Christopher Brenke

Pseudohypoxic brain swelling: a newly defined complication after uneventful brain surgery, probably related to suction drainage.

OBJECTIVEThis is the first description of a severe and sometimes fatal complication after uneventful intracranial surgery. The clinical presentation and imaging features mimic those of global cerebral hypoxia. Extensive investigations were performed to discover the pathogenesis. METHODSSeventeen cases of pseudohypoxic brain swelling (PHBS) were collected from our institution and from various other neurosurgical departments and were studied for common features. PHBS can occur in a mild, moderate, or severe degree. It is characterized by a very early postoperative onset of clinical deterioration (clouded or lost consciousness and pupillary abnormalities), in association with typical bilateral computed tomographic or magnetic resonance imaging changes (hypodensities or altered intensities in the basal ganglia and/or thalamus). The following variables were considered: age, primary pathological lesion and intracranial location, previous cranial surgery, anesthetic risk, type of anesthesia, approach and duration of surgery, intraoperative observations, technical monitoring results, and blood gas analyses. The results of postoperative computed tomography and various other imaging studies, intracranial pressure measurements, transcranial Doppler sonography, toxicological analyses, brain and muscle biopsies, and autopsies were also considered in the investigation. Several countermeasures were instituted and evaluated. RESULTSAnoxemic and ischemic hypoxia was excluded as a cause of PHBS. No evidence was found for inhibition of the respiratory chain, mitochondriopathy, poisoning, or adverse effects of drugs. CONCLUSIONIndications of intracranial hypotension, induced by suction drainage, being the main pathomechanism of PHBS are discussed. A serious warning is issued regarding the use of suction drainage after intracranial surgery.

Non-fusion rates in anterior cervical discectomy and implantation of empty polyetheretherketone cages.

Study Design. A prospective analysis. Objective. Our aim was to assess the radiographically detectable bony fusion in patients with anterior cervical discectomy (ACD) and polyetheretherketone (PEEK)-cage implantation without additional filling. Furthermore, clinical data of patients with and without fusion were compared. Summary of Background Data. PEEK-cage implantation is performed in cervical spinal surgery because of its benefits. However, fusion rates without filling of the cage have not been reported. Methods. Patients selected for ACD with PEEK-cage implantation prospectively underwent plain radiography in anterior-posterior and lateral projections during the postoperative hospital stay and at follow-up. Furthermore, clinical status was evaluated using the Odom scale, the Short Form-36, the Visual Analog Scale (VAS) for arm and neck pain, and the cervical Oswestry score. Fusion status, migration, and subsidence of the PEEK cage were evaluated on the basis of the lateral radiographs. Fusion was confirmed by presence of continuous trabecular bone bridges in the disc space. To exclude an influence of the cage on the evaluation of fusion rates, fusion was evaluated in analogous fashion retrospectively in a control group. Results. A total of 52 patients underwent ACD and interbody fusion. One-level surgery was performed in 44 patients and 2-level surgery in 8 patients. A total of 60 ACD and interbody fusions with a PEEK cage were analyzed. A majority of operations were at the C5/6 level (40 patients, 77%). Cage height was 4 mm in 32 cases, 5 mm in 23 cases, and 6 mm in 5 cases. Bony fusion was present at 43 treated levels (71.7%), whereas at 17 levels (28.3%) no fusion was found. Statistical analysis revealed no significant difference between the fusion and non-fusion groups regarding time to follow-up, implanted cage height. Short Form-36, cervical Oswestry score, VAS arm and neck, or Odom criteria. In the control group, ACD was performed in 29 patients (42 levels; 18 one-level and 12 two-level operations). Bony fusion was present at 30 levels (71.4%), whereas non-fusion was present at 12 treated levels (28.6%). Statistically analysis revealed no significant difference between the study group and the control group regarding time to follow-up or fusion rates. Conclusion. Implantation of empty PEEK cages after ACD shows an unexpectedly low rate effusion according to radiologic criteria, although no statistically significant difference could be observed clinically.

High prevalence of heterotopic ossification after cervical disc arthroplasty: outcome and intraoperative findings following explantation of 22 cervical disc prostheses

OBJECT Cervical disc arthroplasty (CDA) has been increasingly used for the treatment of cervical disc herniations. However, the impact of CDA on adjacent-segment degeneration and the degree of heterotopic ossification (HO) of the treated segment remain a subject of controversy. Due to a product failure of the Galileo-type disc prosthesis, 22 of these devices were explanted. The radiological and clinical course in each case was investigated in detail with an emphasis on the incidence of HO and facet joint degeneration 18 months following the operation. Intraoperative findings regarding ossification and implant fixation were documented. Thus, the authors were able to describe the true rate of adjacent-segment degeneration and HO following CDA and the clinical relevance thereof. METHODS In all 22 patients, functional radiographic imaging was performed prior to surgery, 3 and 12 months after surgery, and prior to disc prosthesis explantation. At all time points, the range of motion (ROM) in the operated and adjacent segments was determined. A motion index was calculated using the preoperative and all postoperative ROMs (preoperative ROM/postoperative ROM). Computed tomography was used preoperatively to measure the height of the index segment, extent of HO, and the degree of the progression of facet arthrosis, and was used postoperatively prior to prosthesis explantation. Patients completed clinical questionnaires that included a visual analog scale and the Neck Disability Index. RESULTS The motion index of the index segment declined gradually from 1.4 at 3 months postoperative to 1.2 prior to explantation, while the motion index of the adjacent upper segment increased from 0.9 to 1.3. The mean ROM of the index segment was 10.4° ± 6.7°, and fusion was observed in 2 (9%) of the 22 patients. Prosthesis migration was present in 3 patients (13.6%). Severe HO (Grades 3 and 4) was present in 17.4%. Computed tomography showed a significant increase of segmental height of the index segment (1.6 ± 1.1 mm, p = 0.035), and a significant increase of left-sided lateral osteophytes (1.7 ± 2.1 mm, p = 0.009). The incidence of severe osteophyte formation (> 2 mm) occurred in 40%. Intraoperative findings reflected the results from CT, with primary lateral proliferation of osteophytes found in approximately 25% of patients. The mean visual analog scale scores were 3.8 ± 2.7 (neck) and 2.4 ± 2.5 (arms), and the mean Neck Disability Index score was 30 ± 22. No correlation was found between radiological and clinical parameters. CONCLUSIONS In this study, a higher incidence of HO after CDA could be demonstrated using CT, compared with studies using fluoroscopy only. However, patient selection and/or the operative technique might have contributed to the high prevalence of osteophyte formation. Thus, the exact indication for CDA has to be reconsidered. Because implant migration was detected, using fixation in the present CDA model appears suboptimal.

Short-term experience with a new absorbable composite cage (β-tricalcium phosphate-polylactic acid) in patients after stand-alone anterior cervical discectomy and fusion.

Study Design. Prospective clinical single center series with 50 patients to include, with planned follow-up intervals at 3 and 12 months postoperative. Objective. Absorbable cages were developed with the purpose to enhance fusion rates and to reduce the rate of cage subsidence. The gradual increase of load transfer during cage degradation facilitates new bone formation, which possibly leads to higher arthrodesis rates. Summary of Background Data. Absorbable cages consisting of a mixture of polylactic and polyglycolic acid (PLLA–PGLA) or poly (L-lactide-co-D, L-lactide) experimentally showed disappointing results with formation of cartilage and fibrous tissue components, which was much less pronounced using composite cages consisting of a polymer and calciumphosphate. Methods. Patients showing degenerative cervical mono- or bi-level pathology were prospectively included. Using anteroposterior and lateral radiographs, segmental height of the treated segments was determined quantitatively. Cage characteristics were described qualitatively. Clinical data such as the Neck Disability Index, pain severity on the visual analogue scale were collected at all time points separately for neck and arm. Results. A total of 33 patients were included, with a mean age of 51.9 ± 9 years. As cage dislocations occurred in 4 out of 33 patients (12.1%), the study was prematurely discontinued. All patients with cage dislocations were surgically revised. Clinical outcome of the remaining patients showed significant improvement of visual analogue scale neck pain from 6.0 ± 2.5 to 2.8 ± 2.3 (P < 0.005), visual analogue scale arm pain from 5.3 ± 2.7 to 1.6 ± 1.6 (P < 0.005), and Neck Disability Index from 21.2 ± 8.6 to 12.5 ± 9.6 (P < 0.005) after surgery. Conclusion. Because of the high rate of cage dislocations, the use of the present composite cage cannot be recommended as a stand-alone device unless implant fixation will not be improved significantly. Evaluation of clinical and radiological long-term effects is essential to estimate the potential benefit of composite cages. Level of Evidence: 2

Surgical Management of Basilar Artery Laceration Caused by Transorbital Penetrating Injury: Case Report

Transorbital penetrating injuries are rare and present with a heterogeneity of intracranial injury patterns that require individualized therapeutic procedures. In this report, we describe the case of a distal basilar artery laceration in a 16-month-old boy caused by accidental transorbital penetration with a pencil. Surgical removal of the pencil was performed, but hemostasis could only be achieved by clipping the impaired vessel. Adequate diagnostics and an individualized surgical strategy are necessary to deal with these life-threatening injuries.

Posterior Cervical Foraminotomy

In the cervical spine, neural impingement can occur in two main locations: within the spinal canal, affecting the spinal cord, the nerve root(s), or both, or within the neuro foramen, where the exiting root can be affected. Cervical radiculopathy (CR) is the condition where one or two nerve roots are mechanically compressed. Degenerative disorders like cervical soft disk herniation, osteochondrotic bone spurs with consecutive foraminal stenosis, or a combination of both are the most common causes.

In vitro flexibility of the cervical spine after ventral uncoforaminotomy : Laboratory investigation

OBJECT Degenerative spine disorders are, in the majority of cases, treated with ventral discectomy followed by fusion (also known as anterior cervical discectomy and fusion). Currently, nonfusion strategies are gaining broader acceptance. The introduction of cervical disc prosthetic devices was a natural consequence of this development. Jho proposed anterior uncoforaminotomy as an alternative motion-preserving procedure at the cervical spine. The clinical results in the literature are controversial, with one focus of disagreement being the impact of the procedure on stability. The aim of this study was to address the changes in spinal stability after uncoforaminotomy. METHODS Six spinal motion segments derived from three fresh-frozen human cervical spine specimens (C2-7) were tested. The donors were two men whose ages at death were 59 and 80 years and one woman whose age was 80 years. Bone mineral density in C-3 ranged from 155 to 175 mg/cm3. The lower part of the segment was rigidly fixed in the spine tester, whereas the upper part was fixed in gimbals with integrated stepper motors. Pure moment loads of +/- 2.5 Nm were applied in flexion/extension, axial rotation, and lateral bending. For each specimen a load-deformation curve, the range of motion (ROM), and the neutral zone (NZ) for negative and positive directions of motion were calculated. Median, maximum, and minimum values were calculated for the six segments and normalized to the intact segment. Tests were done on the intact segment, after unilateral uncoforaminotomy, and after bilateral uncoforaminotomy. RESULTS In lateral bending a strong increase in ROM and NZ was detectable after unilateral uncoforaminotomy on the right side. Overall, the ROM during flexion/extension was less influenced after uncoforaminotomy. The ROM and NZ during axial rotation to the left increased strongly after right unilateral uncoforaminotomy. Changes after bilateral uncoforaminotomy were marked during axial rotation to both sides. CONCLUSIONS Following unilateral uncoforaminotomy, a significant alteration in mobility of the segment is found, especially during lateral bending and axial rotation. The resulting increase in mobility is less pronounced during flexion and least evident on extension. Further investigations of the natural course of disc degeneration and the impact on mobility after uncoforaminotomy are needed.

One-step CAD/CAM titanium cranioplasty after drilling template-assisted resection of intraosseous skull base meningioma: technical note

IntroductionCranial defects following intra-osseous tumor removal may be large and require adequate reconstruction. CAD/CAM implants have been used for years to achieve an optimal cosmetic result. The disadvantage is that such implants require a second surgery. A preoperative virtual planning of resection margins and the simultaneously fabrication of the cranioplasty could be a possibility to subsume the steps tumor resection and cosmetic restoration to a single procedure.MethodsWe present two cases of patients with complex intra-osseous spheno-orbital meningioma. Tumor resection was performed with the help of a drilling template in form of a frame. The template also served as a negative for the computer-designed cranioplasty. The devices were manufactured by DMD GmbH – Digital Medical Design/DDI-Group, Dortmund, Germany.DiscussionThe usage of the template was highly practicable. Small adjustments in bone removal were necessary to achieve an optimal fitting of the implant. The 6-month follow-up showed for one patient a good and for one a satisfactory cosmetic result. No second surgery was necessary.ConclusionsDrilling template application could contribute to challenging cases of large fronto-basal meningiomas with the aim of minimizing operation time and achieving a good esthetic outcome.

Core herniation after implantation of a cervical artificial disc: case report

IntroductionCervical artificial discs (CADs) represent an established surgical option in selected patients with cervical spinal disc degeneration. Though CADs have been available for many years, there is a lack of information concerning long-term safety, durability and implant-related failure rates.Materials and methodsThe authors describe the failure of a M6-C CAD (Spinal Kinetics, Sunnyvale, CA, USA).ResultsEight years after implantation of a CAD of the M6 type, a 39-year-old female presented with new clinical signs of cervical myelopathy. Radiologically, medullar compression due to posterior core herniation was the suspected cause. The damaged CAD was removed and the segment fused. During revision surgery, rupture of the posterior structures could be detected. Possible mechanisms leading to implant failure are discussed.ConclusionAs there is no standard regarding clinical and radiological follow-up for patients with CADs, radiological long-term follow-up investigations seem to be justified for exclusion of implant failure.

Lumbar juxta-facet joint cysts in association with facet joint orientation, -tropism and -arthritis: A case–control study

OBJECTIVE To assess the association between juxta-facet-joint cysts (JFC) occurrence at the lumbar spine and Facet Joint (FJ) orientation, -tropism and -arthritis. METHODS Study group, 36 consecutive patients with JFC and the same number of controls, with degenerative diseases without JFC were match paired for demographics and spine segment. Parameter assessment was by T2-weighted axial MRI scans. JFC diagnosis was confirmed histopathologically. Group comparison was by Students t-test for continuous variables and X(2) for categorical variables. RESULTS Nineteen female and 17 male patients, aged between 45 and 85 years (mean 67.19 ± 10.3 years) had a mean JFC size of 9.26 ± 4.8mm occurring most frequently in the segment L4-L5 (75% n=25) and on the left side (61%). Mean FJ orientation of the study group was significantly more coronal compared to controls (left side 42° vs 36°, p<0.02*, 95% confidence interval: 0.9-11.5 and right side 43° vs 37°, p<0.02*, 95% confidence interval: 0.6-10.6 respectively). However, individual intersegmental analysis for study group patients showed the JFC bearing side to be significantly more sagittally oriented 40° ± 11.2° compared to 45° ± 13.2° for the side without FJC (p<0.03*, 95% confidence interval: 8.1-1.7). 50% of the study group showed FJ asymmetry compared to 30% in controls, with a trend for FJ tropism (p<0.07). Severe (grade 3) FJ arthritis was significantly more predominant in the study group 23/33 (p<0.001*) as compared to controls. CONCLUSIONS Compared to a control group, JFC occurrence is associated with significant higher rates of arthritis and coronally orientated FJ. At intersegment comparison within the same patient cysts located in more sagittally orientated FJ and the asymmetric segments show a trend for FJ tropism.