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The intravertebral vacuum phenomenon
European Journal of Radiology Extra 66 (2008) e55–e57
The intravertebral vacuum phenomenon Erhan Akpinar, Baris Turkbey ∗ , Bagdat Medeyev, Munci Oran Hacettepe University School of Medicine, Department of Radiology, Ankara, Turkey Received 12 February 2008; accepted 21 February 2008
Abstract Vertebral vacuum sign is an uncommon finding, which can easily mimic the air within the disc and can be overlooked. We present a case of intravertebral vacuum phenomenon with exquisite multidetector computed tomography and magnetic resonance imaging findings. © 2008 Elsevier Ireland Ltd. All rights reserved. Keywords: Trauma; Spine; Intravertebral vacuum sign; CT; MRI
1. Introduction The vacuum phenomenon appears as a radiolucent area visible in synovial joints, intervertebral disks, and vertebrae [1]. This phenomenon is explained by gas accumulation, mostly nitrogen, produced by the surrounding soft tissues [2]. The intravertebral vacuum phenomenon, also termed “intravertebral vacuum cleft,” is an uncommon finding. Although the cleft is, in fact, filled with gas, the term “vacuum phenomenon” has become universally accepted [3]. The aim of this paper is to present the multislice computed tomography and magnetic resonance imaging findings of intravertebral vacuum sign in a patient with acute osteoporotic traumatic vertebral compression fracture. 2. Case report A 74-year-old female was admitted to the hospital with history of trauma, abdominal pain and intestinal obstruction. Her past medical history was unremarkable except hypertension and osteoporosis. Physical examination revealed generalized ∗
Corresponding author at: HUTF Radyoloji AD, Sihhiye 06100, Ankara, Turkey. Tel.: +90 3123051188; fax: +90 3123112145. E-mail address: [email protected] (B. Turkbey). 1571-4675/$ – see front matter © 2008 Elsevier Ireland Ltd. All rights reserved. doi:10.1016/j.ejrex.2008.02.006
abdominal tenderness. She was hemodynamically stable with blood pressure of 160/95 mmHg, pulse 84 bpm, respiratory rate 18/min and oxygen saturation 95%. Patient’s laboratory workup was normal. Abdominal X-ray obtained in the supine position and abdominal ultrasound (US) examinations were normal. For further evaluation contrast-enhanced abdominal multislice CT examination was performed (3 mm slice thickness with 1.5 mm reconstruction increment). CT demonstrated a burst fracture of L1 vertebral body, paravertrebral hemorrhage and air within the vertebral body consistent with intravertebral vacuum sign. Additionally the anteroposterior diameter of spinal canal at this level was found to be narrowed (Fig. 1). In order to clarify a possible spinal cord injury, magnetic resonance imaging (MRI) was done. MRI confirmed the CT findings, but no spinal cord injury was depicted (Fig. 2). An intervention was not planned for the burst fracture; nonsteroidal anti-inflammatory (NSAID) drug therapy and electrolyte replacement were given. The symptoms of the patient resolved and she was discharged after 5 days of hospitalization. 3. Discussion The mechanism of gas accumulation within the vertebral body is poorly known [3]. The main hypothesis is the ischemic theory. Maldague reported the association between the pres-
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E. Akpinar et al. / European Journal of Radiology Extra 66 (2008) e55–e57
Fig. 1. 74-year-old woman with acute osteoporotic collapse of L1 vertebra. Axial computed tomography scan shows vacuum phenomenon along with increased density of prevertebral fat. Hypodense lesion in the upper pole of the left kidney is also detected (a). Sagittal reformatted computed tomography scan shows major collapse of L1 with intravertebral gas bubbles and prominent intervertebral gaseous collections in adjacent upper intervertebral disc. The intravertebral and upper disc vacuum phenomena seem to be in continuity through the fractured endplate. Spinal cord is compressed due to indentation of the vertebral corpus (b). Coronal reformatted computed tomography scan demonstrates intravertebral vacuum phenomenon more clearly (c). Osteophytes in multiple levels can also be seen.
ence of gas within the vertebral body and ischemia. Since then, ischemia secondary to trauma is thought to be the physiopathological mechanism of this sign, leading to osteonecrosis and delayed vertebral collapse [4]. However, ischemic necrosis of bone is presumably an accessory, nonspecific process, occurring in some acute vertebral collapses. Furthermore, the presence of some degree of bone necrosis due to corticosteroid medication in elder people would not by itself provide an explanation for the presence of gas within bone [3,5]. The negative pressure between the bone fragments seems to be mandatory for gas to be released from the surrounding tissues in the vacuum phenomenon [2]. It has been well established that the prevalence of intravertebral VP increases when radiographs are taken in the hyperextended position [4]. However, mechanical factors, such as induction of negative pressure within the fractured vertebral body, are probably not sufficient to explain intravertebral vacuum phenomenon [3]. Lafforgue et al. hypothesized that the intravertebral vacuum phenomenon could also be the result of migration of an intradiscal-gaseous collection through the fractured endplate of some osteoporotic collapses [3]. Intravertebral air can also be seen in infections and malignancies, but the pattern of gas formation may differ from those seen with osteonecrosis [6]. When the etiology is infectious, the gas has high pressure and small radiolucent collections may accompany, moreover; the gas may extend to adjacent soft tissues [7]. The presence of gas in vertebral body has been rarely reported in primary or metastatic vertebral malignancies [7,8]. Intravertebral air finding on axial images can easily mimic the air within the disc, thus it can be overlooked. In highly suspicious cases or in patients with axial CT scans in which increased paravertebral soft tissue density secondary to hemorhage, multiplanar reconstructions should be obtained. The introduction of MDCT, allowing rapid acquisition of a large scanning volume with a thin slice collimation, is of special interest in the initial CT assessment of the patient with multiple injuries. The ability for postprocessing of the acquired data set is a major advantage of MDCT scanners. The versatility of the data set for secondary reconstruction of images using different slice thicknesses and field of views during image reconstruction is especially helpful in the evaluation of the thoracolumbar spine. Classification of spinal injuries is considered important with regard to surgical management. An accurate assessment of thoracic and lumbar spine injuries, including fracture classification and determination of fracture stability, often requires thinner slice collimation especially for high-quality multiplanar reformations [9]. Using sagittal and coronal reformat images in addition to axial slices enable us to determine the fracture type, assess vertebral stability, and provide relevant information for further patient management. In conclusion, vertebral vacuum sign has a great benefit in differentiation of osteonecrosis from infections and malignancies. By using MDCT with high resolution multiplanar reconstructions, prompt diagnosis and follow up of this uncommon situation can be made.
E. Akpinar et al. / European Journal of Radiology Extra 66 (2008) e55–e57
e57
Fig. 2. 74-year-old woman with acute osteoporotic collapse of L1 vertebra. Sagittal T1-weighted magnetic resonance image (MRI) (a), sagittal T2-weighted MRI (b) and sagittal fat-suppressed MRI demonstrates collapse of L1 vertebra and displacement of bone fragments in to spinal canal (c). Also, note the heterogenity and hyperintensity of prevertebral fat indicating the acute nature of the disease.
References [1] Resnick D, Niwayama G, Guerra Jr J, Vint V, Usselman J. Spinal vacuum phenomena: anatomical study and review. Radiology 1981;139:341–8. [2] Ford LT, Gilula LA, Murphy WA, Gado M. Analysis of gas in vacuum lumbar disc. AJR 1977;128:1056–7. [3] Lafforgue PF, Chagnaud CJ, Daver LM, et al. Intervertebral disk vacuum phenomenon secondary to vertebral collapse: prevalence and significance. Radiology 1994;193:853–8. [4] Maldague BE, Noel HM, Malghem JJ. The intravertebral vacuum cleft: a sign of ischemic vertebral collapse. Radiology 1978;129:23–9.
[5] Chou LH, Knight RQ. Idiopathic avascular necrosis of a vertebral body. Case report and literature review. Spine 1997;22:1928–32. [6] Theodorou DJ. The intravertebral vacuum cleft sign. Radiology 2001;221(3):787. [7] Kumpan W, Salomonowitz E, Seidl G, Wittich GR. The intravertebral vacuum phenomenon. Skeletal Radiol 1986;15:444–7. [8] Sarli M, Perez Manghi FC, Gallo R, Zanchetta JR. The vacuum cleft sign: an uncommon radiological sign. Osteoporos Int 2005;16:1210–4. [9] Roos JE, Hilfiker P, Platz A, et al. MDCT in emergency radiology: is a standardized chest or abdominal protocol sufficient for evaluation of thoracic and lumbar spine trauma? AJR 2004;183:959–68.
The intravertebral vacuum phenomenon Erhan Akpinar, Baris Turkbey ∗ , Bagdat Medeyev, Munci Oran Hacettepe University School of Medicine, Department of Radiology, Ankara, Turkey Received 12 February 2008; accepted 21 February 2008
Abstract Vertebral vacuum sign is an uncommon finding, which can easily mimic the air within the disc and can be overlooked. We present a case of intravertebral vacuum phenomenon with exquisite multidetector computed tomography and magnetic resonance imaging findings. © 2008 Elsevier Ireland Ltd. All rights reserved. Keywords: Trauma; Spine; Intravertebral vacuum sign; CT; MRI
1. Introduction The vacuum phenomenon appears as a radiolucent area visible in synovial joints, intervertebral disks, and vertebrae [1]. This phenomenon is explained by gas accumulation, mostly nitrogen, produced by the surrounding soft tissues [2]. The intravertebral vacuum phenomenon, also termed “intravertebral vacuum cleft,” is an uncommon finding. Although the cleft is, in fact, filled with gas, the term “vacuum phenomenon” has become universally accepted [3]. The aim of this paper is to present the multislice computed tomography and magnetic resonance imaging findings of intravertebral vacuum sign in a patient with acute osteoporotic traumatic vertebral compression fracture. 2. Case report A 74-year-old female was admitted to the hospital with history of trauma, abdominal pain and intestinal obstruction. Her past medical history was unremarkable except hypertension and osteoporosis. Physical examination revealed generalized ∗
Corresponding author at: HUTF Radyoloji AD, Sihhiye 06100, Ankara, Turkey. Tel.: +90 3123051188; fax: +90 3123112145. E-mail address: [email protected] (B. Turkbey). 1571-4675/$ – see front matter © 2008 Elsevier Ireland Ltd. All rights reserved. doi:10.1016/j.ejrex.2008.02.006
abdominal tenderness. She was hemodynamically stable with blood pressure of 160/95 mmHg, pulse 84 bpm, respiratory rate 18/min and oxygen saturation 95%. Patient’s laboratory workup was normal. Abdominal X-ray obtained in the supine position and abdominal ultrasound (US) examinations were normal. For further evaluation contrast-enhanced abdominal multislice CT examination was performed (3 mm slice thickness with 1.5 mm reconstruction increment). CT demonstrated a burst fracture of L1 vertebral body, paravertrebral hemorrhage and air within the vertebral body consistent with intravertebral vacuum sign. Additionally the anteroposterior diameter of spinal canal at this level was found to be narrowed (Fig. 1). In order to clarify a possible spinal cord injury, magnetic resonance imaging (MRI) was done. MRI confirmed the CT findings, but no spinal cord injury was depicted (Fig. 2). An intervention was not planned for the burst fracture; nonsteroidal anti-inflammatory (NSAID) drug therapy and electrolyte replacement were given. The symptoms of the patient resolved and she was discharged after 5 days of hospitalization. 3. Discussion The mechanism of gas accumulation within the vertebral body is poorly known [3]. The main hypothesis is the ischemic theory. Maldague reported the association between the pres-
e56
E. Akpinar et al. / European Journal of Radiology Extra 66 (2008) e55–e57
Fig. 1. 74-year-old woman with acute osteoporotic collapse of L1 vertebra. Axial computed tomography scan shows vacuum phenomenon along with increased density of prevertebral fat. Hypodense lesion in the upper pole of the left kidney is also detected (a). Sagittal reformatted computed tomography scan shows major collapse of L1 with intravertebral gas bubbles and prominent intervertebral gaseous collections in adjacent upper intervertebral disc. The intravertebral and upper disc vacuum phenomena seem to be in continuity through the fractured endplate. Spinal cord is compressed due to indentation of the vertebral corpus (b). Coronal reformatted computed tomography scan demonstrates intravertebral vacuum phenomenon more clearly (c). Osteophytes in multiple levels can also be seen.
ence of gas within the vertebral body and ischemia. Since then, ischemia secondary to trauma is thought to be the physiopathological mechanism of this sign, leading to osteonecrosis and delayed vertebral collapse [4]. However, ischemic necrosis of bone is presumably an accessory, nonspecific process, occurring in some acute vertebral collapses. Furthermore, the presence of some degree of bone necrosis due to corticosteroid medication in elder people would not by itself provide an explanation for the presence of gas within bone [3,5]. The negative pressure between the bone fragments seems to be mandatory for gas to be released from the surrounding tissues in the vacuum phenomenon [2]. It has been well established that the prevalence of intravertebral VP increases when radiographs are taken in the hyperextended position [4]. However, mechanical factors, such as induction of negative pressure within the fractured vertebral body, are probably not sufficient to explain intravertebral vacuum phenomenon [3]. Lafforgue et al. hypothesized that the intravertebral vacuum phenomenon could also be the result of migration of an intradiscal-gaseous collection through the fractured endplate of some osteoporotic collapses [3]. Intravertebral air can also be seen in infections and malignancies, but the pattern of gas formation may differ from those seen with osteonecrosis [6]. When the etiology is infectious, the gas has high pressure and small radiolucent collections may accompany, moreover; the gas may extend to adjacent soft tissues [7]. The presence of gas in vertebral body has been rarely reported in primary or metastatic vertebral malignancies [7,8]. Intravertebral air finding on axial images can easily mimic the air within the disc, thus it can be overlooked. In highly suspicious cases or in patients with axial CT scans in which increased paravertebral soft tissue density secondary to hemorhage, multiplanar reconstructions should be obtained. The introduction of MDCT, allowing rapid acquisition of a large scanning volume with a thin slice collimation, is of special interest in the initial CT assessment of the patient with multiple injuries. The ability for postprocessing of the acquired data set is a major advantage of MDCT scanners. The versatility of the data set for secondary reconstruction of images using different slice thicknesses and field of views during image reconstruction is especially helpful in the evaluation of the thoracolumbar spine. Classification of spinal injuries is considered important with regard to surgical management. An accurate assessment of thoracic and lumbar spine injuries, including fracture classification and determination of fracture stability, often requires thinner slice collimation especially for high-quality multiplanar reformations [9]. Using sagittal and coronal reformat images in addition to axial slices enable us to determine the fracture type, assess vertebral stability, and provide relevant information for further patient management. In conclusion, vertebral vacuum sign has a great benefit in differentiation of osteonecrosis from infections and malignancies. By using MDCT with high resolution multiplanar reconstructions, prompt diagnosis and follow up of this uncommon situation can be made.
E. Akpinar et al. / European Journal of Radiology Extra 66 (2008) e55–e57
e57
Fig. 2. 74-year-old woman with acute osteoporotic collapse of L1 vertebra. Sagittal T1-weighted magnetic resonance image (MRI) (a), sagittal T2-weighted MRI (b) and sagittal fat-suppressed MRI demonstrates collapse of L1 vertebra and displacement of bone fragments in to spinal canal (c). Also, note the heterogenity and hyperintensity of prevertebral fat indicating the acute nature of the disease.
References [1] Resnick D, Niwayama G, Guerra Jr J, Vint V, Usselman J. Spinal vacuum phenomena: anatomical study and review. Radiology 1981;139:341–8. [2] Ford LT, Gilula LA, Murphy WA, Gado M. Analysis of gas in vacuum lumbar disc. AJR 1977;128:1056–7. [3] Lafforgue PF, Chagnaud CJ, Daver LM, et al. Intervertebral disk vacuum phenomenon secondary to vertebral collapse: prevalence and significance. Radiology 1994;193:853–8. [4] Maldague BE, Noel HM, Malghem JJ. The intravertebral vacuum cleft: a sign of ischemic vertebral collapse. Radiology 1978;129:23–9.
[5] Chou LH, Knight RQ. Idiopathic avascular necrosis of a vertebral body. Case report and literature review. Spine 1997;22:1928–32. [6] Theodorou DJ. The intravertebral vacuum cleft sign. Radiology 2001;221(3):787. [7] Kumpan W, Salomonowitz E, Seidl G, Wittich GR. The intravertebral vacuum phenomenon. Skeletal Radiol 1986;15:444–7. [8] Sarli M, Perez Manghi FC, Gallo R, Zanchetta JR. The vacuum cleft sign: an uncommon radiological sign. Osteoporos Int 2005;16:1210–4. [9] Roos JE, Hilfiker P, Platz A, et al. MDCT in emergency radiology: is a standardized chest or abdominal protocol sufficient for evaluation of thoracic and lumbar spine trauma? AJR 2004;183:959–68.