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Chapter I), and that stimuli which are 'definitely noxious' (Kugelberg et<br />
al., 1960) should by implication be appropriate. This is as incorrect as the<br />
notion that the flexion reflex can be evoked only by stimuli which are<br />
'noxious', i.e. painful in the average subject (Scholten, 1964, 1965 ). Anyone<br />
who has dealt with paraplegic patients knows that even a piece of cottonwool<br />
can sometimes evoke a full flexion reflex (Walshe, 1914; Szapiro,<br />
1958). Because of this, it should be stressed that association of the Babinski<br />
sign with activity in small myelinated fibres (A-delta) and unmyelinated<br />
fibres (C), as derived from latency measurements in conjunction with<br />
blocking techniques (Kugelberg, 1948; Ashby, 1949; Landau and Clare,<br />
1959), does not necessarily implicate harmful stimuli in every case.<br />
Of course stimulus intensity is not irrelevant, but most important of all<br />
is the combined spatial and temporal summation produced by the traditional<br />
moving stimulus. This summation of afferent impulses in the spinal<br />
cord determines the emergence of the characteristic reflex effects: in<br />
normal subjects usually activation of the flexor hallucis brevis, as opposed<br />
to recruitment of the extensor hallucis longus in certain supranuclear<br />
disorders.<br />
Babinski empirically reached a similar conclusion much earlier. In his<br />
first publication of 1896 he mentioned 'piqure' (pricking) of the plantar<br />
surface as the stimulus used, to be replaced in the main paper by stroking<br />
('chatouillement').<br />
CONCLUSIONS<br />
1. The muscle which mediates the Babinski sign is the extensor hallucis<br />
longus, and not the extensor hallucis brevis.<br />
2. The Babinski sign is invariably accompanied by reflex activity in the<br />
tibialis anterior; the reverse is not always true.<br />
3. Electrical stimulation of the sole may activate the extensor hallucis<br />
longus in control subjects, and fail to do so in patients with a Babinski<br />
stgn.<br />
4. Electrical stimulation of the sole often evokes simultaneous activity in<br />
the antagonists for the plantar reflex (extensor hallucis longus and<br />
flexor hallucis brevis), whereas this co-activation is exceptional after<br />
mechanical stimulation.<br />
(cont. next page j<br />
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