anatomy relate to the seat and source of the effusion, the amount and
condition of the blood, the state of the vessels and that of the
brain, including the ventricles. In respect to the seat, the
hemorrhage may occupy the space between the cranial bones and the dura
mater; it may be found on the lower surface of the latter, in the
arachnoid cavity, or in the meshes of the pia mater, the so-called
subarachnoid space. Blood found upon the outer surface of the dura,
between that membrane and the bones, is almost always the result of
traumatic causes, such as blows or other injuries, with or without
fracture, or of caries of the skull. If below the dura, but between
that and the so-called parietal layer of the arachnoid, the lesion
comes under the title of pachymeningitis interna, already described as
an inflammatory disease of the dura with hemorrhagic effusion. The
arachnoid cavity and meshes of the pia are by far the most common
situations in which the blood is found in meningeal hemorrhage. The
origin of the effusion is either the rupture of a capillary aneurism
of one of the arterioles of the membrane or of one of the vessels
themselves in consequence of atheromatous or other degenerations of
its walls. On account of the minute size of the vessels it is seldom
possible to discover the exact point at which the rupture took place.
In rare instances the source of the hemorrhage is within the brain,
the blood being forced through the cerebral tissue, either into the
meshes of the pia {714} or upon the surface of that membrane. The
amount of hemorrhage varies according to conditions which are mostly
unknown, but is probably dependent upon the size of the ruptured
vessel and the conditions under which the accident occurs, such as
muscular effort, cardiac action, etc. In some cases it is so small as
to give rise to no definite symptoms, as is evident from post-mortem
examinations of those who have died from other causes. In these cases
there may be either a single effusion or several. The amount is
largest when the arachnoid cavity is the seat of the extravasation.
The blood, which may be either liquid or more or less coagulated,
according to the time which has elapsed since the hemorrhage, is
usually found upon the convexity of the hemispheres, most frequently
on one side only, and oftenest on the left. But if the rupture have
taken place at the base, it often ascends on each side, as in a case
mentioned above. Where a large vessel has given way, its contents may
cover a great part of the surface of the brain. The coagulum is found
in a thin layer, which at the end of a few days is covered with a
transparent envelope, evidently composed of a deposit or separation of
fibrin. Should the patient survive long enough, this membrane may
become organized, receiving vessels from the adjacent pia, and in turn
become the seat of new hemorrhages, exactly as in the hæmatoma of
internal pachymeningitis. In cases in which absorption of most of the
fluid part of the effusion takes place, the membrane remains more or
less dense and vascular, and usually contains a small quantity of
recently-effused blood within its meshes. Small cysts, containing
transparent or reddish-brown serum, are also occasionally observed
enclosed between the layers of the membrane. In very young children,
whose fontanels are not yet ossified, these cysts sometimes attain to
a large size, containing several pints of fluid, which is more or less
limpid from absorption of the coloring matter of the blood,
constituting the so-called dropsy of the arachnoid.[14] The
convolutions of the brain are more or less flattened according to the
amount of the effusion, and the cortical substance is correspondingly
anæmic from pressure. The blood may make its way, if extravasated in
large quantities, into the ventricles, over the medulla, into the
spinal arachnoid cavity, or even into the central canal of the spinal
cord. The arteries of the brain, especially at the base, are
frequently in a state of atheromatous degeneration, and thrombi often
occupy the sinuses of the dura mater.
[Footnote 14: Charles West, M.D., _Lectures on the Diseases of
Childhood and Infancy_, 6th ed., London, 1874, p. 62. These large
cysts are much more frequently (perhaps solely) found in cases of
hemorrhagic pachymeningitis. (See Barthez and Sanné, _op. cit._, vol.
i. p. 157.)]
DIAGNOSIS.—The distinction between meningeal hemorrhage and cerebral
apoplexy is always difficult, and in the majority of cases impossible.
Sudden pain in the head, vomiting, and lowering of the bodily
temperature (the thermometer should be placed in the rectum), followed
by loss of consciousness, are strongly suggestive of hemorrhage within
the cranium, either cerebral or meningeal. If these symptoms are
followed by coma and resolution without obvious paralysis, the
diagnosis would be almost impossible between intra- and extra-cerebral
extravasation. If the loss of consciousness be not complete, so that
the presence or absence of paralysis can be ascertained, we can
sometimes distinguish the situation of the hemorrhage. Right-sided
hemiplegia, with paralysis of the face or tongue, or with aphasia, is
most probably owing to hemorrhage or {715} embolism somewhere in the
left motor tract, and hence within the brain. If the absence of
paralysis can be certainly ascertained, the probabilities are in favor
of meningeal apoplexy. Convulsions affecting the face or limbs of one
side would point to irritation of the cortical centres of those parts,
and so far to extravasation on the surface of the brain (on the
opposite side), as in Webber's case. Where the amount of hemorrhage is
small it furnishes no diagnostic indications. In the case of new-born
children the presumption is in favor of meningeal effusion.
PROGNOSIS.—If the effusion be considerable in amount, as indicated by
prolonged coma with resolution, the issue is almost inevitably fatal,
though life is occasionally prolonged for a surprising length of time.
Slight hemorrhages are doubtless recovered from, but there are no
means for their certain diagnosis.
TREATMENT.—The treatment, which is essentially the same as that for
cerebral congestion, has for its object the arrest of the hemorrhage,
and, if that can be effected, the absorption of the effused blood. In
view of the former, the patient's head should be elevated and kept
cool by the application of ice. Unless the bowels have previously been
freely moved, saline laxatives, followed by enemata if necessary, must
be given. The state of the bladder must be carefully attended to.
Liquid nourishment alone, in moderate quantities at regular intervals,
is permissible, with stimulants if there be signs of exhaustion. For
the absorption of the effusion mild counter-irritation to the scalp
and the administration of the iodide of potassium may be employed.
Congestion of the Cerebral Pia Mater.
The pia mater consists of two layers, separated by a loose connective
tissue. The outer layer, being that which was formerly called the
visceral layer of the arachnoid, is stretched smoothly over the
convolutions of the brain without dipping into the sulci; the inner
layer is closely connected with the surface of the brain, whose
inequalities it follows. The two layers are more firmly united
together over the convolutions than between them; in the latter
situation the connection is loose, and the space which separates the
surfaces is called the meshes of the pia. The membrane extends into
the ventricles, investing the ependyma and the choroid plexuses, and
over the medulla oblongata and spinal cord. In the normal condition it
is loosely attached to the brain, from which it can be stripped off
without loss of substance. The meshes of the pia, together with the
ventricles, constitute a series of cavities connected with each other,
containing a variable amount of cerebro-spinal fluid, and they
communicate with the lymph-spaces surrounding the blood-vessels.
Pressure within the cranial cavity, from congestion of the vessels or
from the products of inflammation, is thus relieved in a measure by
displacement of the cerebro-spinal fluid, which is driven out through
the perivascular lymph-spaces.
Congestion or hyperæmia of the pia mater probably never occurs
independently of that of the external surface of the brain, on account
of the intimate vascular connection of the two. In the adult it can
only exist to a limited extent, on account of the unyielding nature of
the cranial {716} walls and of the limited compensatory action of the
cerebro-spinal fluid. In young children the incomplete ossification of
the skull and the delicate structure of the vessels are more favorable
to congestion.
ETIOLOGY.—The causes of hyperæmia of the pia mater are in the main the
same as those of congestion of the dura.
SYMPTOMS.—Since congestion of the pia always coexists with that of the
corresponding part of the external portion of the brain, it is
impossible to separate the symptoms belonging to each. They are
therefore usually included under the head of Cerebral Congestion, to
which article the reader is referred.
PATHOLOGICAL ANATOMY.—Arterial hyperæmia of the pia is seldom
discovered after death, the elasticity of the vessels causing
transudation of the fluid part of the blood through their walls.
Venous congestion of the pia is more frequently noticed, usually in
connection with that of the dura, the sinuses with their accompanying
veins being distended with blood, and in cases of long standing often
containing thrombi. Simple hyperæmia of the pia being rarely or never
fatal of itself, these appearances are usually accompanied by those of
inflammation of the membrane or of the cortical layer of the brain
(effusion of lymph or pus), or by hemorrhage.
TREATMENT.—In a case of suspected congestion of the pia the treatment
would be the same as that of cerebral congestion.
Inflammation of the Cerebral Pia Mater.
SYNONYMS.—Meningitis, Leptomeningitis, Acute non-tubercular
hydrocephalus.
Meningitis (by which is generally understood inflammation of the pia)
appears under an acute, a chronic, and an epidemic form. The latter,
being a zymotic disease, is described in a separate article, to which
the reader is referred.
ETIOLOGY.—Meningitis occurs both as a primitive disease and as
secondary to other affections. The former is rare, the latter is more
frequent. The causes of idiopathic meningitis are for the most part
unknown. Exposure to the sun's rays and excessive indulgence in
alcoholic liquors are thought to excite it in some instances. It has
been known to follow blows and falls on the head which have produced
no injury to the skull. It is rather more commonly observed in early
manhood than at other periods of life. Secondary meningitis may follow
injury or disease of the cranial bones or of the dura, and of the
brain. A frequent cause is extension of disease of the ear to the
membranes and substance of the brain. The reader is referred to the
article on MEDICAL OTOLOGY for information concerning the symptoms of
that formidable complication. Certain diseases are known to be
occasionally complicated with meningitis—acute articular rheumatism;
erysipelas of the scalp and of the face; Bright's disease, especially
the chronic interstitial form; peritonitis; ulcerative endocarditis;
pyæmia; the eruptive fevers; the puerperal state; and syphilis.
Meningitis following or complicating acute rheumatism is generally
supposed to be not uncommon, but the number of cases in which the
existence of inflammation of the meninges has been {717} proved by
autopsy is small. Fuller,[15] along with three cases in which
dissection showed suppurative inflammation of the pia, cites several
others in which no cerebral disease was found after death, although
the symptoms gave every indication of it. True meningitis is rare in
chronic Bright's disease, the symptoms resembling it being caused, in
the majority of cases, by uræmia. Meningitis complicating pneumonia is
also rare, although cerebral symptoms are common enough in that
disease, especially in young children with inflammation of the upper
lobes. C. Neuwerk[16] reports seventeen cases of purulent meningitis
complicating acute pneumonia. It was more frequent in men, especially
in alcoholic subjects, than in women. The meningitis was generally
total. The lungs were in a state of gray or yellow hepatization.
[Footnote 15: H. W. Fuller, M.D., _On Rheumatism, Rheumatic Gout, and
Sciatica_, 3d ed., Philada., 1864, p. 271. See also E. Leudet,
_Clinique médicale de l'Hôtel Dieu de Rouen_, Paris, 1874, p. 133.]
[Footnote 16: _Deutsches Archiv für klin. Med._, xxix., 1881, p. 1;
and _Schmidt's Jahrbücher_, Band cxcviii., 1883, Nov. 5.]
SYMPTOMS.—The symptoms of acute leptomeningitis vary much in the
course of the disease. This is readily explained by the complex
character of the functions of the parts involved in the inflammation.
It may be assumed that the cortical layer of the brain is implicated
in every case unless of the most transient and limited kind; the
substance of the brain, cerebellum, and medulla are subjected to
pressure from the afflux of blood, from the effused lymph and pus, and
from the accumulation of serum in the ventricles; the cranial nerves
are exposed to pressure from the deposit of lymph, which may give rise
to irritation or to suspension of function or both; parts at a
distance from the seat of lesion may be functionally disordered by
reflex action through communicating filaments. Finally, the general
system suffers from the effects of the high fever upon the blood and
the nutrition.
It is customary to speak of a stage of excitement followed by one of
depression as characteristic of the course of the disease; but
although active symptoms generally prevail in the early period, to be
succeeded later by coma and paralysis, this disposition is by no means
uniform. Sometimes sopor and paralysis constitute almost the only
symptoms throughout the disease—this is especially noticed in
infants—or active delirium and convulsions may persist until the fatal
termination. More frequently the two conditions alternate several
times with each other. A prodromic period of short duration, a few
hours or a day or two, is sometimes observed in primitive meningitis,
the patients complaining of headache, vertigo, vomiting, restlessness,
or lassitude. Infants are irritable or drowsy, with heat of the head,
quick pulse, and occasional vomiting. In secondary meningitis this
period is usually masked by the symptoms of the primitive disease. In
the majority of cases the beginning of acute meningitis is abrupt.
Rigor is sometimes the first symptom observed, and in children is
usually represented by a convulsion. More commonly, however, the
disease is ushered in by severe headache, which is often referred to
the forehead. The head is hot, the face is flushed, the eyes are
brilliant, the pupils are contracted, the pulse is quick and hard, the
temperature high (104° F. or upward). The patient is wakeful,
restless, and irritable, sensitive to light and to sound. The skin is
hyperæsthetic, {718} especially that of the legs. There may be
wandering or even active delirium. Vomiting is not unfrequent. There
is thirst, but no desire for food. The urine is scanty and
high-colored, the bowels constipated. These symptoms gradually
increase in intensity, especially the pain in the head and the
delirium, and in many cases they are followed by convulsions, at first
in the form of twitchings of the facial muscles or of the limbs,
grinding the teeth, etc., which give place to tonic contractions of
the limbs or of the trunk, often confined at first to one or both
members of the same side, but afterward becoming general; the flexors
of the forearms and of the legs are most usually affected. The upper
dorsal muscles may become contracted, so that the head is drawn
backward, and more rarely trismus occurs.
A diminution in the rapidity of the pulse, which may fall to the
normal rate, or even below that, notwithstanding the persistence of
the high temperature, indicates the beginning of the stage of
depression. This change is sometimes sudden, though more often gradual
in its approach. The activity of the delirium subsides, giving place
to a somnolence which may seem to the inexperienced observer a
favorable indication, but which soon deepens into coma. The face
becomes pale, the features are sunken. Only an occasional grimace or a
movement of the hand to the head shows that the patient is to some
extent conscious of suffering. This condition may alternate with the
previous one from time to time, the comatose state being interrupted
by noisy delirium and tonic or clonic convulsions, or even a partial
return of consciousness, giving rise to fallacious hopes on the part
of the friends, and sometimes deceiving the physician himself into a
belief that a favorable issue is at hand. Before long, however, the
symptoms of brain-compression become permanent. The rigidity of the
limbs gives place to complete resolution. The patient lies absolutely
unconscious, with dilated pupils. The pulse becomes again rapid in
consequence of compression of the medulla, and thread-like and
irregular; for the same reason the respirations increase to 40, 50, or
60 in the minute. The sphincters are relaxed, and the patient dies
without any recurrence of the active symptoms. In rare cases recovery
takes place, although almost never after the symptoms of compression
have continued without interruption for any considerable length of
time. Moreover, it is seldom that recovery takes place in the adult
without leaving some traces of permanent damage, such as general
debility, paralysis of one or more limbs, deafness, mental weakness,
epilepsy, etc. Many cases of general paralysis of the insane and other
forms of so-called mental disease are the result of meningitis.
DURATION.—In the adult usually the disease lasts about a week or ten
days; exceptionally, it may last two or three weeks.
COURSE.—In young children the course of meningitis differs somewhat
from that which is observed in adults, though the symptoms are
essentially the same. It is more sudden in its onset and shorter in
its duration. The prodromal stage may be brief or hardly noticeable;
but in older children restlessness, sensitiveness to light and sound,
wakefulness, slight twitchings of the features or of the limbs, a
half-open condition of the eyelids during sleep, occasional vomiting,
etc., are more commonly noticed. Convulsions are more common than in
the adult, and sometimes constitute the chief symptom. They may be
confined to a single extremity, but in {719} general they shift from
one limb to another. The muscles of the eyeball are usually
implicated, causing strabismus. Retraction of the head is rarely
absent, especially in young infants. These convulsions are almost
always tonic, but occasionally they alternate with clonic ones.
Distension and increased pulsation of the anterior fontanel is always
observed in infants a few months old affected with this disease. When
meningitis is secondary to some other disease, the first symptom
noticed in children is apt to be vomiting, with delirium. According to
Steffen, pneumonia is the disease most frequently complicated with
meningitis in children. As in tubercular meningitis, the most
prominent symptom may be mere sopor, sometimes with intervals of
intelligence. Simple meningitis in children is generally a rapid
disease, proving fatal in most cases within a week, and sometimes even
in a few hours. Exceptionally, it may last much longer. A case
occurring in a girl six years old, the duration of which was
fifty-five days, is reported by J. Bokai, Jr.;[17] the diagnosis was
substantiated by autopsy. Another case, which recovered after seven
weeks, is mentioned by Henoch.[18]
[Footnote 17: _Jahrb. f. Kinderkrankheiten_, N. F., xviii. 1, p. 105;
and _Schmidt's Jahrb._, 1882, No. 6, p. 269.]
[Footnote 18: Eduard Henoch, _Vorlesungen über Kinderkrankheiten_,
Berlin, 1881, p. 277.]
PATHOLOGICAL ANATOMY.—The lesions, which are rarely general, may
occupy a greater or less extent of the membrane. They are usually
disposed symmetrically with regard to the two hemispheres, or occupy
corresponding regions of the base. The vessels are in the beginning of
the disease distended, the finest ramifications being injected, giving
a red color to the membrane, which varies in different places from
crimson to light pink. The perivascular spaces of the larger vessels
are filled with a grayish or yellowish fluid composed of extravasated
liquor sanguinis and white blood-corpuscles. The meshes between the
two layers of the pia are soon infiltrated with pus, and the thickened
membrane can be stripped off from the surface of the brain, which is,
however, adherent to it in places and is torn in the process.
Sometimes a thin layer of pus, which can be scraped off with the
knife, is found upon the surface of the pia. The extent of the lesion
varies much in different cases. It may be confined to a limited region
of the hemispheres, or it may spread to the fissure of Sylvius, where
two surfaces become adherent. Sometimes the concrete pus and fibrin
are deposited in thick masses upon the base of the brain, often
completely surrounding the cranial nerves, and even the medulla. The
inflammation may extend to the lateral ventricles, which become filled
with a turbid fluid containing pus-cells, and sometimes wholly
purulent. The choroid plexuses are often covered with flecks of pus.
When the distension of the ventricles is very great, the gyri of the
brain are more or less flattened by compression against the cranium,
and the outer layer of the cerebral substance is bloodless and
œdematous. The cerebral sinuses are distended with blood, and
frequently contain thrombi due to an early stage of the inflammatory
process, besides recent coagula.
DIAGNOSIS.—The diagnosis of acute meningitis is often difficult, and
sometimes impossible, especially in the early stages, when the line
between congestion and inflammation cannot be drawn, and in
complicated cases. The typical symptoms are sudden and acute pain in
the head, with {720} sensitiveness to light and sound, contracted
pupils, rapid pulse, and vomiting, followed by delirium, convulsions,
and coma. If these symptoms were observed in an individual previously
in good health, they would be strongly suggestive of the disease, and
yet many of them are often present in the beginning of pneumonia,
erysipelas, typhoid, typhus, and other eruptive fevers, uræmia, and
poisoning from narcotic substances. Hence it is important to eliminate
these sources of error before coming to a conclusion, and a neglect of
this precaution is a not infrequent source of error in the diagnosis.
A careful examination of the urine will generally enable us to exclude
uræmia. The presence or absence of the eruptive fevers can usually be
determined by the attendant circumstances, and yet cases of
scarlatina, typhoid fever, variola, etc., beginning with active
cerebral symptoms, are sometimes hastily pronounced to be meningitis
by inexperienced observers. In poisoning by narcotics the history will
often aid us in the diagnosis; moreover, except in the case of opium,
the pupils are dilated instead of being contracted. In traumatic
cases, with fracture of the cranial bones, it is always difficult, and
often impossible, to distinguish between the symptoms of meningitis
and those due to other lesions. In concussion without fracture we must
be guided in our diagnosis by the same rules as in idiopathic cases.
The distinction between extreme congestion of the pia mater and
meningitis must be based chiefly upon the duration of the symptoms.
The former is usually brief in its course; the latter lasts one or two
weeks, and in cases which recover is often followed by after-effects
which are more or less permanent in their duration, such as paralysis
or rigidity of the limbs, mental defects, etc. Rapid recovery from the
acute symptoms would be strongly suspicious of congestion, and
doubtless in many such cases the treatment has been credited with a
success to which it was not entitled. The diagnosis from tubercular
meningitis will be reserved for the article on that disease.
PROGNOSIS.—Acute meningitis is fatal in the majority of cases, though
recovery is possible. A gradual diminution of the severity of the
symptoms, especially in respect to temperature, pulse, pain in the
head, and other cerebral phenomena, would afford encouragement, but we
must not trust too much to the brief appearances of amendment so often
observed.