Schwab_EU Neurology 08/03/2010 15:52 Page 113
Hemicraniectomy – An Overview of Current Status and Future Considerations
Figure 1: Natural Course of Malignant Middle Cerebral Artery Infarction
From left to right: cranial computed tomography (CT) scans on day two, three, four and five after symptom onset resulting in transtentorial herniation.
territory.
17,21,22
Other predictors that have been proposed to predict DEcompressive Craniectomy In MALignant middle cerebral artery
unfavourable outcome are pre-operative midline shift, low pre- infarcts (DECIMAL); and Hemicraniectomy After Middle cerebral artery
operative Glasgow Coma Scale (GCS), presence of anisocoria, early infarction with Life-threatening Edema Trial (HAMLET).
clinical deterioration and internal carotid artery occlusion.
23
In the meta-
analysis by Gupta et al., age was the only prognostic factor for poor DESTINY was an open, controlled, prospective, multicentre,
outcome, whereas time to surgery, the presence of brainstem signs randomised trial. Patients were randomised to either surgical plus
prior to surgery or additional infarction of the ACA or PCA territory were conservative treatment or to conservative treatment alone. The
not associated with outcome.
14
maximum time from symptom onset to treatment start was 36 hours.
All patients were treated in an intensive care unit (ICU) and were
Surgical Techniques intubated and ventilated. DESTINY was based on a sequential
The rationale of decompressive surgery is to remove a part of the design, taking mortality after 30 days as the first end-point, and
neurocranium and to provide space to accommodate the swollen brain. randomisation was planned to go on until statistical significance for
It further aims to normalise intracranial pressure, to avoid ventricular this end-point was reached. Thereafter, patient enrolment would be
compression, and to revert brain tissue shifts. Moreover, cerebral blood interrupted until the six-month functional outcome end-point (primary
flow shall also be restored, which may allow a better perfusion and end-point) – modified Rankin Scale (mRS) dichotomised at a score of
tissue oxygenation of still healthy brain to minimise infarct volume.
24,25
0–3 versus 4–6 – had been collected. Depending on the observed
There are two different techniques: external (removal of the cranial vault difference in functional outcome, the final sample size would be
and duraplasty) or internal (removal of non-viable, i.e. infarcted, tissue) recalculated for a second explorative trial stage. Secondary end-
decompression. The two techniques can be combined.
15,19
points included analysis of the mRS 0–4 versus 5–6 and the
distribution of scores of the mRS at six months and at one year. After
Meanwhile, there is a broad consensus among neurosurgeons about inclusion of 32 patients between February 2004 and October 2005,
the recommended procedure. External decompressive surgery patient recruitment was stopped due to the statistically significant
consists of a large hemicraniectomy and a duraplasty: a large results of mortality: in the intention-to-treat analysis, two of 17
(reversed) question-mark-shaped skin incision based at the ear is patients (11.8%) treated by hemicraniectomy had died, whereas
made. A bone flap with a diameter of at least 12cm (including the seven of 15 patients (50.3%) who received maximum conservative
frontal, parietal, temporal and parts of the occipital squama) is treatment on the ICU alone had died after 30 days (p=0.02). Functional
removed. Additional temporal bone is removed so that the floor of the outcome data after 12 months are summarised in Figure 2: 47.1% of
middle cerebral fossa can be explored. The dura is then opened and the patients in the surgical arm and 26.7% of the patients in
an augmented dural patch, consisting of either homologous periost the conservative arm reached an mRS of 0–3 (p=0.23), and 76.5%
and/or temporal fascia, is inserted (the size may vary; usually, a patch in the surgical arm versus 33.3% in the conservative arm reached an
of 15–20cm in length and 2.5–3.5cm in width is used). The dura is fixed mRS of 0–4 (p=0.01). Analysis of the distribution of the mRS scores
at the margin of the craniotomy to prevent epidural bleeding. The showed positive results in favour of surgery (p=0.04). After a sample
temporal muscle and the skin flap are then re-approximated and size projection for the primary end-point suggested a number of 94
secured. Ischaemic brain tissue is not usually resected. During this patients to be included in each arm, the trial was stopped.
29
procedure a sensor for registration of intracranial pressure can also
easily be inserted. In surviving patients, cranioplasty is performed DECIMAL was another open, controlled, prospective, multicentre
after at least six weeks (usually six to 12 weeks) using the stored bone trial that also randomly assigned patients to either surgical plus
flap or an artificial bone flap.
26
conservative treatment or to conservative treatment alone. Among
other criteria, an infarct volume on diffusion-weighted imaging (DWI)
Randomised Controlled Studies of at least 145cm
3
qualified patients for inclusion. Hemicraniectomy
In 2006 and 2007, data from three randomised trials were published had to be performed within 30 hours after symptom onset and
providing strong evidence for a dramatic reduction in mortality.
27–30
within six hours after randomisation. The primary end-point in
The trials were: DEcompressive Surgery for the Treatment of DECIMAL was functional outcome based on the score on the mRS,
malignant INfarction of the middle cerebral arterY (DESTINY); dichotomised 0–3 versus 4–6. A sequential design for this end-point
EUROPEAN NEUROLOGICAL REVIEW 113
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