- Email: [email protected]
Unilateral ossification of the ligamentum flavum in the cervical spine with atypical radiological appearance
462 Mizuno and Nakagawa
CONCLUSION GCRG is a rare benign lesion with distinct clinicopathological features. A history of previous trauma is noted in some patients. Modern neuro-imaging (CT MR scans) shows an expansile destructive multiloculated bone lesion mimicking a neoplastic mass. Histopathology is confirmatory of this benign lesion. Other giant cell containing lesions such as the giant cell tumour of the bone, an aneurysmal bone cyst and a brown tumour of hyperparathyroidism need to be carefully excluded. Microsurgical excision is curative with a low recurrence rate. REFERENCES 1.
2.
3.
4. 5. 6. 7.
8. 9. 10. 11.
12.
13.
14.
Alappat JP, Pillai AM, Prasanna D, Sambasivan M. Giant cell reparative granuloma of the craniofacial complex. Case report and review of the literature. Br J Neurosurg 1992; 6: 71±74. Ciappetta P, Salvati M, Bernardi C, et al. Giant cell reparative granuloma of the skull base mimicking an intracranial tumor. Case report and review of the literature. Surg Neurol 1990; 33: 52±56. Hamilton HB, Voorhies RM. Tumors of the skull. In: Wilkins RH, Rengachary SS (eds). Neurosurgery, 2nd ed. Vol II, New York: McGraw Hill 1996: 1503±1528. Huvos AG. Bone Tumors: Diagnosis, Treatment and Prognosis. Philadelphia: Saunders 1991. Watkins LD, Uttley D, Archer DJ, et al. Giant cell Tumors of the sphenoid bone. Neurosurgery 1992; 30: 576±581. Felsberg GJ, Tien RD, Mc Lendon RE. Frontoethmoidal giant cell reparative granuloma. AJNR Am J Neuroradiology 1995; 16: 1551±1554. Hyver SW, Ellis DS, Stewart WB, Spencer WH, Barlett PC. Sino-orbital giant cell reparative granuloma. Ophthal Plast Reconstr Surg 1998; 14(3): 178±181. Sebag J, Chapman P, Truman J, Reimersma RR. Giant cell granuloma of the orbit with intracranial extension. Neurosurgery 1985; 16(1): 75±78. Mercado GV, Shields CL, Gunduz K, Shields JA, Eagle RC Jr. Giant cell reparative granuloma of the orbit. Am J Ophthalmol 1999; 127: 485±487. Lin CL, Huang TS. Giant cell reparative granuloma in temporal bonereport of a case. Chang Keng I Hsueh Tsa Chih 1989; 12: 62±66. Maruno M, Yoshimine T, Kubo T, Hayakawa T. A case of giant cell reparative granuloma of the petrous bone. Demonstration of the proliferative component. Surg Neurol 1997; 48: 64±68. Nemoto Y, Inoue Y, Tashiro T, Mochizuki T, Katsuyama J, Hakuba A, Onoyama Y. Central giant cell granuloma of the temporal bone. Am J Neuroradiol 1995; 16(4): 982±985. Garza-Mercado R, Cavazos E, Hernandez-Batres F. Giant cell reparative granuloma of the cranial vault: exceptional bone lesion. Neurosurgery 1984; 15(2): 228±232. Chen SS, Chiang JH, Chang CY. Lao CVB. Lirng JF, Teng MM. Giant cell reparative granuloma: a case report. Chung Hua I Hsueh Tsa Chih (Taipei) 1999; 62: 738±742.
Unilateral ossification of the ligamentum flavum in the cervical spine with atypical radiological appearance Junichi Mizuno MD, Hiroshi Nakagawa MD Department of Neurological Surgery, Aichi Medical University, Nagakute, Aichi, Japan
Summary We report a case of symptomatic unilateral ossification of the ligamentum flavum with unusual radiological presentation in the cervical spine. The patient was a 64 year old man with numbness and weakness of the left upper extremity who was Journal of Clinical Neuroscience (2002) 9(4)
admitted to our hospital. Computerized tomography revealed a triangular-shaped high density mass severely compressing the spinal cord at C6. Concomitant small ossification of the posterior longitudinal ligament was noted from C3 to C6. The ossified mass was completely removed via a unilateral osteoplastic laminectomy of the left C6 and C7. & 2002 Published by Elsevier Science Ltd. Journal of Clinical Neuroscience (2002) 9(4), 462±464 & 2002 Published by Elsevier Science Ltd. DOI: 10.1054/jocn.2001.1001, available online at http://www.idealibrary.com on
Keywords: ligamentum flavum, ossification, cervical spine, computed tomography Received 24 May 2001 Accepted 10 July 2001 Correspondence to: Junichi Mizuno MD, Department of Neurological Surgery, Aichi Medical University, 21 Karamata, Yazako, Nagakute, Aichi-gun, Aichi 480-1195 Japan. Tel.: 81 561 62 3311; Fax: 81 561 63 2879; E-mail: [email protected]
INTRODUCTION Ossification of the ligamentum flavum (OLF) usually occurs in the upper or lower thoracic spine, and is rare in the cervical region.1±3 Common neurological symptoms caused by OLF are myelopathy with long tract signs and segmental painful numbness, although most cases of OLF are asymptomatic.4,5 The pathogenesis of OLF remains controversial; however, systemic hyperostosis together with dynamic and static stress on the ligament is considered to play an important role in the development of OLF.6,7 Men are affected more often than women, and OLF is radiologically observed in patients over 40, which suggests that the aging process may influence OLF similar to other degenerative diseases. Conservative treatment is not effective to resolve myelopathy. Ossification of the ligamentum flavum in this case occurred in a rare location and showed uncommon radiological findings. CASE REPORT The patient was a 64 year old man who presented with a five year history of numbness and weakness in his left upper extremity. Neurological examination revealed mild weakness and hypesthesia in the left C7 and C8 regions with moderate atrophy of the interosseous muscles. Cervical lateral tomography revealed an ossified or calcified lesion at C6 together with segmental ossification of the posterior longitudinal ligament (OPLL) at C4, C5 and C6 (Fig. 1). Computerized tomography (CT) revealed a triangular-shaped high density mass markedly compressing the spinal cord (Fig. 2). Magnetic resonance (MR) imaging revealed a high-signal intensity lesion at C6 (Fig. 3). Unilateral osteoplastic laminectomy of C6 and C7 was performed using a surgical saw. The lamina partially adhered to the mass. The mass was whitish, avascular and extremely hard. There was no normal ligamentum flavum underneath C6±C7. Although the dura was thin, no leakage of cerebrospinal fluid occurred. The ligamentum flavum was intact on the right side. Surgical specimens showed compact lamellar bone with abundant adipose tissue (Fig. 4). No neoplastic cells were observed. Postoperatively the patient was free from numbness in his left upper extremity with some improvement in muscle strength. & 2002 Published by Elsevier Science Ltd.
Unilateral ossification of the ligamentum flavum 463
Fig. 3
MR imaging showing a high-intensity lesion at C6±C7.
Fig. 1 Lateral tomography of the cervical spine showing a large ossified or calcified mass at C6 and C7 (arrow) with segmental OPLL at C4, C5 and C6 (arrow head).
Fig. 4 Photomicrograph of the specimen showing ossification containing abundant bone marrow (hematoxylin-eosin stain, original magnification 20).
Fig. 2 CT at C6±C7 showing a unilateral triangular high-density mass on the left with small OPLL.
DISCUSSION Ossification of the ligamentum flavum is an uncommon etiology for myelopathy. Although any location of the spinal column can be involved, involvement of the cervical spine is rare.1±3 Lateral plain radiographs cannot be used to diagnose OLF at the cervicothoracic junction because of the proximity to the shoulder joint, although this technique is useful in other regions. Lateral tomography or CT are superior to diagnose OLF. There are several radiological classifications of OLF based on the shape and size of the ossified mass.8±10 The shape of ossification varies, but it is commonly a bilateral round-shaped bulging mass with a wide base.11 To our & 2002 Published by Elsevier Science Ltd.
knowledge, there have been no reports of a unilateral triangular-shaped formation of OLF with the intact contralateral ligamentum flavum. Moreover, OLF in this case was revealed as a high-density mass while ordinary ossified masses are usually revealed as asignal or hypo-intense lesions. Thus, we speculated that the ligamentum flavum had been replaced by ossification, and that the high-signal intensity on MR imaging was the result of abundant bone marrow formation in this case. Removal of OLF is the procedure of choice and conservative treatment is usually ineffective to resolve myelopathy. Microsurgical meticulous drilling of the ossified mass is essential to avoid damage to the dura mater, the spinal cord and the nerve roots. Since the dura mater has a tendency to be thin or ossified due to long-term compression, separation of the dura mater from the ossified mass requires very careful attention to avoid dural laceration. Although unilateral triangular-shaped OLF containing abundant adipose tissue in the cervical region is rare and difficult to diagnose, OLF should be included in the differential diagnosis of intraspinal mass lesion. Journal of Clinical Neuroscience (2002) 9(4)
464 Kazemi et al. REFERENCES 1. 2.
3.
4. 5. 6. 7. 8.
9.
10.
11.
Kobayashi S, Okada K, Onoda K, Horikoshi S. Ossification of the cervical ligamentum flavum. Surg Neurol 1991; 35: 234±238. Kubota M, Baba I, Sumida I. Myelopathy due to ossification of the ligamentum flavum of the cervical spine. A report of two cases. Spine 1981; 6: 553±559. Nakajima K, Miyaoka M, Sumie H, Nakazato T, Ishii S. Cervical radiculomyelopathy due to calcification of the ligamentum flavum. Surg Neurol 1984; 21: 479±488. Taneichi H, Kaneda K. Symptomatology of ossification of the ligamentum flavum. Spine and Spinal Cord 1998; 11: 485±489 (Jpn). Saito M. Diagnostic imaging of ossification of the ligamentum flavum. Spine and Spinal Cord 1998; 11: 499±503 (Jpn). Stoltmann HF. The role of the ligamenta flava in the pathogenesis of myelopathy in cervical spondylosis. Brain 1964; 86: 45±54. Otani K, Aihara T, Tanaka A, Shibasaki K. Ossification of the ligamentum flavum of the thoracic spine. Int Orthop 1986; 10: 135±139. Saiki K, Hattori S, Kawai S, Miyamoto T, Tsue K, Kotani H. The ossification of the yellow ligament in the thoracic spine ± Incidence, classification, neurological findings and narrow spinal canal. Seikei Geka 1981; 24: 191±198 (Jpn). Sato T, Kokubu S, Ishii Y. Choice of operative method for ossification of ligamentum flavum based on CT findings. Rinshoseikeigeka 1996; 31: 541±545 (Jpn). Yanagi T, Naito A, Yasuda T, Hashizume Y, Oomori K. The ossification of the ligamentum flavum of the thoracic spine; correlative CT and pathologic study. Seikeigeka 1987; 38: 297±307 (Jpn). Miyasaka K, Kaneda K, Sato S. Myelopathy due to ossification or calcification of the ligamentum flavum: radiologic and histologic evaluations. AJNR 1983; 4: 629±632.
Mistaken identity: a case of false positive on CT angiography N. J. Kazemi1 MBBS, B. Dennien2 FRACR, N. G. Dan1 FRCS FRACS 1 Department of Neurosurgery, 2Department of Radiology, Concord Repatriation General Hospital, University of Sydney, Sydney, Australia
Summary We describe the case of a 42-year-old female presenting with subarachnoid haemorrhage from a posterior inferior cerebellar artery (PICA) aneurysm rupture on intracranial digital subtraction angiography (DSA). One year postoperatively, the patient was followed with CT angiography and was reported to show a de novo aneurysm at the bifurcation of the left internal carotid artery (ICA). Subsequent DSA revealed an aberrant vein crossing over the ICA bifurcation on mask phase images. This is the first reported case of a such a reason for a `false positive' on CT angiography (CTA). The case demonstrates that although CTA has a reported high specificity, careful interpretation of multiple views is required to diagnose intracranial aneurysms when compared to the `gold' standard of CTA. & 2002 Published by Elsevier Science Ltd. Journal of Clinical Neuroscience (2002) 9(4), 464±466 & 2002 Published by Elsevier Science Ltd. DOI: 10.1054/jocn.2001.0984, available online at http://www.idealibrary.com on
Keywords: aneurysm, intracranial, computed tomographic angiography, digital subtraction angiography, subarachnoid haemorrhage Received 11 July 2001 Accepted 31 July 2001 Correspondence to: Dr N. J. Kazemi, 118A Warriewood Road, Warriewood NSW 2102, Australia
Journal of Clinical Neuroscience (2002) 9(4)
Three-dimensional CT angiography (CTA) is increasingly recognised as a useful way of evaluating patients with suspected acute subarachnoid haemorrhage or intracranial aneurysm. In comparison to the gold standard of intracranial digital subtraction angiography (DSA), intracranial CTA is a fast and minimally invasive method with a high diagnostic accuracy, sensitivity and specificity. However, limitations still exist despite continually improving CTA interpretation. Here we illustrate a reason for a false positive result on CTA. A 42-year-old female presented with subarachnoid haemorrhage evident on non-contrast CT scan in February 2000. The scan also revealed intraventricular haemorrhage and hydrocephalus at this time. Subsequent digital subtraction angiography revealed an aneurysm arising from the origin of the left posterior inferior cerebellar artery (PICA) with a branch vessel arising posteriorly from the fundus of the aneurysm. The patient was treated with an external ventricular drain for hydrocephalus and subsequently underwent a craniotomy for intended clipping of the left PICA aneurysm. However, at operation, the fusiform nature of the aneurysm and consideration of the branch vessel resulted in `wrapping' of the aneurysm. The patient's subsequent recovery was delayed by infection, but subsequent progress was otherwise uneventful and the patient was discharged 25 days after admission. Follow-up monitoring with a CT angiogram at 6 months showed a decrease in the size of the PICA aneurysm and no other abnormalities. Subsequent CT angiogram at an outside institution 1 year after initial presentation, however, strongly suggested a de novo aneurysm at the bifurcation of the left internal carotid artery (ICA) (Figs 1±3). The patient was investigated with a digital subtraction angiogram for pre-operative planning (Figs 4±6). In Figures 5 and 6, the arterial and venous selection phases are superimposed and clearly demonstrate no left ICA aneurysm but illustrate an aberrant vein crossing over the left ICA bifurcation. This DSA explains the CTA finding of the aneurysm and is an example of a false positive on CT angiography. DISCUSSION CT angiography is establishing an important place in the detection and pre-operative evaluation of patients with suspected intracranial aneurysms. There are many studies which now demonstrate high sensitivity and specificity rates in the detection of intracranial aneurysms. In the study by Zouaoui,1 CTA demonstrated sensitivity and specificity rates of up to 97% and 100% respectively. CTA is recognised as simple, fast and non-invasive in comparison to DSA, and is useful for screening in relatives of those with intracranial aneurysms.2 The main difficulties in CTA lie with the detection of small aneurysms (<4 mm),3 aneurysms of the proximal ICA and ophthalmic artery close to bone, such as the skull base4,5 and loss of information due to artefact from surgical clips.6,7 This case presents an unusual and previously unreported reason for the detection of a false positive aneurysm on CTA. After aneurysm wrapping, our patient was followed with CT angiography to assess the size of the original PICA aneurysm that had been wrapped, as well as any de novo aneurysm formation. The second aneurysm, reported 1 year postoperatively on CTA at the bifurcation of the left ICA, was seen on axial, coronal and sagittal reformats. & 2002 Published by Elsevier Science Ltd.
CONCLUSION GCRG is a rare benign lesion with distinct clinicopathological features. A history of previous trauma is noted in some patients. Modern neuro-imaging (CT MR scans) shows an expansile destructive multiloculated bone lesion mimicking a neoplastic mass. Histopathology is confirmatory of this benign lesion. Other giant cell containing lesions such as the giant cell tumour of the bone, an aneurysmal bone cyst and a brown tumour of hyperparathyroidism need to be carefully excluded. Microsurgical excision is curative with a low recurrence rate. REFERENCES 1.
2.
3.
4. 5. 6. 7.
8. 9. 10. 11.
12.
13.
14.
Alappat JP, Pillai AM, Prasanna D, Sambasivan M. Giant cell reparative granuloma of the craniofacial complex. Case report and review of the literature. Br J Neurosurg 1992; 6: 71±74. Ciappetta P, Salvati M, Bernardi C, et al. Giant cell reparative granuloma of the skull base mimicking an intracranial tumor. Case report and review of the literature. Surg Neurol 1990; 33: 52±56. Hamilton HB, Voorhies RM. Tumors of the skull. In: Wilkins RH, Rengachary SS (eds). Neurosurgery, 2nd ed. Vol II, New York: McGraw Hill 1996: 1503±1528. Huvos AG. Bone Tumors: Diagnosis, Treatment and Prognosis. Philadelphia: Saunders 1991. Watkins LD, Uttley D, Archer DJ, et al. Giant cell Tumors of the sphenoid bone. Neurosurgery 1992; 30: 576±581. Felsberg GJ, Tien RD, Mc Lendon RE. Frontoethmoidal giant cell reparative granuloma. AJNR Am J Neuroradiology 1995; 16: 1551±1554. Hyver SW, Ellis DS, Stewart WB, Spencer WH, Barlett PC. Sino-orbital giant cell reparative granuloma. Ophthal Plast Reconstr Surg 1998; 14(3): 178±181. Sebag J, Chapman P, Truman J, Reimersma RR. Giant cell granuloma of the orbit with intracranial extension. Neurosurgery 1985; 16(1): 75±78. Mercado GV, Shields CL, Gunduz K, Shields JA, Eagle RC Jr. Giant cell reparative granuloma of the orbit. Am J Ophthalmol 1999; 127: 485±487. Lin CL, Huang TS. Giant cell reparative granuloma in temporal bonereport of a case. Chang Keng I Hsueh Tsa Chih 1989; 12: 62±66. Maruno M, Yoshimine T, Kubo T, Hayakawa T. A case of giant cell reparative granuloma of the petrous bone. Demonstration of the proliferative component. Surg Neurol 1997; 48: 64±68. Nemoto Y, Inoue Y, Tashiro T, Mochizuki T, Katsuyama J, Hakuba A, Onoyama Y. Central giant cell granuloma of the temporal bone. Am J Neuroradiol 1995; 16(4): 982±985. Garza-Mercado R, Cavazos E, Hernandez-Batres F. Giant cell reparative granuloma of the cranial vault: exceptional bone lesion. Neurosurgery 1984; 15(2): 228±232. Chen SS, Chiang JH, Chang CY. Lao CVB. Lirng JF, Teng MM. Giant cell reparative granuloma: a case report. Chung Hua I Hsueh Tsa Chih (Taipei) 1999; 62: 738±742.
Unilateral ossification of the ligamentum flavum in the cervical spine with atypical radiological appearance Junichi Mizuno MD, Hiroshi Nakagawa MD Department of Neurological Surgery, Aichi Medical University, Nagakute, Aichi, Japan
Summary We report a case of symptomatic unilateral ossification of the ligamentum flavum with unusual radiological presentation in the cervical spine. The patient was a 64 year old man with numbness and weakness of the left upper extremity who was Journal of Clinical Neuroscience (2002) 9(4)
admitted to our hospital. Computerized tomography revealed a triangular-shaped high density mass severely compressing the spinal cord at C6. Concomitant small ossification of the posterior longitudinal ligament was noted from C3 to C6. The ossified mass was completely removed via a unilateral osteoplastic laminectomy of the left C6 and C7. & 2002 Published by Elsevier Science Ltd. Journal of Clinical Neuroscience (2002) 9(4), 462±464 & 2002 Published by Elsevier Science Ltd. DOI: 10.1054/jocn.2001.1001, available online at http://www.idealibrary.com on
Keywords: ligamentum flavum, ossification, cervical spine, computed tomography Received 24 May 2001 Accepted 10 July 2001 Correspondence to: Junichi Mizuno MD, Department of Neurological Surgery, Aichi Medical University, 21 Karamata, Yazako, Nagakute, Aichi-gun, Aichi 480-1195 Japan. Tel.: 81 561 62 3311; Fax: 81 561 63 2879; E-mail: [email protected]
INTRODUCTION Ossification of the ligamentum flavum (OLF) usually occurs in the upper or lower thoracic spine, and is rare in the cervical region.1±3 Common neurological symptoms caused by OLF are myelopathy with long tract signs and segmental painful numbness, although most cases of OLF are asymptomatic.4,5 The pathogenesis of OLF remains controversial; however, systemic hyperostosis together with dynamic and static stress on the ligament is considered to play an important role in the development of OLF.6,7 Men are affected more often than women, and OLF is radiologically observed in patients over 40, which suggests that the aging process may influence OLF similar to other degenerative diseases. Conservative treatment is not effective to resolve myelopathy. Ossification of the ligamentum flavum in this case occurred in a rare location and showed uncommon radiological findings. CASE REPORT The patient was a 64 year old man who presented with a five year history of numbness and weakness in his left upper extremity. Neurological examination revealed mild weakness and hypesthesia in the left C7 and C8 regions with moderate atrophy of the interosseous muscles. Cervical lateral tomography revealed an ossified or calcified lesion at C6 together with segmental ossification of the posterior longitudinal ligament (OPLL) at C4, C5 and C6 (Fig. 1). Computerized tomography (CT) revealed a triangular-shaped high density mass markedly compressing the spinal cord (Fig. 2). Magnetic resonance (MR) imaging revealed a high-signal intensity lesion at C6 (Fig. 3). Unilateral osteoplastic laminectomy of C6 and C7 was performed using a surgical saw. The lamina partially adhered to the mass. The mass was whitish, avascular and extremely hard. There was no normal ligamentum flavum underneath C6±C7. Although the dura was thin, no leakage of cerebrospinal fluid occurred. The ligamentum flavum was intact on the right side. Surgical specimens showed compact lamellar bone with abundant adipose tissue (Fig. 4). No neoplastic cells were observed. Postoperatively the patient was free from numbness in his left upper extremity with some improvement in muscle strength. & 2002 Published by Elsevier Science Ltd.
Unilateral ossification of the ligamentum flavum 463
Fig. 3
MR imaging showing a high-intensity lesion at C6±C7.
Fig. 1 Lateral tomography of the cervical spine showing a large ossified or calcified mass at C6 and C7 (arrow) with segmental OPLL at C4, C5 and C6 (arrow head).
Fig. 4 Photomicrograph of the specimen showing ossification containing abundant bone marrow (hematoxylin-eosin stain, original magnification 20).
Fig. 2 CT at C6±C7 showing a unilateral triangular high-density mass on the left with small OPLL.
DISCUSSION Ossification of the ligamentum flavum is an uncommon etiology for myelopathy. Although any location of the spinal column can be involved, involvement of the cervical spine is rare.1±3 Lateral plain radiographs cannot be used to diagnose OLF at the cervicothoracic junction because of the proximity to the shoulder joint, although this technique is useful in other regions. Lateral tomography or CT are superior to diagnose OLF. There are several radiological classifications of OLF based on the shape and size of the ossified mass.8±10 The shape of ossification varies, but it is commonly a bilateral round-shaped bulging mass with a wide base.11 To our & 2002 Published by Elsevier Science Ltd.
knowledge, there have been no reports of a unilateral triangular-shaped formation of OLF with the intact contralateral ligamentum flavum. Moreover, OLF in this case was revealed as a high-density mass while ordinary ossified masses are usually revealed as asignal or hypo-intense lesions. Thus, we speculated that the ligamentum flavum had been replaced by ossification, and that the high-signal intensity on MR imaging was the result of abundant bone marrow formation in this case. Removal of OLF is the procedure of choice and conservative treatment is usually ineffective to resolve myelopathy. Microsurgical meticulous drilling of the ossified mass is essential to avoid damage to the dura mater, the spinal cord and the nerve roots. Since the dura mater has a tendency to be thin or ossified due to long-term compression, separation of the dura mater from the ossified mass requires very careful attention to avoid dural laceration. Although unilateral triangular-shaped OLF containing abundant adipose tissue in the cervical region is rare and difficult to diagnose, OLF should be included in the differential diagnosis of intraspinal mass lesion. Journal of Clinical Neuroscience (2002) 9(4)
464 Kazemi et al. REFERENCES 1. 2.
3.
4. 5. 6. 7. 8.
9.
10.
11.
Kobayashi S, Okada K, Onoda K, Horikoshi S. Ossification of the cervical ligamentum flavum. Surg Neurol 1991; 35: 234±238. Kubota M, Baba I, Sumida I. Myelopathy due to ossification of the ligamentum flavum of the cervical spine. A report of two cases. Spine 1981; 6: 553±559. Nakajima K, Miyaoka M, Sumie H, Nakazato T, Ishii S. Cervical radiculomyelopathy due to calcification of the ligamentum flavum. Surg Neurol 1984; 21: 479±488. Taneichi H, Kaneda K. Symptomatology of ossification of the ligamentum flavum. Spine and Spinal Cord 1998; 11: 485±489 (Jpn). Saito M. Diagnostic imaging of ossification of the ligamentum flavum. Spine and Spinal Cord 1998; 11: 499±503 (Jpn). Stoltmann HF. The role of the ligamenta flava in the pathogenesis of myelopathy in cervical spondylosis. Brain 1964; 86: 45±54. Otani K, Aihara T, Tanaka A, Shibasaki K. Ossification of the ligamentum flavum of the thoracic spine. Int Orthop 1986; 10: 135±139. Saiki K, Hattori S, Kawai S, Miyamoto T, Tsue K, Kotani H. The ossification of the yellow ligament in the thoracic spine ± Incidence, classification, neurological findings and narrow spinal canal. Seikei Geka 1981; 24: 191±198 (Jpn). Sato T, Kokubu S, Ishii Y. Choice of operative method for ossification of ligamentum flavum based on CT findings. Rinshoseikeigeka 1996; 31: 541±545 (Jpn). Yanagi T, Naito A, Yasuda T, Hashizume Y, Oomori K. The ossification of the ligamentum flavum of the thoracic spine; correlative CT and pathologic study. Seikeigeka 1987; 38: 297±307 (Jpn). Miyasaka K, Kaneda K, Sato S. Myelopathy due to ossification or calcification of the ligamentum flavum: radiologic and histologic evaluations. AJNR 1983; 4: 629±632.
Mistaken identity: a case of false positive on CT angiography N. J. Kazemi1 MBBS, B. Dennien2 FRACR, N. G. Dan1 FRCS FRACS 1 Department of Neurosurgery, 2Department of Radiology, Concord Repatriation General Hospital, University of Sydney, Sydney, Australia
Summary We describe the case of a 42-year-old female presenting with subarachnoid haemorrhage from a posterior inferior cerebellar artery (PICA) aneurysm rupture on intracranial digital subtraction angiography (DSA). One year postoperatively, the patient was followed with CT angiography and was reported to show a de novo aneurysm at the bifurcation of the left internal carotid artery (ICA). Subsequent DSA revealed an aberrant vein crossing over the ICA bifurcation on mask phase images. This is the first reported case of a such a reason for a `false positive' on CT angiography (CTA). The case demonstrates that although CTA has a reported high specificity, careful interpretation of multiple views is required to diagnose intracranial aneurysms when compared to the `gold' standard of CTA. & 2002 Published by Elsevier Science Ltd. Journal of Clinical Neuroscience (2002) 9(4), 464±466 & 2002 Published by Elsevier Science Ltd. DOI: 10.1054/jocn.2001.0984, available online at http://www.idealibrary.com on
Keywords: aneurysm, intracranial, computed tomographic angiography, digital subtraction angiography, subarachnoid haemorrhage Received 11 July 2001 Accepted 31 July 2001 Correspondence to: Dr N. J. Kazemi, 118A Warriewood Road, Warriewood NSW 2102, Australia
Journal of Clinical Neuroscience (2002) 9(4)
Three-dimensional CT angiography (CTA) is increasingly recognised as a useful way of evaluating patients with suspected acute subarachnoid haemorrhage or intracranial aneurysm. In comparison to the gold standard of intracranial digital subtraction angiography (DSA), intracranial CTA is a fast and minimally invasive method with a high diagnostic accuracy, sensitivity and specificity. However, limitations still exist despite continually improving CTA interpretation. Here we illustrate a reason for a false positive result on CTA. A 42-year-old female presented with subarachnoid haemorrhage evident on non-contrast CT scan in February 2000. The scan also revealed intraventricular haemorrhage and hydrocephalus at this time. Subsequent digital subtraction angiography revealed an aneurysm arising from the origin of the left posterior inferior cerebellar artery (PICA) with a branch vessel arising posteriorly from the fundus of the aneurysm. The patient was treated with an external ventricular drain for hydrocephalus and subsequently underwent a craniotomy for intended clipping of the left PICA aneurysm. However, at operation, the fusiform nature of the aneurysm and consideration of the branch vessel resulted in `wrapping' of the aneurysm. The patient's subsequent recovery was delayed by infection, but subsequent progress was otherwise uneventful and the patient was discharged 25 days after admission. Follow-up monitoring with a CT angiogram at 6 months showed a decrease in the size of the PICA aneurysm and no other abnormalities. Subsequent CT angiogram at an outside institution 1 year after initial presentation, however, strongly suggested a de novo aneurysm at the bifurcation of the left internal carotid artery (ICA) (Figs 1±3). The patient was investigated with a digital subtraction angiogram for pre-operative planning (Figs 4±6). In Figures 5 and 6, the arterial and venous selection phases are superimposed and clearly demonstrate no left ICA aneurysm but illustrate an aberrant vein crossing over the left ICA bifurcation. This DSA explains the CTA finding of the aneurysm and is an example of a false positive on CT angiography. DISCUSSION CT angiography is establishing an important place in the detection and pre-operative evaluation of patients with suspected intracranial aneurysms. There are many studies which now demonstrate high sensitivity and specificity rates in the detection of intracranial aneurysms. In the study by Zouaoui,1 CTA demonstrated sensitivity and specificity rates of up to 97% and 100% respectively. CTA is recognised as simple, fast and non-invasive in comparison to DSA, and is useful for screening in relatives of those with intracranial aneurysms.2 The main difficulties in CTA lie with the detection of small aneurysms (<4 mm),3 aneurysms of the proximal ICA and ophthalmic artery close to bone, such as the skull base4,5 and loss of information due to artefact from surgical clips.6,7 This case presents an unusual and previously unreported reason for the detection of a false positive aneurysm on CTA. After aneurysm wrapping, our patient was followed with CT angiography to assess the size of the original PICA aneurysm that had been wrapped, as well as any de novo aneurysm formation. The second aneurysm, reported 1 year postoperatively on CTA at the bifurcation of the left ICA, was seen on axial, coronal and sagittal reformats. & 2002 Published by Elsevier Science Ltd.