusively concerned
with distal motor functions. The work of Kuypers ( 1973) has modified this
concept: there are two separate brain stem pathways for control of distal and
of proximal and axial movements, both with a pyramidal contribution. For
man, in the two recent case reports of unilateral infarction of the medullary
pyramid (Chokroverty et al., 1975; Leestma and Noronha, 1976) some
movements ori the affected side were preserved, but these were not described
in detail.
On the other hand, disease seldom produces lesions that exclusively affect
descending projections to proximal muscles. This is illustrated by seven
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