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Sciatica caused by epidural gas. Four case reports
Joint Bone Spine 2001 ; 68 : 434-7 © 2001 Éditions scientifiques et médicales Elsevier SAS. All rights reserved S1297319X01003013/SCO
CASE REPORT
Sciatica caused by epidural gas. Four case reports Françoise Giraud1, Aurélie Fontana1, Joël Mallet2, Louis P. Fischer2, Pierre J. Meunier1* 1 Rheumatology and bony pathology department, pavillon F, hôpital Édouard-Herriot, place d’Arsonval, 69437 Lyon cedex, 03, France; 2Orthopedic surgery and traumatology department, pavillon T, hôpital Édouard-Herriot, place d’Arsonval, 69437 Lyon cedex 03, France
(Submitted for publication December 4, 2000; accepted in revised form February 21, 2001)
Summary – We report four cases of sciatica caused by gas in the epidural space with no other abnormality. Only 21 similar cases have been reported. Clinical features are identical to those of common sciatica, and plain radiographs are often uninformative. Computed tomography shows a low-density epidural collection displacing the nerve root. Joint Bone Spine 2001 ; 68 : 434-7. © 2001 Éditions scientifiques et médicales Elsevier SAS degenerative disk disease / epidural gas / intradiscal vacuum phenomenon / sciatica
Gas within the spine can produce sciatica via two pathophysiological mechanisms: gas can accumulate either within a herniated disk or within the epidural space in the absence of disk herniation. We report four cases of sciatica caused by epidural gas. We are aware of only 21 similar cases in the literature. The initiating event may be degenerative disk disease causing intradiscal cracks, which reduce intradiscal pressure, drawing in gas. The gas can then be expelled into the epidural space through trauma-related tears in the disks and ligaments [1]. The clinical features are similar to those of common sciatica, with mechanical monoradicular pain, antalgic posture, and a positive straight leg-raising test. Lumbar spine radiographs can show disk height loss and gas in the middle of the disk space [2]. Computed tomography (CT) provides the diagnosis by showing a central low-density image with a variable high-density rim and a tiny communication with the disk [3-5]. We report four cases and discuss the diagnosis and management of this rare cause of sciatica.
* Correspondence and reprints.
CASE REPORTS Case 1 This 55-year-old overweight man with chronic low back pain presented with a four-month history of sciatica on the right, in an ill-defined distribution. He denied any precipitating factor. The pain was mechanical and worsened by coughing, sneezing, and straining. The straight leg-raising test was positive on the right at 60°. Motor and sensory function was normal. Plain radiographs suggested degenerative disease of the L5-S1 disk with central intradiscal vacuum phenomenon (figure 1). No disk herniation was seen on CT scans, which disclosed gas in the anterior epidural space impinging on the right S1 root (figures 2 and 3). There was no response to management for 1 month with rest, nonsteroidal anti-inflammatory drugs, an analgesic, and a muscle relaxant. A repeat CT scan showed no change. A glucocorticoid was injected into the epidural space via the left posterior articular route, under CT guidance. The pain improved substantially, although a third CT scan done 1 month later showed only a small decrease in the diameter of the gas collection. Five months after
Sciatica caused by epidural gas
435
Figure 2. Computed tomography of the lumbar spine in case 1, axial section: degenerative L5-S1 disease with calcification of the annulus fibrosus and osteophytes. No disk herniation. Gas collection in the anterior part of the epidural space impinging and displacing the right S1 root.
phenomenon. CT showed epidural gas displacing the right L5 root posteriorly. Because the history of peptic ulcer disease and renal failure contraindicated nonsteroidal anti-inflammatory drugs, high-dose glucocorticoid therapy was given. Control of the diabetes was monitored closely. Two days after treatment initiation, Figure 1. Lateral radiograph of the lumbar spine showing L5-S1 degenerative disease (narrowing of the intervertebral space) and central vacuum phenomenon.
the injection, the patient was free of pain and had returned to his usual activities. Case 2 A 69-year-old-year woman presented with pain and neurological loss in the distribution of the right sciatic nerve. She had chronic renal failure and insulin requiring diabetes mellitus, as well as a remote history of peptic ulcer disease. No precipitating factor to the pain was identified. The pain was inflammatory, causing nocturnal arousals. The straight leg-raising test was positive at 45°, and foot flexor strength was decreased to 3/5. Sphincter function was normal, and there was no evidence of cauda equina syndrome. The C-reactive protein level was normal. Plain radiographs disclosed multilevel degenerative disk disease with no vacuum
Figure 3. Computed tomography, sagittal reconstruction: the L5-S1 disk is not herniated but there is a collection of epidural gas starting under the L5-S1 disk and extending downward over 15 mm, with impingement on the S1 root.
436
F. Giraud et al.
she reported no further nocturnal arousals and had an improvement in foot flexor muscle strength to 4/5. One month later, she was free of pain and had further improved her motor loss. Case 3 This 58-year-old-man sought help for a 2-year history of sciatica on the right, in an ill-defined distribution. Facet joint osteoarthritis was the only finding on plain radiographs. CT showed vacuum phenomenon in all the disks from L3 to S1. Six years later, this patient experienced a recurrence of right-sided sciatica, this time in the distribution of the S1 dermatome. No vacuum phenomenon was visible on the repeat CT scan, but gas was seen in the epidural space on the right. CT coupled with myelography disclosed massive impingement of the gas on the right S1 root. Magnetic resonance imaging (MRI) showed a signal void at L5-S1 with rim enhancement after gadolinium injection. The pain was severe and failed to respond to conservative therapy including two foraminal glucocorticoid injections 15 days apart. Surgery was performed. The root was visualized clearly, and the foramen was unobstructed, but no gas was seen. The procedure consisted in hemilaminectomy above and below the disk followed by light disk curettage. One month later, the pain reduction was satisfactory. However, 1 year later, a recurrence was noted, and a repeat CT scan showed both the gas collection and epidural fibrosis. Case 4 A 30-year-old man was referred to our department for right-sided sciatica and femoral nerve root pain that had started several months earlier. CT and MRI showed disk disease and an L4-L5 disk herniation to the right of the midline. The herniation was removed surgically. The postoperative CT scan evidenced intradiscal vacuum phenomenon with minimal bulging of the disk. Six months after surgery, the pain had resolved completely. However, 3 years later, the patient came back to the clinic for mechanical low back pain and pain in his right knee. There were no physical findings suggestive of disk impingement on a nerve root. Myelography showed a notch in the thecal sac at L4-L5 that precluded visualization of the L5 root. Vacuum phenomenon with a collection of epidural gas rimmed by a thin disk-density wall was seen on CT scans. During CT coupled with discography, the injection produced sharp sciatic pain; a rounded density was seen within
the spinal canal in continuity with the degenerative disk. On MRI scans, this image appended to the disk generated a heterogeneous signal (fluid, air, and fibrosis densities). The pain abated noticeably under conservative treatment. DISCUSSION In addition to our four cases, we are aware of 21 reported cases of sciatica caused by epidural gas. In 1934, Mixter and Barr [6] wrote the first report suggesting a link between common lumbosciatic syndrome and intervertebral disk herniation. Disk herniation is defined as a focal bulge in an intervertebral disk and is widely believed to result from migration of disk material through a radial fissure in a degenerative disk. However, particularly in middle-aged or elderly patients, many disk herniations contain annulus fibrosus, and some contain nothing else. Degenerative lesions cause cracks in the disk, which are promptly filled by gas. This gas may be expelled subsequently into the epidural space, where it may have the same potential for nerve root impingement as solid material does. The symptoms and physical findings are identical to those of disk herniation, although the peak prevalence occurs at an older age because of the relation with degenerative disk disease. Plain radiographs usually show evidence of degenerative disease. Vacuum phenomenon is a less common finding and can occur in other conditions such as crystal-induced arthropathy (spinal chondrocalcinosis), tabes dorsalis, Schmörl’s nodes, and postsurgical or nucleolysis changes [2]. Intradiscal vacuum phenomenon is believed to be the source of the epidural gas, with the gas being expelled through weaker areas of the disk into the epidural space, and the supra- and infrajacent vertebras acting as a piston. The gas is composed primarily of nitrogen [3] and is enclosed in a membrane of cartilage fragments that communicate with the disk [3, 7]. CT is the investigation of choice for the diagnosis. The scans not only show that the collection within the spinal canal is composed of gas but also provide useful information on the condition of the disk and of the rest of the lumbar spine. The typical findings include degenerative disk disease with central vacuum phenomenon and, at the same level, a collection of epidural gas in contact with the nerve root corresponding to the distribution of the pain. This last point is important because epidural gas is sometimes present in asymptomatic patients. The gas collection can range in size from a few
Sciatica caused by epidural gas
millimeters to 1 centimeter and in density from – 200 to – 900 Hounsfield units. Rim enhancement can be seen. MRI yields similar findings, with low signal on T1- and T2-weighted images and postgadolinium rim enhancement. Conservative treatment consisting of rest, a nonsteroidal anti-inflammatory agent, and a muscle relaxant should be tried first, in combination with epidural glucocorticoid injections if needed. Aspiration of the gas collection under fluoroscopic guidance has been used, but when the procedure induced pain relief, this effect lasted 6 months at the most [8-11]. Surgery is in order in patients who fail to respond to conservative therapy. Because the gas is produced within the disk, the procedure consists not only of removing the gas collection but also in curetting the disk space. REFERENCES 1 Ricca GF, Robertson JT, Hines RS. Nerve root compression by herniated intradiscal gas. Case report. J Neurosurg 1990 ; 72 : 282-4. 2 Resnick D, Niwayama G, Guerra J, Vint V, Usselman J. Spinal vacuum phenomena: anatomical study and review. Radiology 1981 ; 139 : 341-8.
437
3 Yoshida H, Shinomiya K, Nakai O, Kurosa Y, Yamaura I. Lumbar nerve root compression caused by lumbar intraspinal gas. Report of three cases. Spine 1997 ; 22 : 348-51. 4 Gebarski SS, Gebarski KS, Gabrielsen TO, Knake JE, Latack JT, Yang JP. Gas as a mass: a symptomatic spinal canalicular collection. J Comput Assisted Tomogr 1984 ; 8 : 145-6. 5 Simonetti G, Martino V, Santilli S, Chiapetta F. Lumbar root compression by a gas containing cyst in the extradural space. Case report. J Neurosurg Sci 1992 ; 36 : 101-2. 6 Mixter WJ, Barr JS. Rupture of the intervertebral disc with involvement of the spinal canal. N Engl J Med 1934 ; 211 : 210-5. 7 Kumar R, West GH, Gillespie JE. Gas in a spinal extradural cyst. Case report. J Neurosurg 1989 ; 67 : 1184-6. 8 Demierre B, Ramadan A, Hauser H. Radicular compression due to a lumbar intraspinal gas pseudocyst. Case report. Neurosurg 1988 ; 22 : 731-3. 9 Godard J, Bonneville JF, Czorny A, Jacquet G, El Mohamad R. Bulles d’air intracanalaires lombaires symptomatiques. À propos de cinq observations. Rachis 1995 ; 7 : 103-7. 10 Rhighini A, Lucchi S, Regnati P, Zavanone M, Bettinelli A. Percutaneous treatment of gas-containing lumbar disc herniation. Report of two cases. J Neurosurg 1990 ; 72 : 282-4. 11 Bosser V, Dietmann JL, Warter JM, Granel de Solignac M, Beaujeux R. L5 radicular pain related to lumbar extradural gas containing pseudocyst. Role of CT guided aspiration. Neuroradiol 1990 ; 31 : 552-3.
CASE REPORT
Sciatica caused by epidural gas. Four case reports Françoise Giraud1, Aurélie Fontana1, Joël Mallet2, Louis P. Fischer2, Pierre J. Meunier1* 1 Rheumatology and bony pathology department, pavillon F, hôpital Édouard-Herriot, place d’Arsonval, 69437 Lyon cedex, 03, France; 2Orthopedic surgery and traumatology department, pavillon T, hôpital Édouard-Herriot, place d’Arsonval, 69437 Lyon cedex 03, France
(Submitted for publication December 4, 2000; accepted in revised form February 21, 2001)
Summary – We report four cases of sciatica caused by gas in the epidural space with no other abnormality. Only 21 similar cases have been reported. Clinical features are identical to those of common sciatica, and plain radiographs are often uninformative. Computed tomography shows a low-density epidural collection displacing the nerve root. Joint Bone Spine 2001 ; 68 : 434-7. © 2001 Éditions scientifiques et médicales Elsevier SAS degenerative disk disease / epidural gas / intradiscal vacuum phenomenon / sciatica
Gas within the spine can produce sciatica via two pathophysiological mechanisms: gas can accumulate either within a herniated disk or within the epidural space in the absence of disk herniation. We report four cases of sciatica caused by epidural gas. We are aware of only 21 similar cases in the literature. The initiating event may be degenerative disk disease causing intradiscal cracks, which reduce intradiscal pressure, drawing in gas. The gas can then be expelled into the epidural space through trauma-related tears in the disks and ligaments [1]. The clinical features are similar to those of common sciatica, with mechanical monoradicular pain, antalgic posture, and a positive straight leg-raising test. Lumbar spine radiographs can show disk height loss and gas in the middle of the disk space [2]. Computed tomography (CT) provides the diagnosis by showing a central low-density image with a variable high-density rim and a tiny communication with the disk [3-5]. We report four cases and discuss the diagnosis and management of this rare cause of sciatica.
* Correspondence and reprints.
CASE REPORTS Case 1 This 55-year-old overweight man with chronic low back pain presented with a four-month history of sciatica on the right, in an ill-defined distribution. He denied any precipitating factor. The pain was mechanical and worsened by coughing, sneezing, and straining. The straight leg-raising test was positive on the right at 60°. Motor and sensory function was normal. Plain radiographs suggested degenerative disease of the L5-S1 disk with central intradiscal vacuum phenomenon (figure 1). No disk herniation was seen on CT scans, which disclosed gas in the anterior epidural space impinging on the right S1 root (figures 2 and 3). There was no response to management for 1 month with rest, nonsteroidal anti-inflammatory drugs, an analgesic, and a muscle relaxant. A repeat CT scan showed no change. A glucocorticoid was injected into the epidural space via the left posterior articular route, under CT guidance. The pain improved substantially, although a third CT scan done 1 month later showed only a small decrease in the diameter of the gas collection. Five months after
Sciatica caused by epidural gas
435
Figure 2. Computed tomography of the lumbar spine in case 1, axial section: degenerative L5-S1 disease with calcification of the annulus fibrosus and osteophytes. No disk herniation. Gas collection in the anterior part of the epidural space impinging and displacing the right S1 root.
phenomenon. CT showed epidural gas displacing the right L5 root posteriorly. Because the history of peptic ulcer disease and renal failure contraindicated nonsteroidal anti-inflammatory drugs, high-dose glucocorticoid therapy was given. Control of the diabetes was monitored closely. Two days after treatment initiation, Figure 1. Lateral radiograph of the lumbar spine showing L5-S1 degenerative disease (narrowing of the intervertebral space) and central vacuum phenomenon.
the injection, the patient was free of pain and had returned to his usual activities. Case 2 A 69-year-old-year woman presented with pain and neurological loss in the distribution of the right sciatic nerve. She had chronic renal failure and insulin requiring diabetes mellitus, as well as a remote history of peptic ulcer disease. No precipitating factor to the pain was identified. The pain was inflammatory, causing nocturnal arousals. The straight leg-raising test was positive at 45°, and foot flexor strength was decreased to 3/5. Sphincter function was normal, and there was no evidence of cauda equina syndrome. The C-reactive protein level was normal. Plain radiographs disclosed multilevel degenerative disk disease with no vacuum
Figure 3. Computed tomography, sagittal reconstruction: the L5-S1 disk is not herniated but there is a collection of epidural gas starting under the L5-S1 disk and extending downward over 15 mm, with impingement on the S1 root.
436
F. Giraud et al.
she reported no further nocturnal arousals and had an improvement in foot flexor muscle strength to 4/5. One month later, she was free of pain and had further improved her motor loss. Case 3 This 58-year-old-man sought help for a 2-year history of sciatica on the right, in an ill-defined distribution. Facet joint osteoarthritis was the only finding on plain radiographs. CT showed vacuum phenomenon in all the disks from L3 to S1. Six years later, this patient experienced a recurrence of right-sided sciatica, this time in the distribution of the S1 dermatome. No vacuum phenomenon was visible on the repeat CT scan, but gas was seen in the epidural space on the right. CT coupled with myelography disclosed massive impingement of the gas on the right S1 root. Magnetic resonance imaging (MRI) showed a signal void at L5-S1 with rim enhancement after gadolinium injection. The pain was severe and failed to respond to conservative therapy including two foraminal glucocorticoid injections 15 days apart. Surgery was performed. The root was visualized clearly, and the foramen was unobstructed, but no gas was seen. The procedure consisted in hemilaminectomy above and below the disk followed by light disk curettage. One month later, the pain reduction was satisfactory. However, 1 year later, a recurrence was noted, and a repeat CT scan showed both the gas collection and epidural fibrosis. Case 4 A 30-year-old man was referred to our department for right-sided sciatica and femoral nerve root pain that had started several months earlier. CT and MRI showed disk disease and an L4-L5 disk herniation to the right of the midline. The herniation was removed surgically. The postoperative CT scan evidenced intradiscal vacuum phenomenon with minimal bulging of the disk. Six months after surgery, the pain had resolved completely. However, 3 years later, the patient came back to the clinic for mechanical low back pain and pain in his right knee. There were no physical findings suggestive of disk impingement on a nerve root. Myelography showed a notch in the thecal sac at L4-L5 that precluded visualization of the L5 root. Vacuum phenomenon with a collection of epidural gas rimmed by a thin disk-density wall was seen on CT scans. During CT coupled with discography, the injection produced sharp sciatic pain; a rounded density was seen within
the spinal canal in continuity with the degenerative disk. On MRI scans, this image appended to the disk generated a heterogeneous signal (fluid, air, and fibrosis densities). The pain abated noticeably under conservative treatment. DISCUSSION In addition to our four cases, we are aware of 21 reported cases of sciatica caused by epidural gas. In 1934, Mixter and Barr [6] wrote the first report suggesting a link between common lumbosciatic syndrome and intervertebral disk herniation. Disk herniation is defined as a focal bulge in an intervertebral disk and is widely believed to result from migration of disk material through a radial fissure in a degenerative disk. However, particularly in middle-aged or elderly patients, many disk herniations contain annulus fibrosus, and some contain nothing else. Degenerative lesions cause cracks in the disk, which are promptly filled by gas. This gas may be expelled subsequently into the epidural space, where it may have the same potential for nerve root impingement as solid material does. The symptoms and physical findings are identical to those of disk herniation, although the peak prevalence occurs at an older age because of the relation with degenerative disk disease. Plain radiographs usually show evidence of degenerative disease. Vacuum phenomenon is a less common finding and can occur in other conditions such as crystal-induced arthropathy (spinal chondrocalcinosis), tabes dorsalis, Schmörl’s nodes, and postsurgical or nucleolysis changes [2]. Intradiscal vacuum phenomenon is believed to be the source of the epidural gas, with the gas being expelled through weaker areas of the disk into the epidural space, and the supra- and infrajacent vertebras acting as a piston. The gas is composed primarily of nitrogen [3] and is enclosed in a membrane of cartilage fragments that communicate with the disk [3, 7]. CT is the investigation of choice for the diagnosis. The scans not only show that the collection within the spinal canal is composed of gas but also provide useful information on the condition of the disk and of the rest of the lumbar spine. The typical findings include degenerative disk disease with central vacuum phenomenon and, at the same level, a collection of epidural gas in contact with the nerve root corresponding to the distribution of the pain. This last point is important because epidural gas is sometimes present in asymptomatic patients. The gas collection can range in size from a few
Sciatica caused by epidural gas
millimeters to 1 centimeter and in density from – 200 to – 900 Hounsfield units. Rim enhancement can be seen. MRI yields similar findings, with low signal on T1- and T2-weighted images and postgadolinium rim enhancement. Conservative treatment consisting of rest, a nonsteroidal anti-inflammatory agent, and a muscle relaxant should be tried first, in combination with epidural glucocorticoid injections if needed. Aspiration of the gas collection under fluoroscopic guidance has been used, but when the procedure induced pain relief, this effect lasted 6 months at the most [8-11]. Surgery is in order in patients who fail to respond to conservative therapy. Because the gas is produced within the disk, the procedure consists not only of removing the gas collection but also in curetting the disk space. REFERENCES 1 Ricca GF, Robertson JT, Hines RS. Nerve root compression by herniated intradiscal gas. Case report. J Neurosurg 1990 ; 72 : 282-4. 2 Resnick D, Niwayama G, Guerra J, Vint V, Usselman J. Spinal vacuum phenomena: anatomical study and review. Radiology 1981 ; 139 : 341-8.
437
3 Yoshida H, Shinomiya K, Nakai O, Kurosa Y, Yamaura I. Lumbar nerve root compression caused by lumbar intraspinal gas. Report of three cases. Spine 1997 ; 22 : 348-51. 4 Gebarski SS, Gebarski KS, Gabrielsen TO, Knake JE, Latack JT, Yang JP. Gas as a mass: a symptomatic spinal canalicular collection. J Comput Assisted Tomogr 1984 ; 8 : 145-6. 5 Simonetti G, Martino V, Santilli S, Chiapetta F. Lumbar root compression by a gas containing cyst in the extradural space. Case report. J Neurosurg Sci 1992 ; 36 : 101-2. 6 Mixter WJ, Barr JS. Rupture of the intervertebral disc with involvement of the spinal canal. N Engl J Med 1934 ; 211 : 210-5. 7 Kumar R, West GH, Gillespie JE. Gas in a spinal extradural cyst. Case report. J Neurosurg 1989 ; 67 : 1184-6. 8 Demierre B, Ramadan A, Hauser H. Radicular compression due to a lumbar intraspinal gas pseudocyst. Case report. Neurosurg 1988 ; 22 : 731-3. 9 Godard J, Bonneville JF, Czorny A, Jacquet G, El Mohamad R. Bulles d’air intracanalaires lombaires symptomatiques. À propos de cinq observations. Rachis 1995 ; 7 : 103-7. 10 Rhighini A, Lucchi S, Regnati P, Zavanone M, Bettinelli A. Percutaneous treatment of gas-containing lumbar disc herniation. Report of two cases. J Neurosurg 1990 ; 72 : 282-4. 11 Bosser V, Dietmann JL, Warter JM, Granel de Solignac M, Beaujeux R. L5 radicular pain related to lumbar extradural gas containing pseudocyst. Role of CT guided aspiration. Neuroradiol 1990 ; 31 : 552-3.