Trend differences in cervical spinal cord injuries before and after the coronavirus disease 2019 pandemic.

STUDY DESIGN: Cross-Sectional Study. OBJECTIVES: To investigate the changes in the characteristics of cervical spinal cord injuries (CSCI) before and after the coronavirus disease 2019 (COVID-19) pandemic among patients transported to our hospital in Japan. SETTING: Hospital with an emergency center in Chiba, Japan. METHODS: Patients eligible for the study were those transported within 24 h of injury and diagnosed with cervical spinal cord injury between January 2018 and December 2021 at our hospital. Medical records were retrospectively examined to investigate the number and characteristics of patients with CSCI. The clinical variables of patients with CSCI were compared according to the time of admission as related to the COVID-19 pandemic: 2018-19 (before) or 2020-21 (after). RESULTS: The total number of patients with CSCI from 2018 to 2021 was 108, with 57 before the COVID-19 pandemic and 51 after the COVID-19 pandemic. The number of severe cases with an injury severity score (ISS) of >16 decreased after COVID-19 (p < 0.05). Falls on level surfaces were the most common cause of injury both before and after COVID-19. Although the ranking of traffic accidents decreased after COVID-19, among those, the number of bicycle injuries tended to increase. CONCLUSIONS: The number of serious cases with an ISS > 16 decreased, presumably because of the decline in high-energy trauma due to the background decrease in the number of traffic accidents.

Association between the early repolarization pattern and nocturnal suicide attempts.

AIM: Numerous recent reports have highlighted the association between mental disorders and electrocardiographic findings. The early repolarization pattern (ERP) on electrocardiogram has been linked with a history of suicide attempts and attention deficit hyperactivity disorder, and associations with impulsivity have also been reported. It is known that suicidal intent is more common at night. Patients who have a mental disorder and ERP may have a higher likelihood of impulsivity, potentially increasing the risk of suicide at night. METHODS: The subjects were 43 patients with a history of suicide attempts who had undergone electrocardiographic examination at Jikei University School of Medicine Kashiwa Hospital and received intervention from our department. Due to the diurnal variation in electrocardiographic findings, only patients who underwent the examination during the daytime were included. Patients' clinical backgrounds were compared according to the presence or absence of ERP, and the association between nocturnal suicide attempts and ERP was examined using multivariate analysis. RESULTS: The frequency of nocturnal suicidal behavior was 76.2% in patients with ERP and 31.8% in those without ERP, but the difference was not significant after Bonferroni correction. In the multivariate analysis, there was a significant association of ERP with nocturnal suicide attempts (p = 0.018). CONCLUSION: The finding of an association between ERP and nocturnal suicide attempts indicates that ERP is a biological indicator that can predict nocturnal suicide attempts.

Yield of Whole Body Computed Tomography in Hyper-Acute Stroke Patients With Large Vessel Occlusion.

PURPOSE: In the majority of cases, large vessel occlusion (LVO) in ischemic stroke patients has an embolic origin. Systemic embolism can occur simultaneously with brain thrombosis. This retrospective study evaluated the frequency and locations of systemic embolism in LVO stroke patients receiving revascularization therapy. MATERIALS AND METHODS: In our facility, we use contrast-enhanced computed tomography (CE-CT) to assess suspected stroke patients and routinely perform CE-CT from the chest to the abdomen after brain CT angiography to rule out contraindications like aortic dissection and trauma for thrombolysis. Systemic embolism is also assessed using these images, while myocardial infarction is evaluated based on electrocardiograms and laboratory findings. Other relevant clinical features of each patient are also analyzed. RESULTS: In total, 612 consecutively admitted stroke patients and 32 LVO patients who underwent revascularization therapy were included in the present study. Systemic embolism was identified in four patients (13%). The spleen was the most commonly affected organ, followed by the heart, kidneys, limbs, and lungs. All four patients with systemic embolism exhibited LVO resulting from embolism as the underlying mechanism. CONCLUSION: Systemic embolism was observed in 13% of our LVO patients, all of whom had LVO of embolic origin.

The predictive value of modified soluble urokinase plasminogen activator receptor (suPAR) with National Early Warning Score (NEWS) for mortality in emergency elderly patients in Japan: a prospective pilot study.

Aim: The aim of this study is to evaluate the ability of soluble urokinase plasminogen activator receptor (suPAR) and modified suPAR with National Early Warning Score (NEWS) for detecting mortality in elderly emergency patients who are older than 70 years. Methods: This is a secondary analysis of our previous study, which was a single-center prospective pilot study, carried out for 21 months in the emergency department of a secondary emergency institution in Japan. This study was carried out between September 16, 2020, and June 21, 2022. The study included all patients without trauma aged 70 years or older who presented to the emergency department. Discrimination was assessed by plotting the receiver-operating characteristic curve and calculating the area under the receiver-operating characteristic curve (AUC). Results: During the study period, 47 eligible older patients were included, among which 8 (17.0%) patients died. The median suPAR was significantly lower in the survivor's group than in the nonsurvivor's group (P < 0.01). For suPAR, the AUC for the prediction of mortality was 0.805 (95% confidence interval 0.633-0.949, P < 0.001). The AUC of modified suPAR with NEWS for mortality was higher than that of suPAR [0.865 (95% confidence interval 0.747-0.958, P < 0.001)]. Conclusion: Our single-center study has demonstrated the high utility of modified suPAR with NEWS as a predictive tool of mortality in elderly emergency patients. Evidence from multicenter studies is needed for introducing modified suPAR with NEWS in the emergency department setting.

The REMIT scale: A novel prediction scale for embolism in hyperacute stroke with large vessel occlusion.

BACKGROUND AND PURPOSE: Large vessel occlusion (LVO) in hyperacute ischemic stroke occurs mainly by one of two mechanisms, embolism or atherosclerosis. However, the mechanism is difficult to identify prior to treatment. We aimed to investigate the factors associated with embolic LVO in hyperacute ischemic stroke, and to develop a preoperative predictive scale for the event. MATERIALS AND METHODS: This retrospective multicenter study was conducted with consecutive ischemic stroke patients with LVO who underwent thrombectomy, thrombolysis, or both. The embolic LVO was defined as an occlusion that underwent recanalization with no residual stenosis. Multivariate logistic regression analysis for embolic LVO was performed to identity the independent risk factors. With this approach, a novel prediction scale (Rating of Embolic Occlusion for Mechanical Thrombectomy [REMIT] scale) was developed. RESULTS: A total of 162 patients (104 men; median age 76 years; interquartile range 68-83) were included in this study. Embolic LVO was observed in 121 patients (75%). Multivariate logistic regression analysis showed that embolic LVO was independently associated with high brain natriuretic peptide (BNP), high National Institutes of Health Stroke Scale (NIHSS) on admission, and absence of non-culprit stenosis (NoCS). The REMIT scale comprises high BNP (>100 pg/dL), high NIHSS (>14) and absence of NoCS, with one point for each risk factor. The frequencies of embolic LVO for the REMIT scale scores were as follows: score 0, 25%; score 1, 60%; score 2, 87%; score 3, 97% (C-statistic 0.80, P < 0.001). CONCLUSION: The novel REMIT scale has predictive value for embolic LVO.

The meaning of non-culprit stenosis in hyperacute stroke with large vessel occlusion.

BACKGROUND AND PURPOSE: To diagnose atherosclerotic occlusion mechanism in acute ischemic stroke patients with large vessel occlusion prior to revascularization therapy is challenging. The aim was to verify the relationship between atherosclerotic occlusion and non-culprit stenosis detected in urgent neuroimaging prior to interventional procedure. MATERIALS AND METHODS: This study collected hyperacute stroke with large vessel occlusion, who underwent revascularization therapy (intravenous thrombolysis, thrombectomy, or both). An atherosclerotic occlusion was defined as an occlusion that did not recanalize or had residual stenosis at the initially occluded lesion, ensured in the second angiographic imaging performed after 1 week. The remaining patients who did not fulfill the definition of atherosclerotic occlusion was classified as embolic occlusion. A non-culprit stenosis was defined as a ≥ 50%-99% stenosis located other than the culprit occluded artery. Logistic regression analyses were performed to determine the factors independently associated with atherosclerotic occlusion. RESULTS: A total of 162 patients (104 men, median age 76 years old) were enrolled in our study. Forty one patients (25%) was atherosclerotic occlusion. Non-culprit stenosis was frequently observed in the atherosclerotic occlusion group than the embolic occlusion group (68% vs. 26%, P < 0.001). The presence of non-culprit stenosis was independently associated with atherosclerotic occlusion (OR, 11.00; 95% CI, 3.96-30.52; P < 0.001). CONCLUSION: In hyperacute stroke receiving endovascular therapy, non-culprit stenosis identification may be needed in order to perform an adequate revascularization, especially for atherosclerotic occlusion.

[Treatment of Mental Disorders During the Acute Phase of Brain Trauma].

During the acute phase of brain trauma, hallucinations, delusions, agitation, and aggression due to delirium and transit syndrome are common. Transit syndrome due to brain trauma is not treated, instead clinicians simply wait for it to pass, whereas delirium is a pathological condition that can be dealt with by stabilizing the general condition, and it is therefore important to identify. After brain trauma, transit syndrome may occur during the acute to subacute phase when consciousness disorder improves. If the patient is difficult to control, it is recommended that treatment be performed in cooperation with a psychiatrist. For agitation caused by brain trauma, administration of mood stabilizers(valproic acid, carbamazepine)and Chinese herbs(yokukansan)may be considered. For depressive symptoms, anxiety, impulsivity, irritability, etc., administration of SSRI as an antidepressant may be considered. Antipsychotics may be considered if antidepressants or mood stabilizers are ineffective against agitation, or if the patient experiences schizophrenia-like symptoms such as delusions.

Cesium uptake and translocation from tea cutting roots (Camellia sinensis L.).

To estimate the uptake of radiocesium (137Cs) by tea plant roots, 1-year-old rooted tea cuttings (Camellia sinensis L. cv. Yabukita) at the time of bud opening were cultivated hydroponically for 27 days in pots containing nutrient solutions with or without 137CsCl (600 Bq mL-1). Total 137Cs radioactivity of whole tea plants were 6.1 kBq g-1 dry weight. The plant/solution 137Cs transfer factors of different tissues were in the range of 2.6 (in mature leaves) to 28.2 mL g-1 dry weight (in roots), which were lower than those reported in wheat and spinach. In total, 69% of 137Cs remained in roots and 31% was transported from roots to shoots. The results indicated that 137Cs was preferentially translocated to new shoots, which are used for manufacturing tea, over mature leaves.

The NAG scale can screen for hematoma expansion in acute intracerebral hemorrhage-a multi-institutional validation.

BACKGROUND: Early hematoma expansion (HE) is seen in approximately 30% of patients with intracerebral hemorrhage (ICH), but detecting patients with a high HE risk is challenging. AIMS: The NAG scale is a simple predictive scale for HE in acute ICH patients. Multi-institutional validation of the usefulness of this scale was the aim of this study. METHODS: We retrospectively reviewed 142 consecutive primary ICH patients admitted to our hospital between September 2016 and December 2018. The NAG scale consists of three factors: National Institutes of Health Stroke Scale (NIHSS) score ≥ 10, anticoagulant use, and glucose ≥133 mg/dl (1 point each). Patients underwent non-contrast computed tomography (CT) within 24 h of symptom onset and follow-up CT 6 h, 24 h, and 7 days after admission. We defined HE as increased hemorrhage volume > 33% or an absolute increase of >6 mL on follow-up CT. Poor prognosis was defined as a modified Rankin scale score of 4-6 at discharge. We performed logistic regression analysis and created receiver operating characteristic curves to determine the discrimination ability of the NAG score. RESULTS: Patients constituted 96 men and 46 women (median age: 64 years; median NIHSS: 11), and HE was observed in 38/142 patients (27%). Higher NAG sores were associated with HE (P < .001), poor prognosis (P < .001), and in-hospital death (P < .001). The C statistic was 0.72 (95% confidence interval [CI]: 0.63-0.82) for HE, 0.67 (95% CI: 0.58-0.76) for poor prognosis, and 0.85 (95% CI: 0.74-0.95) for in-hospital death. Multivariate logistic regression analysis with known risk factors showed that NAG scale score was an independent risk factor for HE (odds ratio: 2.95; 95% CI: 1.57-5.52; P = .001). CONCLUSION: The NAG scale showed good discrimination in our multi-institutional validation.

Comparison of the National Early Warning Score (NEWS) and the Modified Early Warning Score (MEWS) for predicting admission and in-hospital mortality in elderly patients in the pre-hospital setting and in the emergency department.

The aim of this study is to evaluate the usefulness of the pre-hospital National Early Warning Score (pNEWS) and the pre-hospital Modified Early Warning Score (pMEWS) for predicting admission and in-hospital mortality in elderly patients presenting to the emergency department (ED). We also compare the value of the pNEWS with that of the ED NEWS (eNEWS) and ED MEWS (eMEWS) for predicting admission and in-hospital mortality. This retrospective, single-centre observational study was carried out in the ED of Jikei University Kashiwa Hospital, in Chiba, Japan, from 1st April 2017 to 31st March 2018. All patients aged 65 years or older were included in this study. The pNEWS/eNEWS were derived from seven common physiological vital signs: respiratory rate, peripheral oxygen saturation, the presence of inhaled oxygen parameters, body temperature, systolic blood pressure, pulse rate and Alert, responds to Voice, responds to Pain, Unresponsive (AVPU) score, whereas the pMEWS/eMEWS were derived from six common physiological vital signs: respiratory rate, peripheral oxygen saturation, body temperature, systolic blood pressure, pulse rate and AVPU score. Discrimination was assessed by plotting the receiver operating characteristic (ROC) curve and calculating the area under the ROC curve (AUC). The median pNEWS, pMEWS, eNEWS and eMEWS were significantly higher at admission than at discharge (p < 0.001). The median pNEWS, pMEWS, eNEWS and eMEWS of non-survivors were significantly higher than those of the survivors (p < 0.001). The AUC for predicting admission was 0.559 for the pNEWS and 0.547 for the pMEWS. There was no significant difference between the AUCs of the pNEWS and the pMEWS for predicting admission (p = 0.102). The AUCs for predicting in-hospital mortality were 0.678 for the pNEWS and 0.652 for the pMEWS. There was no significant difference between the AUCs of the pNEWS and the pMEWS for predicting in-hospital mortality (p = 0.081). The AUC for predicting admission was 0.628 for the eNEWS and 0.591 for the eMEWS. The AUC of the eNEWS was significantly greater than that of the eMEWS for predicting admission (p < 0.001). The AUC for predicting in-hospital mortality was 0.789 for the eNEWS and 0.720 for the eMEWS. The AUC of the eNEWS was significantly greater than that of the eMEWS for predicting in-hospital mortality (p < 0.001). For admission and in-hospital mortality, the AUC of the eNEWS was significantly greater than that of the pNEWS (p < 0.001, p < 0.001), and the AUC of the eMEWS was significantly greater than that of the pMEWS (p < 0.01, p < 0.05). Our single-centre study has demonstrated the low utility of the pNEWS and the pMEWS as predictors of admission and in-hospital mortality in elderly patients, whereas the eNEWS and the eMEWS predicted admission and in-hospital mortality more accurately. Evidence from multicentre studies is needed before introducing pre-hospital versions of risk-scoring systems.

The Usefulness and Limitations of Point-of-care Cardiac Troponin Measurement in the Emergency Department.

Objective This study was carried out to examine the usefulness of point-of-care (POC) cardiac troponin in diagnosing acute coronary syndrome (ACS) and to understand the limitations of a POC cardiac troponin I/T-based diagnoses. Methods Patients whose cardiac troponin levels were measured in the emergency department using a POC system (AQT System; Radiometer, Tokyo, Japan) between January and December 2016 were retrospectively examined (N=1,449). Patients who were < 20 years of age or who were admitted with cardiopulmonary arrest were excluded. The sensitivity and specificity of the POC cardiac troponin levels for the diagnosis of ACS were determined. Result One hundred and twenty of 1,449 total patients had ACS (acute myocardial infarction, n=88; unstable angina n=32). On comparing the receiver operating characteristic (ROC) curves, the area under the curve (AUC) values for POC cardiac troponin I and cardiac troponin T were 0.833 and 0.786, respectively. The sensitivity and specificity of POC cardiac troponin I when using the 99th percentile (0.023 ng/mL) as the diagnostic cut-off value were 69.0% and 88.1%, respectively. The sensitivity of POC cardiac troponin I (99th percentile) was higher in the patients sampled > 3 hours after symptom onset (83.3%) than in those sampled ≤ 3 hours after symptom onset (58.8%, p < 0.01). Conclusion When sampled > 3 hours after the onset of symptoms, the POC cardiac troponin I level is considered to be suitable for use in diagnosing ACS. However, when sampled ≤ 3 hours after the onset of symptoms, careful interpretation of POC cardiac troponins is therefore required to rule out ACS.

Radiocesium uptake through leaf surfaces of tea plants (Camellia sinensis L.).

To clarify the source of radiocesium detected in newly emerged tea leaves contaminated just before the time of bud opening by fallout of radionuclides from Fukushima Dai-ichi Nuclear Power Plant, 137CsCl solution (0.185 M Bq mL-1) was applied to the front or the backside surfaces of mature leaves of tea plant (Camellia sinensis L. cv. Yabukita) at the time of bud opening. A 21 days after foliar application, the buds had grown and developed to the three- or four-leaf stage. In the front treatment, almost all (95%) of the applied 137Cs was present in the mature leaves (hot mother leaves). In the backside treatment, 68% of applied 137Cs also remained in hot mother leaves, but 22% and 10% was found in the new shoots attached to hot mother leaves and the other parts (non-applied mature leaves, stems and roots), respectively. The images of a hot leaf and its attached new shoots by imaging plate analysis revealed that the results coincided with those of the 137Cs distribution above. These suggested that radiocesium was primarily absorbed from the backside surface of tea leaves through the stoma, and then the greater part was transported to newly emerged tea organs during the new shoot growth period.

Effect of secondary insults upon aquaporin-4 water channels following experimental cortical contusion in rats.

Although secondary insults of hypoxia and hypotension (HH) are generally considered to cause fulminant brain edema in traumatic brain injury (TBI), the combined effect of TBI with HH on brain edema and specifically the expression of aquaporin-4 (AQP4) have not been fully elucidated. The goal of this study was to document the effect of secondary insults on brain water, AQP4 expression, electrolytes, and blood-brain barrier (BBB) permeability during the acute stage of edema development. We measured brain water content and electrolytes (series 1); BBB permeability based on Evans blue (EB) dye extravasation (series 2); and AQP4 expression using immunoblotting (series 3) at 1 h and 5 h following cortical contusion injury (CCI). Secondary insults significantly worsened BBB function at 5 h post injury. Moreover, a significant reduction of upregulation on AQP4 expression was observed in trauma, coupled with a mild secondary insult of hypoxia hypotension. These findings indicate that a secondary insult following CCI at 5 h post injury worsens brain edema, disrupts ionic homeostasis, and blunts the normal upregulation of AQP4 that occurs after trauma, suggesting that the blunting of AQP4 may contribute to the detrimental effects of secondary insults.

The protein kinase C activator phorbol myristate acetate decreases brain edema by aquaporin 4 downregulation after middle cerebral artery occlusion in the rat.

The protein kinase C activator phorbol 12-myristate 13-acetate (PMA) is known to interact with aquaporin 4 (AQP 4), a water-selective transporting protein that is abundant in astrocytes, and has experimentally been found to decrease osmotically-induced cell swelling. The purpose of this study was to examine whether PMA reduces brain edema following focal ischemia induced by middle cerebral artery (MCA) occlusion by modulation of AQP4 expression. Male Sprague-Dawley rats were randomly assigned to either sham surgery (n = 6), or a continuous intravenous infusion of vehicle (1% dimethylsulfoxide), followed by MCA occlusion (n = 18), and administration of PMA at 50 microg/kg (n = 6) or at 200 microg/kg (n = 6) starting 60 min before or 30 min (200 microg/kg; n = 6) or 60 min (200 microg/kg; n = 6) after MCA occlusion. Cerebral blood flow was monitored with laser Doppler over the MCA territory, and confirmed a 70% reduction during occlusion. After a 2-h period of ischemia and 2 h of reperfusion, the animals were sacrificed for assessment of brain water content and sodium and potassium concentration. AQP4 expression was assessed by immunoblotting and quantified by densitometry (n = 24). Statistical analysis was performed by ANOVA followed by Tukey's post-hoc test. PMA treatment at 200 microg/kg significantly reduced brain water concentration in the infarcted area when started 60 min before or 30 min after occlusion (p < 0.001 and p = 0.022, respectively), and prevented the subsequent sodium shift (p < 0.05). PMA normalized the AQP4 upregulation in ischemia (p = 0.021). A downregulation of AQP4 in the ischemic area paralleling the reduction in brain edema formation following PMA treatment suggests that the effect was mediated by AQP4 modulation.

Modulation of AQP4 expression by the selective V1a receptor antagonist, SR49059, decreases trauma-induced brain edema.

BACKGROUND: Currently, there are no pharmacological treatments available for traumatically induced brain edema and the subsequent rise of ICP. Evidence indicates that Aquaporin-4 (AQP4) plays a significant role in the pathophysiology of brain edema. Previously we have reported that SR49059 reduced brain edema secondary to ischemia. We, therefore, examined whether the selective V1a receptor antagonist, SR49059, reduces brain edema by modulating AQP4 expression following cortical contusion injury (CCI). METHODS: Traumatic brain injury (TBI) was produced in thirty-two adult male Sprague-Dawley rats by lateral CCI (6.0 m/sec, 3 mm depth). Animals were randomly assigned to vehicle (n=16) or SR49059 treatment (n=16) groups and administered drug (960 microl/hr i.v.) immediately after injury over a 5 hr period. Animals were sacrificed for assessment of brain water content by Wet/Dry method and AQP4 protein expression by immunoblotting expressed as the ratio of AQP4 and Cyclophilin-A densitometries. FINDINGS: Elevated AQP4 expression levels and water content were observed on the right injured side in both the right anterior (RA) and right posterior (RP) section compared to the left non-injured side inclusive of the left anterior (LA) and right anterior (RA) sections. The average AQP4 expression levels in contused areas for animals receiving SR drug treatment (RA: 1.313 +/- 0.172, RP: 1.308 +/- 0.175) were significantly decreased from vehicle-treated animals (RA: 2.181 +/- 0.232, RP: 2.303 +/- 0.370, p = 0.001, p= 0.003). Water content levels on SR treatment (78.89 +/- 0.14) was also significantly decreased from vehicle levels (80.38 +/- 0.38, p < 0.01) in the traumatized hemisphere. CONCLUSIONS: SR49059 significantly reduced trauma-induced AQP4 up-regulation in the contused hemisphere. Moreover, brain water content was also significantly reduced paralleling the AQP4 suppression. These data provide further support that vasopressin (AVP) and V1a receptors can control water flux through astrocytic plasma membranes by regulating AQP4 expression. Taken in concert, these results affirm our laboratories contention that AQP4 can be effectively modulated pharmacologically.

The modulation of aquaporin-4 by using PKC-activator (phorbol myristate acetate) and V1a receptor antagonist (SR49059) following middle cerebral artery occlusion/reperfusion in the rat.

BACKGROUND: We have pursued the concept that traumatic brain edema is predominantly cellular and that water entry is modulated in part by aquaporins. Aquaporin-4 (AQP4) has been shown to play a significant role in cellular edema formation. Phorbol myristate acetate (PMA) is a potent PKC activator; purportedly involved in modulation of AQP4 activity. Alternatively, AQP4 may be regulated by arginine-vasopressin. Administration of the vasopressin antagonist (SR49059) reduced brain water content and sodium shift following MCAo. To investigate if edema formation is affected by the reduction of AQP4 expression, we utilized PMA and SR49059 following middle cerebral artery occlusion model (MCAo), and measured AQP4 expression by Western-Blot (WB) techniques. METHODS: Male Sprague Dawley rats were randomly assigned to sham (n=4) or MCAo groups (vehicle, PMA or SR49059 infusion; n=6 each). Each solution was infused for 5 hours, starting 1 hour before injury. After a two-hour period of ischemia and two-hour reperfusion, animals were sacrificed and brain regions of interest were processed by WB to quantify the effect of treatment on AQP4 expression. RESULTS: These studies demonstrate that MCAo results in a significant up-regulation of AQP4 on the ischemic zone when compared to the contralateral un-injured hemisphere (p < 0.05) and that PMA and SR49059 treatment significantly down-regulated AQP4 expression compared to the vehicle group (p < 0.05). CONCLUSIONS: These studies support the hypotheses that PMA and SR49059 may be useful in reducing cerebral water accumulation by modulating AQP4 expression and that pharmacological manipulation of AQP4 may emerge as a viable strategy for the reduction of fulminating edema following ischemic injury.

Effects of marrow penetration on bone augmentation within a titanium cap in rabbit calvarium.

BACKGROUND: Some studies have advocated marrow penetration in guided bone augmentation (GBA), whereas others have shown that bone can be generated without marrow penetration. This study examined the effect of marrow penetration and the optimal rate of penetration. METHODS: In 10 rabbits, the calvarium was exposed, and circular grooves were prepared bilaterally. Within the circular groove, the external cortical surface of the skull was perforated mechanically using a number 4 round bur (experimental site), whereas the bone surface on the other groove (control site) was left intact. The rate of penetration was standardized as 28% for the experimental site and 0% for the control site. Subsequently, two standardized titanium caps with an inner diameter of 8 mm and an inner height of 4 mm were anchored in the prepared grooves. Five rabbits each were euthanized at 1 and 3 months, and the percent area of newly generated tissue and mineralized bone in the newly generated tissue under the titanium cap was determined. RESULTS: Histomorphometric analysis showed significantly increased bone neogenesis in the experimental site at 3 months. The percent area of mineralized bone in the newly generated tissue was consistently higher in the experimental site at 3 months. CONCLUSION: In the rabbit calvarium using a titanium cap GBA model, bone augmentation was significantly greater with marrow penetration than without penetration.