- Email: [email protected]
Thoracic extruded disc mimicking spinal cord tumor
The Spine Journal 3 (2003) 82–86
Case Report
Thoracic extruded disc mimicking spinal cord tumor Bikash Bose, MD, FACS, FICS, FAHAa,b a Department of Neurosurgery, Christiana Care Health Care System, C-79 Omega Drive, Newark, DE, 19713 USA Department of Neurosurgery, Jefferson Medical College, 909 Walnut Street, 3rd Floor, Philadelphia, PA, 19107 USA Received 10 September 2001; accepted 15 May 2002
b
Abstract
Background context: Thoracic disc herniation is a rare condition. Distinguishing between a herniated disc and tumor for a lesion found at the thoracic level can be a diagnostic challenge. Purpose: To describe a case of thoracic disc herniation that mimicked a spinal cord tumor. Study design/setting: Case report and review of the literature. Patient sample: Case report. Outcome measures: Report of postoperative symptoms. Methods/description: A 54-year-old man was admitted to the hospital with progressively worsening weakness in both lower extremities, increased numbness of both lower extremities, pain radiating into his groin bilaterally and left foot drop. During a recent visit to his family physician, the patient’s legs gave out and he collapsed. Physical examination revealed markedly increased tone in both extremities. Magnetic resonance images at T11–12 showed signal abnormality in the anterior extradural space, which extended posterior and inferior to the disc level to the left of midline. An extramedullary lesion found in the posterior spinal canal showed a low signal on T1 image and a high but heterogeneous signal on T2-weighted images. Preoperative diagnosis was neoplasm. A bilateral decompressive laminectomy was performed under operative magnification and ultrasonography. A large extruded disc was found that migrated from the ventral aspect around the thecal sac and into the dorsal aspect, which compressed the sac to the right. The extradural lesion was dissected off the surrounding thecal sac. Postoperatively, the patient underwent rehabilitation and is able to walk with only minimal weakness of both legs. Conclusions: Determining the diagnosis for thoracic spinal lesions, either disc herniation or tumor, is a diagnostic challenge. © 2003 Elsevier Science Inc. All rights reserved.
Keywords:
Spine; Thoracic disc; Spinal neoplasm; Differential diagnosis
Introduction Thoracic disc herniation is a rare condition that occurs in only about 1% of all disc herniations [1]. The diagnosis of a lesion at the thoracic level can be difficult, because patients have varied clinical symptoms and pain that make distinguishing between a herniated disc and tumor a diagnostic challenge. Magnetic resonance imaging (MRI) has been instrumental for helping clinicians correctly diagnose soft tissue lesions, but MRI is still not completely accurate. This report reviews a case of thoracic disc herniation that mimFDA device/drug status: not applicable. Nothing of value received from a commercial entity related to this research. * Corresponding author. C-79 Omega Drive, Newark, DE 19713, USA. Tel.: (302) 738-9145; fax: (302) 738-9148. E-mail address: [email protected] (B. Bose)
icked a spinal cord tumor. The patient’s symptoms and results of clinical tests will be summarized, and a review of the literature will provide insight for recognizing and distinguishing between thoracic disc herniation and tumor. Case report The patient was a 54-year-old white man who was admitted to the hospital with progressively worsening weakness in both lower extremities, left great than right, and increased numbness of both lower extremities. He also complained of pain radiating into his groin bilaterally. The patient stated that he developed a left foot drop about 2 days before admission. He stated that his back problems began in 1992 when he was injured while working. At that time, the patient was treated with physical therapy for about 1 year without any significant improvement. He continued to have
1529-9430/03/$ – see front matter © 2003 Elsevier Science Inc. All rights reserved. PII: S1529-9430(02)002 0 6 - 1
B.Bose / The Spine Journal 3 (2003) 82–86
83
Fig. 1. T1-weighted magnetic resonance images (Left) without and (Right) with contrast, showing abnormal mass displacing the spinal cord to the right.
some pain since that time. In early August of 1998, he twisted his back while shoveling dirt. The next day the pain increased significantly, and he developed numbness in his left leg. He was seen in the emergency room and was advised to rest. He was then followed by his family physician. Subsequently, during one of the office visits, the patient’s legs gave out and he collapsed. He denied bowel or bladder incontinence. His past medical history includes renal calculi, surgery for the parathyroid and thyroid glands in 1990 and pneumonia in 1970. He was also seeing a psychiatrist for his emotional problems. The neurological examination showed he was alert, awake and oriented to time, place and person. Pupils were equal and reactive to light and accommodation at 4 mm. Extraocular movements were full. He had no upper extremity drift. Parietal and cerebellar functions were within normal limits. Straight leg–raising test was free to 90 degrees bilaterally. The left iliopsoas was 3/5. The left gluteal and hamstrings were 3/5. The left tibialis anterior was 2/5. The left plantar evertors and flexors were 2/5. On the right side, the same motor groups were 3 to 4-/5. He had no ankle clonus, and toes were down-going. He had markedly increased tone in both extremities. MRI of T11–12 through L5–S1 were obtained to include sagittal T2-weight localizer and sagittal T1 and fast spin echo proton and T2-weighted images. After the administration of intravenous gadolinium contrast, sagittal, axial and coronal T2 and axial T2 fat saturation images were obtained. At T11–12, there was a signal abnormality in the anterior extradural space, which extended posterior and inferior to the disc level to the left of midline (Fig. 1). In the posterior spinal canal, there was an extramedullary lesion,
which was low on T1 signal and high but heterogeneous on T2-weighted images (Fig. 2). There was considerable peripheral enhancement of the lesion after contrast administration (Fig. 3). The lesion measured 3.0 cm in length. The cord was considerably compressed anteriorly and toward the right at the T11–12 level. In addition, the patient had bulging discs at L2–3 and L4–5 levels and disc herniation at L5–S1. A bilateral decompressive laminectomy was performed under operative magnification and ultrasonography. A large extruded disc was found that migrated from the ventral aspect around the thecal sac and into the dorsal aspect, which compressed the sac to the right. The extradural lesion was dissected off the surrounding thecal sac. The lesion was found to be a combination of cartilaginous end plates and disc material. Postoperatively, the patient underwent rehabilitation and is able to walk with only minimal weakness of both legs.
Discussion The differential diagnoses for a patient presenting with the described symptoms and examination findings in this report include epidural abscess, resolving epidural hematoma, synovial cysts, epidermoid cysts, peripheral nerve sheath tumors (neurofibroma, Schwannoma), meningioma and lipomas. MRI is the first imaging choice for demonstrating a herniated disc compressing the subarachnoid space and possibly the cord. Problems may arise in diagnosing calcified thoracic discs because of the inability of MRI to detect calcification [2,3].
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B.Bose / The Spine Journal 3 (2003) 82–86
Fig. 2. Magnetic resonance images showing lesion in posterior spinal canal. (Left) T1 image shows low signal intensity and (Right) T2 image shows high but heterogeneous signal intensity.
An epidural abscess is usually located in the dorsal epidural space because of the close adhesion of the ventral dura, and the posterior longitudinal ligament limits the anterior spread of an abscess. An epidural mass will have low signal intensity compared with normal spinal cord on T1weighted images and has high signal on T2-weighted images. The patterns of enhancement can be homogenous, peripheral (consistent with abscess having a necrotic center) or show a combination of a frank abscess and tissue enhancement [4,5]. Subdural empyema has a similar presentation, although the incidence is more rare. A resolving hematoma can also appear as a ring-enhancing lesion. These diagnoses were ruled out because of the location of the lesion seen on the MRI and because the MRI showed a heterogeneous appearance on T2-weighted images. MRI of a synovial cyst shows focal impression on the cord, but the image intensity is similar to cerebrospinal fluid and does not show enhancement. An epidermoid cyst appears on an MRI as a circumscribed mass with a variable signal intensity depending on cyst contents. These can calcify and appear with peripheral enhancement in MRI [6]. Peripheral nerve sheath tumors can have peripheral enhancement on the MRI if there has been cystic change. They are normally isointense on T1-weighted images and are hy-
perintense on T2-weighted images. Isointense areas or increased intensity of T2-weighted images, and decreased signal on proton density–weighted images and T2-weighted images have been associated with hemorrhage [4]. Lipomas may be intradural (60%) or extradural (40%). They have high signal on T1-weighted images and decreased signal on standard T2-weighted images. With fat suppression techniques, they appear dark. Limpomas can be confused with hemorrhage. However, with fat suppression techniques, signal intensity is low with lipomas and remains high with hemorrhage. Meningiomas are discrete lesions with a female preponderance and constitute 25% of spinal canal neoplasms. They commonly occur in the thoracic spine (80%) [4,7]. Meningiomas appear isointense to slightly hyperintense on T2-weighted images and have a heterogeneous appearance that enhances with contrast. The patient in this case report was suspected to have a tumor for several reasons: 1) thoracic disc herniation is rare; 2) the lesion extended from ventral to the dorsolateral aspect of the spinal canal, whereas most thoracic disc herniations occur in the ventral aspect [8–10]; 3) the lesion did not appear to originate from the intervertebral space [11–13], which is common of a herniated disc and 4) there was no decrease in disc space on the radiograph [14].
B.Bose / The Spine Journal 3 (2003) 82–86
Fig. 3. T1 image with contrast showing considerable peripheral enhancement of the lesion.
To further illustrate the difficulty of distinguishing disc herniation from tumor, some reports describe cases of spinal tumors that mimicked disc disease. Guyer et al. [15] reported on a series of 744 patients who had symptoms of disc herniation and subsequently underwent surgery. Of 744 patients, only 9 patients had a tumor and only 3 were of the thoracic spine. The authors concluded that patients should be suspected of having a tumor if they have painless neurological deficit, night pain or pain that increases when supine, pain disproportionate to that normally expected with disc disease, no change in symptoms after a successful surgery for herniated disc or if the patient is a teenager with symptoms of a disc herniation. The purpose of the report by Guyer et al. [15] was to identify characteristics that could lead the clinician to suspect a tumor versus disc herniation. It is apparent, however, that not only is thoracic disc herniation rare, it is also rare for patients with symptoms of disc degeneration to have tumors [15,16]. Acre and Dohrmann [8] reported that the most common level of thoracic disc herniation was at the T11–12 level (26%), and 75% of the herniations were below the T8 level. Stillerman et al. [17] in a series of 82 herniated thoracic discs, found the most common site was T8–T11. This trend may be explained by the increased mobility and torsion
85
stress seen at the lower thoracic area [8]. Oppenheim et al, [10] in 1993 reported on 12 cases of thoracic disc herniation and reviewed the literature for common clinical characteristics. From their review, they determined that thoracic disc herniation usually occurred in middle age (between age 30 and 50 years), in men (60%) and the location was either central or centrolateral. The patient in our series had a lesion that appeared from ventral to dorsolateral on the MRI. Only one other report exists in the literature of a dorsal thoracic disc herniation [18]. Morizane et al. [18] presented a case of a dorsally sequestered thoracic disc herniation in a 53-year-old man who had acute low back pain but had no apparent trauma. MRI revealed a mass at T10–11 level that connected with the T10 disc. The diagnosis of herniated disc was correctly made from reviewing the MRI and recognizing the connection to the T10 disc level. On MRI evaluation, disc herniation usually can be seen to originate from the intervertebral disc space [11–13]. The patient described in this case report had a mass that appeared intradural extramedullary, which led to our diagnosis of tumor. Some cases of disc herniation that mimicked spinal cord tumor have been reported on the lumbar spine [11–14,19,20], but only a few cases have been reported of the thoracic spine [21]. Goldberg et al. [21] reported on four patients who had thoracic disc herniations that were thought to be tumors. The diagnosis was correctly determined in each case before surgery with MRI evaluation. Two of the patients had confounding factors that included history of breast carcinoma and partially collapsed vertebral bodies that appeared hypointense on the MRI, which is common with metastatic involvement. The hypointense areas were limited to the area of disc herniation, however. The authors suggested that, on T1-weighted images, a hypointense area surrounding a degenerative disc indicates a degenerative process rather than malignancy. The authors further recommended the use of T2-weighted images to facilitate visualization of spinal cord compression caused by small disc protrusions [21]. Much can be learned from studying reported cases about lumbar disc herniations that mimicked tumors [11– 14,19,20]. Two factors about the MRI evaluation of our patient could have led us to a correct diagnosis before surgery. The T2-weighted images with contrast revealed rim enhancement of the lesion, which has been found to be indicative of disc herniation in the lumbar spine [14,20]. Furthermore, the T2-weighted images appeared heterogeneous, whereas tumors usually appear homogenous on MRI [14,19]. Given the other factors of the location of the mass and the lack of disc space narrowing, we believed the patient had a tumor. It is apparent that a definitive diagnosis for a spinal lesion cannot be made by radiographic or MRI evaluation alone. Histological evaluation at the time of surgery is the only way to verify the diagnosis. This review of cases in which the diagnosis was difficult to determine between disc herniation and tumor may give the clinician a systematic approach for arriving at a logical preoperative diagnosis.
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B.Bose / The Spine Journal 3 (2003) 82–86
References [1] Alberico AM, Sahni S, Hall JA, Young HF. High thoracic disc herniation. Neurosurgery 1986;19:449–51. [2] Grossman RI, Yousem DM. Anatomy and degenerative diseases of the spine. In: Grossman RI, Yousem DM, editors. Neuroradiology: the requisites. St. Louis: Mosby, 1994:447–76. [3] Ross JS, Perez-Reyes N, Masaryk TJ, Bohlman H, Modic MT. Thoracic disk herniation: MR imaging. Radiology 1987;165:511–5. [4] Grossman RI, Yousem DM. Nondegenerative diseases of the spine. In: Grossman RI, Yousem DM, editors. Neuroradiology: the requisites. St. Louis: Mosby, 1994:477–504. [5] Tung GA, Yim JW, Mermel LA, Phiip L, Rogg JM. Spinal epidural abscess: correlation between MRI findings and outcome. Neuroradiology 1999;41:904–9. [6] Liu SS, Williams KD, Drayer BP, Spetzler RF, Sonntag VK. Synovial cysts of the lumbosacral spine: diagnosis by MR imaging. Am J Neuroradiol 1989;10:1239–42. [7] Gezen F, Kahraman S, Canakci Z, Beduk A. Review of 36 cases of spinal cord meningioma. Spine 2000;25:727–31. [8] Acre CA, Dohrmann GJ. Thoracic disc herniation: improved diagnosis with computed tomographic scanning and a review of the literature. Surg Neurol 1985;23:356–61. [9] Blumenkopf B. Thoracic intervertebral disc herniations: diagnostic value of magnetic resonance imagining. Neurosurgery 1988;23:36–40. [10] Oppenheim JS, Rothman AS, Sachdev VP. Thoracic herniated discs: review of the literature and 12 cases. Mount Sinai J Med 1993;60:321–6. [11] Cusimano MD, Bukala BP, Bilbao J. Extreme lateral disc herniation
Seventy-Five Years Ago in Spine . . .
[12]
[13] [14]
[15] [16] [17]
[18]
[19] [20]
[21]
manifesting as nerve sheath tumor: case report. J Neurosurg 1995;82: 654–6. Eckardt JJ, Kaplan DD, Batzdorf U, Dawson EG. Extraforaminal disc herniation simulating a retroperitoneal neoplasm: case report. J Bone Joint Surg 1985;67-A:1275–7. Witzmann A, Hammer B, Fischer J. Free sequestered disc herniation at the S2 level misdiagnosed as neuroma. Neuroradiology 1991;33:92–3. Ashkenazi E, Pamerianz S, Floman Y. Foraminal herniation of a lumbar disc mimicking neurinoma on CT and MR imagining. J Spinal Disord 1997;10:448–50. Guyer RD, Collier RR, Ohnmeiss DD, et al. Extraosseous spinal lesions mimicking disc disease. Spine 1988;13:328–31. Epstein JA. Common errors in the diagnosis of herniation of the intervertebral disk. Ind Med Surg 39:480–8. Stillerman CB, Chen TC, Couldwell WT, Zhang W, Weiss MH. Experience in the surgical management of 82 symptomatic herniated thoracic discs and review of the literature. J Neurosurg 1998;88:623–33. Morizane A, Hanakita J, Suwa H, Ohshita N, Gotoh K, Matsuoka T. Dorsally sequestrated thoracic disc herniation: case report. Neurol Med Chir (Tokyo) 1999;39:769–72. Emamian SA, Skriver EB, Henriksen L, Cortsen ME. Lumbar herniated disk mimicking neurinoma: case report. Acta Radiologica 1993;34:127–9. Saruhashi Y, Omura K, Miyamoto K, Katsuura A, Hukuda S. A migrated lumbar disc herniation simulating a dumbbell tumor. J Spinal Disord 1999;12 (4):307–9.[/1a] Goldberg AL, Rothfus WE, Deeb ZL, Khoury MB, Daffner RH. Thoracic disc herniation versus spinal metastases: optimizing diagnosis with magnetic resonance imaging. Skeletal Radiol 1988;17:423–6.
preceded by a note by W.T. Bovie, which described a new, “surgical-current generator.”
References [1] Cushing HW. Electrosurgery as an aid to the removal of intracranial tumors. With a preliminary note on a new surgical-current generator by W.T. Bovie. Surg Gyn Obstet 1928;47:751–84.
The use of electrocoagulation in neurosurgery was established by a publication in 1928, authored by Harvey Williams Cushing (1869–1939). The article was
David Fardon Knoxville, TN
Case Report
Thoracic extruded disc mimicking spinal cord tumor Bikash Bose, MD, FACS, FICS, FAHAa,b a Department of Neurosurgery, Christiana Care Health Care System, C-79 Omega Drive, Newark, DE, 19713 USA Department of Neurosurgery, Jefferson Medical College, 909 Walnut Street, 3rd Floor, Philadelphia, PA, 19107 USA Received 10 September 2001; accepted 15 May 2002
b
Abstract
Background context: Thoracic disc herniation is a rare condition. Distinguishing between a herniated disc and tumor for a lesion found at the thoracic level can be a diagnostic challenge. Purpose: To describe a case of thoracic disc herniation that mimicked a spinal cord tumor. Study design/setting: Case report and review of the literature. Patient sample: Case report. Outcome measures: Report of postoperative symptoms. Methods/description: A 54-year-old man was admitted to the hospital with progressively worsening weakness in both lower extremities, increased numbness of both lower extremities, pain radiating into his groin bilaterally and left foot drop. During a recent visit to his family physician, the patient’s legs gave out and he collapsed. Physical examination revealed markedly increased tone in both extremities. Magnetic resonance images at T11–12 showed signal abnormality in the anterior extradural space, which extended posterior and inferior to the disc level to the left of midline. An extramedullary lesion found in the posterior spinal canal showed a low signal on T1 image and a high but heterogeneous signal on T2-weighted images. Preoperative diagnosis was neoplasm. A bilateral decompressive laminectomy was performed under operative magnification and ultrasonography. A large extruded disc was found that migrated from the ventral aspect around the thecal sac and into the dorsal aspect, which compressed the sac to the right. The extradural lesion was dissected off the surrounding thecal sac. Postoperatively, the patient underwent rehabilitation and is able to walk with only minimal weakness of both legs. Conclusions: Determining the diagnosis for thoracic spinal lesions, either disc herniation or tumor, is a diagnostic challenge. © 2003 Elsevier Science Inc. All rights reserved.
Keywords:
Spine; Thoracic disc; Spinal neoplasm; Differential diagnosis
Introduction Thoracic disc herniation is a rare condition that occurs in only about 1% of all disc herniations [1]. The diagnosis of a lesion at the thoracic level can be difficult, because patients have varied clinical symptoms and pain that make distinguishing between a herniated disc and tumor a diagnostic challenge. Magnetic resonance imaging (MRI) has been instrumental for helping clinicians correctly diagnose soft tissue lesions, but MRI is still not completely accurate. This report reviews a case of thoracic disc herniation that mimFDA device/drug status: not applicable. Nothing of value received from a commercial entity related to this research. * Corresponding author. C-79 Omega Drive, Newark, DE 19713, USA. Tel.: (302) 738-9145; fax: (302) 738-9148. E-mail address: [email protected] (B. Bose)
icked a spinal cord tumor. The patient’s symptoms and results of clinical tests will be summarized, and a review of the literature will provide insight for recognizing and distinguishing between thoracic disc herniation and tumor. Case report The patient was a 54-year-old white man who was admitted to the hospital with progressively worsening weakness in both lower extremities, left great than right, and increased numbness of both lower extremities. He also complained of pain radiating into his groin bilaterally. The patient stated that he developed a left foot drop about 2 days before admission. He stated that his back problems began in 1992 when he was injured while working. At that time, the patient was treated with physical therapy for about 1 year without any significant improvement. He continued to have
1529-9430/03/$ – see front matter © 2003 Elsevier Science Inc. All rights reserved. PII: S1529-9430(02)002 0 6 - 1
B.Bose / The Spine Journal 3 (2003) 82–86
83
Fig. 1. T1-weighted magnetic resonance images (Left) without and (Right) with contrast, showing abnormal mass displacing the spinal cord to the right.
some pain since that time. In early August of 1998, he twisted his back while shoveling dirt. The next day the pain increased significantly, and he developed numbness in his left leg. He was seen in the emergency room and was advised to rest. He was then followed by his family physician. Subsequently, during one of the office visits, the patient’s legs gave out and he collapsed. He denied bowel or bladder incontinence. His past medical history includes renal calculi, surgery for the parathyroid and thyroid glands in 1990 and pneumonia in 1970. He was also seeing a psychiatrist for his emotional problems. The neurological examination showed he was alert, awake and oriented to time, place and person. Pupils were equal and reactive to light and accommodation at 4 mm. Extraocular movements were full. He had no upper extremity drift. Parietal and cerebellar functions were within normal limits. Straight leg–raising test was free to 90 degrees bilaterally. The left iliopsoas was 3/5. The left gluteal and hamstrings were 3/5. The left tibialis anterior was 2/5. The left plantar evertors and flexors were 2/5. On the right side, the same motor groups were 3 to 4-/5. He had no ankle clonus, and toes were down-going. He had markedly increased tone in both extremities. MRI of T11–12 through L5–S1 were obtained to include sagittal T2-weight localizer and sagittal T1 and fast spin echo proton and T2-weighted images. After the administration of intravenous gadolinium contrast, sagittal, axial and coronal T2 and axial T2 fat saturation images were obtained. At T11–12, there was a signal abnormality in the anterior extradural space, which extended posterior and inferior to the disc level to the left of midline (Fig. 1). In the posterior spinal canal, there was an extramedullary lesion,
which was low on T1 signal and high but heterogeneous on T2-weighted images (Fig. 2). There was considerable peripheral enhancement of the lesion after contrast administration (Fig. 3). The lesion measured 3.0 cm in length. The cord was considerably compressed anteriorly and toward the right at the T11–12 level. In addition, the patient had bulging discs at L2–3 and L4–5 levels and disc herniation at L5–S1. A bilateral decompressive laminectomy was performed under operative magnification and ultrasonography. A large extruded disc was found that migrated from the ventral aspect around the thecal sac and into the dorsal aspect, which compressed the sac to the right. The extradural lesion was dissected off the surrounding thecal sac. The lesion was found to be a combination of cartilaginous end plates and disc material. Postoperatively, the patient underwent rehabilitation and is able to walk with only minimal weakness of both legs.
Discussion The differential diagnoses for a patient presenting with the described symptoms and examination findings in this report include epidural abscess, resolving epidural hematoma, synovial cysts, epidermoid cysts, peripheral nerve sheath tumors (neurofibroma, Schwannoma), meningioma and lipomas. MRI is the first imaging choice for demonstrating a herniated disc compressing the subarachnoid space and possibly the cord. Problems may arise in diagnosing calcified thoracic discs because of the inability of MRI to detect calcification [2,3].
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B.Bose / The Spine Journal 3 (2003) 82–86
Fig. 2. Magnetic resonance images showing lesion in posterior spinal canal. (Left) T1 image shows low signal intensity and (Right) T2 image shows high but heterogeneous signal intensity.
An epidural abscess is usually located in the dorsal epidural space because of the close adhesion of the ventral dura, and the posterior longitudinal ligament limits the anterior spread of an abscess. An epidural mass will have low signal intensity compared with normal spinal cord on T1weighted images and has high signal on T2-weighted images. The patterns of enhancement can be homogenous, peripheral (consistent with abscess having a necrotic center) or show a combination of a frank abscess and tissue enhancement [4,5]. Subdural empyema has a similar presentation, although the incidence is more rare. A resolving hematoma can also appear as a ring-enhancing lesion. These diagnoses were ruled out because of the location of the lesion seen on the MRI and because the MRI showed a heterogeneous appearance on T2-weighted images. MRI of a synovial cyst shows focal impression on the cord, but the image intensity is similar to cerebrospinal fluid and does not show enhancement. An epidermoid cyst appears on an MRI as a circumscribed mass with a variable signal intensity depending on cyst contents. These can calcify and appear with peripheral enhancement in MRI [6]. Peripheral nerve sheath tumors can have peripheral enhancement on the MRI if there has been cystic change. They are normally isointense on T1-weighted images and are hy-
perintense on T2-weighted images. Isointense areas or increased intensity of T2-weighted images, and decreased signal on proton density–weighted images and T2-weighted images have been associated with hemorrhage [4]. Lipomas may be intradural (60%) or extradural (40%). They have high signal on T1-weighted images and decreased signal on standard T2-weighted images. With fat suppression techniques, they appear dark. Limpomas can be confused with hemorrhage. However, with fat suppression techniques, signal intensity is low with lipomas and remains high with hemorrhage. Meningiomas are discrete lesions with a female preponderance and constitute 25% of spinal canal neoplasms. They commonly occur in the thoracic spine (80%) [4,7]. Meningiomas appear isointense to slightly hyperintense on T2-weighted images and have a heterogeneous appearance that enhances with contrast. The patient in this case report was suspected to have a tumor for several reasons: 1) thoracic disc herniation is rare; 2) the lesion extended from ventral to the dorsolateral aspect of the spinal canal, whereas most thoracic disc herniations occur in the ventral aspect [8–10]; 3) the lesion did not appear to originate from the intervertebral space [11–13], which is common of a herniated disc and 4) there was no decrease in disc space on the radiograph [14].
B.Bose / The Spine Journal 3 (2003) 82–86
Fig. 3. T1 image with contrast showing considerable peripheral enhancement of the lesion.
To further illustrate the difficulty of distinguishing disc herniation from tumor, some reports describe cases of spinal tumors that mimicked disc disease. Guyer et al. [15] reported on a series of 744 patients who had symptoms of disc herniation and subsequently underwent surgery. Of 744 patients, only 9 patients had a tumor and only 3 were of the thoracic spine. The authors concluded that patients should be suspected of having a tumor if they have painless neurological deficit, night pain or pain that increases when supine, pain disproportionate to that normally expected with disc disease, no change in symptoms after a successful surgery for herniated disc or if the patient is a teenager with symptoms of a disc herniation. The purpose of the report by Guyer et al. [15] was to identify characteristics that could lead the clinician to suspect a tumor versus disc herniation. It is apparent, however, that not only is thoracic disc herniation rare, it is also rare for patients with symptoms of disc degeneration to have tumors [15,16]. Acre and Dohrmann [8] reported that the most common level of thoracic disc herniation was at the T11–12 level (26%), and 75% of the herniations were below the T8 level. Stillerman et al. [17] in a series of 82 herniated thoracic discs, found the most common site was T8–T11. This trend may be explained by the increased mobility and torsion
85
stress seen at the lower thoracic area [8]. Oppenheim et al, [10] in 1993 reported on 12 cases of thoracic disc herniation and reviewed the literature for common clinical characteristics. From their review, they determined that thoracic disc herniation usually occurred in middle age (between age 30 and 50 years), in men (60%) and the location was either central or centrolateral. The patient in our series had a lesion that appeared from ventral to dorsolateral on the MRI. Only one other report exists in the literature of a dorsal thoracic disc herniation [18]. Morizane et al. [18] presented a case of a dorsally sequestered thoracic disc herniation in a 53-year-old man who had acute low back pain but had no apparent trauma. MRI revealed a mass at T10–11 level that connected with the T10 disc. The diagnosis of herniated disc was correctly made from reviewing the MRI and recognizing the connection to the T10 disc level. On MRI evaluation, disc herniation usually can be seen to originate from the intervertebral disc space [11–13]. The patient described in this case report had a mass that appeared intradural extramedullary, which led to our diagnosis of tumor. Some cases of disc herniation that mimicked spinal cord tumor have been reported on the lumbar spine [11–14,19,20], but only a few cases have been reported of the thoracic spine [21]. Goldberg et al. [21] reported on four patients who had thoracic disc herniations that were thought to be tumors. The diagnosis was correctly determined in each case before surgery with MRI evaluation. Two of the patients had confounding factors that included history of breast carcinoma and partially collapsed vertebral bodies that appeared hypointense on the MRI, which is common with metastatic involvement. The hypointense areas were limited to the area of disc herniation, however. The authors suggested that, on T1-weighted images, a hypointense area surrounding a degenerative disc indicates a degenerative process rather than malignancy. The authors further recommended the use of T2-weighted images to facilitate visualization of spinal cord compression caused by small disc protrusions [21]. Much can be learned from studying reported cases about lumbar disc herniations that mimicked tumors [11– 14,19,20]. Two factors about the MRI evaluation of our patient could have led us to a correct diagnosis before surgery. The T2-weighted images with contrast revealed rim enhancement of the lesion, which has been found to be indicative of disc herniation in the lumbar spine [14,20]. Furthermore, the T2-weighted images appeared heterogeneous, whereas tumors usually appear homogenous on MRI [14,19]. Given the other factors of the location of the mass and the lack of disc space narrowing, we believed the patient had a tumor. It is apparent that a definitive diagnosis for a spinal lesion cannot be made by radiographic or MRI evaluation alone. Histological evaluation at the time of surgery is the only way to verify the diagnosis. This review of cases in which the diagnosis was difficult to determine between disc herniation and tumor may give the clinician a systematic approach for arriving at a logical preoperative diagnosis.
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B.Bose / The Spine Journal 3 (2003) 82–86
References [1] Alberico AM, Sahni S, Hall JA, Young HF. High thoracic disc herniation. Neurosurgery 1986;19:449–51. [2] Grossman RI, Yousem DM. Anatomy and degenerative diseases of the spine. In: Grossman RI, Yousem DM, editors. Neuroradiology: the requisites. St. Louis: Mosby, 1994:447–76. [3] Ross JS, Perez-Reyes N, Masaryk TJ, Bohlman H, Modic MT. Thoracic disk herniation: MR imaging. Radiology 1987;165:511–5. [4] Grossman RI, Yousem DM. Nondegenerative diseases of the spine. In: Grossman RI, Yousem DM, editors. Neuroradiology: the requisites. St. Louis: Mosby, 1994:477–504. [5] Tung GA, Yim JW, Mermel LA, Phiip L, Rogg JM. Spinal epidural abscess: correlation between MRI findings and outcome. Neuroradiology 1999;41:904–9. [6] Liu SS, Williams KD, Drayer BP, Spetzler RF, Sonntag VK. Synovial cysts of the lumbosacral spine: diagnosis by MR imaging. Am J Neuroradiol 1989;10:1239–42. [7] Gezen F, Kahraman S, Canakci Z, Beduk A. Review of 36 cases of spinal cord meningioma. Spine 2000;25:727–31. [8] Acre CA, Dohrmann GJ. Thoracic disc herniation: improved diagnosis with computed tomographic scanning and a review of the literature. Surg Neurol 1985;23:356–61. [9] Blumenkopf B. Thoracic intervertebral disc herniations: diagnostic value of magnetic resonance imagining. Neurosurgery 1988;23:36–40. [10] Oppenheim JS, Rothman AS, Sachdev VP. Thoracic herniated discs: review of the literature and 12 cases. Mount Sinai J Med 1993;60:321–6. [11] Cusimano MD, Bukala BP, Bilbao J. Extreme lateral disc herniation
Seventy-Five Years Ago in Spine . . .
[12]
[13] [14]
[15] [16] [17]
[18]
[19] [20]
[21]
manifesting as nerve sheath tumor: case report. J Neurosurg 1995;82: 654–6. Eckardt JJ, Kaplan DD, Batzdorf U, Dawson EG. Extraforaminal disc herniation simulating a retroperitoneal neoplasm: case report. J Bone Joint Surg 1985;67-A:1275–7. Witzmann A, Hammer B, Fischer J. Free sequestered disc herniation at the S2 level misdiagnosed as neuroma. Neuroradiology 1991;33:92–3. Ashkenazi E, Pamerianz S, Floman Y. Foraminal herniation of a lumbar disc mimicking neurinoma on CT and MR imagining. J Spinal Disord 1997;10:448–50. Guyer RD, Collier RR, Ohnmeiss DD, et al. Extraosseous spinal lesions mimicking disc disease. Spine 1988;13:328–31. Epstein JA. Common errors in the diagnosis of herniation of the intervertebral disk. Ind Med Surg 39:480–8. Stillerman CB, Chen TC, Couldwell WT, Zhang W, Weiss MH. Experience in the surgical management of 82 symptomatic herniated thoracic discs and review of the literature. J Neurosurg 1998;88:623–33. Morizane A, Hanakita J, Suwa H, Ohshita N, Gotoh K, Matsuoka T. Dorsally sequestrated thoracic disc herniation: case report. Neurol Med Chir (Tokyo) 1999;39:769–72. Emamian SA, Skriver EB, Henriksen L, Cortsen ME. Lumbar herniated disk mimicking neurinoma: case report. Acta Radiologica 1993;34:127–9. Saruhashi Y, Omura K, Miyamoto K, Katsuura A, Hukuda S. A migrated lumbar disc herniation simulating a dumbbell tumor. J Spinal Disord 1999;12 (4):307–9.[/1a] Goldberg AL, Rothfus WE, Deeb ZL, Khoury MB, Daffner RH. Thoracic disc herniation versus spinal metastases: optimizing diagnosis with magnetic resonance imaging. Skeletal Radiol 1988;17:423–6.
preceded by a note by W.T. Bovie, which described a new, “surgical-current generator.”
References [1] Cushing HW. Electrosurgery as an aid to the removal of intracranial tumors. With a preliminary note on a new surgical-current generator by W.T. Bovie. Surg Gyn Obstet 1928;47:751–84.
The use of electrocoagulation in neurosurgery was established by a publication in 1928, authored by Harvey Williams Cushing (1869–1939). The article was
David Fardon Knoxville, TN