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Proatlas segmentation anomalies: Surgical management of five cases and review of the literature.

Muthukumar N - J Pediatr Neurosci (2016 Jan-Mar)

Bottom Line: CT of the cranioveretebral junction was the key to the diagnosis of this anomaly.All patients improved during follow up.Proatlas segmentation defects are rare anomalies of the craniovertebral junction.

View Article: PubMed Central - PubMed

Affiliation: Department of Neurosurgery, Madurai Medical College, Madurai, Tamil Nadu, India.

ABSTRACT

Objective: Proatlas segementation anomalies are due to defective re-segmentation of the proatlas sclerotome. These anomalies of the craniovertebral junction are rare and have multiple presentations. The aim of this study is to report this author's personal experience in managing five of these patients with different radiological findings necessitating different surgical strategies and to provide a brief review of the relevant literature.

Materials and methods: Five patients, all in the second decade of life were treated between 2010 and 2013. There were three males and two females. All the patients presented with spastic quadriparesis and/or cerebellar signs. Patients underwent plain radiographs, MRI and CT of the craniovertebral junction. CT of the cranioveretebral junction was the key to the diagnosis of this anomaly. Postoperatively, patients were assessed with plain radiographs and CT in all patients and MRI in one.

Results: Two patients underwent craniovertebral realignment with occipitocervical fixation, two patients underwent C1-C2 fixation using Goel-Harms technique and one patient underwent craniovertebral realignment with C1-C2 fixation using spacers in the atlanatoaxial joint and foramen magnum decompression. All patients improved during follow up.

Conclusions: Proatlas segmentation defects are rare anomalies of the craniovertebral junction. Routine use of thin section CT of the craniovertebral junction and an awareness of this entity and its multivarious presentations are necessary for clinicians dealing with abnormalities of the craniovertebral junction.

No MeSH data available.


Related in: MedlinePlus

Three-dimensional computed tomography of the craniovertebral junction showing the absence of the posterior arch on the left side with partial assimilation of the right half of the posterior arch on the right side (white arrow)
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Figure 2: Three-dimensional computed tomography of the craniovertebral junction showing the absence of the posterior arch on the left side with partial assimilation of the right half of the posterior arch on the right side (white arrow)

Mentions: A 19-year-old male presented with 6-month history of progressive difficulty in walking, clumsiness of both upper extremities, and occasional difficulty in swallowing. Examination revealed a moderately built individual with short neck and spastic quadriparesis. There were no cranial nerve palsies or cerebellar signs. Plain radiographs revealed completely assimilated anterior arch of atlas, partially assimilated posterior arch, and atlanto-axial subluxation [Figure 1a and b]. Magnetic resonance imaging (MRI) revealed features of basilar invagination, horizontally oriented clivus with features of ventral brainstem compression, and Chiari I malformation [Figure 1c]. CT of the craniovertebral junction revealed horizontally oriented clivus, basilar invagination, fused anterior arch of atlas, and an accessory ossicle interposed between the clivus and the dens [Figure 1d]. There was also an evidence of partial assimilation of the posterior arch of atlas which was present only on the right side [Figure 2]. On the basis of these radiological features, a diagnosis of basilar invagination with proatlas segmentation anomaly causing ventral brainstem compression was made. It was believed that the Chiari malformation encountered in this patient was the result of reduced posterior fossa volume induced by the above-mentioned abnormalities.[567] Hence, craniovertebral re-alignment by intraoperative traction and occipito-cervical fusion was planned. The patient was placed prone and intraoperative traction was applied with 5 kg. The posterior midline from the occiput up to the mid-cervical region was exposed, and occipito-cervical fusion was done using an occipital plate, C2 crossing translaminar screws, and lateral mass screws of C4 and C5. C3 lateral masses were skipped during screw placement as the lateral mass fractured during drilling. After intraoperative fluoroscopic verification of proper craniovertebral realignment, bone grafts were placed on the exposed bony areas after denuding them. Postoperatively, the patient experienced a significant reduction in spasticity. Postoperative plain radiographs and CT showed proper craniovertebral re-alignment [Figures 3 and 4].


Proatlas segmentation anomalies: Surgical management of five cases and review of the literature.

Muthukumar N - J Pediatr Neurosci (2016 Jan-Mar)

Three-dimensional computed tomography of the craniovertebral junction showing the absence of the posterior arch on the left side with partial assimilation of the right half of the posterior arch on the right side (white arrow)
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4862281&req=5

Figure 2: Three-dimensional computed tomography of the craniovertebral junction showing the absence of the posterior arch on the left side with partial assimilation of the right half of the posterior arch on the right side (white arrow)
Mentions: A 19-year-old male presented with 6-month history of progressive difficulty in walking, clumsiness of both upper extremities, and occasional difficulty in swallowing. Examination revealed a moderately built individual with short neck and spastic quadriparesis. There were no cranial nerve palsies or cerebellar signs. Plain radiographs revealed completely assimilated anterior arch of atlas, partially assimilated posterior arch, and atlanto-axial subluxation [Figure 1a and b]. Magnetic resonance imaging (MRI) revealed features of basilar invagination, horizontally oriented clivus with features of ventral brainstem compression, and Chiari I malformation [Figure 1c]. CT of the craniovertebral junction revealed horizontally oriented clivus, basilar invagination, fused anterior arch of atlas, and an accessory ossicle interposed between the clivus and the dens [Figure 1d]. There was also an evidence of partial assimilation of the posterior arch of atlas which was present only on the right side [Figure 2]. On the basis of these radiological features, a diagnosis of basilar invagination with proatlas segmentation anomaly causing ventral brainstem compression was made. It was believed that the Chiari malformation encountered in this patient was the result of reduced posterior fossa volume induced by the above-mentioned abnormalities.[567] Hence, craniovertebral re-alignment by intraoperative traction and occipito-cervical fusion was planned. The patient was placed prone and intraoperative traction was applied with 5 kg. The posterior midline from the occiput up to the mid-cervical region was exposed, and occipito-cervical fusion was done using an occipital plate, C2 crossing translaminar screws, and lateral mass screws of C4 and C5. C3 lateral masses were skipped during screw placement as the lateral mass fractured during drilling. After intraoperative fluoroscopic verification of proper craniovertebral realignment, bone grafts were placed on the exposed bony areas after denuding them. Postoperatively, the patient experienced a significant reduction in spasticity. Postoperative plain radiographs and CT showed proper craniovertebral re-alignment [Figures 3 and 4].

Bottom Line: CT of the cranioveretebral junction was the key to the diagnosis of this anomaly.All patients improved during follow up.Proatlas segmentation defects are rare anomalies of the craniovertebral junction.

View Article: PubMed Central - PubMed

Affiliation: Department of Neurosurgery, Madurai Medical College, Madurai, Tamil Nadu, India.

ABSTRACT

Objective: Proatlas segementation anomalies are due to defective re-segmentation of the proatlas sclerotome. These anomalies of the craniovertebral junction are rare and have multiple presentations. The aim of this study is to report this author's personal experience in managing five of these patients with different radiological findings necessitating different surgical strategies and to provide a brief review of the relevant literature.

Materials and methods: Five patients, all in the second decade of life were treated between 2010 and 2013. There were three males and two females. All the patients presented with spastic quadriparesis and/or cerebellar signs. Patients underwent plain radiographs, MRI and CT of the craniovertebral junction. CT of the cranioveretebral junction was the key to the diagnosis of this anomaly. Postoperatively, patients were assessed with plain radiographs and CT in all patients and MRI in one.

Results: Two patients underwent craniovertebral realignment with occipitocervical fixation, two patients underwent C1-C2 fixation using Goel-Harms technique and one patient underwent craniovertebral realignment with C1-C2 fixation using spacers in the atlanatoaxial joint and foramen magnum decompression. All patients improved during follow up.

Conclusions: Proatlas segmentation defects are rare anomalies of the craniovertebral junction. Routine use of thin section CT of the craniovertebral junction and an awareness of this entity and its multivarious presentations are necessary for clinicians dealing with abnormalities of the craniovertebral junction.

No MeSH data available.


Related in: MedlinePlus