9 Neurosurgery lectures
20.4 Techniques for craniotomy
20.4.1 PREOPERATIVE PREPARATION
In general, cranial surgery should not be performed
until a stable blood pressure and adequate lung
function, confirmed by blood gas analysis, have been
achieved (Chapter 17).
However, in a patient who is comatose, particularly
if there has been a documented deterioration in
conscious level or development of focal signs, removal
of the hematoma is a matter of great urgency. The
patient should be intubated and hyperventilated, if
this has not already been done, and mannitol 1 g/kg
should be given immediately as the patient is taken to
the operating theater.
Prior to, or during the preparation for craniotomy,
the following ‘checklist’ should be completed:
1. blood to laboratory for:
(a) cross matching (2 units of whole blood);
(b) coagulation studies
(i) prothrombin index
(ii) partial thromboplastin time
(iii) platelet count;
(c) blood gas analysis;
(d) routine full blood count and electrolytes;
2. X-rays of chest and cervical spine (or keep cervical
spine in collar);
3. consent for surgery;
4. Foley catheter in bladder;
5. two large bore peripheral i.v. lines, or one peripheral
and one central line (maintaining
CVP> 5cmH2O);
6. arterial catheter;
7. protection of both eyes from fluids and pressure;
8. adequately secured cuffed endotracheal tube.
The head should be placed on a horseshoe or
doughnut headrest, turned to place the operative side
uppermost and slightly elevated above the level of the
heart. A sandbag placed beneath the ipsilateral shoulder
makes turning the head easier. Pressure points
should be carefully padded. Unless deterioration is
rapid, the scalp should be shaved and prepared withpovidone-iodine as for any other intracranial procedure.
The drapes can be stapled into place to prevent
them becoming dislodged if the head has to be turned
or moved during the procedure. Antibiotics, anticonvulsants
and mannitol are used as required. Strict
attention to anesthetic techniques is vital to avoid
hypercarbia and further elevation of intracranial
pressure.
20.4.2 EXPLORATORY BURRHOLES
With the wider availability of CT, the necessity for
exploratory burrholes is declining. They will be
required only very rarely in hospitals with a CT
scanner; however, they may be life-saving in rural
locations where transfer to a CT-equipped facility may
involve long delays.
The use of exploratory burrholes implies that
confirmation of the position or even the presence of a
hematoma is lacking. It is therefore important to have
access to the whole head and to explore all likely sites
bilaterally before discarding the diagnosis of intracranial
hematoma. The extent of this exploration will
be determined at least in part by the experience and
skills of the operator, given that this will frequently be
a non-neurosurgeon working in less than ideal circumstances.
It should always be possible to obtain
neurosurgical advice by telephone and this should be
encouraged. Specific guidelines for the management
of head injury in remote locations in Australia have
been established by the Neurosurgical Society of
Australasia.
(a) Technique
The patient is placed supine on a horseshoe or
doughnut headrest. The whole head is shaved, prepared
and draped to allow access to both frontal,
parietal and temporal areas. The site for the initial
burrhole is determined according to the most likely
site of the suspected hematoma. If a dilated pupil is
present, it will usually be ipsilateral to the hematoma.
The next most valuable localizing feature is a hemiparesis,
which will usually be contralateral to a hematoma.
If a fracture is present it is most likely to overlie
an extradural hematoma. It must be stressed that none
of these signs is absolute and if no hematoma is found
on the suspected side, the other side should be
explored in all cases.
Unless a fracture is present in a different location,
the first burrhole should be temporal, as this is the site
of most extradural hematomas. It is frequently written
that a burrhole placed as little as 2 mm away from the
edge of an extradural hematoma will fail to identify it,
and this tends to discourage the inexperienced doctor
in a difficult situation.
This is just an extract of these lectures.
There r 8 other lectures included in the folder on the following topics:
-Anterior communicating artery aneurysm
-Arteriovenous malformations
-Gliomas
-Head injury
-Spine injury
-Peripheral nerve injury
-Spinal tumors
-Peripheral nerve tumors
-Spinal nerve tumors
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