VARIETIES OF PARALYSIS FROM DISEASE OF THE BRAIN, ETC. 635
veux, p. 110,) has, by his experiments, thrown much light on the cross
effects of lesions which give rise to paralysis and convulsions, yet he
appears to have gone too far in concluding that lesions on one side of
the cerebrum cannot give rise to convulsions on the same side of the
body; for it is very remarkable that in the cases of lesion of one side
of the brain, collected by Burdach, convulsions occurred in twenty-five
cases on the same side of the body as the disease; in only three cases
on the opposite side. Of these cases, those are, with reference to our
inquiry, especially important in which there was paralysis on the op¬
posite side, with convulsions on the same side as the cerebral lesion. In
thirty-six cases of lesion of one corpus striatum, attended with paralysis
of the opposite side of the body, convulsions occurred on the same side
as the cerebral disease in six instances, and in no instance on the op¬
posite side. This appears to be very much in favour of the old opinion
that, when convulsions occur in cases of lesion of one side of the brain,
with paralysis of the opposite side of the body, they most frequently
affect the same side as that on which the cerebral lesion is seated.
When the decussation of the corpora pyramidalia of the medulla
oblongata became known, it could not fail to be perceived that the cross
actions of the brain upon the body were thereby explained. The oc¬
currence of the paralysis on the opposite side of the body to the cerebral
lesion also proves that these decussating fasciculi themselves are the
parts of the medulla oblongata principally engaged in conducting the
motor influence of the brain to the trunk; whilst the fact, that the other
fasciculi of the cephalic portion of the cord do not decussate, affords an
explanation of those more rare cases in which lesions of the brain pro¬
duce their effects on the same side of the trunk;
There is greater difficulty in explaining the modes of action of the
brain in its influence on the cerebral nerves of the opposite or same side
of the body. For since these nerves arise, for the most part, above the
point of decussation of the pyramidal bodies, the structure on which
the cross action of injuries of the brain on them depends must have
some other seat; and, what involves the question in still more difficulty
is, that in man the nerve of the same side is as frequently affected as
that of the opposite side in cases of cerebral lesion. For a detail of
facts, I must refer to Burdach’s work, in which an admirable industry
is displayed. In twenty-eight cases of cerebral lesion of one side, the
muscles of the opposite side of the face were paralysed; in ten cases,
those of the same side. Paralysis of the eyelid was in six cases on the
same side; in five, pn the opposite. Paralysis of the muscles of the
eyeball, in eight cases on the same side; in four, on the opposite.
Paralysis of the iris, in five cases on the same side; in five also oh the
opposite. (Burdach, op. cit. iii. p. 372.) The tongue is generally
drawn towards the paralysed side of the face.
Cerebral lesions in man as frequently cause paralysis of the retina of
the same as of that of the opposite side. Since each optic nerve derives
a root from both hemispheres, this is in some measure intelligible. But,
according to the theory of the optic nerves, a lesion of one side of the
brain ought to produce not entire blindness of either retina, but merely
paralysis of one half of each, (see the account of single vision with the