| Objective: The first documented use of Cranioplasty(CP) was before the16th century. As a routine neurosurgery operation, in more recent medicine, its use has primarily been limited to cosmetic and protective indications. However, CP gained recent attention after numerous clinical case studies documented neurological benefits, although by yet-unknown mechanisms. Magnaes et al. found that the zero CSF pressure level and the hydrostatic indifferent point were cranially shifted in five patients with large skull defects, and that those parameters returned to normal after CP. Yamaura et al. coined the term "syndrome of the sinking skin flap," reasoning that the neurological benefits of CP were secondary to a micro change in the atmospheric pressure within the brain. Therefore, people believed that the timing of CP should be reconsidered in light of recent studies. Several studies have discussed the topic of CP timing, in terms of complications and outcomes. However, the results remain controversial. Most studies found that early surgery had no effect on the rate of complications, including infections, and improved patient outcome. Conversely, other studies indicated that early CP was associated with a higher risk of complications. To date, the effects and mechanisms of early CP compared to late CP on neurological recovery are poorly understood and have been scarcely evaluated. The present study addresses this topic as it pertains to the recovery after DC and discussion of timing of CP.Our research was designed in two steps:observing therapeutic benefits when performed after DC, as measured by an improvement of cerebral blood flow (CBF), cerebral perfusion, intracranial pressure, EEG, cognitive function, and quality of life; investigating the effects and mechanisms of early CP compared to late CP on neurological recovery, from the perspective of cerebral blood flow, operation efficiency and complication rate.Methods and Results:Part1Observing therapeutic benefits and underlying mechanism when performed after DC. We employed several methods to measure the improvement of cerebral blood flow (with TCD technique), cerebral perfusion (with CTP and PWI-MRI), intracranial pressure, neurological function (with BEAM technique), cognitive function (with SAS and SDS evaluation), and quality of life (with WHOQOL-BREF) after DC. The results showed that after DC, blood flow velocity of MCA ipsilateral to the CP raised significantly from50.8±13.83cm/s (pre-DC) to64.4±10.2cm/s (post-DC)(t=-25.62, P<0.001). Meanwhile, no significant improvement was observed in the other vessels. We also assessed the cerebral perfusion by MR perfusion weighted imaging and CT perfusion techniques before and after3months the CP.And the abnormal index A of cerebral perfusion was significantly lower3months after the CP than that before CP. And the ICP after CP changed significantly (F=4826.592, P<0.001). For EEG examination,θ/β and (δ+θ)/(α+β) power ratio declined significantly after CP. SAS score and NIHSS score declined significantly after CP (SAS t-0.384, P=0.703,NIHSS t=16.793, P<0.001) while the SDS score had no significantly change (t=-0.384, P=0.703)Part2Discussing the timing of early CP and possible benefit-risks. This study retrospectively reviewed43patients undergoing early (<12weeks) or late (≥12weeks) cranioplasty after DC. The CBF velocity was measured by transcranial Doppler ultrasonography and was analyzed prior to and after CP in every patient. The operating time, dissection time and blood loss was measured during the surgery. Complications and NIHSS scoring were recorded. In the early CP group, the CBF velocity increased after the CP procedure in both the ipsilateral MCA (54.3±9.90cm/s vs.69.2±14.1cm/s; t=-4.712, P<0.001) and the ipsilateral ICA (33.2±7.08vs.48.5±9.43cm/s; t=-6.154, P<0.001). In the MCA contralateral to the CP, the CBF velocity also increased (57.8±7.60vs.66.9±7.97cm/s; t=-4.107, P<0.001) after CP. There was no difference in the velocity change in the contralateral ICA (29.6±6.25cm/s vs.30.3±8.37cm/s; t=-0.340, P=0.737).In the late CP group, the CBF velocity increased in the ipsilateral MCA (52.8±12.70cm/s vs.63.4±13.52cm/s; t=-2.167, P=0.045) after CP. In contrast to the early CP group, the CBF velocity in the ipsilateral ICA (38.6±10.39cm/s vs.43.2±10.93cm/s; t=-1.444, P=0.167) and contralateral MCA (59.7±12.61cm/s vs.67.4±13.08cm/s; t=-1.609, P=0.126) increased, but the differences were not statistically significant between pre-and postoperative status. Similar to the early CP group, there was no change in the CBF velocity in the contralateral ICA (31.5±9.76cm/s vs.28.5±9.06cm/s; t=0.929, P=0.366). Change (expressed as delta,△) was defined as the difference in CBF velocity between pre-and postoperative status in the early and late CP groups. In the ipsilateral MCA, the patients in the early CP group had a greater increase in velocity compared to patients in the late CP group (F=4.443, P=0.042). Comparing with the control group, the mean time for dissection was much shorter (12.9±7.2vs30.1±10.8min, P<0.001) and estimated blood loss (226.3±40.3vs381.5±58.9ml, P<0.001) was much smaller in the early cranioplasty group. The difference in subdural fluid collection between the early and late CP groups was not statistically significant (P=0.634). No other statistically significant differences of complication were found.Conclusions:Part1Observing therapeutic benefits and underlying mechanism when performed after DC. The study showed obvious improvement of cerebral blood flow (with TCD technique), cerebral perfusion (with CTP and PWI-MRI), intracranial pressure, neurological function (with BEAM technique), cognitive function (with SAS and SDS evaluation), and quality of life (with WHOQOL-BREF) after DC.Part2Discussing the timing of early CP and possible benefit-risks. The CBF velocity in the middle cerebral artery (MCA) ipsilateral to the CP was increased in both groups and statistically different between groups (p<0.05). On the contralateral side, however, the CBF in the MCA was increased in the early CP group but not the late CP group. Change (expressed as delta,△) was defined as the difference in CBF velocity between pre-and postoperative status in the early and late CP groups. A statistically significant difference was detected in the△of MCA on the ipsilateral side between the early and late groups. There were no differences in the incidence of complications between groups. Early cranioplasty provides more efficiency surgery procedure and losses less blood during the operation. Therefore, early CP has potential benefits for cerebral perfusion and operation efficiency. |
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