Posterior occipitocervical reconstruction using cervical pedicle screws and plate-rod systems

STUDY DESIGN

This retrospective study was conducted to analyze the clinical results in 26 patients with lesions at the craniocervical junction that had been treated by occipitocervical reconstruction using pedicle screws in the cervical spine and occipitocervical rod systems.

OBJECTIVES

To evaluate the effectiveness of pedicle screw fixation in occipitocervical reconstructive surgery and to introduce surgical techniques.

SUMMARY OF BACKGROUND DATA

Many methods of occipitocervical reconstruction have been reported, but there have been no reports of occipitocervical reconstruction using pedicle screws and occipitocervical rod systems for reduction and fixation.

METHODS

Twenty-six patients with lesions at the craniocervical junction underwent reconstructive surgery using pedicle screws in the cervical spine and occipitocervical rod systems. The occipitocervical lesions were atlantoaxial subluxation associated with basilar invagination, which was caused by rheumatoid arthritis in 19 patients and other disorders in 7. The lowest cervical vertebra of fusion in 16 patients was C2, and the remaining 10 patients underwent fusion downward from C3 to C7. Flexion deformity of the occipitoatlantoaxial complex was corrected by application of extensional force, and upward migration of the odontoid process was reduced by application of combined force of extension and distraction between the occiput and the cervical pedicle screws.

RESULTS

Solid fusion was achieved in all patients except two with metastatic vertebral tumors who did not receive bone graft for fusion. Correction of malalignment at the craniocervical junction was adequate, and postoperative magnetic resonance imaging showed improvement of anterior compression of the medulla oblongata. There were no neurovascular complications of cervical pedicle screws.

CONCLUSIONS

Occipitocervical reconstruction by the combination of cervical pedicle screws and occipitocervical rod systems provided the high fusion rate and sufficient correction of malalignment in the occipitoatlantoaxial region. Results of this study showed the effectiveness of cervical pedicle screw as a fixation anchor for occipitocervical reconstruction.

Microsurgical anatomy of the transcondylar, supracondylar, and paracondylar extensions of the far-lateral approach

Despite a large number of reports of the use of the far-lateral approach, some of the basic detail that is important in safely completing this exposure has not been defined or remains poorly understood. The basic far-lateral exposure provides access for the following approaches: 1) the transcondylar approach directed through the occipital condyle or the adjoining portions of the occipital and atlantal condyles; 2) the supracondylar approach directed through the area above the occipital condyle; and 3) the paracondylar exposure directed through the area lateral to the occipital condyle. The transcondylar approach provides access to the lower clivus and premedullary area. The supracondylar approach provides access to the region of, and medial to, the hypoglossal canal and jugular tubercle. The paracondylar approach, which includes drilling of the jugular process of the occipital bone in the area lateral to the occipital condyle, provides access to the posterior portion of the jugular foramen and to the mastoid on the lateral side of the jugular foramen. In this study, the anatomy important to completing the far-lateral approach and these modifications was examined in 12 cadaveric specimens. In the standard posterior and posterolateral approaches, an understanding of the individual suboccipital muscles is not essential. However, these muscles provide important landmarks for the far-lateral approach and its modifications. Other important considerations include the relationship of the occipital condyle to the foramen magnum, hypoglossal canal, jugular tubercle, the jugular process of the occipital bone, the mastoid, and the facial canal. These and other relationships important to completing these exposures were examined in this study.

Patient Outcome at Long-term Follow-up after Aggressive Microsurgical Resection of Cranial Base Chordomas

OBJECTIVE:

In this study, we evaluated patients' clinical outcome and recurrence rates at long-term follow-up after aggressive microsurgical resection of cranial base chordomas.

METHODS:

Seventy-four patients with chordomas underwent operations during a 16-year period from 1988 to 2004. The philosophy was to perform complete resection whenever possible and to provide adjuvant radiotherapy for remnants. Staged operations were performed for extensive tumors or if a sizable tumor remnant was noted after the first resection. Patients included primary (previously untreated) and previously operated or irradiated cases. Information was prospectively gathered concerning the patients' neurological condition, Karnofsky Performance Scale score, and tumor status on magnetic resonance imaging scans.

RESULTS:

There were 47 primarily operated patients (63.5%) and 27 patients (36.5%) who had previously undergone surgery or radiotherapy. A total of 121 procedures were performed in 74 patients. The mean follow-up period was 96 months, with a range of 1 to 198 months. A single stage removal was performed in 41 (55.4%) of the patients and multiple stage removal was performed in 33 (44.5%) of the patients. Gross total removal was accomplished in 53 (71.6%) of the patients, and subtotal resection was accomplished in 21 (28.4%) of the patients. During the follow-up period, 24 (32%) of the patients had no evidence of disease, 37 (50%) of the patients were alive with evidence of disease, 11 (14.8%) of the patients died of disease, and two (2.7%) of the patients died of complications. Recurrence-free survival at 10 years was 31% for the whole group, 42% for the primarily operated patients, and 26% for the reoperation cases (P = 0.0001). The average Karnofsky Performance Scale score was 80 ± 11.7 preoperatively, 84 ± 8.9 at the 1-year follow-up, and 86 ± 12.8 at the last follow-up in surviving patients. No conclusion could be drawn regarding the value of radiotherapy because of the treatment philosophy and the small number of patients.

CONCLUSION:

Aggressive microsurgical resection of chordomas can be followed by long-term, tumor-free survival with good functional outcome. A more conservative strategy is recommended in reoperation cases, especially after previous radiotherapy, to reduce postoperative complications.

Atlantoaxial transarticular screw fixation: a review of surgical indications, fusion rate, complications, and lessons learned in 191 adult patients

OBJECT

In this, the first of two articles regarding C1-2 transarticular screw fixation, the authors assessed the rate of fusion, surgery-related complications, and lessons learned after C1-2 transarticular screw fixation in an adult patient series.

METHODS

The authors retrospectively reviewed 191 consecutive patients (107 women and 84 men; mean age 49.7 years, range 17-90 years) in whom at least one C1-2 transarticular screw was placed. Overall 353 transarticular screws were placed for trauma (85 patients), rheumatoid arthritis (63 patients), congenital anomaly (26 patients), os odontoideum (four patients), neoplasm (eight patients), and chronic cervical instability (five patients). Among these, 67 transarticular screws were placed in 36 patients as part of an occipitocervical construct. Seventeen patients had undergone 24 posterior C1-2 fusion attempts prior to referral. The mean follow-up period was 15.2 months (range 0.1-106.3 months). Fusion was achieved in 98% of cases followed to commencement of fusion or for at least 24 months. The mean duration until fusion was 9.5 months (range 3-48 months). Complications occurred in 32 patients. Most were minor; however, five patients suffered vertebral artery (VA) injury. One bilateral VA injury resulted in patient death. The others did not result in any permanent neurological sequelae.

CONCLUSIONS

Based on this series, the authors have learned important lessons that can improve outcomes and safety. These include techniques to improve screw-related patient positioning, development of optimal instrumentation, improved screw materials and design, and defining the role for stereotactic navigation. Atlantoaxial transarticular screw fixation is highly effective in achieving fusion, and the complication rate is low when performed by properly trained surgeons.

Endoscopic endonasal approach to the ventral cranio-cervical junction: anatomical study

OBJECTIVE

In order to develop an endoscopic endonasal approach to the ventral cranio-cervical junction and odontoid process under the concept of a minimally invasive surgical strategy, a cadaver study was performed.

METHODS

Sixteen artery-injected adult head specimens were used. Endonasal endoscopic approach was made through one- or two-nostril routes following the Jho's endonasal paraseptal technique. Rod-lens endoscopes, which were 2.7 or 4 mm in diameter, 18 cm in length with 0-, 30-, and 70-degree lenses, were used.

RESULTS

Surgical landmarks leading to the craniocervical junction were the inferior margin of the middle turbinate, nasopharynx and Eustachian tube. The nasopharynx was readily identified following the inferior margin of the middle turbinate. The line drawn between the Eustachian tubes indicated the juncture between the clivus and atlas. With a midline mucosal incision, the ventral cranio-cervical junction was exposed. Odontoid resection was performed with removal of the anterior arch of the atlas. Clival resection can be performed as much rostral as required. Maneuverability of the surgical instruments was better with a two-nostril technique than with a one-nostril. Although the entire midline clivus was accessible rostrally, C-2 was the caudal limit through this endonasal route. A suturing device needed to be developed for mucosal or dural closure for live operations.

CONCLUSION

This cadaver study demonstrates that an endoscopic endonasal approach to the ventral cranio-cervical junction and odontoid process can be a valid alternative to the conventional transoral approach.

Extreme lateral transcondylar approach: technical improvements and lessons learned

An extreme lateral transcondylar or extreme lateral transfacetal surgical approach was used to treat 22 patients with complex lesions over a 22-month period. The lesions included basilar invagination with vertebral artery pathology, giant aneurysm or arteriovenous fistula of the vertebral artery, meningioma, chordoma, chondrosarcoma, and paraganglioma. The approach was used alone or in combination with a presigmoid petrosal or subtemporal-infratemporal approach. Refinements of the operative technique, treatment strategies for complex lesions, and the avoidance of complications are discussed. Complications included cerebrospinal fluid leakage, meningitis, pseudomeningocele, hemiparesis or quadriparesis, lower cranial nerve deficits, and vertebral artery injury requiring repair. With treatment, major neurological deficits resolved completely in three patients and partially in two. There was no operative mortality, but four patients died during the follow-up period. For the 18 surviving patients, the mean preoperative and postoperative Karnofsky scores were 81 and 93, respectively. For the four who died, the mean preoperative Karnofsky score was 73 and the mean postoperative score was 63.

The jugular foramen: microsurgical anatomy and operative approaches

The jugular foramen, based on these studies of microsurgical anatomy, is divided into three compartments: two venous and a neural or intrajugular compartment. The venous compartments consist of a larger posterolateral venous channel, the sigmoid part, which receives the flow of the sigmoid sinus, and a smaller anteromedial venous channel, the petrosal part, which receives the drainage of the inferior petrosal sinus. The petrosal part forms a characteristic venous confluens by also receiving tributaries from the hypoglossal canal, petroclival fissure, and vertebral venous plexus. The petrosal part empties into the sigmoid part through an opening in the medial wall of the jugular bulb between the glossopharyngeal nerve anteriorly and the vagus and accessory nerves posteriorly. The intrajugular or neural part, through which the glossopharyngeal, vagus, and accessory nerves course, is located between the sigmoid and petrosal parts at the site of the intrajugular processes of the temporal and occipital bones, which are joined by a fibrous or osseous bridge. The glossopharyngeal, vagus, and accessory nerves penetrate the dura on the medial margin of the intrajugular process of the temporal bone to reach the medial wall of the internal jugular vein. The operative approaches, which access the foramen and adjacent areas and are demonstrated in a stepwise manner, are the postauricular transtemporal, retrosigmoid, extreme lateral transcondylar, and preauricular subtemporal-infratemporal approaches.

Atlantoaxial transarticular screw fixation: a review of surgical indications, fusion rate, complications, and lessons learned in 67 pediatric patients

OBJECT

In this, the second of two articles regarding C1-2 transarticular screw fixation, the authors discuss their surgical experience in treating patients 16 years of age and younger, detailing the rate of fusion, complication avoidance, and lessons learned in the pediatric population.

METHODS

The authors retrospectively reviewed 67 consecutive patients (23 girls and 44 boys) younger than 16 years of age in whom at least one C1-2 transarticular screw fixation procedure was performed. A total of 127 transarticular screws were placed in these 67 patients whose mean age at time of surgery was 9 years (range 1.7-16 years). The indications for surgery were trauma in 24 patients, os odontoideum in 22 patients, and congenital anomaly in 17 patients. Forty-four patients underwent atlantoaxial fusion and 23 patients underwent occipitocervical fusion. Two of the 67 patients underwent halo therapy postoperatively. All patients were followed for a minimum of 3 months. In all 67 patients successful fusion was achieved. Complications occurred in seven patients (10.4%), including two vertebral artery injuries.

CONCLUSIONS

The use of C1-2 transarticular screw fixation, combined with appropriate atlantoaxial and craniovertebral bone/graft constructs, resulted in a 100% fusion rate in a large consecutive series of pediatric patients. The risks of C1-2 transarticular screw fixation can be minimized in this population by undertaking careful patient selection and meticulous preoperative planning.

Statistical methods in finite element analysis

Finite element analysis (FEA) is a commonly used tool within many areas of engineering and can provide useful information in structural analysis of mechanical systems. However, most analyses within the field of biomechanics usually take no account either of the wide variation in material properties and geometry that may occur in natural tissues or manufacturing imperfections in synthetic materials. This paper discusses two different methods of incorporating uncertainty in FE models. The first, Taguchi's robust parameter design, uses orthogonal matrices to determine how to vary the parameters in a series of FE models, and provides information on the sensitivity of a model to input parameters. The second, probabilistic analysis, enables the distribution of a response variable to be determined from the distributions of the input variables. The methods are demonstrated using a simple example of an FE model of a beam that is assigned material properties and geometry over a range similar to an orthopaedic fixation plate. In addition to showing how each method may be used on its own, we also show how computational effort may be minimised by first identifying the most important input variables before determining the effects of imprecision.

Primary craniovertebral anomalies and the hindbrain herniation syndrome (Chiari I): data base analysis

This prospective study analyzes 100 patients with Chiari malformation and primary craniovertebral junction (CVJ) anomalies (3-66 years). Neurodiagnostic investigations employed tomography, gas myelography, CT and CT myelography, and MRI. Factors considered were reducibility, mode of encroachment, cerebrospinal fluid (CSF) dynamics and syringohydromyelia. Sixty-six patients with irreducible pathology underwent ventral or ventrolateral decompression and dorsal stabilization. Dorsal occipitocervical fixation was performed in reducible lesions that also required dorsal decompression (n = 34). Proatlas remnants were identified in 8 and atlas assimilation in 92 patients. Paramesial invagination was present in 20, syringohydromyelia in 46, and vertebral segmentation defects in 66 others. Completely reducible abnormalities were identified in 16 of 20 patients aged 2-14 years, and partially reducible abnormalities in 4 of 16 patients aged 14-20 years, 8 of 48 patients aged 20-40 years and 6 of 16 patients aged 40-60 years. The critical sagittal canal diameter at the foramen magnum was 19 mm. Twenty-two patients had previous posterior decompression and 27 had previous syrinx to subarachnoid shunt with delayed deterioration. Improvement occurred in all after ventral or ventrolateral decompression with resolution of the syringohydromyelia and normalization of CSF flow. We conclude that: (1) hindbrain herniation syndrome is frequently seen with fourth occipital sclerotome abnormalities; (2) Chiari malformation with craniovertebral abnormalities become symptomatic with a canal diameter of < 19 mm; (3) abnormal ventral bony pathology is reducible in children wit atlas assimilation and later becomes irreducible invagination, therefore early operation with fusion is recommended; (4) ventral decompression relieves brain stem, cerebellar symptoms and syringohydromyelia; (5) CSF studies with cine MRI shows reversal of craniospinal CSF dissociation after ventral CVJ decompression and; (6) craniovertebral anomalies associated with Chiari malformations must be addressed early and appropriately.

Lateral approaches to the petroclival region

The microsurgical anatomy that provides the basis for dealing with lesions arising in the petroclival region was reviewed in 15 adult cadaver heads and 25 dry skulls. The eight surgical approaches studied were the retrosigmoid, extreme lateral transcondylar, translabyrinthine, transcochlear, combined supra and infratentorial presigmoid, subtemporal anterior transpetrosal, subtemporal preauricular infratemporal, and the postauricular transtemporal approach. Considerations important in the selection of these approaches are discussed. Special attention was directed to the course of the facial nerve and internal carotid artery in the temporal bone and the major venous pathways draining the region.

Occipitocervical fusion with posterior plate and screw instrumentation. A long-term follow-up study

STUDY DESIGN

Thirty-two patients at one institution underwent occipitocervical fusions with posterior plate and screw instrumentation. The average follow-up was greater than 4 years (50 months).

METHODS

AO plates and screws were used and in more than 50% of the cases, the Magerl transarticular C1-C2 screw technique enhanced the occipitocervical instrumentation. In nine patients, cement was used and thus are excluded in evaluation of fusion results. All 23 patients attained solid fusions. No pseudarthrosis occurred. The average time to fusion was 13 weeks. Halos or traction immobilization was not used postoperatively. The average time of the simple orthosis wear was 11 weeks. Patients were out of bed on an average of the second postoperative day with a range of 1-4 days postoperatively. Reduction of the atlantoaxial joint was required in 10 of the 23 patients. At follow-up, nine remain reduced.

RESULTS

In one patient, the atlantodens interval approximated the preoperative distance and radiographs demonstrated one transarticular C1-C2 screw was not placed satisfactorily. The average operative time was 172 minutes, and the average blood loss was 956 cc. The neurologic status of the patients improved or remained the same. No patient deteriorated neurologically. A total of 78 occipital screws were placed. No complications resulted from any of these screws. One intraoperative complication occurred secondary to massive bleeding after a transarticular screw hole was drilled. Bone wax was placed over the drill hole and the bleeding ceased. No postoperative problems occurred in this patient. Most specifically, no central nervous system sequela was evident.

CONCLUSIONS

The conclusions from this study are that posterior occipitocervical fusion can be performed very safely with plate and screw instrumentation. An extremely high fusion rate can be expected with minimal complications and minimal postoperative immobilization. This technique, however, is technically demanding.

Reconstruction of craniofacial bone defects with individual alloplastic implants based on CAD/CAM-manipulated CT-data

Reconstruction of craniofacial bone defects by intraoperative modelling of autogenous or alloplastic materials may cause undesirable results concerning the implant shape or the long-term maintenance of this shape. Furthermore, the use of alloplastic materials to be modelled intraoperatively may result in an inflammatory tissue response. Therefore the question is raised whether CAD/CAM-techniques may be used for the pre-operative geometric modelling of the implant based on helical computed tomography data. A numerically based 3-dimensional model of the skull defect serves as the basis for a freeform-surfaces design of the implant shape, position and thickness, using modelling tools and programmes developed for industrial CAD/CAM. The precise and individual fit of the implant results from generating its margins by the borders of the defect, whereas the implant surface is generated by the geometry of the non-affected neighbouring bone contours. The implant data run a numerically controlled milling machine to fabricate the individual implant. The reconstruction of post-traumatic defects of the forehead, of post-surgical temporal defects after intracranial haemorrhage, and of a parieto-occipital defect due to ablative tumour surgery are presented as the first clinical experiences of this new method.

Quantitative description of the far-lateral transcondylar transtubercular approach to the foramen magnum and clivus

OBJECT

The purpose of this study was to evaluate the far-lateral transcondylar transtubercular approach (complete FLA) based on quantitative measurements of the exposure of the foramen magnum and petroclival area obtained after each successive step of this approach.

METHODS

The complete FLA was reproduced in eight specially prepared cadaveric heads (a total of 15 sides). The approach was divided into six steps: 1) C-1 hemilaminectomy and suboccipital craniectomy with unroofing of the sigmoid sinus (basic FLA); 2) partial resection of the occipital condyle (up to the hypoglossal canal); 3) removal of the jugular tuberculum; 4) mastoidectomy (limited to the labyrinth and the fallopian canal) and retraction of the sigmoid sinus; 5) resection of the lateral mass of C-1 with mobilization of the vertebral artery; and 6) resection of the remaining portion of the occipital condyle. After each successive step, a standard set of measurements was obtained using a frameless stereotactic device. The measurements were used to estimate two parameters: the size of the exposed petroclival area and the size of a spatial cone directed toward the anterior rim of the foramen magnum, which depicts the amount of surgical freedom available for manipulation of instruments. The initial basic FLA provided exposure of only 21 +/- 6% of the petroclival area that was exposed with the full, six-step maximally aggressive (complete) FLA. Likewise, only 18 +/- 9% of the final surgical freedom was obtained after the basic FLA was performed. Each subsequent step of the approach increased both petroclival exposure and surgical freedom. The most dramatic increase in petroclival exposure was noted after removal of the jugular tuberculum (71 +/- 12% of final exposure), whereas the least improvement in exposure occurred after the final step, which consisted of total condyle resection.

CONCLUSIONS

The complete FLA provides wide and sufficient exposure of the foramen magnum and lower to middle clivus. The complete FLA consists of several steps, each of which contributes to increasing petroclival exposure and surgical freedom. However, the FLA may be limited to the less aggressive steps, while still achieving significant exposure and surgical freedom. The choice of complete or basic FLA thus depends on the underlying pathological condition and the degree of exposure required for effective surgical treatment.

En bloc resection of multilevel cervical chordoma with C-2 involvement. Case report and description of operative technique

Chordomas are locally aggressive neoplasms with an extremely high propensity to recur locally following resection, despite adjuvant therapy. This biological behavior has led most authors to conclude that en bloc resection provides the best chance for the patient's prolonged disease-free survival and possible cure. The authors present a case of an extensive upper cervical chordoma treated by en bloc resection, reconstruction, and long-segment stabilization. Total spondylectomy of C2-4 with sacrifice of the right C2-4 nerve roots and a segment of the right vertebral artery was performed. The inherent anatomical complexities of en bloc resection in the upper cervical spine are discussed. To the authors' knowledge, this represents the first report of an en bloc resection for multi-level cervical chordoma.

An anatomic study of the thickness of the occipital bone. Implications for occipitocervical instrumentation

STUDY DESIGN

The authors measured the thickness and quality of occipital bone regions to determine screw placement during occipitocervical fusion and described the projection of the posterior dural venous sinuses.

OBJECTIVE

This study provides anatomic data relevant to areas of screw placement into the occiput during occipitocervical fixation.

SUMMARY OF BACKGROUND DATA

Few reports exist regarding the morphometrics of the occipital bone and intracranial structures relevant to occipitocervical fusion.

METHOD

The thickness of the posterior inferior occipital bone was measured relative to a 10 x 5 cm grid. Sections were evaluated grossly and histologically. The projections of the posterior dural venous sinuses were determined by direct measurements.

RESULTS

The maximum thickness of the occipital bone, which ranged from 11.5 to 15.1 mm in males and from 9.7 to 12.0 mm in females, was at the level of the external occipital protuberance. The occipital bone was thicker than 8 mm in an area extending laterally from the external occipital protuberance for 23 mm and consisted of dense cortical bone with little or no diploic bone. The projection of most of the torcula on the external surface of the occipital bone was located superior to the center of the external occipital protuberance (mean, 12.6 mm superior and 4.7 mm inferior to external occipital protuberance), whereas that of the transverse sinus was distributed more evenly above and below the external occipital protuberance (mean, 7.3 mm superior and 6.5 mm inferior).

CONCLUSIONS

Screws that are 8-mm long may be inserted in the region of the superior nuchal line (Level 0) extending 2 cm laterally from the center of the external occipital protuberance, 1 cm from the midline at a level 1 cm inferior to the external occipital protuberance (Level 1), and 0.5 cm from the midline at a level 2 cm inferior to the external occipital protuberance (Level 2). The major dural venous sinuses are situated immediately beneath the thickest regions of the occiput and are at risk of penetrative injury during screw placement.

Far-lateral approach to intradural lesions of the foramen magnum without resection of the occipital condyle

OBJECT

The goal of this study was to determine whether drilling out the occipital condyle facilitates surgery via the far-lateral approach by comparing data from 10 clinical cases with that from studies of eight cadaver heads.

METHODS

During the last 6 years at Louisiana State University Health Sciences Center-Shreveport, 10 patients underwent surgery via the far-lateral approach to the foramen magnum. Six of these patients harbored anterior foramen magnum meningiomas, one patient a dermoid cyst, two patients vertebral artery (VA) aneurysms, and an additional patient suffered from rheumatoid disease of the craniocervical junction. The surgical approach consisted of retromastoid craniectomy and C-1 laminectomy. The seven tumors and the pannus of rheumatoid disease were completely excised, and the two aneurysms were clipped without drilling the occipital condyle. In one patient a chronic subdural hematoma was found 3 months after surgery, but no patient displayed any complication associated with surgery. It is significant that in no patient was a cerebrospinal fluid leak present. All patients experienced improved neurological function postoperatively. To compare surgical visibility, eight cadaveric specimens (16 sides) were studied, including delineation of the VA and its segments around the craniocervical junction. Increase in visibility as a function of fractional removal of the occipital condyle was quantified by measuring the degrees of visibility gained by removing one third and one half of the occipital condyle. Removal of one third of the occipital condyle produced a mean increase of 15.9 degrees visibility, and removal of one half produced a mean increase of 19.9 degrees.

CONCLUSIONS

On the basis of their findings the authors conclude that removal of the occipital condyle is not necessary for the safe and complete resection of anterior intradural foramen magnum tumors.

The far lateral/combined supra- and infratentorial approach. A human cadaveric prosection model for routes of access to the petroclival region and ventral brain stem

A far lateral approach to the ventral brain stem, lower clivus, and anterior foramen magnum is described. Methods for further exposure of the superior petroclival region by incorporating a subtemporal craniotomy and posterior petrosectomy are also demonstrated. Eight sequentially illustrated steps depict this technique. The far lateral/combined supra- and infratentorial exposure is a comprehensive surgical approach that provides direct access to the entire anterior and lateral brain stem and craniovertebral junction. It minimizes brain-stem retraction and maximizes visualization of the neurovascular structures.

Reduction of rheumatoid periodontoid pannus following posterior occipito-cervical fusion visualised by magnetic resonance imaging

Nine patients (four females and five males) with chronic rheumatoid arthritis (RA) and atlanto-axial (AA) instability subjected to occipito-cervical fusion were evaluated clinically and radiologically. All of them had soft tissue formation (pannus) around the odontoid peg. The age ranged from 50 to 79 years (mean: 66). The duration of the RA disease was 3-48 years (mean: 18.5). All patients were seropositive. Both conventional radiography and magnetic resonance imaging (MR) were performed pre- and postoperatively. All fusions except one were stable. One patient was re-fused after 2 months because of wire break. With regard to pain all patients had improved and eight were pain free. Six patients who experienced signs of myelopathy prior to the fusion had improved at follow up. MR revealed reduction of pannus in all nine cases. This was obvious in one patient within 6 weeks postoperatively. The MR findings of a reduction or even disappearance of pannus following posterior fusion should decrease the need for transoral surgery.

Radiologic and clinical spectrum of occipital condyle fractures: retrospective review of 107 consecutive fractures in 95 patients

OBJECTIVE

We proposed to characterize the radiologic spectrum of occipital condyle fractures in a large series of patients and to correlate fracture pathology with neurosurgical treatment and patient outcome.

MATERIALS AND METHODS

We conducted a retrospective review of the findings on conventional radiography, CT, and MR imaging in 95 patients with 107 occipital condyle fractures. We described fracture patterns according to two previously published classification systems. Clinical findings, neurosurgical management, and patient outcome were obtained from the medical records.

RESULTS

Inferomedial avulsions (Anderson and Montesano type III) were the most common type of occipital condyle fracture, constituting 80 (75%) of 107 overall fractures. Unilateral occipital condyle fractures were found in 73 (77%) of 95 patients, and 58 patients were treated nonoperatively; occipitocervical fusion was required in nine patients for complex C1-C2 injuries, and six patients died. Bilateral occipital condyle fractures or occipitoatlantoaxial joint injuries were seen in 22 (23%) of 95 patients. Occipitocervical fusion or halo traction for the craniocervical junction was required in 12 patients, all of whom had CT evidence of bilateral occipitoatlantoaxial joint disruption and six of whom showed normal craniocervical relationships on conventional radiographs. Six patients with nondisplaced fractures were treated nonoperatively, and four patients died. Thirty (32%) of 95 patients showed continued disability, whereas 55 (57.5%) of 95 patients had good outcomes at 1 month. Associated cervical spine injuries were present in 29 (31%) of 95 patients.

CONCLUSION

Given their associated traumatic brain and cervical spine injuries, occipital condyle fractures are markers of high-energy traumas. That conventional radiographs alone may miss up to half of the patients with acute craniocervical instability has not been well established. Avulsion fracture type and fracture displacement are associated with both injury mechanism and the need for surgical stabilization. In this series, most unilateral occipital condyle fractures were treated nonoperatively, whereas bilateral occipitoatlantoaxial joint injuries with findings of instability usually required surgical stabilization.

Posterior skull surgery in craniosynostosis

In 1984, two young infants with unusual "clover-leaf" patterns of skull deformity were treated by posterior skull-releasing surgery that dramatically improved their overall skull shape, to the extent that further operative intervention was not required. This focused our attention on the posterior skull and its role in craniosynostosis. In cases of multi-suture craniosynostosis and craniofacial syndromes severely raised intracranial pressure is frequent, demanding early surgery. One of the problems identified with such surgery undertaken before 6 months of age is recurrent craniosynostosis needing later re-operation. This occurred in 15 (5%) of 275 patients treated between 1978 and 1994. Since 1986, in the presence of significant raised intracranial pressure it has been our policy to do an initial posterior skull release or decompression. This takes the pressure of the growing brain away from the orbits, allowing us to defer fronto-orbital advancement until the age of 12 months or later. Three patients managed in this way completely avoided anterior surgery, while in another 9 patients re-operation for recurrent anterior deformity has not been required. The exception to this policy has been the presence of severe exorbitism posing a threat to vision. Under these circumstances early fronto-orbital advancement is mandatory, and an additional posterior skull release may be helpful later. Debate continues especially on the management of unilateral lambdoid synostosis. The recent increase in positional posterior plagiocephaly. possibly related to supine nursing of newborns, has emphasised the need to differentiate between a fixed deformity, which might require surgical correction, and positional moulding of the occiput, which improves spontaneously. This paper reports our experience with 22 patients treated by posterior skull surgery, either alone or as an additional procedure, which we believe has a definitive role in the management of craniosynostosis.

The role of plate and screw fixation in occipitocervical fusion in rheumatoid arthritis

STUDY DESIGN

In a clinical retrospective study, the results of occipitocervical fusion in patients with rheumatoid arthritis were studied and analyzed.

OBJECTIVES

The results of two different operative techniques were compared. The advantages of screw fixation compared with wiring techniques in this population of patients were investigated.

SUMMARY OF BACKGROUND DATA

Numerous different implants have been presented in the literature for occipitocervical fusion in patients with rheumatoid arthritis. The use of wires being the standard fixation technique.

METHODS

Occipitocervical fusion was performed in patients with rheumatoid arthritis: 26 patients with the wiring technique and 33 patients with a new Y-plate fixation. The results were compared at a follow-up period of 24 months and 50 months, respectively. Clinical and radiologic results were investigated.

RESULTS

The atlantodental distance could be significantly better reduced in the group with the Y-plate fixation and the neurologic improvement in the wiring group was 40%, whereas in the Y-plate fixation 86% of neurologic improvement was observed. Pseudarthrosis was seen in 27% of the wiring technique and in 6% in the plate and screw fixation technique.

CONCLUSIONS

In occipitocervical fusion for patients with rheumatoid arthritis, the screw and plate fixation technique provides superior results than other techniques using wire fixations.

Occipitocervical fusion with rigid internal fixation: long-term follow-up data in 69 patients

Object.

Instability of the occipitocervical junction may result from degenerative disease, infection, tumor, and trauma. Surgical stabilization involving screw fixation and rigid implants has been found to be biomechanically superior to wire-based implants. To evaluate the long-term results in a large and diverse patient population, the authors prospectively studied a consecutive group of 69 patients.

Methods.

All patients underwent occipitocervical fusion in which rigid posterior instrumentation included either plates or rods and screws. Patients ranged in age from 11 to 90 years (mean 51.4 years); there were 34 female and 35 male patients. The mean follow-up duration was 37 months (range 6–66 months). Fifty-seven (83%) of the 69 patients had long-standing occipitocervical anomalies, whereas the remainder presented with acute instability. Basilar invagination was present in 20 patients.

Results.

Correction of a severe cervical kyphotic deformity was accomplished in six patients. There were no fatalities or medical complications associated with the procedures. During the follow-up period, 87% of the patients exhibited improvement in their myelopathic symptoms; in 13% the symptoms were unchanged. Complications were minimal. Stability was demonstrated on flexion/extension studies in all cases. There were no treatment-related deaths, although four patients died within the follow-up period, all due to progression of metastatic disease.

Conclusions.

The authors found that rigid internal fixation of the occipitocervical complex was safe, effective, and technically possible for spine surgeons familiar with occipital bone anatomy and lateral mass fixation.

Pain after surgery for acoustic neuroma

Postoperative pain after surgery in the cerebellopontine angle (CPA) is acknowledged to occur, but is rarely taken into account as a factor in the analysis of morbidity of such surgery. It is widely acknowledged that some patients, having undergone such surgery, particularly by means of the suboccipital approach, report significant post-operative pain and headache. This study was undertaken to determine the incidence and severity of pain after excision of acoustic neuromas and to establish whether this differed between the suboccipital and translabyrinthine routes. Ninety-one percent of all patients (n = 58), who had the suboccipital approach used for removal of their tumor, were surveyed. A smaller group (n = 40), matched for tumor size, age, and sex, but in whom the translabyrinthine approach was used, was similarly studied. A standard questionnaire, designed to detect and quantify postoperative pain, was administered to each patient. Of patients who underwent tumor excision by means of the suboccipital approach, 63.7% experienced significant local discomfort and headache, whereas this was notably absent in all those who had undergone translabyrinthine excision. In view of the significant morbidity noted to follow the suboccipital approach, several modifications of the surgical technique used were devised.