THE PAINS OF LOCOMOTOR ATAXY.
Considering the vast amount that has been written about this disease
during the last few years, it might be thought superfluous for me to
give any description of its general features. But it unfortunately
happens that there is still great divergence of opinion among
authorities as to the true limitation of the group of cases that can
properly be ranked under this title, and, indeed, as to the propriety of
employing the title at all. The phrase ataxie locomotrice progressive,
as every one knows, was applied by Duchenne de Boulogne to a class of
cases which really only form a subdivision of the group known under the
older title of _tabes dorsalis_ and the most advanced German
pathologists maintain that the old word was better, and that Duchenne
was altogether wrong in making the one symptom, ataxy of locomotion, the
bases of a new phraseology;[49] more especially as his theory as to the
seat of the morbid changes was undoubtedly erroneous.
In this country, however, there is as yet no disposition to give up the
phrase locomotor ataxy, and it only remains to define with sufficient
care the class of cases to which the word is here meant to apply. The
disease is understood to depend upon a degeneration of the spinal cord,
of which the following description is given by Lockhart Clarke:[50] "In
true locomotor ataxy, the spinal cord is invariably altered in
structure. Its membranes, however, are sometimes apparently unaffected,
or affected only in a slight degree; but generally they are much
congested, and I have seen them thickened posteriorly by exudations, and
adherent, not only to each other, but to the posterior surface of the
cord. The posterior columns, including the posterior nerve-roots, are
the parts of the cord which are chiefly altered in structure. This
alteration is peculiar, and consists of atrophy and degeneration of the
nerve fibres to a greater or less extent, with hypertrophy of the
connective tissue, which give to the columns a grayish and more
transparent aspect; in this tissue are embedded a multitude of corpora
amylacea. Many of the blood vessels that travel the columns are loaded
or surrounded to a variable depth by oil-globules of various sizes. For
the production of ataxy, it seems to be necessary that the changes
extend along a certain length, from one to two inches of the cord. The
posterior nerve-roots, both within and without the cord, are frequently
affected by the same kind of degeneration, which sometimes extends to
the surface even of the lateral columns, and occasionally along the
edges of the anterior. Not unfrequently the extremity of the posterior
cornua, and even deeper parts of the gray substance, are more or less
damaged by areas of disintegration. The morbid process appears to travel
from centre to periphery, that is, from the spinal cord to the posterior
roots. In the cerebral nerves, on the contrary, the morbid change seems
to travel in the opposite direction, that is, from the periphery toward
the centres. From the optic nerves it has been found to extend as far as
the corpora geniculata, but seldom as far as the corpora quadrigemina.
With the exception of the fifth, seventh, and eighth pair, all the
cerebral nerves have occasionally been found more or less altered in
structure."
The symptoms which occur in cases in which the above are the morbid
appearances found after death are (roughly speaking) as follows:[51] "A
peculiar gait, arising from want of co-ordinating power in the lower
extremities, a gait precipitate and staggering, the legs starting hither
and thither in a very disorderly manner, and the heels coming down with
a stamp at each step."
No true paralysis in the lower extremities or elsewhere. Characteristic
neuralgic pains, erratic paroxysmal in the feet and legs chiefly--pains
of a boring, throbbing, shooting character, like those caused by a sharp
electric shock.
More or less numbness, in the feet and legs chiefly, in all forms of
sensibility, excepting that by which differences of temperature are
recognized.
Frequent impairment of sight or hearing, one or both.
Frequent transitory or permanent strabismus or ptosis, one or both.
No very obvious paralysis of the bladder or lower bowel.
No necessary impairment of sexual power.
No tingling or kindred phenomenon.
No marked tremulous, convulsive, or spasmodic phenomena.
No marked impairment of muscular nutrition and irritability.
No impairment of the mental faculties.
Occasional injection of the conjunctivae, with contraction of the pupils.
The probable limitation of the distinctive phenomenon of locomotor ataxy
(the want of co-ordinating motor power) to the lower extremities.
The above description includes all the necessary facts for the
recognition of the disease, except one, namely, that the use of the
eyesight is always needed in order to prevent the patient from falling
during progression; and is usually necessary even to enable him to stand
upright without falling.
The pains of locomotor ataxy are early phenomena in most cases, and they
are usually present, more or less, throughout the course of the disease.
They are often preceded by strabismus, with or without ptosis; the
strabismus, is usually accompanied by amblyopia. It may happen, however,
that neuralgic pains are, for a considerable time, the only noticeable
phenomena; or they may be attended with a certain amount of anaesthesia.
The most frequent type of the pains is lancinating or stabbing; they are
like violent neuralgias occurring successively in various nerves;
shifting about from one to another. Sometimes it will happen that the
pain remains fixed to one particular nerve for hours together; but it
never continues long without showing the characteristic tendency to move
about. Most commonly our diagnosis is soon assisted by the occurrence of
a greater or less degree of ataxy. But, even before the setting in of
definite atactic symptoms, the shifting character of the pains, and the
development of a very noticeable amount of anaesthesia, together with the
absence of anything like positive motor paralysis, will have given us
the necessary clew.
The effect of treatment, or rather its want of effect, usually affords
powerful assistance in distinguishing the pains of locomotor ataxy from
those of true neuralgia. Even where the pain has been fixed for some
hours in a single nerve, and has been stopped by some powerful remedy
(such as hypodermic morphia), it will be apt speedily to recur, and
frequently in some quite distant nerve.
Locomotor ataxy is a disease affecting chiefly the male sex, and
occurring in the immense majority of cases between the thirty-fifth and
the fiftieth year.
Not merely is it strictly limited to individuals who belong to families
with neurotic tendencies, but it is itself frequently seen to occur in
several members of the same family, and sometimes of the same
generation. When, therefore, we meet with neuralgic pains of the
shifting type above described, it is very important at once to make
careful inquiries whether any members of the family have suffered from
symptoms of ataxy going on to a fatal result. Otherwise, we might be the
more readily deceived into the idea that the pains were merely
neuralgic, because the symptoms of the disease are not unfrequently
provoked by such causes as fatigue and exposure to cold or wet, which
are also very ordinary exciting causes of true neuralgia.
FOOTNOTES:
[49] The most complete and careful work of the German school, on this
subject, is the "Lehre von der Tabes dorsualis," of E. Cyon. (Berlin,
1867.)
[50] _Lancet_, June 10, 1865. (Comment on a case of Dr. J. Hughlings
Jackson's.)
[51] Radcliffe, in "Reynolds's System of Medicine," vol. ii.