Diffuse cerebral air embolism following trauma: striking postmortem CT findings

Postmortem magnetic resonance imaging revealed bilateral globi pallidi lesions in a death associated with prolonged carbon monoxide poisoning: a case report

A man and a woman were found dead in the same car with a burned coal briquette. The cause of death of the woman was assigned to acute carbon monoxide (CO) poisoning without difficulty based on typical findings associated with this condition, including elevation of carboxyhaemoglobin (COHb). However, the man had an unremarkable elevation of COHb and a higher rectal temperature compared to that of the woman. Postmortem computed tomography (PMCT) revealed ambiguous low-density areas in the bilateral globi pallidi. Further analysis by postmortem magnetic resonance (PMMR) imaging showed these lesions more clearly; the lesions appeared as marked high signal intensity areas on both the T2-weighted images and the fluid-attenuated inversion recovery sequences. A subsequent autopsy revealed signs of pneumonia, dehydration, starvation, and hypothermia, suggesting that the man died from prolonged CO poisoning. Both globi pallidi contained grossly ambiguous lesions, and a detailed neuropathologic investigation revealed these lesions to be coagulative necrotic areas; this finding was compatible with a diagnosis of prolonged CO poisoning. This case report shows that postmortem imaging, especially PMMR, is useful for detecting necrotic lesions associated with prolonged CO poisoning. This report further exemplifies the utility of PMMR for detecting brain lesions, which may be difficult to detect by macroscopic analysis.

Significance of intracranial gas on post-mortem computed tomography in traumatic cases in the context of medico-legal opinions

The detection of intracranial gas (ICG) in people who died due to trauma became possible once postmortem computed tomography (PMCT) became available in addition to traditional post-mortem examinations. The aim of this study was to determine the importance of ICG in the context of medico-legal opinions. We assessed 159 cases of trauma-induced death. Cadavers with pronounced signs of decomposition, open skull fractures, and after neurosurgical operations were excluded. Both PMCT findings and data from autopsy reports were analyzed. ICG was found in 38.99% (n = 62) of the cadavers, 96.77% (n = 60) of which presented with pneumocephalus (PNC) and 40.23% (n = 25) with intravascular gas (IVG). There was a strong correlation between ICG and skull fractures/brain injuries, as well as chest injuries, especially lung injuries. In 13 cases, ICG presented without skull fractures; three of these cases died as a result of stab and incised wounds to the neck and chest. The mean time between trauma and death was significantly longer in the non-ICG group than the ICG group at 2.94 days (0–48 days) and 0.01 day (0–1 day), respectively (p < 0.0001). The presence of ICG is a result of severe neck and chest injuries, including stab and incised wounds. The victims die in a very short amount of time after suffering trauma resulting in ICG. The ability to demonstrate ICG on PMCT scans can be of significance in forming medico-legal opinions.

Massive systemic arterial air embolism caused by an air shunt after blunt chest trauma: A case report

INTRODUCTION

Systemic arterial air embolism (SAAE) is a rare but fatal condition, with only a few cases reported, and the detailed etiology underlying SAAE remains unknown. We report a first case of massive SAAE after blunt chest injury, wherein the presence of traumatic air shunt was confirmed by direct observation during surgery. We also summarize our experience with six other SAAE cases.

PRESENTATION OF CASE

A 68-year-old woman was admitted in a state of cardiac arrest after a fall. Emergency room thoracotomy determined complete transection of left main bronchus and left superior pulmonary vein. Postmortem computed tomography (CT) revealed full of air in the aortic arch, the descending aorta, and the great vessels. Therefore, one of the cause of death might be SAAE.

DISCUSSION

An air shunt after blunt chest trauma can cause SAAE, and clinical signs and operative findings can provide clues for possible SAAE. The bronchopulmonary vein fistula, the aortic injury and full-thickness myocardial injury have the potential to become traumatic air shunts. In cases with a coexisting air shunt, pneumothorax, lung contusions and positive-pressure ventilation can be risk factors for SAAE, as sources of air continually entering the systemic arterial circulation.

CONCLUSION

SAAE is caused by an air shunt following trauma. Clinical signs and operative findings summarized in this case should aid in the recognition of possible SAAE.

Cerebral Air Embolism: A Clinical, Radiologic and Histopathologic Correlation

Cerebral air embolism is a recognized life-threatening complication, sometimes iatrogenic. Its timely diagnosis is essential because it can result in neurologic deficits or death. We report a case of a 58-year-old man who died from cerebral air embolism diagnosed by nonenhanced computed tomography scan of the head after a cardiac bypass surgery with Biventricular Assist Device and multiple vascular line placements. Autopsy revealed extensive subcutaneous emphysema, intravascular and perivascular air bubbles in the central nervous system and associated cerebral and cerebellar hemorrhagic infarction. The autopsy was helpful in documenting the extent of the air embolism and its appearance in soft tissue and central nervous system.

Subarachnoid Pleural Fistula Due to Gunshot Wound

Subarachnoid pleural fistula (SPF) is an extremely rare complication that occurs after dural space and vertebral columns injuries. SPF is divided into two diagnoses based on the absence or presence of pneumocephalus and pneumorrachis. While pneumocephalus is defined as the presence of air the cranial cavity, if there is air in the spinal canal, this is defined as pneumorrhachis. In general, the association of SPF with pneumocephalus and pneumorrachis is rare but can occur after blunt trauma. In our patient, pneumorrhachis and pneumocephalus with SBF developed after the patient suffered a gunshot wound. This paper reports an SPF case accompanied by pneumorrachis and pneumocephalus, which occurred after thoracic spine injury due to a gunshot wound.

Appearance of gas collections after scuba diving death: a computed tomography study in a porcine model

INTRODUCTION

Postmortem computed tomography can easily demonstrate gas collections after diving accidents. Thus, it is often used to support the diagnosis of air embolism secondary to barotrauma. However, many other phenomenons (putrefaction, resuscitation maneuvers, and postmortem tissue offgassing) can also cause postmortem gas effusions and lead to a wrong diagnosis of barotrauma.

OBJECTIVES

The aim of this study is to determine topography and time of onset of postmortem gas collections respectively due to putrefaction, resuscitation maneuvers, and tissue offgassing.

MATERIALS AND METHODS

A controlled experimental study was conducted on nine pigs. Three groups of three pigs were studied postmortem by CT from H0 to H24: one control group of nonresuscitated nondivers, one group of divers exposed premortem to an absolute maximal pressure of 5 b for 16 min followed by decompression procedures, and one group of nondivers resuscitated by manual ventilation and thoracic compression for 20 min. The study of intravascular gas was conducted using CT scan and correlated with the results of the autopsy.

RESULTS

The CT scan reveals that, starting 3 h after death, a substantial amount of gas is observed in the venous and arterial systems in the group of divers. Arterial gas appears 24 h after death for the resuscitated group and is absent for the first 24 h for the control group. Concerning the putrefaction gas, this provokes intravenous and portal gas collections starting 6 h after death. Subcutaneous emphysema was observed in two of the three animals from the resuscitated group, corresponding to the thoracic compression areas.

CONCLUSION

In fatal scuba diving accidents, offgassing appears early (starting from the first hour after death) in the venous system then spreads to the arterial system after about 3 h. The presence of intra-arterial gas is therefore not specific to barotrauma. To affirm a death by barotrauma followed by a gas embolism, a postmortem scanner should be conducted very early. Subcutaneous emphysema should not be mistaken as diagnostic criteria of barotrauma because it can be caused by the resuscitation maneuvers.

Acute management of vascular air embolism

Vascular air embolism (VAE) is known since early nineteenth century. It is the entrainment of air or gas from operative field or other communications into the venous or arterial vasculature. Exact incidence of VAE is difficult to estimate. High risk surgeries for VAE are sitting position and posterior fossa neurosurgeries, cesarean section, laparoscopic, orthopedic, surgeries invasive procedures, pulmonary overpressure syndrome, and decompression syndrome. Risk factors for VAE are operative site 5 cm above the heart, creation of pressure gradient which will facilitate entry of air into the circulation, orogenital sex during pregnancy, rapid ascent in scuba (self contained underwater breathing apparatus) divers and barotrauma or chest trauma. Large bolus of air can lead to right ventricular air lock and immediate fatality. In up to 35% patient, the foramen ovale is patent which can cause paradoxical arterial air embolism. VAE affects cardiovascular, pulmonary and central nervous system. High index of clinical suspicion is must to diagnose VAE. The transesophgeal echocardiography is the most sensitive device which will detect smallest amount of air in the circulation. Treatment of VAE is to prevent further entrainment of air, reduce the volume of air entrained and haemodynamic support. Mortality of VAE ranges from 48 to 80%. VAE can be prevented significantly by proper positioning during surgery, optimal hydration, avoiding use of nitrous oxide, meticulous care during insertion, removal of central venous catheter, proper guidance, and training of scuba divers.

Intravascular gas distribution in the upper abdomen of non-traumatic in-hospital death cases on postmortem computed tomography

OBJECTIVES

To investigate the occurrence of intravascular gas in the liver, kidneys, spleen, and pancreas by postmortem computed tomography (PMCT) in cases of non-traumatic in-hospital deaths and elucidate the relationship between the PMCT data and clinical information or autopsy results.

METHODS

The study included 45 cadavers of patients who died while receiving treatment in our academic tertiary-care hospital between April and December 2009. All subjects underwent PMCT and conventional autopsy. The appearance of postmortem gas in the liver, kidney, spleen, and pancreas was assessed using PMCT and scored using a subjective scale (liver, L0-L3; kidney, K0-K2; spleen, S0-S1; and pancreas, P0-P1), and the distribution of gases in the vessels of the liver (arteries, veins, and portal veins) was analyzed. The relationship between the gas score and time elapsed since death, cardiopulmonary resuscitation (CPR), administration of antibiotics, a history of bacteremia, or cause of death was assessed statistically.

RESULTS

Positive correlations were found between administration of CPR and liver and kidney gas scores (P=0.008 and 0.002, respectively), but not with spleen and pancreas gas (P=0.291 and 0.535, respectively). No significant relationship between distribution of gas in the vessels of the liver and CPR was found. No other significant correlations between gas and any of the other parameters described above were found. While significant correlations were detected in no-CPR cases between liver gas, kidney gas, spleen gas, and pancreas gas (P<0.001 for all six combinations), no correlation between these parameters was detected in the CPR cases.

CONCLUSIONS

The present study was the first statistical analysis of intravascular gas in the liver, kidneys, spleen, and pancreas by using PMCT in non-traumatic in-hospital death cases. The results showed that PMCT in the presence and absence of CPR reveals differences in intraorgan gas distribution. In addition, the detection of intraorgan gas on PMCT cannot be used to predict time elapsed since death, and it is not affected by the administration of antibiotics, a history of bacteremia, and cause of death. Awareness of these postmortem changes is important for the accurate interpretation of PMCT results.

Acute management of vascular air embolism

Vascular air embolism (VAE) is known since early nineteenth century. It is the entrainment of air or gas from operative field or other communications into the venous or arterial vasculature. Exact incidence of VAE is difficult to estimate. High risk surgeries for VAE are sitting position and posterior fossa neurosurgeries, cesarean section, laparoscopic, orthopedic, surgeries invasive procedures, pulmonary overpressure syndrome, and decompression syndrome. Risk factors for VAE are operative site 5 cm above the heart, creation of pressure gradient which will facilitate entry of air into the circulation, orogenital sex during pregnancy, rapid ascent in scuba (self contained underwater breathing apparatus) divers and barotrauma or chest trauma. Large bolus of air can lead to right ventricular air lock and immediate fatality. In up to 35% patient, the foramen ovale is patent which can cause paradoxical arterial air embolism. VAE affects cardiovascular, pulmonary and central nervous system. High index of clinical suspicion is must to diagnose VAE. The transesophgeal echocardiography is the most sensitive device which will detect smallest amount of air in the circulation. Treatment of VAE is to prevent further entrainment of air, reduce the volume of air entrained and haemodynamic support. Mortality of VAE ranges from 48 to 80%. VAE can be prevented significantly by proper positioning during surgery, optimal hydration, avoiding use of nitrous oxide, meticulous care during insertion, removal of central venous catheter, proper guidance, and training of scuba divers.

Cerebral air embolism: acute imaging

Iatrogenic cerebral air embolism secondary to right subclavian vein recatheterization was imaged acutely by computed tomography (CT) and magnetic resonance imaging (MRI). However, CT showed intravascular air with misleadingly high attenuation values sampled to a minimum of -39 HU. Diffusion-weighted imaging, not previously reported in this setting, clearly showed hyperintense acute infarctions in corresponding vascular territories 8.5 hours postprocedure (less than 6 hours after referable symptomatology noted), whereas T2-weighted fluid-attenuated inversion recovery and turbo gradient spin echo images did not. The combination of CT and diffusion-weighted MRI appears ideal for evaluating suspected cerebral air embolism in the acute setting.

Systemic air embolism after cardiopulmonary resuscitation in a preterm infant

We report a preterm infant with extensive systemic air embolism after cardiopulmonary resuscitation for cardiac arrest due to an occluding thrombus in the inferior vena cava. After excluding other potential causes (air infusion, necrotizing enterocolitis or pulmonary leakage syndrome), we postulate that the pressure gradient needed for air embolism to occur is related to the resuscitation procedure. An important clue of air embolism was noted on the chest X-ray taken before death showing intracardial air.

CONCLUSION

Systemic air embolism may occur as a very rare complication after cardiopulmonary resuscitation.

Arterial cerebral air embolism at the site of a spontaneous pontine hemorrhage in a patient receiving erroneous continuous positive pressure ventilation

We report the case of a 48-year-old male with iatrogenic arterial cerebral air embolism at the site of a spontaneous pontine hemorrhage. The patient inadvertently received continuous positive pressure ventilation without exhalation for a few minutes, resulting in pneumothorax, interstitial emphysema, pneumoperitoneum, and arterial cerebral air embolism at the site of the intracerebral hemorrhage. This is the first report of pneumocephalus without head trauma or previous surgery in which the air embolism occurs at the site of a spontaneous intracerebral hemorrhage. We hypothesize that air preferentially leaked into the brain parenchyma through the weakened perforating pontine artery that caused the intracerebral bleeding.

Post-mortem forensic neuroimaging: correlation of MSCT and MRI findings with autopsy results

Multislice-computed tomography (MSCT) and magnetic resonance imaging (MRI) are increasingly used for forensic purposes. Based on broad experience in clinical neuroimaging, post-mortem MSCT and MRI were performed in 57 forensic cases with the goal to evaluate the radiological methods concerning their usability for forensic head and brain examination. An experienced clinical radiologist evaluated the imaging data. The results were compared to the autopsy findings that served as the gold standard with regard to common forensic neurotrauma findings such as skull fractures, soft tissue lesions of the scalp, various forms of intracranial hemorrhage or signs of increased brain pressure. The sensitivity of the imaging methods ranged from 100% (e.g., heat-induced alterations, intracranial gas) to zero (e.g., mediobasal impression marks as a sign of increased brain pressure, plaques jaunes). The agreement between MRI and CT was 69%. The radiological methods prevalently failed in the detection of lesions smaller than 3mm of size, whereas they were generally satisfactory concerning the evaluation of intracranial hemorrhage. Due to its advanced 2D and 3D post-processing possibilities, CT in particular possessed certain advantages in comparison with autopsy with regard to forensic reconstruction. MRI showed forensically relevant findings not seen during autopsy in several cases. The partly limited sensitivity of imaging that was observed in this retrospective study was based on several factors: besides general technical limitations it became apparent that clinical radiologists require a sound basic forensic background in order to detect specific signs. Focused teaching sessions will be essential to improve the outcome in future examinations. On the other hand, the autopsy protocols should be further standardized to allow an exact comparison of imaging and autopsy data. In consideration of these facts, MRI and CT have the power to play an important role in future forensic neuropathological examination.

Massive cerebral air embolism after cardiopulmonary resuscitation

We report a case of massive intracerebral air embolism after cardiopulmonary resuscitation in a patient with a fatal head injury. There was no pneumothorax or extravascular pneumocephalus, however, air was found in the internal carotid artery. Massive cerebral air embolism may occur after entrance of air into the circulatory system via ruptured pulmonary vessels during cardiopulmonary resuscitation.

Massive intracerebral air embolism associated with meningitis and lumbar spondylitis: case report

BACKGROUND

Massive intracerebral air embolism is a rare pathologic state and never in association with meningitis and lumbar spondylitis. To the best of our knowledge, our presented case is the first of a massive intracerebral air embolism associated with meningitis and lumbar spondylitis of Klebsiella pneumonia.

CASE DESCRIPTION

A 55-year-old man presented with a high fever and low back pain. Blood culture showed Klebsiella pneumonia. Lumbar computed tomography (CT) revealed discitis at L1-2 and L2-3 levels and paraspinal abscess in which air was found. Despite management with antibiotics, patient's consciousness deteriorated, and brain CT revealed diffuse intravenous air embolism and severe brain swelling. Cerebrospinal fluid (CSF) examination demonstrated bacterial meningitis, and the CSF culture showed Klebsiella pneumonia. Later, septic shock occurred and patient expired.

CONCLUSION

Intracerebral air embolism can occur in the Klebsiella pneumonia meningitis that resulted from lumbar spondylitis and sepsis.

Cerebral air emboli from angiography in a patient with stroke. A case report

A 42-year-old woman with subarachnoid and intracerebral hemorrhage was investigated with diagnostic angiography, disclosing an occlusion of the left internal carotid artery and the middle cerebral artery. CT examination immediately after the angiography revealed a 12-h-old infarct of the left middle cerebral artery territory. There was also gas in the arteries supplying the infarcted part of the brain, but not in other vessels. Air had most probably been introduced during the angiography and had consequently been "trapped" in the cortical arteries of the ischemic brain. In the non-ischemic parts of the brain air may have passed through the vessels leaving no trace.