Limits...
Traumatic odontoid process synchondrosis fracture with atlantoaxial instability in a calf: clinical presentation and imaging findings.

Hülsmeyer VI, Flatz K, Putschbach K, Bechter MR, Weiler S, Fischer A, Feist M - Ir Vet J (2015)

Bottom Line: Advanced diagnostic imaging was considered to allow better planning of potential surgical stabilisation and to exclude any additional lesions of the cervical vertebral column.Advanced diagnostic imaging and post-mortem examination did not identify any other cervical lesion.This case report indicates that the odontoid process synchondrosis is a potential predisposed injury site and that traumatic odontoid process synchondrosis fractures should be considered as a potential differential in calves with acute cervical pain and/or signs of a cervical myelopathy.

View Article: PubMed Central - PubMed

Affiliation: Section of Neurology, Clinic of Small Animal Medicine at the Centre for Clinical Veterinary Medicine, Ludwig Maximilian University, Veterinärstr.13, 80539 Munich, Germany.

ABSTRACT
A 6-week-old female Simmental calf was evaluated for acute non-ambulatory tetraparesis. Physical and laboratory examinations revealed no clinically relevant abnormalities. Neurological findings were consistent with acute, progressive and painful cervical myelopathy. Radiographs displayed a fractured odontoid process (dens axis) and vertebral step misalignment at the fracture site. A traumatic origin was suspected. Advanced diagnostic imaging was considered to allow better planning of potential surgical stabilisation and to exclude any additional lesions of the cervical vertebral column. However, during trailer transportation to the advanced diagnostic imaging and surgery site, the calf deteriorated neurologically and was humanely euthanised. Magnetic resonance imaging (MRI) and computed tomography (CT) were performed immediately post-mortem for scientific reasons. The MRI examination reflected the radiographic findings and confirmed severe spinal cord compression at the fracture site. In addition, a T2W-hyperintense signal change within the paravertebral soft tissue dorsal to the fracture site was indicative of a traumatic event. CT identified the fracture site at the synchondrosis between the odontoid process and the body of the axis, and this finding was confirmed by post-mortem examination. Advanced diagnostic imaging and post-mortem examination did not identify any other cervical lesion. In summary, this calf was diagnosed with a traumatic odontoid process synchondrosis fracture, which has not been reported previously in calves but presents a challenging and well-known fracture type in young children. This case report indicates that the odontoid process synchondrosis is a potential predisposed injury site and that traumatic odontoid process synchondrosis fractures should be considered as a potential differential in calves with acute cervical pain and/or signs of a cervical myelopathy.

No MeSH data available.


Related in: MedlinePlus

Post-mortem sagittal T2W-image of the cervical vertebral column. The MRI revealed similar findings as the radiographs but displayed pronounced spinal cord involvement. The images reflect displacement of the C2 vertebral body with step misalignment of the vertebral canal and severe spinal cord compression at this level. Next to the compression site, the spinal cord (continuous arrows) shows a T2-hyperintense intramedullary signal. The considered differentials were spinal cord oedema, haemorrhage or myelomalacia. The T2-hyperintense area within the paravertebral musculature located dorsal to the fracture site (broken arrow) is indicative of a traumatic dorsal event. Asterisk = odontoid process.
© Copyright Policy - open-access
Related In: Results  -  Collection

License 1 - License 2
getmorefigures.php?uid=PMC4416342&req=5

Fig2: Post-mortem sagittal T2W-image of the cervical vertebral column. The MRI revealed similar findings as the radiographs but displayed pronounced spinal cord involvement. The images reflect displacement of the C2 vertebral body with step misalignment of the vertebral canal and severe spinal cord compression at this level. Next to the compression site, the spinal cord (continuous arrows) shows a T2-hyperintense intramedullary signal. The considered differentials were spinal cord oedema, haemorrhage or myelomalacia. The T2-hyperintense area within the paravertebral musculature located dorsal to the fracture site (broken arrow) is indicative of a traumatic dorsal event. Asterisk = odontoid process.

Mentions: A 6-week-old female Simmental calf was found in lateral recumbency (igloo system, housed with one other calf). The non-ambulatory and recumbent calf was pre-treated by the referring veterinarian with metamizole and then referred to the Clinic for Ruminants for further evaluation. The physical and laboratory examinations (CBC, serum biochemistry profile and blood gases) showed no clinically relevant abnormalities. On neurological examination, the calf appeared conscious and responsive to stimuli but presented in lateral recumbency with non-ambulatory tetraparesis (minimal voluntary movements of all four limbs were preserved). Cranial nerve function was normal. With support, the calf could be raised but showed reduced to absent postural reactions in all limbs. Spinal reflexes were all normal, with increased muscle tone. Conscious pain perception was evaluated to be preserved. Pronounced upper cervical hyperaesthesia with intermittent opisthotonus was evident on neck palpation. Based on neurological findings, the lesion was localised to the C1-C5 spinal cord segments. Based on the clinical history and the calf’s age, the most likely differentials were considered to be trauma, anomaly or inflammation. Lateral cervical digital radiographs (Axiom Luminos dRF, Siemens Healthcare, Erlangen, Germany KV: 69,8, mAS: 25), identified a fractured odontoid process, which appeared to be still attached to the body of the atlas. However, dorsal dislocation of the C2 vertebral body was obvious (Figure 1). The remaining cervical vertebrae displayed no obvious radiographic abnormalities. Based on the radiographic findings our initial diagnosis was a traumatic odontoid process fracture. Instability and spinal cord compression at the fracture site were highly suspected due to the radiographic findings and neurological presentation. Therefore, surgical decompression, anatomical alignment, and stabilisation were favoured for our calf rather than conservative management (such as neck splinting). Potential surgical stabilisation was planned to be performed in collaboration with our small animal neurosurgeons located at the Clinic for Small Animal Surgery and Reproduction. Although the diagnosis of an odontoid process fracture was already established on radiographs, advanced diagnostic imaging was considered to allow better surgical planning and to screen for other traumatic lesions within the remaining cervical vertebrae (because it is reported that multiple vertebral lesions may occur in 5-10% of small animal trauma patients [19,20]). In addition, the owner requested advanced diagnostic imaging examination prior to a cost-consuming surgery to definitively exclude any concurrent and injury-predisposing congenital abnormality at the atlantooccipital region. In the case of a concurrent congenital atlantooccipital fusion, the calf’s owner would have denied any further treatment due to the condition’s potential heritability and associated limitation of future breeding uses. However, because of rapidly deteriorating neurological signs and respiratory distress during trailer transportation to the advanced diagnostic imaging and surgery sites (both located at the Clinic for Small Animal Surgery and Reproduction), the calf was euthanised. MRI and CT examinations were performed immediately post-mortem for scientific reasons. The MRI examination was performed using a 1.5 T magnetic resonance unit (Magnetom Symphony, Siemens Healthcare, Erlangen, Germany). The dead calf was positioned in sternal recumbency because this allowed positioning with only minor neck manipulation (compared with dorsal recumbency) and hence was assumed to lower the risk of artificial and manipulation-induced fracture dislocation; however, dorsal recumbency would have allowed closer contact between the area of interest and the table coils. T1-weighted (T1W; TR: 768, TE: 13), T2-weighted (T2W; TR: 3980, TE: 109) and short tau inversion recovery (STIR; TR: 5790, TE: 61, TI: 140) pulse sequences of the cervical vertebral column were obtained in the sagittal (T1W, T2W and STIR) and dorsal planes (STIR) with a slice thickness of 3 mm (STIR) and 2.5 mm (T1W and T2W). The MRI examination confirmed severe spinal cord compression at the level of the fracture site due to dorsal displacement of the C2 vertebral body and pronounced vertebral step misalignment (Figure 2). Cranial and caudal to the compression site, the spinal cord appeared swollen and exhibited a hyperintense intramedullary signal on the T2W-images and on the STIR-images, with mixed intensity (but predominantly hypointense appearance) on the T1W-images. Based on signal-pattern spinal cord oedema, intramedullary haemorrhage or myelomalacia were considered as potential differentials. A T2* gradient echo (T2*-GRE) sequence would have been helpful to further characterise this spinal cord T2W-hyperintensity but unfortunately was not performed. Dorsal to the compression site, the paravertebral musculature showed a focal area of T2-hyperintensity (with similar appearance on the STIR-images), which was supposed to be indicative of a dorsal traumatic event at this level. A post-mortem CT examination of the cervical vertebral column was performed with a 64-slice, helical CT scanner (Somatom Definition AS, Siemens Healthcare, Erlangen, Germany). Transverse images of the cervical vertebral column were acquired (64 x 0.6-mm detector collimation, 120 KVp, 120 ma, 1 sec rotation time and 512 x 512 reconstructed image matrix). A bone algorithm (B70s convolution Kernel) was used for reconstruction. CT images reflected MRI findings and furthermore identified the fracture site at the synchondrosis between the body of the axis and the odontoid process (Figure 3). The fracture line was directed in a dorsoventral oblique direction from the dorsal area of the odontoid process to the ventral aspect of the body of the axis. Additional findings were bony fragments at the ventral aspect of the fracture line. The degree of odontoid process displacement was calculated to be approximately 40%, employing the following formula used in young children with odontoid process synchondrosis fractures: Distance of maximum displacement of the fractured odontoid process (distance from the cortex of the odontoid to the outer cortex of the body of C2) divided by the anteroposterior diameter (equals the dorsoventral diameter in animals) of the odontoid [21]. Potential congenital malformations predisposing to atlantoaxial instability and other traumatic lesions of the remaining vertebrae were definitely ruled out by advanced diagnostic imaging examination and subsequent necropsy. In summary, this calf was diagnosed with a traumatic odontoid process synchondrosis fracture.Figure 1


Traumatic odontoid process synchondrosis fracture with atlantoaxial instability in a calf: clinical presentation and imaging findings.

Hülsmeyer VI, Flatz K, Putschbach K, Bechter MR, Weiler S, Fischer A, Feist M - Ir Vet J (2015)

Post-mortem sagittal T2W-image of the cervical vertebral column. The MRI revealed similar findings as the radiographs but displayed pronounced spinal cord involvement. The images reflect displacement of the C2 vertebral body with step misalignment of the vertebral canal and severe spinal cord compression at this level. Next to the compression site, the spinal cord (continuous arrows) shows a T2-hyperintense intramedullary signal. The considered differentials were spinal cord oedema, haemorrhage or myelomalacia. The T2-hyperintense area within the paravertebral musculature located dorsal to the fracture site (broken arrow) is indicative of a traumatic dorsal event. Asterisk = odontoid process.
© Copyright Policy - open-access
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC4416342&req=5

Fig2: Post-mortem sagittal T2W-image of the cervical vertebral column. The MRI revealed similar findings as the radiographs but displayed pronounced spinal cord involvement. The images reflect displacement of the C2 vertebral body with step misalignment of the vertebral canal and severe spinal cord compression at this level. Next to the compression site, the spinal cord (continuous arrows) shows a T2-hyperintense intramedullary signal. The considered differentials were spinal cord oedema, haemorrhage or myelomalacia. The T2-hyperintense area within the paravertebral musculature located dorsal to the fracture site (broken arrow) is indicative of a traumatic dorsal event. Asterisk = odontoid process.
Mentions: A 6-week-old female Simmental calf was found in lateral recumbency (igloo system, housed with one other calf). The non-ambulatory and recumbent calf was pre-treated by the referring veterinarian with metamizole and then referred to the Clinic for Ruminants for further evaluation. The physical and laboratory examinations (CBC, serum biochemistry profile and blood gases) showed no clinically relevant abnormalities. On neurological examination, the calf appeared conscious and responsive to stimuli but presented in lateral recumbency with non-ambulatory tetraparesis (minimal voluntary movements of all four limbs were preserved). Cranial nerve function was normal. With support, the calf could be raised but showed reduced to absent postural reactions in all limbs. Spinal reflexes were all normal, with increased muscle tone. Conscious pain perception was evaluated to be preserved. Pronounced upper cervical hyperaesthesia with intermittent opisthotonus was evident on neck palpation. Based on neurological findings, the lesion was localised to the C1-C5 spinal cord segments. Based on the clinical history and the calf’s age, the most likely differentials were considered to be trauma, anomaly or inflammation. Lateral cervical digital radiographs (Axiom Luminos dRF, Siemens Healthcare, Erlangen, Germany KV: 69,8, mAS: 25), identified a fractured odontoid process, which appeared to be still attached to the body of the atlas. However, dorsal dislocation of the C2 vertebral body was obvious (Figure 1). The remaining cervical vertebrae displayed no obvious radiographic abnormalities. Based on the radiographic findings our initial diagnosis was a traumatic odontoid process fracture. Instability and spinal cord compression at the fracture site were highly suspected due to the radiographic findings and neurological presentation. Therefore, surgical decompression, anatomical alignment, and stabilisation were favoured for our calf rather than conservative management (such as neck splinting). Potential surgical stabilisation was planned to be performed in collaboration with our small animal neurosurgeons located at the Clinic for Small Animal Surgery and Reproduction. Although the diagnosis of an odontoid process fracture was already established on radiographs, advanced diagnostic imaging was considered to allow better surgical planning and to screen for other traumatic lesions within the remaining cervical vertebrae (because it is reported that multiple vertebral lesions may occur in 5-10% of small animal trauma patients [19,20]). In addition, the owner requested advanced diagnostic imaging examination prior to a cost-consuming surgery to definitively exclude any concurrent and injury-predisposing congenital abnormality at the atlantooccipital region. In the case of a concurrent congenital atlantooccipital fusion, the calf’s owner would have denied any further treatment due to the condition’s potential heritability and associated limitation of future breeding uses. However, because of rapidly deteriorating neurological signs and respiratory distress during trailer transportation to the advanced diagnostic imaging and surgery sites (both located at the Clinic for Small Animal Surgery and Reproduction), the calf was euthanised. MRI and CT examinations were performed immediately post-mortem for scientific reasons. The MRI examination was performed using a 1.5 T magnetic resonance unit (Magnetom Symphony, Siemens Healthcare, Erlangen, Germany). The dead calf was positioned in sternal recumbency because this allowed positioning with only minor neck manipulation (compared with dorsal recumbency) and hence was assumed to lower the risk of artificial and manipulation-induced fracture dislocation; however, dorsal recumbency would have allowed closer contact between the area of interest and the table coils. T1-weighted (T1W; TR: 768, TE: 13), T2-weighted (T2W; TR: 3980, TE: 109) and short tau inversion recovery (STIR; TR: 5790, TE: 61, TI: 140) pulse sequences of the cervical vertebral column were obtained in the sagittal (T1W, T2W and STIR) and dorsal planes (STIR) with a slice thickness of 3 mm (STIR) and 2.5 mm (T1W and T2W). The MRI examination confirmed severe spinal cord compression at the level of the fracture site due to dorsal displacement of the C2 vertebral body and pronounced vertebral step misalignment (Figure 2). Cranial and caudal to the compression site, the spinal cord appeared swollen and exhibited a hyperintense intramedullary signal on the T2W-images and on the STIR-images, with mixed intensity (but predominantly hypointense appearance) on the T1W-images. Based on signal-pattern spinal cord oedema, intramedullary haemorrhage or myelomalacia were considered as potential differentials. A T2* gradient echo (T2*-GRE) sequence would have been helpful to further characterise this spinal cord T2W-hyperintensity but unfortunately was not performed. Dorsal to the compression site, the paravertebral musculature showed a focal area of T2-hyperintensity (with similar appearance on the STIR-images), which was supposed to be indicative of a dorsal traumatic event at this level. A post-mortem CT examination of the cervical vertebral column was performed with a 64-slice, helical CT scanner (Somatom Definition AS, Siemens Healthcare, Erlangen, Germany). Transverse images of the cervical vertebral column were acquired (64 x 0.6-mm detector collimation, 120 KVp, 120 ma, 1 sec rotation time and 512 x 512 reconstructed image matrix). A bone algorithm (B70s convolution Kernel) was used for reconstruction. CT images reflected MRI findings and furthermore identified the fracture site at the synchondrosis between the body of the axis and the odontoid process (Figure 3). The fracture line was directed in a dorsoventral oblique direction from the dorsal area of the odontoid process to the ventral aspect of the body of the axis. Additional findings were bony fragments at the ventral aspect of the fracture line. The degree of odontoid process displacement was calculated to be approximately 40%, employing the following formula used in young children with odontoid process synchondrosis fractures: Distance of maximum displacement of the fractured odontoid process (distance from the cortex of the odontoid to the outer cortex of the body of C2) divided by the anteroposterior diameter (equals the dorsoventral diameter in animals) of the odontoid [21]. Potential congenital malformations predisposing to atlantoaxial instability and other traumatic lesions of the remaining vertebrae were definitely ruled out by advanced diagnostic imaging examination and subsequent necropsy. In summary, this calf was diagnosed with a traumatic odontoid process synchondrosis fracture.Figure 1

Bottom Line: Advanced diagnostic imaging was considered to allow better planning of potential surgical stabilisation and to exclude any additional lesions of the cervical vertebral column.Advanced diagnostic imaging and post-mortem examination did not identify any other cervical lesion.This case report indicates that the odontoid process synchondrosis is a potential predisposed injury site and that traumatic odontoid process synchondrosis fractures should be considered as a potential differential in calves with acute cervical pain and/or signs of a cervical myelopathy.

View Article: PubMed Central - PubMed

Affiliation: Section of Neurology, Clinic of Small Animal Medicine at the Centre for Clinical Veterinary Medicine, Ludwig Maximilian University, Veterinärstr.13, 80539 Munich, Germany.

ABSTRACT
A 6-week-old female Simmental calf was evaluated for acute non-ambulatory tetraparesis. Physical and laboratory examinations revealed no clinically relevant abnormalities. Neurological findings were consistent with acute, progressive and painful cervical myelopathy. Radiographs displayed a fractured odontoid process (dens axis) and vertebral step misalignment at the fracture site. A traumatic origin was suspected. Advanced diagnostic imaging was considered to allow better planning of potential surgical stabilisation and to exclude any additional lesions of the cervical vertebral column. However, during trailer transportation to the advanced diagnostic imaging and surgery site, the calf deteriorated neurologically and was humanely euthanised. Magnetic resonance imaging (MRI) and computed tomography (CT) were performed immediately post-mortem for scientific reasons. The MRI examination reflected the radiographic findings and confirmed severe spinal cord compression at the fracture site. In addition, a T2W-hyperintense signal change within the paravertebral soft tissue dorsal to the fracture site was indicative of a traumatic event. CT identified the fracture site at the synchondrosis between the odontoid process and the body of the axis, and this finding was confirmed by post-mortem examination. Advanced diagnostic imaging and post-mortem examination did not identify any other cervical lesion. In summary, this calf was diagnosed with a traumatic odontoid process synchondrosis fracture, which has not been reported previously in calves but presents a challenging and well-known fracture type in young children. This case report indicates that the odontoid process synchondrosis is a potential predisposed injury site and that traumatic odontoid process synchondrosis fractures should be considered as a potential differential in calves with acute cervical pain and/or signs of a cervical myelopathy.

No MeSH data available.


Related in: MedlinePlus