THE PLANTAR REFLEX - RePub

craniocaudal direction 'leg fibres' comprise projections to neurones from
the L, segment down to 5 2 . As the upgoing roe sign is a manifestation of
pathological recruitment of the extensor hallucis longus muscle into the
flexion reflex synergy (see Chapter III), and as the motoneurones of this
muscle are located in the dorsolateral parr of the ventral horn of the L 5
segment (Sharrard, 1955 ), why should we a priori expect it when there is,
for instance, weakness of hip flexion (L 1
-L 3
) or an increased knee jerk
(L 2
-L 1
)? In addition to divergence of pyramidal projections in a craniocaudal
direction, the descending innervation within each segment is not
restricted to the anterior horns, but includes important cofitributions to
the intermediate zone and even the dorsal horn (Kuypers, 1973 ). In
consequence, if we should find that the Babinski sign showed little
segmental specificity, particularly in relation to motor deficits (projections
to anterior horn cells), it might be possible ro connect it with multisegmental
release of the flexion reflex as a whole (projections to interneurones,
which are heavily interconnected).
The question I shall attempt to answer in this chapter is now as follows.
Given that the Babinski sign is not always associated with all other
components of the pyramidal syndrome, is it possible to relate it more
closely to certain features of the pyramidal syndrome? Such correlations
might, in turn, give insight into physiological and anatomical connections:
- if the Babin.rki sign is released by a disturbance of projections to
motoneurones, we should expect it to be always accompanied by motor
deficits in foot and toe muscles;
- if the Babinski sign is the result of general release of the interneuronal
pool in the intermediate zone of the spinal gray matter, we should
expect exaggeration of the entire flexion reflex in all cases.
A few earlier studies have registered the concurrence of various deficits
and release phenomena in the lower limbs. Graeffner (1906) examined
116 patients with hemiplegia and found an increased knee jerk more often
(77%) than an upgoing toe sign (63%). Lassek (1945) assembled 1600
cases with one or two Babinski signs from the literature: motor deficits
(97%) and increased patellar reflexes (66%) were ar the top of the list.
Dohrmann and Nowack (1974) looked for mutual correlations among
various features on the side of a Babinski sign (61 patients, some bilateral).
For the leg they found significant correlations only between hyperreflexia
and clonus (the authors admit they were not surprised by this) and
between weakness and hypertonus.
In view of the theoretical presumption that the upgoing roe sign might
be preferentially associated either with distal motor deficits or with
exaggeration of the flexion reflex as a whole, examination of the patients
in the present study included not only the power of various foot and toe
119