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Curtis A. Dickman and Volker K. H. Sonntag

✓ Sixteen patients referred for atlantoaxial fixation failures were treated surgically with revision procedures during the past decade. Of these 16 patients, atlantoaxial instability occurred because of rheumatoid arthritis in five, os odontoideum in seven, transverse ligament disruption in two, and odontoid fracture nonunion in two. The 16 individuals (10 men, six women; mean age 43.7 years; age range 20–77 years) had undergone a total of 20 C1–2 internal fixation procedures that failed.

Surgical strategies for definitive revision of the nonunions in these 16 subjects included 10 rigid internal fixations with transarticular screws, three revised C1–2 fixations with autogenous bone struts and wire or cables, and three extended fixations with occipitocervical instrumentation. Autogenous grafts were used in all revisions. A postoperative halo brace was used in five individuals with osteoporotic bone; all patients wore a restrictive postoperative cervical orthosis.

Postoperatively, 15 patients (94%) had a stable construct (mean follow up 35 months; range 12–79 months), which included 13 osseous unions and two stable fibrous unions. One patient had nonunion; he fractured his anterior C1–2 transarticular screws 2 years postoperatively. He had occipital radicular pain without myelopathy but refused further surgery.

Atlantoaxial pseudarthroses were effectively treated by addressing the pathological, biomechanical, and technical reasons for failed fusion. Successful fusion after reoperation was improved by using autologous bone grafts, adequately controlling atlantoaxial motion (with rigid transarticular screws internally or externally with a halo vest), compressing the bone grafts between the arches of C-1 and C-2 with wire cables, meticulously preparing the fusion bed, and by optimizing the pharmacological and clinical parameters to promote bone healing.

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James M. Herman and Volker K. H. Sonntag

✓ Between 1987 and 1991, 20 patients with symptomatic postlaminectomy kyphosis were treated with anterior decompression, bone graft, and anterior cervical plate. The patients were predominantly male (14:6) with a mean age of 58 years. The initial laminectomy was performed for either spondylosis (80%) or spinal tumor (20%). All patients had anterior compressive pathology, which was associated with instability (45%), neck pain (75%), myeloradiculopathy (90%), or severe neck deformity (30%). The mean degree of kyphosis was 38°. Treatment consisted of a trial of cervical traction (75%), anterior corpectomy (95%), intersegmental decompression (5%), bone fusion (100%), and fixation with either Caspar (85%) or Synthes (15%) anterior plating at a mean of 3.8 levels. Halo fixation was used in 10% of patients. Postoperative complications included vocal cord paresis (15%), pneumonia (10%), wound dehiscence (5%), and screw pull-out (5%). At follow-up evaluation, a mean of 28 months after treatment, all patients had a solid fusion and a mean curvature improvement to 16° residual kyphosis. Neurologically, 10% were cured, 55% were improved and returned to premorbid function, 30% were stable, and 5% had late progression. These data suggest that immediate fixation with anterior plating facilitates solid fusion, maintains spinal curvature, and promotes neurological improvement.

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David I. Levy and Volker K. H. Sonntag

✓ Spinal dural lacerations can be a difficult part of spinal surgery. A dural tear can result in complications that include meningitis and pseudocyst formation. Appropriate treatment for these tears is generally suturing, using 4.0, 5.0, or 6.0 suture. For successful closure of dural lacerations, the authors have collaborated in the design of a titanium clip, which resembles an aneurysm clip in appearance and is applied with standard aneurysm clip appliers. The titanium clip was tested against suture and Weck hemostatic vascular clips and found to have excellent tissue-approximating capacity and a rapid application time. It is believed that this is an appropriate device for the repair of spinal dural lacerations.

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Mark G. Burnett and Volker K. H. Sonntag

✓ Decisions regarding the return of injured athletes to contact sports after spinal surgery can be complicated. The authors offer a brief overview of the return-to-play guidelines used successfully at their institution for the past two decades when caring for professional and amateur athletes after spinal surgery.

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Volker K. H. Sonntag and Bennett M. Stein

✓ A review of arteriopathic complications in three of seven patients receiving epsilon-aminocaproic acid (EACA) is presented. All seven patients with subarachnoid hemorrhage due to ruptured aneurysm were receiving EACA in the presurgical treatment period. Each of the three patients showed cerebral arteriographic changes resembling arteritis or intravascular thrombosis, and a deteriorating clinical course.

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The transoral approach to the superior cervical spine

A review of 53 cases of extradural cervicomedullary compression

Mark N. Hadley, Robert F. Spetzler and Volker K. H. Sonntag

✓ The transoral-transclival surgical approach is the most direct operative approach to pathology ventral to the brain stem and superior spinal cord. In selected patients, this approach is efficacious in the treatment of extradural compressive lesions from the cervicomedullary junction to the C-4 vertebra.

The authors have used the transoral surgical approach in treating 53 patients with lesions compressing the ventral extradural brain stem or the cervical cord. The evaluation, management, and long-term outcome of these patients are described (median follow-up time 24 months). The operative morbidity rate in this series was 6%, and the operative mortality rate was zero. The authors review specific features of the transoral procedure, including methods of retraction, microsurgical techniques, and adjunctive measures to avoid cerebrospinal fluid fistulae, that contributed to these good results.

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Christopher G. Paramore, Curtis A. Dickman and Volker K. H. Sonntag

✓ Although they are excellent clinical tools, Caspar anterior cervical plates have not been studied closely with regard to their mechanisms of failure. As more extensive operations are contemplated on older, sicker patients, it is imperative to know when a plating system might be prone to failure and what the mechanism of that failure might be. Therefore, the authors reviewed 49 patients undergoing Caspar plate placement in whom sufficient radiographs were obtained to determine if the fate of the hardware was related to the patient's age, type of operation, and the length of construct. Eleven of 49 patients suffered hardware failure, defined as any amount of screw backout or breakage, plate pullout, or pseudarthrosis. Four patients underwent hardware removal; one underwent posterior fusion for pseudarthrosis. Only two required treatment in a halo brace. There was an eventual fusion rate of 100%, including one fibrous union, and one of the patients who underwent repeat surgery was lost to follow-up review. No graft extrusions or new neurological deficits were incurred as a result of hardware failure. Plate length predicted plate failure in a statistically significant manner. Increasing age and reoperation correlated with plate failure but were not statistically significant in this small number of patients. Telescoping of the bone graft and vertebral bodies, with concomitant migration of the plate and slippage of the screws, was common. However, telescoping was more profound in the group in which the plates failed. The authors conclude that Caspar plate failures are more likely to occur in the elderly and in patients who need longer constructs. Bone fusion can be expected even when the hardware loosens.

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Christopher G. Paramore, Curtis A. Dickman and Volker K. H. Sonntag

✓ Posterior transarticular screw fixation of the C1–2 complex has become an accepted method of rigid internal fixation for patients requiring posterior C1–2 fusion. The principal limitation of this procedure is the location of the vertebral artery, because an anomalous position may prohibit screw placement. In this study, a consecutive series of computerized tomography (CT) scans was reviewed, and the suitability of each patient for transarticular screw fixation was evaluated.

All of the fine-slice axial C1–2 CT scans and reconstructions performed on a spiral scanner over 2 years were reviewed. A novel screw trajectory reconstruction was designed to visualize the potential path of a transarticular screw in the plane of the reconstruction. Scans were reviewed for bone anatomy and the position of the transverse foramen.

Seventeen (18%) of 94 patients had a high-riding transverse foramen on at least one side of the C-2 vertebra that would prohibit the placement of transarticular screws. The left side was involved in nine patients and the right in five. Three patients had bilateral anomalies. The mean age of the group with anomalies (35.9 years, range 10–76) was not significantly different from the overall mean age (35.7 years, range 6–94). An additional five patients (5%) were considered to have anatomy in which screw placement was feasible but risky. On the basis of these data, it is postulated that 18% to 23% of patients may not be suitable candidates for posterior C1–2 transarticular screw fixation on at least one side.

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Richard M. Westmark, Kaye D. Westmark and Volker K. H. Sonntag

✓ The authors report the case of a 48-year-old woman who experienced spontaneous resolution of a large herniated disc at C6–7. Spontaneous resolution of a herniated lumbar disc was first documented by computerized tomography. This case is another example of a rare spontaneous resolution of a cervical disc herniation documented by magnetic resonance imaging.

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Dean Chou, Roger Hartl and Volker K. H. Sonntag

✓ Conus medullaris injury from burst fractures is known to occur in conjunction with other neurological deficits, including lower-extremity motor weakness or sensory changes. Rarely does an isolated conus medullaris injury occur from an extradural cause without other neurological deficits. The authors report four cases of L-1 burst fractures in which conus medullaris dysfunction was the sole neurological injury in the absence of lower-extremity involvement.