Case of Atlantoaxial Dislocation with Assimilated C1, Absent Posterior C2, Butterfly C3, and Fused Subaxial Cervical Spine: Management Dilemma with Multiple Segmentation and Formation Defects.

Segmentation defects are often seen with congenital atlantoaxial dislocation (AAD) though an associated absence of posterior arch of C2 and butterfly C3 is rare. Apart from rarity, the combination of formation and segmentation defects adds to the management dilemma. We report a case of AAD with assimilated atlas, absent C2 posterior arch, C3 butterfly vertebra with floating posterior elements, and fused C4-C6. The child was managed by C1-C2 fusion alone with immediate symptomatic improvement. The presence of formation defects such as adjacent butterfly vertebra and absent posterior elements does not alter the management of AAD. Fusing the C1-C2 joints appears to be a balanced approach.

Revisiting the differences between irreducible and reducible atlantoaxial dislocation in the era of direct posterior approach and C1-2 joint manipulation.

OBJECTIVE The current management of atlantoaxial dislocation (AAD) focuses on the C1-2 joints, commonly approached through a posterior route. The distinction between reducible AAD (RAAD) and irreducible AAD (IrAAD) seems to be less important in modern times. The roles of preoperative traction and dynamic radiographs are questionable. This study evaluated whether differentiating between the 2 groups is important in today's era. METHODS Ninety-six consecutive patients with congenital AAD (33 RAAD and 63 IrAAD), who underwent surgery through a posterior approach alone, were studied. The preoperative and follow-up clinical statuses for both groups were studied and compared using Japanese Orthopaedic Association (JOA) scores. The radiological findings of the 2 groups were compared, and the intraoperative challenges described. RESULTS A poor preoperative JOA score (clinical status) was seen in one-fifth of patients with IrAAD, although the mean JOA score was nearly similar in the RAAD and IrAAD groups. There was significant improvement in follow-up JOA score in both groups. However, segmentation defects (such as an assimilated arch of the atlas and C2-3 fusion) and anomalous vertebral arteries were found significantly more often in cases of IrAAD compared with those of RAAD. Os odontoideum was commonly seen in the RAAD group. The C1-2 joints were acute in IrAAD compared with RAAD. Preoperative traction in IrAAD resulted in vertical distraction and improvement in clinical and respiratory status. Surgery for IrAAD required much more drilling and manipulation of the C1-2 joints while safeguarding the anomalous vertebral artery. CONCLUSIONS Bony and vascular anomalies were much more common in patients with IrAAD, which made surgery more challenging than it was in RAAD despite similar approaches. An irreducible dislocation seen on preoperative radiographs made surgeons aware of difficulties that were likely to be encountered and helped them to better plan the surgery. Distraction achieved through preoperative traction reaffirmed the feasibility of intraoperative reduction. This made the differentiation between the 2 groups and the use of preoperative traction equally important.

Shattering the Rock: Technique of Bilateral Optic Nerve Mobilization and Drilling Heavily Calcified Craniopharyngiomas for Its Excision.

BACKGROUND: Resection of heavily calcified craniopharyngioma is quite challenging. The stretched optic nerves, perforators, and stalk are likely to be jeopardized further during attempts to break the calcified chunks, especially through narrow corridors. We describe a surgical technique to mobilize bilateral optic nerves and drill the calcified chunk to crumple it. METHODS: This technique was used in 6 patients with heavily calcified craniopharyngiomas (2 recurrent) who had presented with progressive visual loss. Frontotemporal craniotomy was used in 5 patients, and fronto-temporo-orbito-zygomatic craniotomy was used in 1 patient with a large retrosellar component. The Sylvian fissure was widely split. The bilateral optic canal was deroofed, and the falciform ligament was cut to mobilize both optic nerves. The calcified tumor could be dissected and mobilized into the widened corridor where the tumor was drilled. Multiple holes were drilled in the calcified chunk to shatter it to small pieces. These pieces were then dissected from perforators and stalk, while protecting them. RESULTS: Symptoms improved in all of the patients. Gross total excision could be achieved in 3 patients, near total excision in 2 patients (both recurrent), and subtotal excision in 1 patient (because of extensive skull base involvement). All of the patients had transient diabetes insipidus. Two patients who had preoperative hypopituitarism required long-term postoperative hormonal replacement. There were no approach-related complications. CONCLUSIONS: Mobilizing bilateral optic nerves improves the exposure and allows dissection of arachnoid from calcified craniopharyngiomas. Its drilling through widened corridors helps to shatter it. Using the technique, the neurovascular structures can possibly be better preserved while achieving maximal resection.

Redefining Congenital Atlantoaxial Dislocation: Objective Assessment in Each Plane Before and After Operation.

BACKGROUND: The C1-C2 joint has multiple degrees of freedom of movement and C1-C2 dislocation (AAD) is often multiplanar. The existing methodology to assess the dislocation is limited to few planes. The object of this study is to redefine and objectively assess congenital AAD in each possible plane, before and after the operation. METHODS: This study consisted of 95 patients of irreducible congenital AAD operated on with the posterior approach alone. Preoperative and postoperative computed tomography imaging was studied in the axial, coronal, and sagittal planes. The relationship of C1-C2 along with the C1-C2 joint inclination was studied in each plane. The extent and type of dislocation was objectively assessed in each plane (newer indices) and compared with follow-up imaging for correction. The preoperative and postoperative Japenese orthopaedics association scores were compared. RESULTS: The commonest variety (61 patients) was a combination of anteroposterior (AP) and vertical C1-C2 dislocation. Five patients had predominant APnteroposterior, 6 vertical, 4 axial rotational, 9 lateral angular tilt, and 3 had lateral transalational. Seven patients had a combination of dislocation in AP, vertical, and rotational planes. AP dislocation was seen with sagittal inclination of C1-C2 joints and vertical dislocation with coronal inclination. Asymmetry in the joint's sagittal inclination added to a rotational component, whereas asymmetry in the coronal angulation caused lateral angular tilt. Pure rotational or lateral translation dislocation had near-normal C1-C2 orientation. Preoperative Japenese orthopaedics association score was worst in the lateral tilt and the lateral translation. Correction in all planes was achieved in all patients. CONCLUSIONS: The objective assessment of C1-C2 dislocation and joints in each plane was to determine its management and help in achieving multiplanar correction.

Atlantoaxial dislocation adjacent to kyphotic deformity in a case of adult Larsen syndrome.

Kyphotic deformity is often seen in Larsen syndrome. However, its progress in adults is not clear. The adjacent level compression in these patients adds to the difficulty regarding the level that needs to be operated. A 56-year-old male presented with neck pain and spastic quadriplegia. Radiology showed kyphotic deformity (sequelae of Larsen syndrome) with atlantoaxial dislocation. Cord compression was apparent at both levels but careful evaluation showed C1-2 level compression and some compression below the kyphotic deformity. The kyphotic spine was already fused and the canal diameter was adequate. The adjacent level C1-2 was fused and he improved dramatically. Correction of long-standing kyphotic deformity may not be necessary, as it unlikely to progress because of its tendency to fuse naturally. Rather, the adjacent levels are likely to compress the cord due to excessive stress. A proper clinical history and a thorough radiological examination help the surgeon to make an appropriate decision.

Congenital C1-2 Lateral Translational Dislocation: Case Illustration with Pre- and Postoperative Imaging.

BACKGROUND: Congenital atlantoaxial dislocation has been commonly described in the antero-posterior or vertical plane (basilar invagination). However, dislocation in the lateral translational plane due to congenital deformity is rare. CASE REPORT: We present a case of a young male who presented with os odontoideum with C1-2 dislocation in the lateral plane along with antero-posterior dislocation. He was operated on through a midline posterior incision, and the C1-2 facet was manipulated so as to correct the dislocation in all planes. CONCLUSION: With os odontoideum, the C1-2 joints can exhibit movements that are out of the ordinary, even in the lateral translational plane. It suggests that the ligaments and joint capsule may weaken with time. Careful radiological evaluation helps in diagnosing this rare condition. An understanding of 3D facetal anatomy is important to achieve complete correction.

Comprehensive drilling of the C1-2 facets to achieve direct posterior reduction in irreducible atlantoaxial dislocation.

OBJECT: The cause of irreducibility in irreducible atlantoaxial dislocation (AAD) appears to be the orientation of the C1-2 facets. The current management strategies for irreducible AAD are directed at removing the cause of irreducibility followed by fusion, rather than transoral decompression and posterior fusion. The technique described in this paper addresses C1-2 facet mobilization by facetectomies to aid intraoperative manipulation. METHODS: Using this technique, reduction was achieved in 19 patients with congenital irreducible AAD treated between January 2011 and December 2013. The C1-2 joints were studied preoperatively, and particular attention was paid to the facet orientation. Intraoperatively, oblique C1-2 joints were opened widely, and extensive drilling of the facets was performed to make them close to flat and parallel to each other, converting an irreducible AAD to a reducible one. Anomalous vertebral arteries (VAs) were addressed appropriately. Further reduction was then achieved after vertical distraction and joint manipulation. RESULTS: Adequate facet drilling was achieved in all but 2 patients, due to VA injury in 1 patient and an acute sagittal angle operated on 2 years previously in the other patient. Complete reduction could be achieved in 17 patients and partial in the remaining 2. All patients showed clinical improvement. Two patients showed partial redislocation due to graft subsidence. The fusion rates were excellent. CONCLUSIONS: Comprehensive drilling of the C1-2 facets appears to be a logical and effective technique for achieving direct posterior reduction in irreducible AAD. The extensive drilling makes large surfaces raw, increasing fusion rates.