Evaluation of a freehand pedicle drilling tool for help in posterior pedicle screw placement

Abstracts / Surgical Neurology 68 (2007) 192–204 patients in whom delayed surgery was performed after dynamic x-rays and/ or magnetic resonance imaging (MRI) showed evidence for instability. Materials and methods: We collected the data of 5 patients who were recently admitted at the emergency department of our hospital after cervical spine injury. The following parameters were extracted from each patient file: mechanism and type of injury, initial diagnosis and management after plain x-rays and CT, time delay in diagnosis of instability, investigations leading to this diagnosis, and final management. Results: All 5 patients had a mild cervical trauma with no other important injuries and only neck pain. Plain x-rays and CT showed no clear abnormalities in 3 patients, a bilateral nondisplaced cervical facet fracture C5-C6 in 1 patient with Forestier disease and a slight angulation abnormality of the cervical lordosis in 1 patient. The time delay in the diagnosis of ligamentous instability varied between 2 and 6 weeks, and this diagnosis was achieved via MRI and dynamic x-rays in 3 patients, by dynamic x-rays alone in 1 patient, and by a new CT and dynamic x-rays of the cervical spine in the patient with Forestier disease. All patients received collar stabilization in the initial management and underwent delayed surgery consisting of an instrumented anterior cervical fusion in 1 or more levels using bone grafts. Conclusions: We retrospectively reviewed the records of 5 patients who were recently admitted to our hospital in which ligamentous instability was diagnosed by means of delayed dynamic x-rays and MRI, leading to instrumented anterior cervical fusion. We postulate that initial dynamic xrays and/or MRI should be part of the immediate management in cervical spine injury if no clear osseous or unstable injuries are diagnosed on plain xrays and CT, even in patients who complain only of neck pain. (A good article on the evaluation of neck injury with a message that dynamic imaging is necessary to rule out motion.—Ed) doi:10.1016/j.surneu.2007.06.041

Intraoperative MRI at 3.0 T: feasibility, safety, and preliminary results A. Jankovski, G. Vaz, E. Fomekong, T. Duprez, M.-A. Docquier, M. Van Boven, L. Hermoye, G. Cosnard, C. Raftopoulos Brussels We developed an intraoperative magnetic resonance imaging (iMRI) suite at 3.0 T allowing for the separate or combined use of the operating and MRI room. Both rooms were connected and a trail-guided surgical table slid the patient from the OR to the MRI room. Methods: We included the first 21 patients (glioma, 6; meningioma, 3; schwannoma, 1; pituitary adenoma, 3; intraventricular tumor, 2; metastasis, 3; epilepsy surgery, 3). Their average age was 50.8 years and the average weight was 11-105 kg. Each phase and unexpected event was recorded as well as their duration for the last 10 patients. Results: We performed 26 procedures subdivided into presurgical (n = 3), intrasurgical (n = 9), and postsurgical (n = 14) iMRI. The iMRI procedure took an average time of 77.8 minutes (range, 58-129 minutes) from the end of surgical closure until the restarting of surgery. Minor dysfunctions lengthened the iMRI procedure in 12 cases. Surgery was performed devoid of iMRI-linked constraints, and every planned iMRI could be achieved. No infection or accident due to iMRI occurred, and 2 cases of minor burn were observed. Three patients (1 glioma and 2 metastasis) benefited from a second surgical look, and 2 had a second intra- or postsurgical iMRI. Thus, complete tumor resection was achieved in 16 of 18 cases in which the goal of surgery was a total tumor removal. Five intraoperative iMRI interpretations were modified postoperatively (3 glioma, 1 metastasis, 1 pituitary adenoma). Control MRI of these 5 cases demonstrated that the postoperative interpretation of the iMRI was wrong in 3 cases. Conclusion: The iMRI procedure at 3.0 T is time consuming but proved to be a safe and reliable tool that allowed us to improve the extent of tumor resection in 3 of 21 cases. This technique appeared to be most useful and most difficult to interpret for glioma and metastasis surgery. doi:10.1016/j.surneu.2007.06.042

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Swing mandibula approach for C4 cervical somatotomy with mesh titanium cage and osteosynthesis in a patient with Klippel-Feil syndrome and basilar impression: case report and surgical technique G. Lesage, G. Michielsen, E. Fossion Antwerp Purpose: This study was conducted to report the swing mandibula operative technique in patients with anatomical anomalies of the upper cervical spine for an easy approach. Background: A 34-year-old patient underwent a cervical medullopathy because of cervical canal stenosis at level C3-C4. The patient was diagnosed with Klippel-Feil syndrome at levels C2-C3 and C5-C6, superior odontoid migration (basilar impression), and torsion of the cervical spine. Anatomically, a classical anterolateral approach was not possible. Therefore, a swing mandibula technique was used for good presentation of the affected level. Surgical technique: Through a submandibular incision, the inferior mandibular border was dissected. The masseter muscle and the parotid gland were elevated by subperiostal dissection up to the mandibular notch. The vertical ramus of the mandibula was visualized and a vertical split osteotomy was performed behind the alveolar canal. The osteotomized ramus was then elevated by flexion and the horizontal mandibula was retracted anteriorly, ensuring a complete approach to the anterior border of the cervical spine. The patient underwent a somatotomy of C3 via the use of a high-speed drill. The posterior longitudinal ligament was resected. Fusion was accomplished with a titanium mesh cage, filled with spongeous bone from the crista iliaca, and anterior plate osteosynthesis. The mandibula was repositioned with 2 L-shaped plates and the masseter muscles were sutured. Result: Postoperatively, the patient showed good recovery from pain symptoms, without sensory disturbances in mouth and lips and without dysphagia. Postoperative x-ray and CT scans revealed good positioning of the cervical osteosynthesis. Conclusion: The swing mandibula technique proves to be a very good approach to the upper cervical spine in elective cases, with excellent visualization of the anterior cervical spine. When performed in the most posterior part of the mandibula, the inferior alveolar nerve can be spared and hence, sensory disturbances can be avoided. doi:10.1016/j.surneu.2007.06.043

Evaluation of a freehand pedicle drilling tool for help in posterior pedicle screw placement A. Lubansu, A. Nzokou, B. Pirotte, N. Massager, F. Lefranc, J. Brotchi, O. Dewitte Brussels Introduction: Posterior pedicle screw fixation (PPSF) is an efficient technique of spinal instrumentation. Stability is dependent on the optimal positioning of the screws. We evaluated the effectiveness of a freehand electrical conductivity measuring and drilling device (PediGuard, SpineVision™) to prevent the misplacement of screws in PPSF. Methods: Between January 2005 and May 2006, 50 patients were treated by PPSF. After localization of the pedicle entry point, the Pediguard was used to find the right trajectory. During drilling, it analyzes the electrical conductivity of tissues at the tip and provides the surgeon with visual and audio feedback to discriminate cancellous bone, cortical bone, and soft tissues. The screws were then placed and controlled by fluoroscopy. Computed tomography scan was taken postoperatively to assess the screw position according to the Youkilis classification. Results: Thirty-two women and 18 men (mean age, 50 years) were treated (33 degenerative lesions, 11 fractures, 1 spinal tuberculosis, and 2 tumor diseases). A total of 271 screws were inserted from D4 to S1. On computed tomography scans, 261 (96.3%) screws were correctly placed, 10 (3.7%) screws were misplaced (4 grade III violations of lateral wall of pedicle, 3 grade II, and 3 grade I): 6 thoracic and 4 lumbar. No neurologic deficit was recorded.

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Abstracts / Surgical Neurology 68 (2007) 192–204

Discussion: Various misplacement rates (5.4%-40%) are reported in the literature. Some techniques (surgical navigation, electromography, SSEPs) aid to better choose the optimal trajectory, but no technique allows the detection of a pedicle breach in real-time. PediGuard is a freehand device that allows detection of pedicle wall violation with a sensitivity of 98%. Conclusion: PediGuard is easy to use (not requiring hardware and ancillary tools), helps to optimize the good positioning rate (96.3%) of the screws, and could help to reduce the amount of x-ray exposure during posterior pedicle screw fixation. doi:10.1016/j.surneu.2007.06.044

Myxopapillary ependymoma with extensive spinal and intracranial dissemination at diagnosis: an exceptional case report M. Moens, A. De Smedt, A. Michotte, B. Neyns, J. Sadones, T. Stadnik, J. D'Haens, C. Chaskis Brussels Myxopapillary ependymoma commonly affects the filum terminale. They are usually well-circumscribed lesions, making complete removal possible in most cases. Subarachnoidal seeding has been reported months or years after partial or subtotal resection, and more rarely infratentorial metastases. We report an exceptional case presenting with diffuse metastases along the spinal and intracranial subarachnoidal space from the sacral level up to the lateral sulci. This 25-year-old white man presented with a 2.5-month history of severe back pain when lying and dysesthesia in both legs. Neurologic examination showed only some fasciculations in both quadriceps muscles and was otherwise normal. Magnetic resonance imaging revealed numerous enhancing nodular lesions, measuring from 1 to 3 cm, scattered throughout the whole spinal cord, around the brainstem and in the sylvian sulci. We performed a dorsal laminectomy at D4 level because of severe spinal cord compression. Pathologic examination demonstrated a myxopapillary ependymoma. The patient made an uneventful postoperative recovery. Oral chemotherapy was started to avoid radiotherapy regarding the important tumor extent. Despite stable magnetic resonance imaging, the patient complained of increased back pain and bilateral leg dysesthesia after 2 cycles of temozolamide and was subsequently treated by radiation therapy. Myxopillary ependymoma is considered a benign tumor (WHO grade I) arising from the medullar conus and filum terminale involving the whole central nervous system. They may rarely be located extradurally at the sacral level, presumably from the coccygeal medullary vestige. Men are significantly more affected in contrast to the slight female predominance reported in intramedullary ependymoma. The tumor tends to grow slowly, without infiltration of the surrounding neural tissue with seldom metastasis. Intracranial seeding has been reported several months or years after subtotal or partial removal, but spontaneous intracranial seeding at diagnosis is extremely rare.

doi:10.1016/j.surneu.2007.06.045

Anterior subluxation—an unusual complication of arthroplasty A. Nzokou, A. Lubansu, C. Loqa, B. Pirotte, J. Brotchi, M. Levivier, O. Dewitte Brussels Introduction: Cervical arthroplasty is proposed by many authors as an alternative to anterior cervical interbody fusion in the treatment of cervical disk herniation. Its purpose is to maintain the segmental mobility and to prevent adjacent discopathies. Few complications are reported after this treatment. Heterotopic ossification and the spontaneous fusion of the prosthesis are the most frequently described complications. We report 4

cases of anterior subluxation of a porous coated motion (PCM) cervical prosthesis (Cervitech, Rockaway, NJ). Materials and methods: Between February 2005 and December 2005, 15 patients (7 women, 8 men; average age, 47.73 years; range, 27-70 years), underwent an operation for cervical disk herniation by arthroplasty using a PCM. The PCM is an unconstrained prosthesis placed after cervical discectomy. A clinical and radiographic follow-up was performed at 6 weeks, and 3, 6, 12, and 24 months after the operation. Results: Among the 15 patients, 2 had a clinical history of preliminary treatment of cervical disck herniation (1 on the same level, 1 on an adjacent level). Three patients had an operation on 2 levels. The operated level was C6-C7 in 10 cases, C5-C6 in 7 cases, and C4-C5 in 1 case. The average time of intervention was 112 minutes. A follow-up period ranging from 8 to 18 months (average, 15.8 months) was possible. Although no pre- or postoperative complication was observed, 4 patients showed an anterior subluxation of their prosthesis at 3, 9, and 12 months (2 cases). Only 3 cases required a surgical reoperation. Discussion: In a retrospective analysis of our cases, no preoperative factor of cervical hypermobility could be found. No sign of postoperative hypermobility could be described on follow-up x-rays. The only supporting factor noted was the systematic opening of the posterior longitudinal ligament. Conclusion: We reported an unusual complication of cervical arthroplasty that has occurred with unconstrained prosthesis. doi:10.1016/j.surneu.2007.06.046

Strict application of sterile technique for shunt placement reduces the shunt infection rate in children: a prospective series of 107 consecutive procedures with no postoperative infection B. Pirotte, A. Lubansu, N. Massager, F. Lefranc, M. Bruneau, N. Van Cutsem, C. Fricx, B. Byl, A. Vandesteene, J. Brotchi Brussels Introduction: Shunt infection may have devastating consequences, especially in young children. Microbial colonies can fix to the implanted materials during the shunt placement procedure even when we apply a skilful surgical technique. We evaluated whether the rigid application of shunt placement protocol allows the eradication of postoperative shunt infection. Methods: From 2001 to 2006 (minimal follow-up of 4 months), 94 consecutive children (46 girls/48 boys; 45 aged b1 year) with symptomatic hydrocephalus (secondary to tumor [30], ventricular hemorrhage [25], noninfectious obstruction [16], meningitis [7], trauma [5], open myelomeningocoele [5], idiopathic [5], arachnoid cyst [2]) underwent a ventriculoperitoneal shunt placement (Delta valve; Medtronic PS Medical, Goleta, CA, USA). Thirteen children underwent reoperation for shunt revision. All procedures (n = 107) were performed (n = 103) or closely supervised (n = 4) by the author. Protocol included intravenous perioperative antibiotics, avoidance of preoperative hair shaving and exposure of implants, scheduling operation in the morning, keeping doors closed and operating staff minimal, rigid adherence to classical aseptic technique, and operative duration of less than 30 minutes. Results: In all cases, the procedure could be scheduled as first morning operation within 3 days. However, in those requiring an emergency procedure (44/107), only 30 of 44 cases could be scheduled as first operation the next day. Actual application of the protocol was the main obstacle encountered. Technical recommendations were not strictly followed by nonsurgeon staff members (52/107 procedures performed with 6 persons in the room; doors opening during surgery in 62/107). Only 1 infection occurred, 6 months postoperatively, secondary to appendicitis with peritonitis. The infecting agent, Streptococcus faecalis, appeared to ascend from the abdominal cavity, and the fluid in the valve remained sterile. After peritonitis was cured, shunt reinsertion did not lead to further infection. Conclusion: This study shows that, although not consistently followed, a rigidly applied protocol and strict adherence to sterile technique can reduce