DISEASES OF THE CRANIAL BONES
Suppurative periostitis and osteomyelitis--Tuberculosis--
Syphilis--Tumours.
#Suppurative Periostitis and Osteomyelitis.#--These conditions may be
the result of infection through the blood stream, but as a rule they
follow upon a breach of the surface caused by a wound, a severe burn
as in epileptics, a tertiary syphilitic ulcer, or a compound fracture
that has become infected. Sometimes they follow suppuration in the
middle ear and mastoid or in the frontal sinus, and epithelioma and
rodent cancer that has ulcerated and become infected after spreading
from the face towards the vertex. They are occasionally associated
with acute cellulitis of the scalp. When the infection is blood-borne
suppuration occurs on both aspects of the bone--a point of importance
in treatment.
The illness is usually ushered in by a rigor, and this is soon
followed by other signs of suppuration--high temperature, pain and
tenderness, and the formation of a fluctuating swelling in relation to
the bone. When pus forms between the bone and the dura, there is a
characteristic oedema of the overlying area of the scalp--spoken of as
_Pott's puffy tumour_--which is of value as indicating the extent of
the disease in the bone, and of the collection of pus between it and
the dura. When suppuration occurs under the pericranium, an incision
gives exit to a quantity of pus, and exposes an area of bare bone. If
the incision is made early, this bone may soon be covered by
granulations and recover its vitality; but if operation is delayed, it
usually undergoes necrosis. The sequestrum that forms includes, as a
rule, only the outer table, but in some cases the whole thickness of
the bone undergoes necrosis. In either case the separation of the
sequestrum is an exceedingly slow process, and is not accompanied by
the formation of new bone. When the whole thickness of the skull is
lost, there may be a protrusion of the contents of the skull--hernia
cerebri; should the patient survive, the gap becomes filled in by a
dense fibrous membrane which is fused with the dura mater.
Serious complications, in the form of meningitis, cerebral abscess,
sinus phlebitis, and general pyaemia, are liable to develop at any time
during the progress of the infection, and we have seen pyaemia develop
after the suppuration in the skull had been recovered from.
_Treatment._--Early, free, and, if necessary, multiple incisions are
indicated to admit of disinfection of the affected area, and of the
establishment of drainage. If the symptoms point to suppuration having
occurred between the bone and the dura, the skull should be trephined
and further bone removed with the rongeur forceps as may be required.
Time may be saved by separating the sequestrum with the aid of an
elevator or sharp spoon, or by chiselling away the dead part till
healthy vascular bone is reached.
#Tuberculosis# of the cranial vault is usually met with in children.
The disease commences in the diploe, and results in the formation of a
central sequestrum, around and beneath which the tuberculous process
spreads. Granulations form between the skull and the dura, and on the
outer aspect lifting up the pericranium. The sequestrum is slowly
thrown off, and when separated is circular like a coin and presents
worm-eaten edges.
A circumscribed, tender swelling forms, at first yielding an obscure
sensation of fluctuation, but later, when the pus is no longer
confined under the pericranium, assuming the characters of a cold
abscess, which gradually becomes superficial, and eventually bursts
through the scalp, forming one or more sinuses.
The abscess should be laid open, all tuberculous granulations scraped
away, and the sequestrum removed, with the aid of the chisel if it has
not already become loose. On inserting the finger through the opening,
it appears to penetrate to an alarming extent; this is due to the
accumulation of tuberculous material between the skull and the dura
mater, depressing the latter. After healing is completed, a depression
or gap in the bone remains.
#Syphilis.#--Syphilitic affections occur during the tertiary period of
the disease, and usually implicate the frontal and parietal bones
(Fig. 202). They are described in Volume I., p. 462.
[Illustration: FIG. 202.--Skull of woman illustrating the appearances
of Tertiary Syphilis of Frontal Bone--Corona Veneris--in the healed
condition.]
#Tumours.#--_Osteoma_ of the skull has been described with diseases of
bone (Volume I., p. 481).
_Sarcoma._--All forms of sarcoma are met with, implicating the bones
of the skull. They may originate in the pericranium, in the diploe, or
in the dura mater, and usually involve the bones of the vault. They
sometimes occur in children (Fig. 203).
[Illustration: FIG. 203.--Sarcoma of Orbital Plate of Frontal Bone in
a child at age of 11 months, and 18 months.
(Mr. D. M. Greig's case.)]
The tumour grows chiefly towards the surface, but it also tends to
invade the cranial cavity, and may thus assume the shape of a
dumb-bell. Its growth is usually rapid, and results in the formation
of a diffuse soft swelling, which sometimes pulsates, and sooner or
later fungates through the skin. On account of its rapid growth the
tumour is liable to be mistaken for an abscess, and in some cases the
nature of the disease is only discovered after making an exploratory
incision, and finding that the finger passes through a softened area
in the bone.
When the cranial cavity is encroached upon, signs of compression
ensue. After the tumour has fungated, infective complications within
the skull are liable to develop. In all cases the prognosis is
extremely unfavourable.
If diagnosed sufficiently early, an attempt may be made to remove the
tumour, but often the operation has to be abandoned, either on account
of the haemorrhage which attends it, or because of the extent of the
disease.
The bones of the skull may become the seat of _secondary growths_ by
the direct spread of cancer from the soft parts, _e.g._ rodent cancer
(Fig. 204), or by metastasis of cancer or sarcoma from distant parts
of the body, or of thyreoid tumours. Metastatic cancer would appear to
be conveyed by the blood stream; it may occur in a diffuse
form--cancerous osteomalacia--softening the calvaria so that at the
post-mortem examination it may be removed with the knife instead of
the saw; or it occurs in a discrete or scattered form, and then the
macerated skull presents a number of circular and oval perforations.
[Illustration: FIG. 204.--Destruction of Bones of Left Orbit, caused
by Rodent Cancer. The patient died of septic meningitis.
(Mr. D. M. Greig's case.)]