- Email: [email protected]
Rapidly Progressing Symptomatic Calcification of Ligamentum Flavum in Thoracic Spine After Osteoporotic Vertebral Fractures
Case Report
Rapidly Progressing Symptomatic Calcification of Ligamentum Flavum in Thoracic Spine After Osteoporotic Vertebral Fractures Naohisa Miyakoshi, Michio Hongo, Yuji Kasukawa, Yoshinori Ishikawa, Daisuke Kudo, Yoichi Shimada
Key words Calcification of ligamentum flavum - Osteoporotic vertebral fracture - Spine surgery - Thoracic spine -
Abbreviations and Acronyms CLF: Calcification of the ligamentum flavum MRI: Magnetic resonance imaging OVF: Osteoporotic vertebral fracture STIR: Short-tau inversion recovery Department of Orthopedic Surgery, Akita University Graduate School of Medicine, Akita, Japan To whom correspondence should be addressed: Naohisa Miyakoshi, M.D., Ph.D. [E-mail: [email protected]] Citation: World Neurosurg. (2019) 132:63-66. https://doi.org/10.1016/j.wneu.2019.08.177 Journal homepage: www.journals.elsevier.com/worldneurosurgery Available online: www.sciencedirect.com 1878-8750/$ - see front matter ª 2019 Elsevier Inc. All rights reserved.
- BACKGROUND:
Symptomatic calcification of the ligamentum flavum (CLF) is common in the cervical spine but rare in the thoracic spine. Rapidly progressing CLF in the thoracic spine has not been reported in the literature.
- CASE
DESCRIPTION: A 76-year-old Asian male experienced back pain after a fall and was diagnosed with osteoporotic vertebral fractures at T11 and L1. He was treated conservatively because of the lack of neurologic deficits. Nine months after the initial visit, he complained of progressive incomplete paraplegia. Magnetic resonance imaging and computed tomography of the thoracic spine showed CLF at T11-T12 severely compressing the spinal cord. This finding had not been seen on imaging studies at the initial visit. The patient underwent surgical resection of CLF and posterior instrumented spine fusion. Symptoms of muscle weakness recovered postoperatively.
- CONCLUSIONS:
In this case, sequential imaging studies with a 9-month interval showed evidence of rapidly progressing thoracic CLF. The preceding osteoporotic vertebral fracture may have triggered the development of CLF. CASE PRESENTATION History and Examination A 76-year-old Asian male experienced back pain after falling to the floor in his house.
He was diagnosed with OVFs at the T11 and L1 vertebrae and admitted to a nearby hospital. He was treated conservatively using a thoracolumbosacral orthosis because of the lack of neurologic deficits.
INTRODUCTION Calcification of the ligamentum flavum (CLF) is characterized by deposition of calcified granules of calcium pyrophosphate within the ligamentum flavum without bone formation.1 Because CLF is common in the cervical spine,2-6 most clinical reports of symptomatic CLF causing myelopathy have described involvement of the cervical spine and CLF in the thoracic spine is rare.1,7-9 In this report, we describe the case of a patient with thoracic CLF who showed rapidly progressing CLF after osteoporotic vertebral fractures (OVFs). Because calcification is a slow process, many years may pass before pathologic calcification reaches sufficient size to cause symptoms.3 In this regard, the course of the present case with rapid progression was unusual and no such case appears to have been reported previously. Sequential imaging studies in this case showed evidence of rapid progression of the thoracic CLF.
Figure 1. Sagittal magnetic resonance image (MRI) of the spine with fat suppression using short-tau inversion recovery (A) and axial T2-weighted MRI at T11-T12 (B) revealed fresh vertebral fractures at T11 and L1 without spinal canal stenosis.
WORLD NEUROSURGERY 132: 63-66, DECEMBER 2019
www.journals.elsevier.com/world-neurosurgery
63
CASE REPORT NAOHISA MIYAKOSHI ET AL.
PROGRESSING CLF IN THORACIC SPINE
Figure 2. Sagittal and axial T2-weighted magnetic resonance images obtained 9 months after initial visit revealed progression of osteoporotic vertebral fractures and spinal cord compression by a posterior mass within
He had a history of several medical treatments for carcinoma of the hypopharynx, early gastric cancer, and autoimmune hepatitis, with the latter treated using 6 mg/day of prednisolone for several years. Laboratory data showed no specific findings other than osteoporosis.
the ligamentum flavum at the T11-T12 level (A and B). Sagittal and axial computed tomography images show intraspinal canal calcification posterior to the spinal cord at the T11-T12 level (C and D).
On admission to the hospital, sagittal magnetic resonance imaging (MRI) with fat suppression using short-tau inversion recovery (STIR) (Figure 1A) and axial T2weighted MRI (see Figure 1B) revealed fresh vertebral fractures at T11 and L1 without spinal canal stenosis. Back pain
Figure 3. Postoperative anteroposterior and lateral spine radiographs after T12 vertebroplasty and posterior instrumented fusion at the T10-L2 level.
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was relieved by bed rest and thoracolumbosacral orthotic for about 1 month, and he was discharged from hospital. However, antiosteoporotic pharmacotherapy was not introduced by this hospital. Nine months after the initial onset, he complained of weakness and numbness in bilateral lower extremities with no specific antecedent episode and revisited the same hospital. Sagittal and axial T2-weighted MRI revealed multiple OVFs and spinal canal stenosis at the T11-T12 level due to a protruding mass of ligamentum flavum severely compressing the spinal cord (Figure 2A and B). Computed tomography showed the protruding mass at T11-T12 contained calcified deposits, suspected as representing CLF (see Figure 2C and D). The patient was referred to our hospital due to impairment of standing resulting from progressive paraplegia showing weakness of the lower extremities (manual muscle testing, grade 1e2/5). Operation We performed posterior decompression of T11-T12 with resection of the CLF and posterior instrumented fusion from T10 to L2 combined with vertebroplasty using hydroxyapatite blocks for the fractured T12 vertebra (Figure 3). Intraoperatively, the ligamentum flavum contained a white, chalky, rough, granular substance that was adherent to the dura mater. Histologic examination of the resected ligamentum flavum revealed
WORLD NEUROSURGERY, https://doi.org/10.1016/j.wneu.2019.08.177
CASE REPORT NAOHISA MIYAKOSHI ET AL.
PROGRESSING CLF IN THORACIC SPINE
Figure 4. Histopathologic specimens reveal degeneration of the ligamentum flavum with calcification and chondrometaplasia; these findings are identical to CLF (hematoxylin-eosin stain, 10).
degeneration of the ligamentum flavum with calcification and chondrometaplasia (Figure 4). These findings were consisted with CLF. The postoperative course was uneventful. Muscle weakness recovered completely, and the patient became able to walk with a cane. DISCUSSION CLF is a disease involving crystal deposition macroscopically observable as a white,
chalky, rough, granular substance surrounded by degenerated ligamentum flavum. CLF is quite different from ossification of the ligamentum flavum, which exhibits bony continuity with the laminae. CLF has ordinarily been described as showing no continuity with the lamina, and the superficial and deep layers of the ligamentum flavum remain relatively preserved.5,10 CLF has usually been reported in the cervical spine.2-6 Symptomatic CLF in the thoracic spine is extremely rare, and to the
best of our knowledge only 7 cases (including the present case) with a mean age of 53.6 years (range, 45e76 years) have been reported in the English literature1,7-9 (Table 1). All 7 cases complained of weakness in the lower extremities and improved after surgical decompression. However, among these cases, the present case was the first to show evidence of rapidly progressing calcification on sequential imaging studies. The pathogenesis of CLF remains to be fully elucidated. However, studies on the cervical CLF have shown that the disease is more prevalent in females and have suggested that in addition to the aging process, predisposing factors for the disease include spinal trauma, long-standing motion loading or mechanical stress to the ligamentum flavum, vascular disturbance affecting the ligament, metabolic diseases including diabetes mellitus, and chondrocytic metaplasia.3-6 In the present case, the preceding OVFs may have triggered the development of CLF. Intravertebral instability due to collapsing OVF may result in repeated stress on the ligamentum flavum at the same level and may thus promote calcification. Repetitive microtrauma to the ligamentum flavum has been suspected to represent an initial inciting event that can lead to neovascularization, and calcium crystal deposition may occur because of
Table 1. Calcification of Ligamentum Flavum (CLF) in Thoracic Spine Requiring Surgical Decompression Age (years)/Sex
Level of Involvement
Main Clinical Presentation
Coexisting Spinal Disorder
Treatment and Outcome
Muthukumar et al., 20007
45/Female
T8-T9
Weakness of both lower limbs
—
Laminectomy; improved
Muthukumar et al., 20038
60/Male
T10-T11
Paraplegia after trauma
—
Laminectomy; improved
45/Female
T10-T12
Weakness of both lower limbs
—
Laminectomy; improved
55/Female
T7-T8
Weakness of both lower limbs
—
Laminectomy; improved
Giulioni et al., 20071
47/Female
T11-T12
Spastic paraparesis
—
Laminectomy; improved
Shiguematsu et al., 20129
47/Female
T10-T11
Spastic paraparesis
T1-T3 OLF/OPLL
Laminectomy; improved
Present case*
76/Male
T11-T12
Weakness of both lower limbs
Osteoporotic vertebral fracture
Laminectomy, vertebroplasty, and posterior instrumented fusion; improved
Authors (year)
OLF, ossification of the ligamentum flavum; OPLL, ossification of the posterior longitudinal ligament. *Rapidly progressed CLF was confirmed from sequential imaging findings.
WORLD NEUROSURGERY 132: 63-66, DECEMBER 2019
www.journals.elsevier.com/world-neurosurgery
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CASE REPORT NAOHISA MIYAKOSHI ET AL.
the increased permeability of the newly formed vessels.3,11 Although OVFs are the most common clinical manifestation of osteoporosis, no previous reports have described OVF as a potential trigger of symptomatic CLF. Although the present case showed no specific laboratory findings suggesting a disease of mineral metabolism, the present patient was a cancer survivor and had several comorbidities affecting osteoporosis. We could not deny the possibility that these underlying conditions may have some relationship with CLF. Ziadé et al12 reported an unusual case of recurrent epidural calcification (but not CLF) in the degenerated lumbar spine of a 71-year-old woman occurring over an 18-month period. In that case, the possible mechanism of calcification occurring over a relatively short period of time was suspected to involve the proinflammatory effects of calcium pyrophosphate or hydroxyapatite crystal deposition within the epidural space.12 However, the true cause remains unknown because surgery was not performed, and no further examinations (including histopathologic investigations) were undertaken.12 Similar to that case, a chronic inflammatory state after injury may have been a possible contributor to the pathogenesis of CLF in the present case. However, histopathologic examinations in the present case did not show definitive evidence of inflammation.
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PROGRESSING CLF IN THORACIC SPINE
CONCLUSIONS The present case represents the first report of rapidly progressing symptomatic CLF in the thoracic spine. Sequential imaging studies with a 9-month interval showed evidence of rapidly progressing thoracic CLF. The preceding OVF may have triggered the development of CLF. REFERENCES 1. Giulioni M, Zucchelli M, Damiani S. Thoracic myelopathy caused by calcified ligamentum flavum. Joint Bone Spine. 2007;74:504-505. 2. Fye KH, Weinstein PR, Donald F. Compressive cervical myelopathy due to calcium pyrophosphate dihydrate deposition disease: report of a case and review of the literature. Arch Intern Med. 1999;159: 189-193. 3. Khan MH, Smith PN, Donaldson WF 3rd. Acute quadriparesis caused by calcification of the entire cervical ligamentum flavum in a white female— report of an unusual case and a brief review of the literature: case report. Spine (Phila Pa 1976). 2005; 30:E687-E691. 4. Mwaka ES, Yayama T, Uchida K, et al. Calcium pyrophosphate dehydrate crystal deposition in the ligamentum flavum of the cervical spine: histopathological and immunohistochemical findings. Clin Exp Rheumatol. 2009;27:430-438. 5. Takahashi T, Hanakita J, Minami M. Pathophysiology of calcification and ossification of the ligamentum flavum in the cervical spine. Neurosurg Clin N Am. 2018;29:47-54.
drate deposition disease causing thoracic cord compression: case report. Neurosurgery. 2000;46: 222-225. 8. Muthukumar N, Karuppaswamy U. Tumoral calcium pyrophosphate dihydrate deposition disease of the ligamentum flavum. Neurosurgery. 2003;53: 103-108. 9. Shiguematsu FY, de Souza EC, Zimmermann AF, Castro GR, Pereira IA, Neves FS. Thoracic myelopathy due to calcification of the ligamentum flavum with hyperproteinorachia and responsive to steroid therapy: case report. Rev Bras Reumatol. 2012;52:438-446. 10. Nouri A, Tetreault L, Singh A, Karadimas SK, Fehlings MG. Degenerative cervical myelopathy: epidemiology, genetics, and pathogenesis. Spine (Phila Pa 1976). 2015;40:E675-E693. 11. Hijioka A, Suzuki K, Nakamura T, Yokoyama M, Kanazawa Y. Light and electron microscopy of hydroxyapatite depositions in the ligamentum flavum. Spine (Phila Pa 1976). 1994;19:2626-2631. 12. Ziade M, Zufferey P, So AK. Recurrent acute low back pain secondary to lumbar epidural calcification. Skeletal Radiol. 2007;36(suppl 1):S116-S119.
Conflict of interest statement: The authors declare that the article content was composed in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest. Received 6 August 2019; accepted 22 August 2019 Citation: World Neurosurg. (2019) 132:63-66. https://doi.org/10.1016/j.wneu.2019.08.177
6. Yamagami T, Kawano N, Nakano H. Calcification of the cervical ligamentum flavum–case report. Neurol Med Chir (Tokyo). 2000;40:234-238.
Journal homepage: www.journals.elsevier.com/worldneurosurgery
7. Muthukumar N, Karuppaswamy U, Sankarasubbu B. Calcium pyrophosphate dihy-
1878-8750/$ - see front matter ª 2019 Elsevier Inc. All rights reserved.
Available online: www.sciencedirect.com
WORLD NEUROSURGERY, https://doi.org/10.1016/j.wneu.2019.08.177
Rapidly Progressing Symptomatic Calcification of Ligamentum Flavum in Thoracic Spine After Osteoporotic Vertebral Fractures Naohisa Miyakoshi, Michio Hongo, Yuji Kasukawa, Yoshinori Ishikawa, Daisuke Kudo, Yoichi Shimada
Key words Calcification of ligamentum flavum - Osteoporotic vertebral fracture - Spine surgery - Thoracic spine -
Abbreviations and Acronyms CLF: Calcification of the ligamentum flavum MRI: Magnetic resonance imaging OVF: Osteoporotic vertebral fracture STIR: Short-tau inversion recovery Department of Orthopedic Surgery, Akita University Graduate School of Medicine, Akita, Japan To whom correspondence should be addressed: Naohisa Miyakoshi, M.D., Ph.D. [E-mail: [email protected]] Citation: World Neurosurg. (2019) 132:63-66. https://doi.org/10.1016/j.wneu.2019.08.177 Journal homepage: www.journals.elsevier.com/worldneurosurgery Available online: www.sciencedirect.com 1878-8750/$ - see front matter ª 2019 Elsevier Inc. All rights reserved.
- BACKGROUND:
Symptomatic calcification of the ligamentum flavum (CLF) is common in the cervical spine but rare in the thoracic spine. Rapidly progressing CLF in the thoracic spine has not been reported in the literature.
- CASE
DESCRIPTION: A 76-year-old Asian male experienced back pain after a fall and was diagnosed with osteoporotic vertebral fractures at T11 and L1. He was treated conservatively because of the lack of neurologic deficits. Nine months after the initial visit, he complained of progressive incomplete paraplegia. Magnetic resonance imaging and computed tomography of the thoracic spine showed CLF at T11-T12 severely compressing the spinal cord. This finding had not been seen on imaging studies at the initial visit. The patient underwent surgical resection of CLF and posterior instrumented spine fusion. Symptoms of muscle weakness recovered postoperatively.
- CONCLUSIONS:
In this case, sequential imaging studies with a 9-month interval showed evidence of rapidly progressing thoracic CLF. The preceding osteoporotic vertebral fracture may have triggered the development of CLF. CASE PRESENTATION History and Examination A 76-year-old Asian male experienced back pain after falling to the floor in his house.
He was diagnosed with OVFs at the T11 and L1 vertebrae and admitted to a nearby hospital. He was treated conservatively using a thoracolumbosacral orthosis because of the lack of neurologic deficits.
INTRODUCTION Calcification of the ligamentum flavum (CLF) is characterized by deposition of calcified granules of calcium pyrophosphate within the ligamentum flavum without bone formation.1 Because CLF is common in the cervical spine,2-6 most clinical reports of symptomatic CLF causing myelopathy have described involvement of the cervical spine and CLF in the thoracic spine is rare.1,7-9 In this report, we describe the case of a patient with thoracic CLF who showed rapidly progressing CLF after osteoporotic vertebral fractures (OVFs). Because calcification is a slow process, many years may pass before pathologic calcification reaches sufficient size to cause symptoms.3 In this regard, the course of the present case with rapid progression was unusual and no such case appears to have been reported previously. Sequential imaging studies in this case showed evidence of rapid progression of the thoracic CLF.
Figure 1. Sagittal magnetic resonance image (MRI) of the spine with fat suppression using short-tau inversion recovery (A) and axial T2-weighted MRI at T11-T12 (B) revealed fresh vertebral fractures at T11 and L1 without spinal canal stenosis.
WORLD NEUROSURGERY 132: 63-66, DECEMBER 2019
www.journals.elsevier.com/world-neurosurgery
63
CASE REPORT NAOHISA MIYAKOSHI ET AL.
PROGRESSING CLF IN THORACIC SPINE
Figure 2. Sagittal and axial T2-weighted magnetic resonance images obtained 9 months after initial visit revealed progression of osteoporotic vertebral fractures and spinal cord compression by a posterior mass within
He had a history of several medical treatments for carcinoma of the hypopharynx, early gastric cancer, and autoimmune hepatitis, with the latter treated using 6 mg/day of prednisolone for several years. Laboratory data showed no specific findings other than osteoporosis.
the ligamentum flavum at the T11-T12 level (A and B). Sagittal and axial computed tomography images show intraspinal canal calcification posterior to the spinal cord at the T11-T12 level (C and D).
On admission to the hospital, sagittal magnetic resonance imaging (MRI) with fat suppression using short-tau inversion recovery (STIR) (Figure 1A) and axial T2weighted MRI (see Figure 1B) revealed fresh vertebral fractures at T11 and L1 without spinal canal stenosis. Back pain
Figure 3. Postoperative anteroposterior and lateral spine radiographs after T12 vertebroplasty and posterior instrumented fusion at the T10-L2 level.
64
www.SCIENCEDIRECT.com
was relieved by bed rest and thoracolumbosacral orthotic for about 1 month, and he was discharged from hospital. However, antiosteoporotic pharmacotherapy was not introduced by this hospital. Nine months after the initial onset, he complained of weakness and numbness in bilateral lower extremities with no specific antecedent episode and revisited the same hospital. Sagittal and axial T2-weighted MRI revealed multiple OVFs and spinal canal stenosis at the T11-T12 level due to a protruding mass of ligamentum flavum severely compressing the spinal cord (Figure 2A and B). Computed tomography showed the protruding mass at T11-T12 contained calcified deposits, suspected as representing CLF (see Figure 2C and D). The patient was referred to our hospital due to impairment of standing resulting from progressive paraplegia showing weakness of the lower extremities (manual muscle testing, grade 1e2/5). Operation We performed posterior decompression of T11-T12 with resection of the CLF and posterior instrumented fusion from T10 to L2 combined with vertebroplasty using hydroxyapatite blocks for the fractured T12 vertebra (Figure 3). Intraoperatively, the ligamentum flavum contained a white, chalky, rough, granular substance that was adherent to the dura mater. Histologic examination of the resected ligamentum flavum revealed
WORLD NEUROSURGERY, https://doi.org/10.1016/j.wneu.2019.08.177
CASE REPORT NAOHISA MIYAKOSHI ET AL.
PROGRESSING CLF IN THORACIC SPINE
Figure 4. Histopathologic specimens reveal degeneration of the ligamentum flavum with calcification and chondrometaplasia; these findings are identical to CLF (hematoxylin-eosin stain, 10).
degeneration of the ligamentum flavum with calcification and chondrometaplasia (Figure 4). These findings were consisted with CLF. The postoperative course was uneventful. Muscle weakness recovered completely, and the patient became able to walk with a cane. DISCUSSION CLF is a disease involving crystal deposition macroscopically observable as a white,
chalky, rough, granular substance surrounded by degenerated ligamentum flavum. CLF is quite different from ossification of the ligamentum flavum, which exhibits bony continuity with the laminae. CLF has ordinarily been described as showing no continuity with the lamina, and the superficial and deep layers of the ligamentum flavum remain relatively preserved.5,10 CLF has usually been reported in the cervical spine.2-6 Symptomatic CLF in the thoracic spine is extremely rare, and to the
best of our knowledge only 7 cases (including the present case) with a mean age of 53.6 years (range, 45e76 years) have been reported in the English literature1,7-9 (Table 1). All 7 cases complained of weakness in the lower extremities and improved after surgical decompression. However, among these cases, the present case was the first to show evidence of rapidly progressing calcification on sequential imaging studies. The pathogenesis of CLF remains to be fully elucidated. However, studies on the cervical CLF have shown that the disease is more prevalent in females and have suggested that in addition to the aging process, predisposing factors for the disease include spinal trauma, long-standing motion loading or mechanical stress to the ligamentum flavum, vascular disturbance affecting the ligament, metabolic diseases including diabetes mellitus, and chondrocytic metaplasia.3-6 In the present case, the preceding OVFs may have triggered the development of CLF. Intravertebral instability due to collapsing OVF may result in repeated stress on the ligamentum flavum at the same level and may thus promote calcification. Repetitive microtrauma to the ligamentum flavum has been suspected to represent an initial inciting event that can lead to neovascularization, and calcium crystal deposition may occur because of
Table 1. Calcification of Ligamentum Flavum (CLF) in Thoracic Spine Requiring Surgical Decompression Age (years)/Sex
Level of Involvement
Main Clinical Presentation
Coexisting Spinal Disorder
Treatment and Outcome
Muthukumar et al., 20007
45/Female
T8-T9
Weakness of both lower limbs
—
Laminectomy; improved
Muthukumar et al., 20038
60/Male
T10-T11
Paraplegia after trauma
—
Laminectomy; improved
45/Female
T10-T12
Weakness of both lower limbs
—
Laminectomy; improved
55/Female
T7-T8
Weakness of both lower limbs
—
Laminectomy; improved
Giulioni et al., 20071
47/Female
T11-T12
Spastic paraparesis
—
Laminectomy; improved
Shiguematsu et al., 20129
47/Female
T10-T11
Spastic paraparesis
T1-T3 OLF/OPLL
Laminectomy; improved
Present case*
76/Male
T11-T12
Weakness of both lower limbs
Osteoporotic vertebral fracture
Laminectomy, vertebroplasty, and posterior instrumented fusion; improved
Authors (year)
OLF, ossification of the ligamentum flavum; OPLL, ossification of the posterior longitudinal ligament. *Rapidly progressed CLF was confirmed from sequential imaging findings.
WORLD NEUROSURGERY 132: 63-66, DECEMBER 2019
www.journals.elsevier.com/world-neurosurgery
65
CASE REPORT NAOHISA MIYAKOSHI ET AL.
the increased permeability of the newly formed vessels.3,11 Although OVFs are the most common clinical manifestation of osteoporosis, no previous reports have described OVF as a potential trigger of symptomatic CLF. Although the present case showed no specific laboratory findings suggesting a disease of mineral metabolism, the present patient was a cancer survivor and had several comorbidities affecting osteoporosis. We could not deny the possibility that these underlying conditions may have some relationship with CLF. Ziadé et al12 reported an unusual case of recurrent epidural calcification (but not CLF) in the degenerated lumbar spine of a 71-year-old woman occurring over an 18-month period. In that case, the possible mechanism of calcification occurring over a relatively short period of time was suspected to involve the proinflammatory effects of calcium pyrophosphate or hydroxyapatite crystal deposition within the epidural space.12 However, the true cause remains unknown because surgery was not performed, and no further examinations (including histopathologic investigations) were undertaken.12 Similar to that case, a chronic inflammatory state after injury may have been a possible contributor to the pathogenesis of CLF in the present case. However, histopathologic examinations in the present case did not show definitive evidence of inflammation.
66
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PROGRESSING CLF IN THORACIC SPINE
CONCLUSIONS The present case represents the first report of rapidly progressing symptomatic CLF in the thoracic spine. Sequential imaging studies with a 9-month interval showed evidence of rapidly progressing thoracic CLF. The preceding OVF may have triggered the development of CLF. REFERENCES 1. Giulioni M, Zucchelli M, Damiani S. Thoracic myelopathy caused by calcified ligamentum flavum. Joint Bone Spine. 2007;74:504-505. 2. Fye KH, Weinstein PR, Donald F. Compressive cervical myelopathy due to calcium pyrophosphate dihydrate deposition disease: report of a case and review of the literature. Arch Intern Med. 1999;159: 189-193. 3. Khan MH, Smith PN, Donaldson WF 3rd. Acute quadriparesis caused by calcification of the entire cervical ligamentum flavum in a white female— report of an unusual case and a brief review of the literature: case report. Spine (Phila Pa 1976). 2005; 30:E687-E691. 4. Mwaka ES, Yayama T, Uchida K, et al. Calcium pyrophosphate dehydrate crystal deposition in the ligamentum flavum of the cervical spine: histopathological and immunohistochemical findings. Clin Exp Rheumatol. 2009;27:430-438. 5. Takahashi T, Hanakita J, Minami M. Pathophysiology of calcification and ossification of the ligamentum flavum in the cervical spine. Neurosurg Clin N Am. 2018;29:47-54.
drate deposition disease causing thoracic cord compression: case report. Neurosurgery. 2000;46: 222-225. 8. Muthukumar N, Karuppaswamy U. Tumoral calcium pyrophosphate dihydrate deposition disease of the ligamentum flavum. Neurosurgery. 2003;53: 103-108. 9. Shiguematsu FY, de Souza EC, Zimmermann AF, Castro GR, Pereira IA, Neves FS. Thoracic myelopathy due to calcification of the ligamentum flavum with hyperproteinorachia and responsive to steroid therapy: case report. Rev Bras Reumatol. 2012;52:438-446. 10. Nouri A, Tetreault L, Singh A, Karadimas SK, Fehlings MG. Degenerative cervical myelopathy: epidemiology, genetics, and pathogenesis. Spine (Phila Pa 1976). 2015;40:E675-E693. 11. Hijioka A, Suzuki K, Nakamura T, Yokoyama M, Kanazawa Y. Light and electron microscopy of hydroxyapatite depositions in the ligamentum flavum. Spine (Phila Pa 1976). 1994;19:2626-2631. 12. Ziade M, Zufferey P, So AK. Recurrent acute low back pain secondary to lumbar epidural calcification. Skeletal Radiol. 2007;36(suppl 1):S116-S119.
Conflict of interest statement: The authors declare that the article content was composed in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest. Received 6 August 2019; accepted 22 August 2019 Citation: World Neurosurg. (2019) 132:63-66. https://doi.org/10.1016/j.wneu.2019.08.177
6. Yamagami T, Kawano N, Nakano H. Calcification of the cervical ligamentum flavum–case report. Neurol Med Chir (Tokyo). 2000;40:234-238.
Journal homepage: www.journals.elsevier.com/worldneurosurgery
7. Muthukumar N, Karuppaswamy U, Sankarasubbu B. Calcium pyrophosphate dihy-
1878-8750/$ - see front matter ª 2019 Elsevier Inc. All rights reserved.
Available online: www.sciencedirect.com
WORLD NEUROSURGERY, https://doi.org/10.1016/j.wneu.2019.08.177