PATHOLOGY. 237 
torture when in a healthy ftate; and, like them, when 
inflamed, it acquires a high degree of morbid fenfibility. 
To this we attribute the head-ache, more or lefs violent, 
which invariably attends on arachnoiditis. This mem¬ 
brane is inflamed by the fame caufes which inflame other 
ferous membranes; and, like them, frequently throws 
out aqueous collections, or forms adhefions where the 
furfaces were before free; or, like thofe fubftances, it 
forces out a whitifli or jero-albuminous fluid, fome- 
times forming layers of falfe membrane. 
The primary and moll frequent caufes of the difeafe, 
are percufllons of the head, expofure to the fun, organic 
iefions of the brain itfelf, apopleCtic difpofition, and de¬ 
prefling paflions. Among the fecondary caufes, in point 
of frequency or importance, are metaftafes of different 
kinds, fuppreflion of habitual difcharges, the ufe of 
ftrong drinks, and the common caufes of other internal 
phlegmafiae, as of pleuritis, gaftritis, &c. 
The firft ftage of arachnoiditis is marked by an increafe 
of the fenfibility, and by head-ache, one of the moll con¬ 
ftant characters of the difeafe. A tendency to fopor is 
fometimes manifefted, efpecially when the difeafe is 
Yeated at the bafe of the brain. The ftomach alfo is 
fympathetically affeCted with naufea or vomiting. A 
febrile movement is generally elfabliflted in the fyftem, 
varying according to the age of the fubjeCt, the fenfibi¬ 
lity of the conftitution, and the degree of the inflam¬ 
mation. In fome rare cafes, efpecially of metaftafis, 
coma fets in from the beginning, and all the fymptoms 
of the third period or ftage (defcribed hereafter) com¬ 
mence at once, and are quickly followed by death. The 
duration of this firft ftage is ufually from a few hours to 
three or four days. 
The fecond ftage or period, which is that of re-aCtion, 
is accompanied with difturbance in the locomotive 
powers, correfponding with that of the brain itfelf. It 
is in this ftage that we obferve convulfions, delirium, reft- 
lefliiefs, ofcillations or commencing dilatation, of the pu¬ 
pils, and other phenomena of cerebral inflammation. 
In this ftage the pain in the head is lefs conftant than in 
the firft ftage, thefenforium appearing lefs fenfible ofim- 
preflions, as well internal as external. This ftage varies 
in duration, from two, three, or four, days, to one or 
even two weeks. It exhibits fome difference in fymp¬ 
toms according to the principal feat of the difeafe. When 
the latter is at the bafe of the brain or in the ventricles, 
coma is almoft effential, and is combined with convul¬ 
fions, agitation, affeCtion of the eyes, &c. whereas, if 
the arachnitis be on the convexity of the hemifpheres, 
delirium is the early and regular and charaCteriftic phe¬ 
nomenon. 
The third ftage is that of the fhorteft duration, vary¬ 
ing from a few hours to three or four days, and rarely 
palling that period. This is the ftage of collapfe ; the 
abolition of fenfe, lofs of motive power, paralyfis, local 
or general, and coma, being the charaCteriftic fymptoms. 
In this ftage, however, the features of various cerebral 
affections are combined, and confequently all diftinCtions 
between arachnoiditis and inflammations of other parts 
of the brain confounded. 
The collapfe fo charaCteriftic of the third period or 
ftage, and the excitement which diftinguifhes the fecond, 
have this peculiarity, that, while one part of the body 
fhall prefent the phenomena of one of thefe ftages, ano¬ 
ther part fhall prefent thofe of the other. For ex¬ 
ample, in the face, we fhall often fee the mufcles of 
the eye-lids paralytic, while thofe about the mouth are 
convulfed. It is principally when the arachnoiditis ex- 
ifts about the bafe of the brain, near the decuffation of 
the optic nerves, that this medley of fymptoms belong¬ 
ing to two different ftages is obferved. It is almoft need- 
lefs to fay, that a return to health from any of thefe 
ftages (this is rarely the cafe from the third) is marked 
by a diminution of intenfity in the fymptoms, and a 
final ceflation of them. At the fame time it is often dif¬ 
ficult to diftinguifh the tranfition from one ftage into 
another, efpecially of the firft into the fecond, and the 
fecond into the third. No fingle fymptom can be de¬ 
pended on for this difcrimination j the whole mull be 
taken in connexion. 
The fymptom of the greateft importance in the inva- 
fion of this difeafe is head-ache. It is often intenfe, but 
varies confiderably according to its feat. Cephalalgia 
then, occurring fuddenly, and efpecially when violent, 
fliould always excite fufpicion of arachnoiditis, whether 
it takes place in a perfon previoufly well, or labouring 
under fome other difeafe. 
As far as regards the expreflion of the countenance in 
arachnoiditis, a general character of furprife and ftupor 
is obferved, which it is impoflible to defcribe, but which 
cannot eafily be miftaken, after being once feen. More¬ 
over the pupils are dilated or contracted, or alternately 
in each ftate. The globe of the eye prefents a greater 
or lefs degree of rednefs in the conjunCtiva ; fquinting 
on one or both fides; conftant rolling of the organ, its 
reverfion upwards, and finally paralyfis of the upper eye¬ 
lid. Few cafes occur without fome affeCtion of the 
pupils. 
The mufcular aCtions of the face are fometimes de¬ 
ranged; and trifmus is by no means a very unfrequent 
attendant on this complaint. It feldom occurs till after 
the firft ftage is pall. Grinding of the teeth, and foam¬ 
ing at the mouth, are generally feen only among child¬ 
ren ; and in the fecond and third ftages of the difeafe. 
Spafmodic or convulfive movements of the facial muf¬ 
cles are not very frequent, and never feen but in the ad¬ 
vanced ftages. Generally fpeaking, the face is coloured 
and animated in arachnoiditis $ fometimes, however, it is 
pale and void of expreflion. 
Delirium frequently aft'eCts adults, who are moft dif- 
pofed to arachnoiditis of the convexity of the brain. It 
is generally of the tranquil kind, or a muttering of hair- 
articulated words between the teeth. It is feldom fo in¬ 
tenfe but that the patient can be roufed to anfwer dif- 
tinCtly at times. Thefe remarks appertain to the firft and 
fecond ftages. In the third, there is generally an anni¬ 
hilation of the intellectual faculties. The commence¬ 
ment of delirium may, for the moft part, be confidered 
as the fign of tranfition from the firft to the fecond ftage, 
and forms the moft charaCteriftic feature of arachnoiditis 
of the convexity of the hemifpheres. Where there is no 
delirium, there is generally either dulnefs. morofenefs, 
irafcibility, or preternatural excitement, and unufual ex¬ 
hilaration. In almoft all cafes, however, we fee a marked 
diminution of the cerebral faculties, or an itnpoflibility, 
as it were, of bringing them into action $ fo much fo, 
that many patients can only be induced to utter mono- 
fyllables. 
Somnolency is one of the moft frequent of all the phe¬ 
nomena of arachnoiditis. When the difeafe purfues its 
ordinary courfe, this fymptom does not appear till the 
end of the firft or beginning of the fecond ftage. In a 
very few cafes it has been obferved from the very com¬ 
mencement. Head-ache is almoft infeparable from the 
firft and part of the fecond ftage of the difeafe. It is 
highly probable that it continues to the laft, though not 
complained of by the patients, who are overwhelmed by 
the force of the difeafe, and incapable of diftinguiftiing 
any particular fymptom. They generally characterize 
the pain as heavy, numb, or (hooting, ufually occupying 
the whole, but fometimes only half, of the head. The 
apparent feat of the pain is not always the feat of the 
difeafe. Stupor, characterized by a kind of felf aban¬ 
donment, lofs of all energy, and countenance of furprife, 
is common to every ftage of the difeafe, but efpecially 
the two firft. In a very few cafes there has been obfti- 
nate pervigilium, inftead of fomnolency ; and in a ftili 
fewer ((howing that there is no rule without exception), 
