Reprinted from The Journal of Nervous and Mental Disease, January, 1892. 
INEQUALITY OF THE PUPILS IN EPILEPTICS, 
WITH A NOTE ON LATENT ANISOCORIA.1 
By WILLIAM BROWNING, M.D., Brooklyn, N. Y. 
r condition of inequality of the pupils, technically 
I termed anisocoria, is not very rare even in persons 
of average health. No great importance attaches 
to it in any class of troubles, but as an objective sign it is 
worthy of further study. 
Its occasional occurrence in epilepsy has long been 
noticed, and a diagnostic value has even been attributed to 
it in suspected cases of the nocturnal form (Fiirstner, 1886). 
It is of course merely a symptom, occurring casually 
where there happens to be some implication, if only ex- 
haustion, of the pupillary paths or centres. 
In a series of 150 consecutive cases of epilepsy observed 
for interval symptoms at the Long Island Hospital Dispen- 
sary in the last eight years, this condition was noted alto- 
gether in 16,2 although varying some in degree and con- 
stancy. Of these 16 cases, 12 were males and 4 females (of 
the whole series of 150, 84 were males and 66 females). 
Only 3 (y were in patients over 22 years, while two-fifths 
(f) of the whole series were over that age. One of these 
three older patients was a typical Jacksonian, another was 
probably some secondary form of convulsions, and the third 
showed slight indications of tabes : hence it is evident that 
in idiopathic epilepsy, anisocoria occurs predominantly 
among the younger patients. 
A few quotations from authorities at hand will serve for 
comparison. 
Schleick (1886), in examining 127 hospital epileptics, 
found only one case of decided difference in the width of the 
pupils, the eyes being otherwise normal. Marie (Arch. de 
1 Presented to the American Neurological Association, Washington, 
D. C., Sept. 22, 23 and 24, 1891. 
2 In one other case it was questionable, but put down as negative. In 
still another, the outline of one pupil may not have been Regular. Nenrolg., 1882, Paris) observed an inequality in 8 of 53 in- 
stitution cases (about 15%), the difference amounting to 
} mm. in 6 and to f mm. in 2. Musso (1884, quoted by 
Hare) found that there was in 22.8"/0 (of 70 cases) an in- 
equality of the pupils. Addison (1867, also from Hare) 
found an inequality in 2 of 50 insane epileptics. Oliver, of 
Philadelphia, from his studies on 50 adult American male 
epileptics at the Norristown Asylum (1887), says: “Pupils 
are, as a rule, equal in size and alike in shape." 
As to the proportion in non-epileptics, or as to what 
proportion of the above cases may be due to local anom- 
alies of the eye itself, we have no figures for comparison. 
The different proportions found by the above authorities 
may be partly due to closeness as well as time of observa- 
tion. For, in frequent cases, there is just a suggestion of 
inequality, yet not so pronounced as to be at first unmis- 
takable. Moreover, the condition seems to be somewhat 
more frequent and more marked directly after an attack. 
The different age of the patients, as already indicated, may 
have some influence. 
Probably the above proportion in my own cases, of 16 
in 150, might have been increased had the slighter inequal- 
ities been more carefully sought, especially in the earlier 
cases of the series. But a close scrutiny even of this lim- 
ited number suffices to show certain important differences, 
and to suggest more exactly why there may readily be a 
wide diversity in such statistics. 
Three somewhat distinct types are distinguishable. 
1. Where there is a very considerable inequality. 
This form—doubtless the only one heeded by many ob- 
servers3—occurred in a special class of patients. There 
were three such cases, and each was in an epileptic with 
decidedly unilateral symptoms, These were all in younger 
males, though of course this form might well occur at any 
age. 
One of the three was a syphilitic with typical Jackson- 
ian seizures. The second was probably hereditarily syph- 
2 
WILLIAM BROWNING. 
3 As, e. g., Schleick, Addison and Oliver, mentioned above. INEQUALITY OF THE PUPILS IN EPILEPTICS. 
3 
ilitic (when finally relieved of his epilepsy the pupils grad- 
ually became equal). The third patient had suffered a 
traumatic cerebral hemorrhage as a cause. 
These cases show that any great inequality of the pupil 
in an epileptic depends on some localized intracranial 
trouble, i. e., it is then not so much an epileptic as a focal 
symptom. 
Of course it goes without saying that in plenty of cases 
of unilateral epilepsy there is no anisocoria. 
2. Cases of slight inequality, and in which the condition 
is fairly constant. 
This does not preclude some variation from one obser- 
vation to a subsequent one. In a few cases the immediate 
effect of the seizures is noticeable, but even then it is rather 
to accentuate the condition than to develop it anew each 
time. 
Of this form there were ten examples, indicating that 
it is more frequent in epileptics than the other two forms 
combined. In certain of these the difference was so trifling 
that the observation had to be independently corroborated 
before its acceptance. Doubtless in these cases the pe- 
culiarity is only functional. It might simply be classed as 
an exhaustion-sign, like the pareses seen at times after 
seizures, but for its greater persistence when once present. 
Sometimes in these first two forms the wider pupil was ob- 
served to re-act less than the other, indicating (according to 
Heddaeus) that then the inequality was due to sphincter- 
paresis of the wider pupil.4 
3. Latent anisocoria—distinct inequality only in faint 
illumination. 
Various non-epileptic cases first convinced me that 
there is a frequent form of latent pupillary inequality—pos- 
4Dr. James Oliver (Brain, October, 1888, p. 359) says : “When the pu- 
pils are unequal [in epileptics], the last effort at accommodation may 
determine equality, the inequality only reappearing with the state of com- 
parative rest. In testing the reaction to light, I have frequently remarked 
that, whilst the pupils may, in conjunction, react well to this excitation, 
separately the one more dilated will be found to contract with less certainty 
and less markedly than the smaller, and at the same time, manifests a 
greater tendency to return forthwith to its pre-existing state of dilatation.” WILLIAM BROWNING. 
4 
sibly not well recognized as yet—and that a more exact 
method of examination and specification might be adopted. 
These were cases of astigmatism, brain-tumor, old' apo- 
plexy with atrophy of one optic nerve (the most striking 
case of all), various other nerve troubles, and also individ- 
uals otherwise apparently normal. In these there was a 
more or less marked inequality during faint or poor illumin- 
ation, but such inequality quite disappeared on strongly and 
generally illuminating both eyes. 
Dr. J. C. Shaw also tells me of a case in a syphilitic 
ataxic in whom with scant illumination there was irregular 
outline as well as inequality of pupils, both abnormal con- 
ditions disappearing completely on exposure to strong 
diffused light. 
To guard against the frequently deceitful effects of 
shadows, if lateral illumination be used in examining for 
slight degrees of this form, it should be tried alike from 
each side before deciding. 
As a plausible explanation it may be suggeste4 that 
whilst the passive (z. e., sympathetic) innervation of the 
pupils is in such cases unequal or disproportionate, the re- 
flex impulse—equal for the two eyes—is, when fully called 
into play, quantitively so far in excess as to completely 
overbear all passive ones and so for the time being to 
wholly dictate the pupillary condition. The relative super- 
iority of the oculomotor control of the pupil, as compared 
with the sympathetic, is of course a matter of every-day 
observation. 
This explanation interprets the morbid phenomenon as 
a symptom resulting not simply from bilaterally uneven 
sympathetic action, but as one that only appears at times 
when the action of the oculomotor is relatively or abso- 
lutely in abeyance. 
Hence we should distinguish : 
(1) A passive or latent anisocoria. 
(2) An active or at least continuous inequality. 
If possible, the type observed should always be specified. 
Of course the first two forms of inequality above described 
belong to the second of these classes. INEQUALITY OF THE PUPILS IN EPILEPTICS. 
5 
Certainly, even with this precaution, it remains a rela- 
tive matter so far as estimating the degree of illumination 
—and in some of these latent cases the visual power was 
greatly reduced in one or both eyes. The minimum limit 
is, however, furnished by the least illumination consistent 
with a proper inspection of the pupil. 
Although most of these observations were in other 
troubles, this form was demonstrable in 2 of the last 50 
epileptics; and a recent examination of an earlier case (still 
an epileptic) discloses a marked example of this. Doubt- 
less, an ignoring of this matter in making examinations 
might give a certain diversity of results, although as a 
whole, an exclusively latent inequality is evidently not very 
common in these patients. 
As a rule, including the epileptic cases, the inequality 
even in least illumination was very slight; but in one case 
(non-epileptic), it was as great as almost ever seen from 
natural causes. 
Of the three classes of cases, it can confidently be as- 
serted that in the present series, all those of the first class 
have been noted, and hence for this type they may serve 
as a proper average (1 in 50). 
But at first, little attention was paid to the second and 
third classes. If, however, only the last 50 cases in the 
series be considered, it transpires that amongst these, pupil- 
lary inequality occurred 8 times (those of the first form all 
happened to occur in the first 100 cases). This gives i6°/0 
and agrees very well with that of Marie (15%) or that of 
Musso (22.8%). Together, these give 32 cases of anisocoria 
in 173 cases of epilepsy, or about 18.5°/0. In other words, it 
appears that on an average one epileptic in every five or 
six will, if examined with care, prove to have some, though 
usually slight, inequality of the pupils. As this conclusion 
is based on the fairly harmonious results of three observers 
in different countries, it is admissible to infer that those 
finding a smaller proportion must have simply overlooked 
the common slighter difference in size of the pupils.