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Surgical Outcome after Decompressive Craniectomy in Patients with Extensive Cerebral Infarction
The development of a space-occupying hemispheric infarction occurs in a subset of patients with ischaemic cerebrovascular stroke. It is a life-threatening condition with a high mortality rate of up to 80% with medical therapy alone. Previous retrospective and uncontrolled case series have suggested that decompressive hemicraniectomy can significantly reduce mortality to 20-30% compared to conservative treatment. This evidence has now been confirmed by the data of prospective randomised studies. The data also indicate that the reduction of mortality is not accompanied by an increase in the number of completely disabled patients. However, the number of disabled patients depending on the assistance of others increases significantly, and the patients and their caregivers need to be comprehensively informed about the long-term consequences prior to surgery. Furthermore, questions concerning the optimal time point for decompression and the upper age limit at which patients still benefit from surgery remain unanswered. Thus the indication for surgery is to a great extent still dependent on the individual situation of the patient and the experience of the treating physicians. This review covers the indications, the surgical technique, the prognostic factors and the clinical outcome with this procedure based on the data of retrospective series and the results of the recently published prospective randomised trials.
The exact effects of decompressive craniectomy on intracranial pressure (ICP) and cerebral tissue oxygenation (ptiO2) are still unclear. Therefore, we have monitored ICP and ptiO2 intra-operatively and correlated these values to different operative steps during craniectomy.
ICP and ptiO2 values have been monitored both, simultaneously and continuously, in 15 patients with cerebral edema due to posttraumatic or postischemic brain swelling. Indications for craniectomy were an increase in ICP above 25 mmHg or a decrease in ptiO2 below 10 mmHg resistant to conservative treatment (e.g. mannitol, hyperventilation, adequate arterial blood oxygenation, etc.). In all cases, we performed a fronto-temporo-parietal craniectomy (15 x 12 cm) and dura enlargement with galea-periosteum. During craniectomy, monitoring of ICP and ptiO2 in the affected hemisphere was continued. Values were recorded and correlated with the different operative steps.
We performed craniectomy according to our treatment protocol in 5 patients. Prior to surgery, mean ICP values were 25.6 mmHg (range: 23-29 mmHg), mean ptiO2 values were 5.9 mmHg (range: 2.4-9.5 mmHg), and mean CPP values were 66 mmHg (range: 60-70 mmHg). After removing the bone flap, ICP values dropped to physiological values (mean: 7.4 mmHg), whereas ptiO2 values increased only slightly (mean: 11 mmHg). Opening of the dura resulted in a further decrease of ICP (mean 4.8 mmHg) and an increase of ptiO2 to normal limits (mean: 18.8 mmHg). After skin closure, mean ICP was 6.8 mmHg and mean ptiO2 was 21.7 mmHg, respectively. We found a significant decrease of ICP after craniectomy (p<0.042) and after dura enlargement (p<0.039) as well as a statistically significant increase in ptiO2 after craniectomy (p<0.043) and after dura enlargement (p<0.041).
As a large bone flap in decompressive craniectomy is essential for adequate ICP reduction, the results of the presented cases suggest that dura enlargement is the crucial step to restore adequate brain tissue oxygenation and that ptiO2 monitoring could be an important tool for timing craniectomy in the future.