Decompressive hemicraniectomy (DHC) is the most effective intervention to treat the
space-occupying effect of malignant cerebral infarction. Therefore, it is recommended
by international guidelines to improve survival and potentially neurological outcome
in selected patients with malignant middle-cerebral-artery (MCA) infarction.[1] In several studies, timing was identified as a relevant factor for the treatment
effect of hemicraniectomy in patients with malignant cerebral infarction.[2]
[3] Later, the randomized HAMLET trial[4] confirmed this finding, showing reduction of case fatality and poor outcome in patients
treated within 48 hours of stroke onset but no effect on functional outcome in patients
with treatment delayed up to 96 hours. Consequently, the pooled analysis of the randomized
trials DECIMAL,[5] DESTINY,[6] and HAMLET[4] included only patients treated within 48 hours after stroke onset regardless of
symptoms suggesting transtentorial herniation. In this large analysis of randomized
patients (n = 93), all < 60 years old with severe stroke (NIHSS > 16), decompressive surgery
led to higher rates of survival with mRS ≤ 4 (75 versus 24%; pooled absolute risk
reduction 51%; 95% confidence interval [CI]: 34–69)), survival with mRS ≤ 3 (43 versus
21%; 23% [5–41]) and survival irrespective of functional outcome (78 versus 29%; 50%
[33–67]). These results translate into impressive numbers needed to treat of 2 for
survival with mRS ≤ 4, 4 for survival with mRS ≤ 3 and 2 for survival irrespective
of functional outcome.[7] The DESTINY II trial revealed effectiveness of decompressive hemicraniectomy in
patients > 60 years old for survival with mRS ≤ 4, indicating nonsevere disability
(38 versus 18%; OR 2.91 [95%CI: 1.06–7.49]; p = 0.04).[8]
In this issue of Arquivos de Neuro-Psiquiatria, Rodrigues et al.[9] present a study of 43 malignant MCA stroke patients treated with decompressive hemicraniectomy
in a Brazilian tertiary hospital. The authors investigated the time course of hemispheric
cerebral volume after decompressive hemicraniectomy using hemispheric volumetric measurements
of all computed tomography scans (CT scans) performed during inpatient stay before
and after DHC. In the study cohort, decompressive hemicraniectomy was performed 41.88
(Standard deviation 29.32) hours after stroke onset. The peak of the hemisphere volume
was reached at day 7 (168.84 [95%CI: 142.08–195.59] hours) after the ischemic event.
However, the steepest increase in hemisphere volume was demonstrated in the early
phase after stroke onset and ∼ 28% of patients showed ipsilateral mydriasis before
DHC.
This highlights the importance of timely selection of malignant cerebral infarction
patients requiring and potentially benefiting from decompressive hemicraniectomy.
Advanced cerebral imaging could be supportive for this selection process. In an analysis
of the DESTINY registry including 140 malignant middle-cerebral-artery infarction
patients treated with decompressive hemicraniectomy and available semiautomatic quantification
of infarction, an association of infarct volume with outcome could be demonstrated.
In multivariable logistic regression, beside age and stroke severity, infarct size
before hemicraniectomy was an independent predictor of unfavorable outcome (OR 1.27
for 10 ml increase [95%CI: 1.12–1.44]; p < 0.001). Additionally, the authors calculated an infarction volume threshold for
unfavorable outcome with high specificity (94% for the overall cohort and 92% in younger
patients [≤ 60 years old]) as > 258 ml before hemicraniectomy.[10]
Furthermore, beside the proper selection of malignant cerebral infarction patients
with potential to benefit from decompressive hemicraniectomy, quality of the neuro-surgical
procedure is crucial for the treatment effect. In an interdisciplinary neurological-neurosurgical
study including 60 malignant MCA infarction patients treated with DHC, the incidence
of hemicraniectomy-associated parenchymal hemorrhages and hemicraniectomy-associated
infarcts was 41.6 and 28.4%, respectively.[11] Small operative bone defects were associated with hemicraniectomy-related bleeding,
leading to a significantly increased risk for mortality in these patients (survival
rate 55 versus 80%; p < 0.05). The authors therefore suggested a bone deficit of at least 12 cm and additional
duraplasty, as suboptimal hemicraniectomy might reduce the positive treatment effect
and adversely affect functional outcome and mortality.
The late occurrence of the peak hemisphere volume in the study by Rodriguez et al.
points at the importance of postsurgical monitoring of the decompressive effect of
the hemicraniectomy. Besides neuro-radiological cerebral imaging, bedside examinations
by palpation of the hemicraniectomy area, automated pupillometry and midline shift
monitoring using (transcranial) ultrasound could play an important role here and should
be performed frequently in DHC patients. Here again, timely detection of requirement
for and initiation of additional (rescue) intracranial pressure treatments as osmotic
therapy or hypothermia in selected patients may be relevant for the patients' clinical
course.[12]
Even though broader availability of mechanical thrombectomy for large vessel occlusion
acute ischemic stroke may reduce the incidence of malignant infarctions,[13] timing is the most important part in the management of patients with incipient malignant
MCA- stroke.
