[Influence of Cervical Spondylotic Spinal Cord Compression on Cerebral Cortical Adaptation. Radiological Study]. / Vliv cervikální spondylogenní mísní komprese na korové funkce mozku. Radiologická studie.

PURPOSE OF THE STUDY: The aim of the study was to measure the sensorimotor brain adaptation activity, shown on functional magnetic resonance images (fMRI), in relation to the degree and extent of spinal cord compression or cervical spondylotic myelopathy (CSM) detected by cervical spine MRI. MATERIAL AND METHODS: Twenty-one patients (average age, 57 years; 9 men and 12 women) with anterior cervical cord compression detected on cervical MRI scans were included. On the images, the degree of spinal canal stenosis, the spinal cord compression based on the antero-posterior diameter of the spinal canal and on transverse areas of the cervical spinal cord and cervical spinal canal, and changes in spinal cord signal intensity were identified. Clinical examination included neurological status, Japanese Orthopaedic Association (JOA) score, Neck Disability Index (NDI) and pain intensity assessment using the Visual Analogue Scale (VAS). Electrophysiological tests involving motor evoked and sensory evoked potential (MEP and SEP) recording were conducted and, using fMRI, brain activity during movement of both arms was measured. Based on the transverse spinal cord area of above or below 70 mm2, the patients were placed into two subgroups. According to changes in spinal cord signal intensity, the patients were included into three subgroups with normal findings, incipient myelopathy and advanced myelopathy, respectively. Surgery was carried out from the anterior approach and involved cervical disc replacement. All examinations were performed again at 6 months after surgery. Pre- and post-operative results were compared within each set of subgroups and statistically evaluated. RESULTS: The average pre-operative values were found to increase post-operatively as follows: from 6.4 mm to 8.9 mm (by 39%) for the antero-posterior diameter of the spinal canal; from 129.3 mm2 to 162.8 mm2 (by 26%) for the transverse area of the spinal canal; from 72.6 mm2 to 87.4 mm2 (by 20%) for the transverse spinal cord area; and from 16.3 to 17.4 for the JOA score. The average NDI decreased from 37.9 to 23.7 and the average VAS fell from 6.4 to 1.5. All patients with the change of spinal cord signal that indicated advanced myelopathy also had relevant pathological findings on MEP/SEP examination and this was statistically significant. There was no significant difference in fMRI scans between the two subgroups established on the basis of transverse spinal cord area measurements. In the patients grouped by a change in spinal cord signals, the pre-operative fMRI showed a significantly higher brain activation volume in the subgroup with advanced myelopathy, as compared with the two other subgroups. Surgery resulted in a moderate reduction of the volume of active brain tissue in all three groups. In the patients with advanced myelopathy evaluated in relation to local changes in brain activation, surgery led to a significant decrease in activation volumes in the ipsilateral primary motor cortex and cerebellar hemisphere. There was also a significant increase in activation of the contralateral supplementary motor cortex. DISCUSSION: It is evident that the brain responds to spinal cord damage by increased activity, but with a certain delay. A slightly altered spinal cord signal intensity, such as in incipient myelopathy, apparently does not result in brain activation. On the other hand, significant changes in signal intensity in advanced myelopathy are related to deterioration of spinal cord function, as shown by MEP and SEP examination results, and an increase in both the volume and intensity of cortical motor activation as a compensation mechanism for myelopathy. CONCLUSIONS Hyperintense spinal cord signals on T2-weighted images correlated with the pathological spinal cord function detected by electrophysiological test in all patients. The transverse spinal cord area (around 70 mm2) showed no significant correlation with either sensory and motor brain adaptations or the results of SEP and MEP testing; therefore, as a criterion for indication to surgery it is of no value. The patients with advanced myelopathy, as detected by spinal cord MRI, had a significantly higher pre-operative cortical motor activation on fMRI than patients with normal findings or those with incipient myelopathy. In addition, the patterns of cortical motor activation altered significantly at 6 months after spinal cord decompression, which was shown by an increase or decrease in activation of the relevant motor cortex areas.

[Surgery for degenerative spondylolisthesis of the lumbar spine using intra-articular fusion. A prospective study]. / Operace degenerativní spondylolistézy bederní pátere metodou intraartikulární fúze: prospektivní studie.

PURPOSE OF THE STUDY: The aim of the study is to present our surgical method of treating degenerative spondylolisthesis, which includes radical bilateral laminectomy to relieve compression on the spinal cord, transpedicular fixation of the segment and arthrodesis by bilateral intra-articular fusion. MATERIAL AND METHODS: This surgery was indicated in patients with grade I or grade II of degenerative sponylolisthesis with a 4-mm or more slippage. Our prospectively studied group consisted of 46 patients (17 men, 29 women; average age, 64.2 years; range, 39-84 years). Before surgery and at 1 year after the procedure, the intensity of axial pain and that of radicular pain were each assessed using the visual Analogue Scale (VAS). Difficulty in performing daily living activities was measured by the Oswestry Disability Index (ODI). The surgical procedure included laminectomy, partial medial facetectomy, foraminotomy to relieve pressure on the spinal nerve roots and transpedicular fixation to provide stability. Using a cutter, cartilage was separated off the cortical bone and, in order to facilitate fusion, bone cavities thus produced were filed with corticospongious grafts harvested from the removed vertebral arch with Kerrison forceps. At 1-year follow-up, dynamic X-ray was used to evaluate spine alignment and, on a CT scan, the degree of intra-articular fusion was assessed. Fusion was achieved when bone density measurement showed more than 350 Hounsfield Units (HU). For the measurements, the authors used their own modified method by means of a Region of Interest (ROI) analysis. The clinical and radiographic results were statistically evaluated. RESULTS: At 1 year after surgery, lumbar flexion-extension bending X-ray films revealed stability of the treated segments in all patients (100%). CT examination showed bone density higher than 350 HU at both joints, i.e., complete bone fusion, also in all 46 patients. The mean post-operative ODI score was significantly lower than its mean pre-operative value (23.6 vs 55.4), which was improvement by 57.4%. The differences in pre- and post-operative VAS scores were also statistically significant. The mean VAS score for low back pain decreased from 7.61 to 1.74, i.e., improvement by 77.1%, and the mean vAS score for radicular pain dropped from 6.98 to 1.24, i.e., improvement by 82.2%. Assessed by Odom's outcome criteria, the results were excellent in 26 patients and very good in 20 patients, and they were not related to age, gender or the spinal level treated. Any complications associated with the operative procedure or wound healing and requiring repeated surgical treatment were not recorded. DISCUSSION: The surgical technique described here has advantages over other methods in reliable achieving nerve decompression, joint fusion and spinal stability at low costs and short operative time. In addition, it avoids the necessity of harvesting bone from the iliac crest. CONCLUSIONS: At 1-year follow-up all patients showed better health conditions, with improvement in average scores for the ODI by 57%, for low back pain by 77% and for radicular and claudication pain by 82%. The technique of intra-articular fusion for treatment of degenerative spondylolisthesis resulted in solid bone fusion and spinal stability in all patients.

[Effects of spinal cord decompression in patients with cervical spondylotic myelopathy oncortical brain activations]. / Efekt dekomprese krcní míchy pri spondylogenní myelopatii na korové funkce mozku.

INTRODUCTION: The aim of this project was to compare and evaluate cortical sensorimotor adaptations as measured by brain fMRI (functional magnetic resonance imaging) in patients before and after surgery for cervical spondylotic myelopathy (CSM), i.e., after spinal cord decompression. MATERIAL AND METHODS: Study inclusion required evidence of CSM on MRI of the cervical spine, anterior compression of the spinal cord by osteophytes, or disc herniation. We measured the antero-posterior diameter of the spinal canal stenosis before and 3 months after surgery. Surgery was performed at one or two levels from the anterior approach with implantation of radiolucent spacers, without plate fixation. Each participant underwent two fMRI brain examinations, the first one preoperatively and the second one 6 months following surgery. Subjects performed acoustically paced repetitive wrist flexion and extension of each upper extremity according to block design. MRI data were acquired using 1.5 Tesla scanners. Statistical analysis was carried out using the general linear model implemented in FEAT 6.00 (FMRI Expert Analysis Tool), part of the FSL 5.0 package (FMRIB Software Library). The group differences were evaluated using paired t-test and the resulting statistical maps evaluated as Z-score (standardised value of the t-test) were thresholded at a corrected significance level of p <0.05. The study group consisted of 7 patients including 5 female and 2 male patients, with the average age of 55.7 years. Patients with cervical spondylogenous radiculopathy were evaluated as a control group. RESULTS: The analysis of mean group effects in brain fMRI during flexion and extension of both wrists revealed significant activation in dorsal primary motor cortex contralaterally to the active extremity and in adjacent secondary motor and sensory areas, bilaterally in supplementary motor areas, the anterior cingulum, primary auditory cortex, in the region of the basal ganglia, thalamus and cerebellum. After surgery, the cortical activations and maximum Z-scores decreased in most areas. Analysis of differences between sessions before and after surgery showed a statistically significant activation decrease during movement of both extremities in the right parietal operculum and the posterior temporal lobe. During left wrist movement, there was additional activation decrease in the right superior parietal lobe, the supramarginal gyrus, insular cortex, and the central operculum. In contrast, an activation decrease was detected in the left middle temporal gyrus during right wrist movement. CONCLUSION: An average difference of anteroposterior cervical spinal canal distance before and after surgery of CSM was 2.67 millimetres, representing a 40% increase; the cross-sectional area of the spinal canal increased by 37% and that of the spinal cord by 36%. Functional MRI of the brain revealed significant activation especially in primary and secondary motor cortex and sensory areas in patients with CSM. After surgical decompression of the spinal cord, cortical activations and maximum Z-score decreased in the majority of areas. We proved decreased cortical activation on functional MRI of the brain after surgery in patients with CSM (evaluated according to MRI of cervical spine), even at an initial stage of the disease.

[Use of artifiial bone in lateral interbody fusion of the lumbar spine: a prospective radiographic study]. / Pouzití umelé kostní náhrady pri laterální mezitelové fúzi na bederní páteri: prospektivní radiologická studie.

PURPOSE OF THE STUDY: The aim of the study was to evaluate the extent of fusion using synthetic ß-tricalcium phosphate as a bone substitute in extreme lateral interbody fusion (XLIF). MATERIAL AND METHODS: In this prospective study, patients undergoing XLIF with an Oracle cage filed with the artifiial bone ChronOs Strip (Synthes, USA) were evaluated. The group consisted of 61 patients, 33 women and 28 men, with an average age of 50.9 years (range, 21 to 73 years). A total of 64 segments were operated on. Stand-alone interbody fusion was performed in 14 segments, lateral plate fiation in 19, transpedicular (TP) fiation before XLIF was carried out in 14 and TP fiation after XLIF in 17 segments. At one-year follow-up, dynamic X-rays to exclude instability, and CT images were obtained in order to evaluate the extent of bone fusion outside the implant (complete fusion, partial fusion, no fusion) and inside it (% of the bone fusion surface area). In addition, bone mineral density following fusion mass bone quality (expressed in Hounsfild units [HU]) was assessed inside the implant at the site of ChronOs Strip placement, using a region of interest (ROI) analysis. For the evaluation of fusion bone quality inside the implant on CT scans with HU qualifiation, the authors propose the following scale: 1. no fusion (0-99 HU) 2. Uncertain fusion (100-190 HU) 3. Probable fusion (200-299 HU) 4. Reliable fusion (300 and more HU) All results were statistically evaluated in relation to the gender, age, treated segment, surgical diagnosis, method of fiation, implant height and intervertebral space reduction at one-year follow-up. RESULTS: Fusion outside the implant was complete in 18 segments (28%) and partial in 27 (42%); in 19 segments (30%) it was not detected. The bone fusion surface area inside the implant was 54.5% (0-100%) on the average. It was related to age and implant height; the surface area increased with increasing age and with increasing implant height. Solid bone fusion inside the implant, as assessed on CT images using HU, was reliable in 36 segments (56%), probable in 11 (17%), uncertain in 10 (16%) and was not detected in seven segments (11%). A signifiant relationship was found between the quality of bone fusion and the type of fiation. Of the segments treated by stand-alone XLIF, 29% showed no fusion while the segments managed by lateral plate fiation had 32% of them with probable fusion. Correlations were also found with the height of an implant (the higher the implant, the more reliable its fusion), with age (the higher age, the higher bone density) and with the spinal level (the lower level, the lower bone density). In 45 (70%) segments, bone mineral density inside the implant was higher than the density of surrounding spongious bone. The average density inside the implant was 333.7 HU (14-1075) and that of the surrounding bone was 244.6 HU (66-500). The intervertebral space was reduced by an average of 1.1 mm (0-6.2). All treated segments were found stable on dynamic X-rays. DISCUSSION: The use of a tricortical bone graft collected from the iliac crest is associated with pain at the harvest donor site in 2.8% to 39% of the cases, and this has been an impetus for many surgeons to use bone substitutes. In terms of the final outcome, i.e., solid bone fusion, the difference between the resorption rates of allogenous graft/artificial bone and ingrowth of autologous bone (from vertebral bodies) plays the most decisive role. CONCLUSIONS: The change of (3-tricalcium phosphate to bone tissue is not always reliable and this can largely be expected when the resorption rate of ChronOs strip is low, i.e., at higher patient age and with a higher height of the implant.The authors recommend increasing the probability of solid fusion in XLIF by using lateral plate fixation.The method of assessing bone fusion by measuring bone density on CT scans proved to be useful because of its objectivity, and it can replace the current assessments based only on subjective judgement.