Stroke caused by cerebral air embolism during endoscopy

Abstract

Intracranial air may occur spontaneously. It can develop as a result of trauma, or it may be introduced iatrogenically. In most reported cases of cerebral air embolism, the air was found in the cerebrospinal fluid-containing compartments, the epidural space, or in the intracranial venous system. Arterial pneumocephalus is uncommon. A case of stroke caused by cerebral arterial air embolism during upper endoscopy is described. The most likely explanation for the embolism is the development of a bronchovenous connection after alveolar rupture.Case reportFever developed during the morning before the endoscopy. Blood cultures were positive for Enterobacter and Streptococcus 2 days after the procedure and treatment was initiated with antibiotics. Evidence of pneumonia was noted on chest radiograph. Cardiac US was normal. Because of a swelling in the neck, US was performed; needle aspiration under US guidance obtained only air. This finding was thought to be related to the development of a fistula after laryngectomy. The patient underwent no additional procedures. He was discharged 1 month after the cerebrovascular insult with a residual left hemiparesis.DiscussionPneumocephalus, a general term for air within the cranium, may be associated with skull fracture, an intrathecal procedure, cerebral angiography, infection, neoplasms, congenital skull defects, and barotrauma.1Thompson TD Levy E Kanal E Lunsford D Iatrogenic pneumocephalus secondary to intravenous catheterization.J Neurosurg. 1999; 91: 878-880Crossref PubMed Scopus (14) Google Scholar Cerebral air embolism can be due to either a massive venous air embolism or a direct communication between the right and the left side of the heart. The foramen ovale is patent at autopsy in 10% to 40% of cases.2Thompson T Evans W Paradoxical embolism.Q J Med. 1930; 23: 135-150Crossref Scopus (235) Google Scholar Air embolism has also been described after insertion of a subclavian intravenous catheter.3Hwang TL Fremaux R Sears ES MacFadyen B Hills B Mader JT et al.Confirmation of cerebral air embolism with computerized tomography.Ann Neurol. 1983; 13: 214-215Crossref PubMed Scopus (30) Google Scholar This has been attributed to entry of air into the subclavian vein, induced by inspiration, during the interval between catheter insertion and connection to the intravenous tubing. Inspiration results in a differential pressure gradient, causing air to be sucked into the catheter, which then collects in the right heart and pulmonary arterial tree. Reflex constriction of the pulmonary vasculature increases pressure in the right heart, which results in transient opening of an anatomically patent foramen ovale. These mechanisms are unlikely in our patient because no venous gas was introduced.Another possible mechanism for the entry of air into the arterial system in our patient, in the absence of a massive air embolism or a communication between the right and left heart, is a bronchovenous connection (after an alveolar rupture) with a pressure gradient adequate to allow air to reach the arterial system. This is the mechanism operative in barotrauma (e.g., diving accident, inhalation of pressurized helium, cardiopulmonary resuscitation); it may also occur in patients with adult respiratory distress syndrome and those undergoing positive pressure mechanical ventilation.4Nakao N Moriwaki H Oiwa Y Barotraumatic cerebral air embolism following scuba diving.Brain Nerve. 1990; 42: 1097100Google Scholar, 5Marini JJ Culver BH Systemic gas embolism complicating mechanical ventilation in the adult respiratory distress syndrome.Ann Intern Med. 1989; 110: 699-703Crossref PubMed Scopus (86) Google Scholar, 6Pao BS Hayden SR Cerebral gas embolism resulting from inhalation of pressurized helium.Ann Emerg Med. 1996; 28: 363-366Abstract Full Text Full Text PDF PubMed Scopus (10) Google Scholar, 7Imanishi M Nishimura A Tabuse H Miyamoto S Sakaki T Iwasaki S Intracranial gas on CT after cardiopulmonary resuscitation: 4 cases.Neuroradiology. 1998; 40: 154-157Crossref PubMed Scopus (24) Google Scholar The retractive tendency of infiltrated parenchyma in these patients may tether and open vascular channels disrupted by inflammation or necrosis, allowing entry of interstitial gas that has leaked from ruptured alveoli.8Schlaepfer K Air embolism following various diagnostic or therapeutic procedures in diseases of pleura and lung.Bull Johns Hopkins Hosp. 1922; 33: 321-330Google Scholar Interstitial gas may escape into the pleural space and cause a pneumothorax, or it may decompress into the tissues of the neck, trunk, or retroperitoneum.9Macklin MT Macklin CC Malignant interstitial emphysema of the lungs and mediastinum as an important occult complication in many respiratory diseases and other conditions.Medicine. 1944; 23: 281-358Crossref Scopus (612) Google Scholar A similar event may have occurred in our patient, who suddenly developed bronchospasm and became cyanotic. An increase in intrathoracic pressure in our patient, who had extensive sequelae of pulmonary tuberculosis, may have caused shearing of small vessels and rupture of alveoli, allowing gas to gain access to the pulmonary venous system through the disrupted interstitium.There are other reports of air embolism during GI endoscopy. In a patient with a gastric ulcer, autopsy revealed a vessel exposed to the insufflation of air during the procedure.10Katzgraber F Glenewinkel F Fischler S Rittner C Mechanism of fatal air embolism after gastrointestinal endoscopy.Int J Legal Med. 1998; 111: 154-156Crossref PubMed Scopus (53) Google Scholar In another patient, who had a patent foramen ovale, air had been insufflated during endoscopy after dilation of an esophageal stricture for the purpose of obtaining biopsy specimens from the narrowed region.11Raju GS Bendixen BH Khan J Summers RW Cerebrovascular accident during endoscopy: consider cerebral air embolism, a rapidly reversible event with hyperbaric oxygen therapy.Gastrointest Endosc. 1998; 47: 70-73Abstract Full Text Full Text PDF PubMed Scopus (22) Google Scholar It was theorized that air had probably gained entry to the circulatory system by means of tiny mucosal tears and then into the esophageal venous channels. There is also a report of a patient with a duodenal ulcer and a duodenocaval fistula who had a stroke as a result of an air embolism.12Christl SU Scheppach W Peters U Kirchner T Cerebral air embolism after gastroduodenoscopy: complication of a duodenocaval fistula.Gastrointest Endosc. 1994; 40: 376-378Abstract Full Text Full Text PDF PubMed Scopus (37) Google Scholar The esophagus, stomach, and duodenum were normal endoscopically in our patient.CT has an important role in confirming the diagnosis of cerebral air embolism, particularly when the acute clinical presentation does not suggest this diagnosis, as in our patient. However, air is usually not evident by CT because the presence of air bubbles in the brain is highly unusual. Vasospasm occurs once bubbles obstruct flow in an artery, the end result being an infarct. Because our patient was in a semierect position during endoscopy, the location of the infarct in the right hemisphere is logical because of the anatomic position of the right common carotid artery. Hyperbaric oxygen is a well-established, lifesaving emergency treatment for cerebral air embolism because it reduces the size of the intravascular air bubbles that obstruct or occlude the arteries.13Tibbles PM Edelsberg JS Hyperbaric oxygen therapy.N Engl J Med. 1996; 334: 1642-1648Crossref PubMed Scopus (725) Google Scholar Because CT may not reveal air within the brain, diffusion-weighted magnetic resonance imaging should be obtained because this can demonstrate infarcted tissue within 20 minutes. If air embolism is suspected, treatment with hyperbaric oxygen therapy should be considered as soon as possible. To our knowledge, this is the first report of cerebral air embolism during a routine, uneventful GI endoscopy in a patient who did not have a patent foramen ovale. Intracranial air may occur spontaneously. It can develop as a result of trauma, or it may be introduced iatrogenically. In most reported cases of cerebral air embolism, the air was found in the cerebrospinal fluid-containing compartments, the epidural space, or in the intracranial venous system. Arterial pneumocephalus is uncommon. A case of stroke caused by cerebral arterial air embolism during upper endoscopy is described. The most likely explanation for the embolism is the development of a bronchovenous connection after alveolar rupture. Case reportFever developed during the morning before the endoscopy. Blood cultures were positive for Enterobacter and Streptococcus 2 days after the procedure and treatment was initiated with antibiotics. Evidence of pneumonia was noted on chest radiograph. Cardiac US was normal. Because of a swelling in the neck, US was performed; needle aspiration under US guidance obtained only air. This finding was thought to be related to the development of a fistula after laryngectomy. The patient underwent no additional procedures. He was discharged 1 month after the cerebrovascular insult with a residual left hemiparesis. Fever developed during the morning before the endoscopy. Blood cultures were positive for Enterobacter and Streptococcus 2 days after the procedure and treatment was initiated with antibiotics. Evidence of pneumonia was noted on chest radiograph. Cardiac US was normal. Because of a swelling in the neck, US was performed; needle aspiration under US guidance obtained only air. This finding was thought to be related to the development of a fistula after laryngectomy. The patient underwent no additional procedures. He was discharged 1 month after the cerebrovascular insult with a residual left hemiparesis. DiscussionPneumocephalus, a general term for air within the cranium, may be associated with skull fracture, an intrathecal procedure, cerebral angiography, infection, neoplasms, congenital skull defects, and barotrauma.1Thompson TD Levy E Kanal E Lunsford D Iatrogenic pneumocephalus secondary to intravenous catheterization.J Neurosurg. 1999; 91: 878-880Crossref PubMed Scopus (14) Google Scholar Cerebral air embolism can be due to either a massive venous air embolism or a direct communication between the right and the left side of the heart. The foramen ovale is patent at autopsy in 10% to 40% of cases.2Thompson T Evans W Paradoxical embolism.Q J Med. 1930; 23: 135-150Crossref Scopus (235) Google Scholar Air embolism has also been described after insertion of a subclavian intravenous catheter.3Hwang TL Fremaux R Sears ES MacFadyen B Hills B Mader JT et al.Confirmation of cerebral air embolism with computerized tomography.Ann Neurol. 1983; 13: 214-215Crossref PubMed Scopus (30) Google Scholar This has been attributed to entry of air into the subclavian vein, induced by inspiration, during the interval between catheter insertion and connection to the intravenous tubing. Inspiration results in a differential pressure gradient, causing air to be sucked into the catheter, which then collects in the right heart and pulmonary arterial tree. Reflex constriction of the pulmonary vasculature increases pressure in the right heart, which results in transient opening of an anatomically patent foramen ovale. These mechanisms are unlikely in our patient because no venous gas was introduced.Another possible mechanism for the entry of air into the arterial system in our patient, in the absence of a massive air embolism or a communication between the right and left heart, is a bronchovenous connection (after an alveolar rupture) with a pressure gradient adequate to allow air to reach the arterial system. This is the mechanism operative in barotrauma (e.g., diving accident, inhalation of pressurized helium, cardiopulmonary resuscitation); it may also occur in patients with adult respiratory distress syndrome and those undergoing positive pressure mechanical ventilation.4Nakao N Moriwaki H Oiwa Y Barotraumatic cerebral air embolism following scuba diving.Brain Nerve. 1990; 42: 1097100Google Scholar, 5Marini JJ Culver BH Systemic gas embolism complicating mechanical ventilation in the adult respiratory distress syndrome.Ann Intern Med. 1989; 110: 699-703Crossref PubMed Scopus (86) Google Scholar, 6Pao BS Hayden SR Cerebral gas embolism resulting from inhalation of pressurized helium.Ann Emerg Med. 1996; 28: 363-366Abstract Full Text Full Text PDF PubMed Scopus (10) Google Scholar, 7Imanishi M Nishimura A Tabuse H Miyamoto S Sakaki T Iwasaki S Intracranial gas on CT after cardiopulmonary resuscitation: 4 cases.Neuroradiology. 1998; 40: 154-157Crossref PubMed Scopus (24) Google Scholar The retractive tendency of infiltrated parenchyma in these patients may tether and open vascular channels disrupted by inflammation or necrosis, allowing entry of interstitial gas that has leaked from ruptured alveoli.8Schlaepfer K Air embolism following various diagnostic or therapeutic procedures in diseases of pleura and lung.Bull Johns Hopkins Hosp. 1922; 33: 321-330Google Scholar Interstitial gas may escape into the pleural space and cause a pneumothorax, or it may decompress into the tissues of the neck, trunk, or retroperitoneum.9Macklin MT Macklin CC Malignant interstitial emphysema of the lungs and mediastinum as an important occult complication in many respiratory diseases and other conditions.Medicine. 1944; 23: 281-358Crossref Scopus (612) Google Scholar A similar event may have occurred in our patient, who suddenly developed bronchospasm and became cyanotic. An increase in intrathoracic pressure in our patient, who had extensive sequelae of pulmonary tuberculosis, may have caused shearing of small vessels and rupture of alveoli, allowing gas to gain access to the pulmonary venous system through the disrupted interstitium.There are other reports of air embolism during GI endoscopy. In a patient with a gastric ulcer, autopsy revealed a vessel exposed to the insufflation of air during the procedure.10Katzgraber F Glenewinkel F Fischler S Rittner C Mechanism of fatal air embolism after gastrointestinal endoscopy.Int J Legal Med. 1998; 111: 154-156Crossref PubMed Scopus (53) Google Scholar In another patient, who had a patent foramen ovale, air had been insufflated during endoscopy after dilation of an esophageal stricture for the purpose of obtaining biopsy specimens from the narrowed region.11Raju GS Bendixen BH Khan J Summers RW Cerebrovascular accident during endoscopy: consider cerebral air embolism, a rapidly reversible event with hyperbaric oxygen therapy.Gastrointest Endosc. 1998; 47: 70-73Abstract Full Text Full Text PDF PubMed Scopus (22) Google Scholar It was theorized that air had probably gained entry to the circulatory system by means of tiny mucosal tears and then into the esophageal venous channels. There is also a report of a patient with a duodenal ulcer and a duodenocaval fistula who had a stroke as a result of an air embolism.12Christl SU Scheppach W Peters U Kirchner T Cerebral air embolism after gastroduodenoscopy: complication of a duodenocaval fistula.Gastrointest Endosc. 1994; 40: 376-378Abstract Full Text Full Text PDF PubMed Scopus (37) Google Scholar The esophagus, stomach, and duodenum were normal endoscopically in our patient.CT has an important role in confirming the diagnosis of cerebral air embolism, particularly when the acute clinical presentation does not suggest this diagnosis, as in our patient. However, air is usually not evident by CT because the presence of air bubbles in the brain is highly unusual. Vasospasm occurs once bubbles obstruct flow in an artery, the end result being an infarct. Because our patient was in a semierect position during endoscopy, the location of the infarct in the right hemisphere is logical because of the anatomic position of the right common carotid artery. Hyperbaric oxygen is a well-established, lifesaving emergency treatment for cerebral air embolism because it reduces the size of the intravascular air bubbles that obstruct or occlude the arteries.13Tibbles PM Edelsberg JS Hyperbaric oxygen therapy.N Engl J Med. 1996; 334: 1642-1648Crossref PubMed Scopus (725) Google Scholar Because CT may not reveal air within the brain, diffusion-weighted magnetic resonance imaging should be obtained because this can demonstrate infarcted tissue within 20 minutes. If air embolism is suspected, treatment with hyperbaric oxygen therapy should be considered as soon as possible. To our knowledge, this is the first report of cerebral air embolism during a routine, uneventful GI endoscopy in a patient who did not have a patent foramen ovale. Pneumocephalus, a general term for air within the cranium, may be associated with skull fracture, an intrathecal procedure, cerebral angiography, infection, neoplasms, congenital skull defects, and barotrauma.1Thompson TD Levy E Kanal E Lunsford D Iatrogenic pneumocephalus secondary to intravenous catheterization.J Neurosurg. 1999; 91: 878-880Crossref PubMed Scopus (14) Google Scholar Cerebral air embolism can be due to either a massive venous air embolism or a direct communication between the right and the left side of the heart. The foramen ovale is patent at autopsy in 10% to 40% of cases.2Thompson T Evans W Paradoxical embolism.Q J Med. 1930; 23: 135-150Crossref Scopus (235) Google Scholar Air embolism has also been described after insertion of a subclavian intravenous catheter.3Hwang TL Fremaux R Sears ES MacFadyen B Hills B Mader JT et al.Confirmation of cerebral air embolism with computerized tomography.Ann Neurol. 1983; 13: 214-215Crossref PubMed Scopus (30) Google Scholar This has been attributed to entry of air into the subclavian vein, induced by inspiration, during the interval between catheter insertion and connection to the intravenous tubing. Inspiration results in a differential pressure gradient, causing air to be sucked into the catheter, which then collects in the right heart and pulmonary arterial tree. Reflex constriction of the pulmonary vasculature increases pressure in the right heart, which results in transient opening of an anatomically patent foramen ovale. These mechanisms are unlikely in our patient because no venous gas was introduced. Another possible mechanism for the entry of air into the arterial system in our patient, in the absence of a massive air embolism or a communication between the right and left heart, is a bronchovenous connection (after an alveolar rupture) with a pressure gradient adequate to allow air to reach the arterial system. This is the mechanism operative in barotrauma (e.g., diving accident, inhalation of pressurized helium, cardiopulmonary resuscitation); it may also occur in patients with adult respiratory distress syndrome and those undergoing positive pressure mechanical ventilation.4Nakao N Moriwaki H Oiwa Y Barotraumatic cerebral air embolism following scuba diving.Brain Nerve. 1990; 42: 1097100Google Scholar, 5Marini JJ Culver BH Systemic gas embolism complicating mechanical ventilation in the adult respiratory distress syndrome.Ann Intern Med. 1989; 110: 699-703Crossref PubMed Scopus (86) Google Scholar, 6Pao BS Hayden SR Cerebral gas embolism resulting from inhalation of pressurized helium.Ann Emerg Med. 1996; 28: 363-366Abstract Full Text Full Text PDF PubMed Scopus (10) Google Scholar, 7Imanishi M Nishimura A Tabuse H Miyamoto S Sakaki T Iwasaki S Intracranial gas on CT after cardiopulmonary resuscitation: 4 cases.Neuroradiology. 1998; 40: 154-157Crossref PubMed Scopus (24) Google Scholar The retractive tendency of infiltrated parenchyma in these patients may tether and open vascular channels disrupted by inflammation or necrosis, allowing entry of interstitial gas that has leaked from ruptured alveoli.8Schlaepfer K Air embolism following various diagnostic or therapeutic procedures in diseases of pleura and lung.Bull Johns Hopkins Hosp. 1922; 33: 321-330Google Scholar Interstitial gas may escape into the pleural space and cause a pneumothorax, or it may decompress into the tissues of the neck, trunk, or retroperitoneum.9Macklin MT Macklin CC Malignant interstitial emphysema of the lungs and mediastinum as an important occult complication in many respiratory diseases and other conditions.Medicine. 1944; 23: 281-358Crossref Scopus (612) Google Scholar A similar event may have occurred in our patient, who suddenly developed bronchospasm and became cyanotic. An increase in intrathoracic pressure in our patient, who had extensive sequelae of pulmonary tuberculosis, may have caused shearing of small vessels and rupture of alveoli, allowing gas to gain access to the pulmonary venous system through the disrupted interstitium. There are other reports of air embolism during GI endoscopy. In a patient with a gastric ulcer, autopsy revealed a vessel exposed to the insufflation of air during the procedure.10Katzgraber F Glenewinkel F Fischler S Rittner C Mechanism of fatal air embolism after gastrointestinal endoscopy.Int J Legal Med. 1998; 111: 154-156Crossref PubMed Scopus (53) Google Scholar In another patient, who had a patent foramen ovale, air had been insufflated during endoscopy after dilation of an esophageal stricture for the purpose of obtaining biopsy specimens from the narrowed region.11Raju GS Bendixen BH Khan J Summers RW Cerebrovascular accident during endoscopy: consider cerebral air embolism, a rapidly reversible event with hyperbaric oxygen therapy.Gastrointest Endosc. 1998; 47: 70-73Abstract Full Text Full Text PDF PubMed Scopus (22) Google Scholar It was theorized that air had probably gained entry to the circulatory system by means of tiny mucosal tears and then into the esophageal venous channels. There is also a report of a patient with a duodenal ulcer and a duodenocaval fistula who had a stroke as a result of an air embolism.12Christl SU Scheppach W Peters U Kirchner T Cerebral air embolism after gastroduodenoscopy: complication of a duodenocaval fistula.Gastrointest Endosc. 1994; 40: 376-378Abstract Full Text Full Text PDF PubMed Scopus (37) Google Scholar The esophagus, stomach, and duodenum were normal endoscopically in our patient. CT has an important role in confirming the diagnosis of cerebral air embolism, particularly when the acute clinical presentation does not suggest this diagnosis, as in our patient. However, air is usually not evident by CT because the presence of air bubbles in the brain is highly unusual. Vasospasm occurs once bubbles obstruct flow in an artery, the end result being an infarct. Because our patient was in a semierect position during endoscopy, the location of the infarct in the right hemisphere is logical because of the anatomic position of the right common carotid artery. Hyperbaric oxygen is a well-established, lifesaving emergency treatment for cerebral air embolism because it reduces the size of the intravascular air bubbles that obstruct or occlude the arteries.13Tibbles PM Edelsberg JS Hyperbaric oxygen therapy.N Engl J Med. 1996; 334: 1642-1648Crossref PubMed Scopus (725) Google Scholar Because CT may not reveal air within the brain, diffusion-weighted magnetic resonance imaging should be obtained because this can demonstrate infarcted tissue within 20 minutes. If air embolism is suspected, treatment with hyperbaric oxygen therapy should be considered as soon as possible. To our knowledge, this is the first report of cerebral air embolism during a routine, uneventful GI endoscopy in a patient who did not have a patent foramen ovale.