Images in Pediatric Neurosurgery Pediatr Neurosurg 2013;49:320–323 DOI: 10.1159/000367664
Received: June 1, 2014 Accepted after revision: August 18, 2014 Published online: October 21, 2014
Butterfly C2 Vertebra: An Unusual Finding in a Case of Os Odontoideum Devi Prasad Patra a Pravin Salunke a Gobinda Pramanick b Departments of a Neurosurgery and b Radiodiagnosis, Postgraduate Institute of Medical Education and Research, Chandigarh, India
The development of C2 (or the axis) is distinctly different from the remaining cervical vertebra. The time course of the ossification and development of this vertebra is variable and may extend a few years after birth [1, 2]. These cartilaginous junctions may persist for a long time as radiolucent areas in a few, but a true anomaly like the nonfused or absent posterior arch of the axis is rare [3]. A posterior midline synchondrosis is occasionally seen in the dens as radiolucency [2, 4]. Though rare, clefts and nonfusion of the posterior arch (cervical spina bifida) have been reported with craniofacial anomalies like cleft lip and palate [5]. However, a midline cleft in the body of the axis (butterfly C2) has never been reported. We report a butterfly C2 in a young girl with os odontoideum. A 10-year-old female child presented with progressive spastic quadriparesis associated with bowel bladder involvement and recurrent nonhealing ulcers of the hands for 8 months. There was no craniofacial abnormality. Radiology revealed os odontoideum with atlantoaxial dislocation, causing compression of the cervicomedullary junction (fig. 1). The body of the axis showed a peculiar abnormality. The lower posterior half constituted of 2 parts joining anterosuperiorly to a midline structure like wings of a butterfly joining its body. Additionally, a sclerotic sagittally oriented midline septum extending across © 2014 S. Karger AG, Basel 1016–2291/14/0495–0320$39.50/0 E-Mail [email protected] www.karger.com/pne
the remaining body was noticed (fig. 1a, d). The lateral masses were well formed. Of interest, there was associated midline sagittal radiolucency of both the anterior and posterior arch of the atlas. The patient was operated on through a posterior approach and atlantoaxial fusion in a reduced position was achieved with C1 lateral mass screws, C2 pedicle screws and rods. As the bony strut connecting the 2 halves of the body of the axis was thick and appeared to be strong, the adjacent vertebra (C3) was not included in the fusion. Postoperatively, the patient recovered well, with improvement in spasticity and power. A CT scan at the 6-month follow-up showed C1-2 lateral mass fusion. There was no splaying of the C2 body (fig. 2). The development of the axis is complex. It usually develops from 5 ossification centers: paired centers for the neural arches, 1 basal center for the body, a dentate center for the odontoid, and 1 apical center [2]. The dens itself develops from bilateral ossification centers that usually unite at midline by birth. The apical center begins to ossify at 2 years of age and is usually complete by the age of 6, though occasionally it may not ossify till adolescence [2]. The parents have agreed to the submission of the letter to this journal and have given their consent.
Dr. Pravin Salunke, Assistant Professor Department of Neurosurgery Postgraduate Institute of Medical Education and Research Sector 12, Chandigarh 160012 (India) E-Mail drpravin_salunke @ yahoo.co.uk
Color version available online
a
b
c
d
Fig. 1. a Axial CT section through C2 showing a midline cleft in
the posterior cortex of the body and a sclerotic line along the midline across the remaining body. b Axial CT section through C1 and dens showing normal posterior cortex of the dens. c, d Coronal reconstructed images of the upper cervical spine showing midline
e
sagittal split of the body of the axis (c) and a vertical midsagittal sclerotic line in the remaining C2 body anteriorly (d). e Midsagittal T2-weighted MRI showing cervicomedullary compression due to os odontoideum.
The neurocentral synchondroses fuse by the age of 3.8 years in a paramedian location. The superior portion of the neurocentral synchondrosis fuses later than the inferior portion. The ossification of the synchondroses of the axis may be delayed (appearing as radiolucency in postnatal computed tomograms), the most common being the dentocentral synchondrosis and the posterior midline synchondrosis. An apparent deficiency of the posterior cortex of the dens along the midline is occasionally seen as late as 7 years of age [2]. A central sclerotic line that lies in a horizontal plane may be visible in the dentocentral synchondrosis well after its complete ossification [1]. Anomalous ossification centers in the axis, though rare compared to the atlas, have been reported in a few cases where it was bilateral and symmetrical and intercalated into the neurocentral synchondrosis [2]. Midline clefts in the C1 anterior and posterior arches, dens and aplasia of the posterior C2 arch have been previously described [1–7]. A midline cleft of the C2 body has
never been described in the past, though a defect of the lower cervical vertebral body (butterfly vertebra) has been reported [8]. Clefts at various levels of cervical vertebrae may or may not be associated with syndromes and have been tabulated in table 1. In our case there was associated midline deficiency in the posterior inferior body of the axis with slight splaying of the 2 halves. As described above, the body of the axis is formed by a single midline basal ossification center that fuses with the paired neural arches in the paramedian location. The nonfusion of the neurocentral synchondroses appear as paramedian radiolucencies in a sagittal plane in the body of the axis in the coronal images of the CT scans in postnatal life. The posterior sagittal cleft, as seen in our case, cannot be explained by the normally described ossification centers. It suggests the presence of some anomalous ossification center that probably has intercalated in the neurocentral synchondrosis. The presence of a midsagittal vertical sclerotic septum dividing the remaining
Butterfly C2 Vertebra: An Unusual Finding in a Case of Os Odontoideum
Pediatr Neurosurg 2013;49:320–323 DOI: 10.1159/000367664
321
Color version available online
a
b
c
d
e
f
Fig. 2. a, b Parasagittal CT section showing fusion of C1-2 lateral masses on either side. c Midsagittal CT image showing good reduction. d Axial CT section through C2 showing the bony strut con-
necting the 2 halves of the body of C2 that prevented splaying following instrumentation. e, f Coronal CT sections through the C2 body showing the split limited to the posterior half of the C2 body.
Table 1. Literature describing midline clefts of cervical vertebrae
Midline clefts of cervical spine
Possible syndromic association
Literature described (first author)
C1 (atlas) anterior arch
Klippel-Feil syndrome Treacher Collins syndrome Median cleft face syndrome
Karwacki [1] Piatt [2] Pang [4] Martirosyan [6] Chapman [7]
C1 (atlas) posterior arch
Klippel-Feil syndrome Treacher Collins syndrome
Karwacki [1] Piatt [2] Pang [4] Martirosyan [6]
Odontoid cleft
Median cleft face syndrome
Karwacki [1] Piatt [2] Pang [4] Chapman [7]
C2 (axis) posterior arch C3–C7 (C6–C7 butterfly vertebrae and posterior cervical spina bifida)
322
Pediatr Neurosurg 2013;49:320–323 DOI: 10.1159/000367664
Piatt [2] Behari [3] Crouzon’s syndrome Cleft lip and palate
Hemmer [8] Uğar [5]
Patra /Salunke /Pramanick
body of C2 suggests ossification of this abnormal synchondrosis. It is, however, very unusual for such an intercalation of an anomalous ossification center in neurocentral synchondrosis to produce 2 symmetrical ossification centers. Another possibility is that of the notochord abnormally dividing the central ossification center into 2 halves as described for butterfly vertebra elsewhere [8]. A butterfly cervical vertebra has been described in association with Cruzon’s syndrome [8]. However, it is rare and usually affects the C5 and C6 levels. A C2 butterfly vertebra has never been described. Also, the presence of a midsagittal sclerotic line in the remaining body of C2 goes against the notochord dividing the single ossification center partially. The presence of a butterfly vertebra may be detected incidentally, as in our case. The extent of the midline defect of the C2 body would decide the level and number of
vertebral bodies to be fused. In the case of a complete split of the body, C2 screws alone would lead to splaying of the 2 halves. To avoid this, adjacent vertebrae need to be included in the fusion. In younger children, there would be little effect on growth or further restriction of motion if the fusion is extended to the adjacent level. However, in the case of a partial cleft with good strut connecting the 2 halves of the vertebra, splaying is unlikely and including the adjacent vertebra in fusion may not be necessary. Apart from the rarity, this anomaly draws our attention to the multiple complex processes involved in the formation of the upper cervical vertebrae.
Disclosure Statement This study received no financial support. The authors have no conflicts of interest to declare.
References 1 Karwacki GM, Schneider JF: Normal ossification patterns of atlas and axis: a CT study. AJNR Am J Neuroradiol 2012;33:1882–1887. 2 Piatt JH Jr, Grissom LE: Developmental anatomy of the atlas and axis in childhood by computed tomography. J Neurosurg Pediatr 2011; 8:235–243. 3 Behari S, Kiran Kumar MV, Banerji D, Chhabra DK, Jain VK: Atlantoaxial dislocation associated with the maldevelopment of the posterior neural arch of axis causing compressive myelopathy. Neurol India 2004; 52: 489–491.
Butterfly C2 Vertebra: An Unusual Finding in a Case of Os Odontoideum
4 Pang D, Thompson DN: Embryology and bony malformations of the craniovertebral junction. Childs Nerv Syst 2011;27:523–564. 5 Uğar DA, Semb G: The prevalence of anomalies of the upper cervical vertebrae in subjects with cleft lip, cleft palate, or both. Cleft Palate Craniofac J 2001;38:498–503.
6 Martirosyan NL, Cavalcanti DD, Kalani MY, Maughan PH, Theodore N: Aplasia of the anterior arch of atlas associated with multiple congenital disorders: case report. Neurosurgery 2011;69:E1317–E1320. 7 Chapman S, Goldin JH, Hendel RG, Hockley AD, Wake MC, Weale P: The median cleft face syndrome with associated cleft mandible, bifid odontoid peg and agenesis of the anterior arch of atlas. Br J Oral Maxillofac Surg 1991;29:279–281. 8 Hemmer KM, McAlister WH, Marsh JL: Cervical spine anomalies in the craniosynostosis syndromes. Cleft Palate J 1987;24:328–333.
Pediatr Neurosurg 2013;49:320–323 DOI: 10.1159/000367664
323
Copyright: S. Karger AG, Basel 2014. Reproduced with the permission of S. Karger AG, Basel. Further reproduction or distribution (electronic or otherwise) is prohibited without permission from the copyright holder.
Received: June 1, 2014 Accepted after revision: August 18, 2014 Published online: October 21, 2014
Butterfly C2 Vertebra: An Unusual Finding in a Case of Os Odontoideum Devi Prasad Patra a Pravin Salunke a Gobinda Pramanick b Departments of a Neurosurgery and b Radiodiagnosis, Postgraduate Institute of Medical Education and Research, Chandigarh, India
The development of C2 (or the axis) is distinctly different from the remaining cervical vertebra. The time course of the ossification and development of this vertebra is variable and may extend a few years after birth [1, 2]. These cartilaginous junctions may persist for a long time as radiolucent areas in a few, but a true anomaly like the nonfused or absent posterior arch of the axis is rare [3]. A posterior midline synchondrosis is occasionally seen in the dens as radiolucency [2, 4]. Though rare, clefts and nonfusion of the posterior arch (cervical spina bifida) have been reported with craniofacial anomalies like cleft lip and palate [5]. However, a midline cleft in the body of the axis (butterfly C2) has never been reported. We report a butterfly C2 in a young girl with os odontoideum. A 10-year-old female child presented with progressive spastic quadriparesis associated with bowel bladder involvement and recurrent nonhealing ulcers of the hands for 8 months. There was no craniofacial abnormality. Radiology revealed os odontoideum with atlantoaxial dislocation, causing compression of the cervicomedullary junction (fig. 1). The body of the axis showed a peculiar abnormality. The lower posterior half constituted of 2 parts joining anterosuperiorly to a midline structure like wings of a butterfly joining its body. Additionally, a sclerotic sagittally oriented midline septum extending across © 2014 S. Karger AG, Basel 1016–2291/14/0495–0320$39.50/0 E-Mail [email protected] www.karger.com/pne
the remaining body was noticed (fig. 1a, d). The lateral masses were well formed. Of interest, there was associated midline sagittal radiolucency of both the anterior and posterior arch of the atlas. The patient was operated on through a posterior approach and atlantoaxial fusion in a reduced position was achieved with C1 lateral mass screws, C2 pedicle screws and rods. As the bony strut connecting the 2 halves of the body of the axis was thick and appeared to be strong, the adjacent vertebra (C3) was not included in the fusion. Postoperatively, the patient recovered well, with improvement in spasticity and power. A CT scan at the 6-month follow-up showed C1-2 lateral mass fusion. There was no splaying of the C2 body (fig. 2). The development of the axis is complex. It usually develops from 5 ossification centers: paired centers for the neural arches, 1 basal center for the body, a dentate center for the odontoid, and 1 apical center [2]. The dens itself develops from bilateral ossification centers that usually unite at midline by birth. The apical center begins to ossify at 2 years of age and is usually complete by the age of 6, though occasionally it may not ossify till adolescence [2]. The parents have agreed to the submission of the letter to this journal and have given their consent.
Dr. Pravin Salunke, Assistant Professor Department of Neurosurgery Postgraduate Institute of Medical Education and Research Sector 12, Chandigarh 160012 (India) E-Mail drpravin_salunke @ yahoo.co.uk
Color version available online
a
b
c
d
Fig. 1. a Axial CT section through C2 showing a midline cleft in
the posterior cortex of the body and a sclerotic line along the midline across the remaining body. b Axial CT section through C1 and dens showing normal posterior cortex of the dens. c, d Coronal reconstructed images of the upper cervical spine showing midline
e
sagittal split of the body of the axis (c) and a vertical midsagittal sclerotic line in the remaining C2 body anteriorly (d). e Midsagittal T2-weighted MRI showing cervicomedullary compression due to os odontoideum.
The neurocentral synchondroses fuse by the age of 3.8 years in a paramedian location. The superior portion of the neurocentral synchondrosis fuses later than the inferior portion. The ossification of the synchondroses of the axis may be delayed (appearing as radiolucency in postnatal computed tomograms), the most common being the dentocentral synchondrosis and the posterior midline synchondrosis. An apparent deficiency of the posterior cortex of the dens along the midline is occasionally seen as late as 7 years of age [2]. A central sclerotic line that lies in a horizontal plane may be visible in the dentocentral synchondrosis well after its complete ossification [1]. Anomalous ossification centers in the axis, though rare compared to the atlas, have been reported in a few cases where it was bilateral and symmetrical and intercalated into the neurocentral synchondrosis [2]. Midline clefts in the C1 anterior and posterior arches, dens and aplasia of the posterior C2 arch have been previously described [1–7]. A midline cleft of the C2 body has
never been described in the past, though a defect of the lower cervical vertebral body (butterfly vertebra) has been reported [8]. Clefts at various levels of cervical vertebrae may or may not be associated with syndromes and have been tabulated in table 1. In our case there was associated midline deficiency in the posterior inferior body of the axis with slight splaying of the 2 halves. As described above, the body of the axis is formed by a single midline basal ossification center that fuses with the paired neural arches in the paramedian location. The nonfusion of the neurocentral synchondroses appear as paramedian radiolucencies in a sagittal plane in the body of the axis in the coronal images of the CT scans in postnatal life. The posterior sagittal cleft, as seen in our case, cannot be explained by the normally described ossification centers. It suggests the presence of some anomalous ossification center that probably has intercalated in the neurocentral synchondrosis. The presence of a midsagittal vertical sclerotic septum dividing the remaining
Butterfly C2 Vertebra: An Unusual Finding in a Case of Os Odontoideum
Pediatr Neurosurg 2013;49:320–323 DOI: 10.1159/000367664
321
Color version available online
a
b
c
d
e
f
Fig. 2. a, b Parasagittal CT section showing fusion of C1-2 lateral masses on either side. c Midsagittal CT image showing good reduction. d Axial CT section through C2 showing the bony strut con-
necting the 2 halves of the body of C2 that prevented splaying following instrumentation. e, f Coronal CT sections through the C2 body showing the split limited to the posterior half of the C2 body.
Table 1. Literature describing midline clefts of cervical vertebrae
Midline clefts of cervical spine
Possible syndromic association
Literature described (first author)
C1 (atlas) anterior arch
Klippel-Feil syndrome Treacher Collins syndrome Median cleft face syndrome
Karwacki [1] Piatt [2] Pang [4] Martirosyan [6] Chapman [7]
C1 (atlas) posterior arch
Klippel-Feil syndrome Treacher Collins syndrome
Karwacki [1] Piatt [2] Pang [4] Martirosyan [6]
Odontoid cleft
Median cleft face syndrome
Karwacki [1] Piatt [2] Pang [4] Chapman [7]
C2 (axis) posterior arch C3–C7 (C6–C7 butterfly vertebrae and posterior cervical spina bifida)
322
Pediatr Neurosurg 2013;49:320–323 DOI: 10.1159/000367664
Piatt [2] Behari [3] Crouzon’s syndrome Cleft lip and palate
Hemmer [8] Uğar [5]
Patra /Salunke /Pramanick
body of C2 suggests ossification of this abnormal synchondrosis. It is, however, very unusual for such an intercalation of an anomalous ossification center in neurocentral synchondrosis to produce 2 symmetrical ossification centers. Another possibility is that of the notochord abnormally dividing the central ossification center into 2 halves as described for butterfly vertebra elsewhere [8]. A butterfly cervical vertebra has been described in association with Cruzon’s syndrome [8]. However, it is rare and usually affects the C5 and C6 levels. A C2 butterfly vertebra has never been described. Also, the presence of a midsagittal sclerotic line in the remaining body of C2 goes against the notochord dividing the single ossification center partially. The presence of a butterfly vertebra may be detected incidentally, as in our case. The extent of the midline defect of the C2 body would decide the level and number of
vertebral bodies to be fused. In the case of a complete split of the body, C2 screws alone would lead to splaying of the 2 halves. To avoid this, adjacent vertebrae need to be included in the fusion. In younger children, there would be little effect on growth or further restriction of motion if the fusion is extended to the adjacent level. However, in the case of a partial cleft with good strut connecting the 2 halves of the vertebra, splaying is unlikely and including the adjacent vertebra in fusion may not be necessary. Apart from the rarity, this anomaly draws our attention to the multiple complex processes involved in the formation of the upper cervical vertebrae.
Disclosure Statement This study received no financial support. The authors have no conflicts of interest to declare.
References 1 Karwacki GM, Schneider JF: Normal ossification patterns of atlas and axis: a CT study. AJNR Am J Neuroradiol 2012;33:1882–1887. 2 Piatt JH Jr, Grissom LE: Developmental anatomy of the atlas and axis in childhood by computed tomography. J Neurosurg Pediatr 2011; 8:235–243. 3 Behari S, Kiran Kumar MV, Banerji D, Chhabra DK, Jain VK: Atlantoaxial dislocation associated with the maldevelopment of the posterior neural arch of axis causing compressive myelopathy. Neurol India 2004; 52: 489–491.
Butterfly C2 Vertebra: An Unusual Finding in a Case of Os Odontoideum
4 Pang D, Thompson DN: Embryology and bony malformations of the craniovertebral junction. Childs Nerv Syst 2011;27:523–564. 5 Uğar DA, Semb G: The prevalence of anomalies of the upper cervical vertebrae in subjects with cleft lip, cleft palate, or both. Cleft Palate Craniofac J 2001;38:498–503.
6 Martirosyan NL, Cavalcanti DD, Kalani MY, Maughan PH, Theodore N: Aplasia of the anterior arch of atlas associated with multiple congenital disorders: case report. Neurosurgery 2011;69:E1317–E1320. 7 Chapman S, Goldin JH, Hendel RG, Hockley AD, Wake MC, Weale P: The median cleft face syndrome with associated cleft mandible, bifid odontoid peg and agenesis of the anterior arch of atlas. Br J Oral Maxillofac Surg 1991;29:279–281. 8 Hemmer KM, McAlister WH, Marsh JL: Cervical spine anomalies in the craniosynostosis syndromes. Cleft Palate J 1987;24:328–333.
Pediatr Neurosurg 2013;49:320–323 DOI: 10.1159/000367664
323
Copyright: S. Karger AG, Basel 2014. Reproduced with the permission of S. Karger AG, Basel. Further reproduction or distribution (electronic or otherwise) is prohibited without permission from the copyright holder.
