The Neuroradiology Journal 20: 287-290, 2007
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Recurrent Cerebral Fat Embolism Due to Pleural Irrigation: Fat Density Lesions on CT. A Case Report A.YILMAZ*, S. KURT**, B. SARIKAYA***, M. MURAT FIRAT***, S. OCAL*, A. YEGINSU**** * Department of Pulmonary Disease, ** Neurology, *** Radiology, **** Chest Surgery, Gaziosmanpasa University School of Medicine; Tokat, Turkey
Key words: computed tomography, fat embolism, pleural irrigation, stroke
SUMMARY – Fat embolism syndrome is a rare, but life-threatening problem and is usually associated with severe trauma. Neurological symptoms are variable, and the clinical diagnosis is difficult. We describe a patient with fat density lesions on cranial CT sections and discuss the etiopathogenesis of cerebral fat embolism (CFE) in this patient who does not have a history of long bone fracture, but metastatic lung disease and empyema. This is probably the first case report of CFE secondary to pleural irrigation of empyema with demonstrative CT findings.
Introduction Fat embolism syndrome, that commonly occurs 12-36 hours after trauma or surgery, generally consists of respiratory insufficiency, petechial skin lesions, and cerebral deterioration 1,2. Neurological involvement in fat embolism syndrome is termed cerebral fat embolism (CFE) and is generally considered a diagnostic challenge. CFE usually occurs secondary to paradoxical embolism in lower extremity long bone fractures 3. However, literature reports include different causes and sources of CFE including drug overdose, severe infections, diabetes mellitus and burns 4. The pathophysiology of CFE remains unclear, and the extent to which it represents a primary embolic occlusive or a secondary neurotoxic process is undetermined 5. Herein we describe an adult male patient presenting with malignant pleural effusion who had several stroke attacks immediately after pleural irrigation. Cranial CT scans obtained after the second attack demonstrated hypodense lesions of fat density. Alhough we did not have MRI confirmation, the CT images are of sufficient interest and worth mentioning because of the demonstrative CT findings associated with CFE. CFE findings are very rare
in the literature and there are no reports of stroke attacks due to CFE immediately after pleural irrigation. Case Report A 66-year-old man with a history of malignant mixed tumor of the right parotid gland presented with malignant pleural effusion and empyema. The patient had undergone surgery and received chemotherapy thereafter at another medical center. The patient was hospitalized and a thoracic tube was placed for drainage. The patient had two stroke attacks within a week, both of which occurred during pleural irrigation. The first stroke attack was characterized by left sided hemiplegia, dysphasia and confusion. However, the second attack occurred predominantly as right-sided hemiplegia and stuporous consciousness. After the first attack anticoagulation therapy was administered and the second attack occurred when the patient was on anticoagulation therapy. Cranial CTs were obtained after both attacks. The findings on the first CT performed within two hours of the initial stroke were nonspecific and a hemorrhage was easily ruled out. 287
Recurrent Cerebral Fat Embolism Due to Pleural Irrigation: Fat Density Lesions on CT
A
A.Yilmaz
B
Figure 1 A,B Sections close to the vertex showing hypodense lesions in the left cerebral hemisphere consistent with anterior cerebral artery feeding area. All the lesions are of fat density.
CT performed just after the second attack demonstrated bizarre, scattered, hypodense round lesions in the left cerebral hemisphere consistent with the left anterior cerebral artery feeding area. When specific densities of the lesions were obtained, all revealed fat density with a mean value of -60 HU (Hounsfield units). All of the hypodense lesions disappeared on the cranial CT obtained two days later. The patient’s neurological status also improved close to baseline. Retrospective questioning and examination revealed no recent bone trauma or metastatic bone disease. During and after the stroke episodes the patient was also free of petechial lesions and respiratory insufficiency. The biochemical analysis of pleural fluid was not consistent with chylous effusion and echocardiographic examination also failed to disclose any patency in the foramen ovale or septal defect. In addition, chest radiography revealed no evidence of pulmonary arteriovenous malformations. Doppler ultrasonography of the neck vessels was performed to exclude traumatic dissection but was found to be normal. Discussion Fat embolism is a serious complication of long bone fractures and orthopedic surgery involving the medullary cavity. The incidence 288
of fat embolism syndrome after bone fractures has been reported to be in the range of 0.5%3.5% 6-7. The severity is variable, and the outcomes range from complete recovery to death 7 . There are several reports of isolated neurologic disorder after CFE 8,9. Clinical manifestations of CFE are protean and nonspecific and may include headache, decreased consciousness level or coma, seizures or irritability. The etiopatogenesis of fat emboli after trauma is not clear. Two hypotheses that may coexist are mechanical, in which there is dissemination of bone marrow elements from the trauma site, and biochemical, in which elevated plasma catecholamine levels act to release lipids from body stores and destabilize circulating chylomicrons. Subsequently the action of pulmonary lipases results in the release of free fatty acids and the induction of a systemic inflammatory response. Microemboli may pass into the systemic circulation either via cardiac or intrapulmonary right-left shunts or directly through the pulmonary capillary bed without a shunt 9. Lipids are absorbed from the intestinal tract and transported into the lungs via the thoracic duct and first catabolized by pulmonary endothelial cells. Lipid metabolism and the barrier preventing lipid transport into the systemic circulation from the lungs, may be destroyed in various pulmonary parenchymal diseases. This condition may facilitate fat embolism so
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that the emboli are formed from a fusion of preexisting tiny chylomicrons in physiological suspension within the plasma 4. Absorbed chylomicrons from the intestine enter the venous system through the thoracic duct most commonly at the junction of the left subclavian vein and left internal jugular vein. Intrapulmonary lipases seem to have an important role in the metabolism of chylomicrons that reach the lungs. Some experiments have also shown that liver does not play a significant role in the metabolism of native VLDL or chylomicrons. Elmaraghi et Al proposed fat embolism as a variant of post-traumatic pulmonary insufficiency and Schemitch et Al also demonstrated that deformable fat globules can pass to the circulation through the injured lung vasculature under high pulmonary arterial pressures, secondary to pulmonary ischemic insults by an experimental canine model 10,11. Recently in another experimental study Aydin et Al compared pulmonary contusion with long bone fractures with ten rabbits in each group and concluded that pulmonary contusion is more important than long bone fracture 4. We assume that each time pleural irrigation with iodopovidon is performed, increased intrapleural pressure may act like a pulmonary contusion. Iodopovidone is an effective, safe, readily available and inexpensive alternative to achieve chemical pleurodesis in cases of recurrent incapacitating effusions, regardless of etiology 12. Adverse effects like pleuritic chest pain, fever and systemic
The Neuroradiology Journal 20: 287-290, 2007
hypotension after the instillation of the sclerosing agent have been reported 12. Stroke attacks secondary to CFE immediately after pleural irrigation with iodopovidone seems to be unique in the literature to date. The diagnosis of fat embolism syndrome is another challenging issue. Cerebral CT scans have usually been reported as negative in the acute phase. However, Lee et Al reported a fat attenuation filling defect in a region of the proximal left middle cerebral artery trunk 13. In addition, Sasano et Al performed CT on postoperative day 14 showing multiple small low density areas in the white matter 14. MRI is more sensitive and multiple small scattered hyperintense T2 lesions have been demonstrated. However T2-weighted scans are limited because it may take several days for the findings to develop and also the lesions may remain rather nonspesific 3. Although we did not perform CT angiography and MRI in our case, the size, distribution and density of the lesions occurred concomitantly with the deterioration of the patient’s neurologic status and disappeared when the neurologic status improved. These CT findings have not been mentioned in the literature so far. The lesions were all thought to be intravascular, and/or perivascular probably due to breakdown of the blood-brain barrier. Also, several stroke attacks resulting from CFE immediately after pleural irrigation is another noteworthy feature.
References 1 Sevitt S: The significance and pathology of fat embolism: Ann Clin Res 9: 173-180, 1977. 2 Kamenar E, Burger P: Cerebral fat embolism: a neuropathological study of a microembolic state. Stroke 11: 477-484, 1980. 3 Brant-Zawadski M: MR imaging of the brain. Radiology 166: 1-10, 1988. 4 Aydin MD, Akcay F, Aydin N et Al: Cerebral fat embolism: pulmonary contusion is a more important etiology than long bone fractures. Clin Neuropathol 24: 86-90, 2005. 5 Butteriss DJA, Mahad D, Soh C et Al: Reversible cytotoxic cerebral edema in cerebral fat embolism. Am J Neuroradiol 27: 620-623, 2006. 6 Gurd AR: Fat embolism: an aid to diagnosis. J Bone Joint Surg Br 52: 732-737, 1970.
7 Johnson MJ, Lucas GL: Fat embolism syndrome. Orthopedics 19: 41-48, 1996. 8 Finlay ME, Benson MD: Case report: magnetic resonance imaging in cerebral fat embolism. Clin Radiol 51: 445-446, 1996. 9 Bardana D, Rudan J, Cervenko F et Al: Fat embolism syndrome in a patient demonstrating only neurologic symptoms. Can J Surg 41: 398-402, 1998. 10 Elmaraghi AW, Aksenow S, Byrick RJ et Al: Pathophysiologic effect of fat embolism in a canine model of pulmonary contusion. J Bone Joint Surg Am 81: 11551164, 1999. 11 Schemitch EH, Turchin DC, Anderson GI et Al: Pulmonary and systemic fat embolisation after medullary canal pressurisation: a hemodynamic and histologic investigation in the dog. J Trauma 45: 738-742, 1988.
289
Recurrent Cerebral Fat Embolism Due to Pleural Irrigation: Fat Density Lesions on CT
12 Agarwal R, Agarwal AN, Gupta D: Efficacy and safety of iodopovidone pleurodesis through tube thoracostomy. Respirology 11: 105-108, 2006. 13 Lee TC, Bartlett ES, Fox AJ et Al: The Hypodense Artery Sign. Am J Neuroradiol 26: 2027-2029, 2005. 14 Sasano N, Ishida S, Tetsu S et Al: Cerebral fat embolism diagnosed by magnetic resonance imaging at one, eight, and 50 days after hip arthroplasty: a case report. Can J Anesth 51: 875-9, 2004.
290
A.Yilmaz
Semiha Kurt, MD Department of Neurology Gaziosmanpasa University School of Medicine Tokat, 60100, Turkey Phone: +90 3562129500 Fax: +90 3562129417 E-mail: [email protected]
www. centauro. it
Recurrent Cerebral Fat Embolism Due to Pleural Irrigation: Fat Density Lesions on CT. A Case Report A.YILMAZ*, S. KURT**, B. SARIKAYA***, M. MURAT FIRAT***, S. OCAL*, A. YEGINSU**** * Department of Pulmonary Disease, ** Neurology, *** Radiology, **** Chest Surgery, Gaziosmanpasa University School of Medicine; Tokat, Turkey
Key words: computed tomography, fat embolism, pleural irrigation, stroke
SUMMARY – Fat embolism syndrome is a rare, but life-threatening problem and is usually associated with severe trauma. Neurological symptoms are variable, and the clinical diagnosis is difficult. We describe a patient with fat density lesions on cranial CT sections and discuss the etiopathogenesis of cerebral fat embolism (CFE) in this patient who does not have a history of long bone fracture, but metastatic lung disease and empyema. This is probably the first case report of CFE secondary to pleural irrigation of empyema with demonstrative CT findings.
Introduction Fat embolism syndrome, that commonly occurs 12-36 hours after trauma or surgery, generally consists of respiratory insufficiency, petechial skin lesions, and cerebral deterioration 1,2. Neurological involvement in fat embolism syndrome is termed cerebral fat embolism (CFE) and is generally considered a diagnostic challenge. CFE usually occurs secondary to paradoxical embolism in lower extremity long bone fractures 3. However, literature reports include different causes and sources of CFE including drug overdose, severe infections, diabetes mellitus and burns 4. The pathophysiology of CFE remains unclear, and the extent to which it represents a primary embolic occlusive or a secondary neurotoxic process is undetermined 5. Herein we describe an adult male patient presenting with malignant pleural effusion who had several stroke attacks immediately after pleural irrigation. Cranial CT scans obtained after the second attack demonstrated hypodense lesions of fat density. Alhough we did not have MRI confirmation, the CT images are of sufficient interest and worth mentioning because of the demonstrative CT findings associated with CFE. CFE findings are very rare
in the literature and there are no reports of stroke attacks due to CFE immediately after pleural irrigation. Case Report A 66-year-old man with a history of malignant mixed tumor of the right parotid gland presented with malignant pleural effusion and empyema. The patient had undergone surgery and received chemotherapy thereafter at another medical center. The patient was hospitalized and a thoracic tube was placed for drainage. The patient had two stroke attacks within a week, both of which occurred during pleural irrigation. The first stroke attack was characterized by left sided hemiplegia, dysphasia and confusion. However, the second attack occurred predominantly as right-sided hemiplegia and stuporous consciousness. After the first attack anticoagulation therapy was administered and the second attack occurred when the patient was on anticoagulation therapy. Cranial CTs were obtained after both attacks. The findings on the first CT performed within two hours of the initial stroke were nonspecific and a hemorrhage was easily ruled out. 287
Recurrent Cerebral Fat Embolism Due to Pleural Irrigation: Fat Density Lesions on CT
A
A.Yilmaz
B
Figure 1 A,B Sections close to the vertex showing hypodense lesions in the left cerebral hemisphere consistent with anterior cerebral artery feeding area. All the lesions are of fat density.
CT performed just after the second attack demonstrated bizarre, scattered, hypodense round lesions in the left cerebral hemisphere consistent with the left anterior cerebral artery feeding area. When specific densities of the lesions were obtained, all revealed fat density with a mean value of -60 HU (Hounsfield units). All of the hypodense lesions disappeared on the cranial CT obtained two days later. The patient’s neurological status also improved close to baseline. Retrospective questioning and examination revealed no recent bone trauma or metastatic bone disease. During and after the stroke episodes the patient was also free of petechial lesions and respiratory insufficiency. The biochemical analysis of pleural fluid was not consistent with chylous effusion and echocardiographic examination also failed to disclose any patency in the foramen ovale or septal defect. In addition, chest radiography revealed no evidence of pulmonary arteriovenous malformations. Doppler ultrasonography of the neck vessels was performed to exclude traumatic dissection but was found to be normal. Discussion Fat embolism is a serious complication of long bone fractures and orthopedic surgery involving the medullary cavity. The incidence 288
of fat embolism syndrome after bone fractures has been reported to be in the range of 0.5%3.5% 6-7. The severity is variable, and the outcomes range from complete recovery to death 7 . There are several reports of isolated neurologic disorder after CFE 8,9. Clinical manifestations of CFE are protean and nonspecific and may include headache, decreased consciousness level or coma, seizures or irritability. The etiopatogenesis of fat emboli after trauma is not clear. Two hypotheses that may coexist are mechanical, in which there is dissemination of bone marrow elements from the trauma site, and biochemical, in which elevated plasma catecholamine levels act to release lipids from body stores and destabilize circulating chylomicrons. Subsequently the action of pulmonary lipases results in the release of free fatty acids and the induction of a systemic inflammatory response. Microemboli may pass into the systemic circulation either via cardiac or intrapulmonary right-left shunts or directly through the pulmonary capillary bed without a shunt 9. Lipids are absorbed from the intestinal tract and transported into the lungs via the thoracic duct and first catabolized by pulmonary endothelial cells. Lipid metabolism and the barrier preventing lipid transport into the systemic circulation from the lungs, may be destroyed in various pulmonary parenchymal diseases. This condition may facilitate fat embolism so
www. centauro. it
that the emboli are formed from a fusion of preexisting tiny chylomicrons in physiological suspension within the plasma 4. Absorbed chylomicrons from the intestine enter the venous system through the thoracic duct most commonly at the junction of the left subclavian vein and left internal jugular vein. Intrapulmonary lipases seem to have an important role in the metabolism of chylomicrons that reach the lungs. Some experiments have also shown that liver does not play a significant role in the metabolism of native VLDL or chylomicrons. Elmaraghi et Al proposed fat embolism as a variant of post-traumatic pulmonary insufficiency and Schemitch et Al also demonstrated that deformable fat globules can pass to the circulation through the injured lung vasculature under high pulmonary arterial pressures, secondary to pulmonary ischemic insults by an experimental canine model 10,11. Recently in another experimental study Aydin et Al compared pulmonary contusion with long bone fractures with ten rabbits in each group and concluded that pulmonary contusion is more important than long bone fracture 4. We assume that each time pleural irrigation with iodopovidon is performed, increased intrapleural pressure may act like a pulmonary contusion. Iodopovidone is an effective, safe, readily available and inexpensive alternative to achieve chemical pleurodesis in cases of recurrent incapacitating effusions, regardless of etiology 12. Adverse effects like pleuritic chest pain, fever and systemic
The Neuroradiology Journal 20: 287-290, 2007
hypotension after the instillation of the sclerosing agent have been reported 12. Stroke attacks secondary to CFE immediately after pleural irrigation with iodopovidone seems to be unique in the literature to date. The diagnosis of fat embolism syndrome is another challenging issue. Cerebral CT scans have usually been reported as negative in the acute phase. However, Lee et Al reported a fat attenuation filling defect in a region of the proximal left middle cerebral artery trunk 13. In addition, Sasano et Al performed CT on postoperative day 14 showing multiple small low density areas in the white matter 14. MRI is more sensitive and multiple small scattered hyperintense T2 lesions have been demonstrated. However T2-weighted scans are limited because it may take several days for the findings to develop and also the lesions may remain rather nonspesific 3. Although we did not perform CT angiography and MRI in our case, the size, distribution and density of the lesions occurred concomitantly with the deterioration of the patient’s neurologic status and disappeared when the neurologic status improved. These CT findings have not been mentioned in the literature so far. The lesions were all thought to be intravascular, and/or perivascular probably due to breakdown of the blood-brain barrier. Also, several stroke attacks resulting from CFE immediately after pleural irrigation is another noteworthy feature.
References 1 Sevitt S: The significance and pathology of fat embolism: Ann Clin Res 9: 173-180, 1977. 2 Kamenar E, Burger P: Cerebral fat embolism: a neuropathological study of a microembolic state. Stroke 11: 477-484, 1980. 3 Brant-Zawadski M: MR imaging of the brain. Radiology 166: 1-10, 1988. 4 Aydin MD, Akcay F, Aydin N et Al: Cerebral fat embolism: pulmonary contusion is a more important etiology than long bone fractures. Clin Neuropathol 24: 86-90, 2005. 5 Butteriss DJA, Mahad D, Soh C et Al: Reversible cytotoxic cerebral edema in cerebral fat embolism. Am J Neuroradiol 27: 620-623, 2006. 6 Gurd AR: Fat embolism: an aid to diagnosis. J Bone Joint Surg Br 52: 732-737, 1970.
7 Johnson MJ, Lucas GL: Fat embolism syndrome. Orthopedics 19: 41-48, 1996. 8 Finlay ME, Benson MD: Case report: magnetic resonance imaging in cerebral fat embolism. Clin Radiol 51: 445-446, 1996. 9 Bardana D, Rudan J, Cervenko F et Al: Fat embolism syndrome in a patient demonstrating only neurologic symptoms. Can J Surg 41: 398-402, 1998. 10 Elmaraghi AW, Aksenow S, Byrick RJ et Al: Pathophysiologic effect of fat embolism in a canine model of pulmonary contusion. J Bone Joint Surg Am 81: 11551164, 1999. 11 Schemitch EH, Turchin DC, Anderson GI et Al: Pulmonary and systemic fat embolisation after medullary canal pressurisation: a hemodynamic and histologic investigation in the dog. J Trauma 45: 738-742, 1988.
289
Recurrent Cerebral Fat Embolism Due to Pleural Irrigation: Fat Density Lesions on CT
12 Agarwal R, Agarwal AN, Gupta D: Efficacy and safety of iodopovidone pleurodesis through tube thoracostomy. Respirology 11: 105-108, 2006. 13 Lee TC, Bartlett ES, Fox AJ et Al: The Hypodense Artery Sign. Am J Neuroradiol 26: 2027-2029, 2005. 14 Sasano N, Ishida S, Tetsu S et Al: Cerebral fat embolism diagnosed by magnetic resonance imaging at one, eight, and 50 days after hip arthroplasty: a case report. Can J Anesth 51: 875-9, 2004.
290
A.Yilmaz
Semiha Kurt, MD Department of Neurology Gaziosmanpasa University School of Medicine Tokat, 60100, Turkey Phone: +90 3562129500 Fax: +90 3562129417 E-mail: [email protected]
