Depth-Specific Hypoxic Responses to Spreading Depolarizations in Gyrencephalic Swine Cortex Unveiled by Photoacoustic Imaging.

Spreading depolarizations (SDs) are a marker of brain injury and have a causative effect on ischemic lesion progression. The hemodynamic responses elicited by SDs are contingent upon the metabolic integrity of the affected tissue, with vasoconstrictive reactions leading to pronounced hypoxia often indicating poor outcomes. The stratification of hemodynamic responses within different cortical layers remains poorly characterized. This pilot study sought to elucidate the depth-specific hemodynamic changes in response to SDs within the gray matter of the gyrencephalic swine brain. Employing a potassium chloride-induced SD model, we utilized multispectral photoacoustic imaging (PAI) to estimate regional cerebral oxygen saturation (rcSO2%) changes consequent to potassium chloride-induced SDs. Regions of interest were demarcated at three cortical depths covering up to 4 mm. Electrocorticography (ECoG) strips were placed to validate the presence of SDs. Through PAI, we detected 12 distinct rcSO2% responses, which corresponded with SDs detected in ECoG. Notably, a higher frequency of hypoxic responses was observed in the deeper cortical layers compared to superficial layers, where hyperoxic and mixed responses predominated (p < 0.001). This data provides novel insights into the differential oxygenation patterns across cortical layers in response to SDs, underlining the complexity of cerebral hemodynamics post-injury.

Thoracic Cage Deformity Correction in Patients with Lenke Type 1 Adolescent Idiopathic Scoliosis.

Whether the thoracic cage deformity in adolescent idiopathic scoliosis (AIS) can be sufficiently treated with vertebral derotation alone, has been quite controversial. Our aim is to control the hypothesis that the rib cage deformity (RCD) may be adequately corrected when only vertebral derotation is applied. We studied retrospectively patients treated for AIS with posterior spinal fusion without costoplasty. The RCD was assessed on lateral radiographs by rib index (RI). The correction of RI after surgery was calculated. Of the 103 patients that were finally included in our study, 29 patients (22 females and 7 males; mean age, 14.5 ± 2.1 years) represented Group A (Harrington rod instrumentation - no derotation), while 74 patients (61 females and 13 males; mean age, 14.1 ± 2.4 years) were operated with either a full pedicle screw system or a hybrid construct with hooks and pedicle screws (Group B-derotation). RI was significantly corrected after surgery in both groups. RI was significantly greater in Group A after surgery. Whatsoever, the correction of RI, thereby the RCD correction, did not significantly differ among groups. In conclusion, it cannot be suggested by the present study that vertebral derotation alone can offer an absolute correction of the deformity of the thoracic cage in patients with Lenke Type 1 AIS, and it seems also that the development of RCD may not exclusively result from the spinal deformity, thus questions can be further raised regarding scoliogeny per se.

Rib Hump Deformity Correction in Patients with Adolescent Idiopathic Scoliosis: A Comparison of Three Spinal Fusion Systems.

The aim of the present study is to control the hypothesis that the rib hump deformity can be adequately corrected when applying vertebral derotation. We retrospectively studied patients treated with full pedicle screw systems (group A), hybrid constructs (group B), and Harrington rod instrumentation (group C). No costoplasties were performed in the patients included in our study. Derotation was applied in groups A and B. The rib hump deformity was assessed on lateral radiographic studies by rib index (RI). Of the 72 patients that were finally included in our study, 30 patients (24 females and 6 males; mean age, 14.5 ± 2.2 years) were treated with a full pedicle screw system, 23 patients (19 females and 4 males; mean age, 13.8 ± 1.9 years) were treated with a hybrid construct, and 19 patients (16 females and 3 males; mean age, 14.3 ± 2 years) received the Harrington rod instrumentation. In all groups RI was significantly corrected after surgery. Before surgery no difference in RI was found among groups; however, after surgery RI was found significantly higher in group C as compared to groups A and B. The between-group analysis revealed that the correction of RI, and thereby the rib hump deformity correction, did not significantly differ among the three patient groups. In conclusion, it cannot be suggested based on the present study that vertebral derotation alone can offer an adequate correction of the rib hump deformity. Further, the development of rib cage deformity and its degree of interdependence with the scoliotic spinal deformity has to be further investigated and assessed, as it seems that it may not necessarily result directly from the primary vertebral deformity.

Complications of spine surgery for metastasis.

The spinal column represents the third most common site for metastases after the lungs and the liver, and the most common site for metastatic bone disease. With life-extending advances in the systemic treatment of cancer patients, the surgical procedures performed for spinal metastases will increase, and their related complications will increase unavoidably. Furthermore, considering the high complication rates reported in the spinal literature regarding spine surgery overall, it becomes clear that a better understanding of complications that the cancer patients with spinal metastases may experience is necessary. This article aims to summarize and critically examine the current evidence for complications after spine surgery for metastatic spinal disease, in both the perioperative and postoperative period. This paper would be useful for the treating physicians of these patients in their clinical practice.

Sagittal alignment assessment after short-segment lumbar fusion for degenerative disc disease.

PURPOSE: To investigate whether differences in spinopelvic parameters, and especially spinopelvic alignment, could be associated with adjacent segment disease (ASD) or pseudarthrosis after short-segment lumbar fusion. METHODS: Retrospective study of patients offered mono- or bisegmental transforaminal lumbar interbody fusion (TLIF) with polyetheretherketone (PEEK) or titanium cages, due to degenerative disease. Of 419 patients, 32 (7.6%) presented pseudarthrosis (nonunion group), 29 (6.9%) developed symptomatic ASD (ASD group), and 358 patients (85.5%) showed evidence of uncomplicated fusion (control group). Standard spinopelvic parameters were measured in all patients before and after surgery. The differences of the values within the parameters (Δ values) were also calculated. A comparative analysis within and among groups was performed. Patients were also analyzed by cage characteristics (large vs small, titanium vs PEEK). RESULTS: All studied parameters changed significantly after surgery both in the control and ASD group, while in the nonunion group, only LL and PI-LL changed significantly (PI-LL increased from 10 ± 11° to 14 ± 10°, p = 0.008). Patients in the nonunion group presented greater SS before and after surgery, greater PI-LL after surgery, and higher PI, while ASD patients presented greater absolute mean ΔPT value. Age, size, and type of cage were not related to fusion, nonunion, or ASD. CONCLUSIONS: Greater SS, greater PI, and a PI-LL mismatch greater than 10° are associated with failed bony fusion, while ASD is related to a greater difference between the pre-operative and post-operative values of PT. Neither the type nor the size of cage seem to have a significant impact on either solid bony fusion, nonunion, or ASD rates. Thus, we recommend on the study of patients' sagittal alignment in the pre-operative setting even when treating patients with short-segment lumbar interbody fusion.

Acquired spondylolysis and spinopelvic sagittal alignment.

Acquired spondylolysis represents an uncommon complication of spine surgery, of an unknown incidence and etiology. We studied patients presenting this rare entity, with the purpose to investigate the incidence, imaging findings, patients' clinical characteristics, as well as to provide an interpretation of the mechanisms that may lead to this phenomenon. The presented working hypothesis, regarding etiology, suggests that there is a relation between variations in spinopelvic sagittal alignment and acquired spondylolysis. Between January 2010 and January 2015, six patients presented spondylolysis after short-segment transforaminal lumbar interbody fusion, at a mean time of 43 months after surgery. The preoperative intactness and postoperative defect of pars interarticularis were documented with computed tomography scans in all patients. Standard radiographical spinopelvic parameters were measured before and after surgery. The optimum values of lumbar lordosis (LL) and pelvic incidence minus lumbar lordosis modifier (PI-LL mismatch) were calculated as well. The incidence of acquired spondylolysis was 0.95% among patients with short-segment lumbar fusion. Patients presented high-grade PI with a vertically orientated sacral endplate, while LL was found 9° greater and PI-LL mismatch 9° lower than the respective optimum values, indicating a non-harmonized alignment. In conclusion, acquired spondylolysis, though rare, may occur in patients with high-grade PI and sacral slope, and suboptimal spinopelvic sagittal alignment after lumbar spine surgery, thereby highlighting the importance of detailed preoperative planning in spine surgery, along with the study of sagittal balance.

Surgical treatment for metastases of the cervical spine.

BACKGROUND: There are limited information and inconclusive results for the management of patients with cervical spine metastases. Therefore, we performed this study to evaluate the survival and outcome of these patients, and the surgical risk and complications. MATERIALS AND METHODS: We retrospectively studied 24 patients [14 men and 10 women; mean age, 71 years (range 54-89 years)], with cervical spine metastases, who underwent palliative surgical treatment, from December 2010 to December 2016. Mean follow-up was 14 months (range 1-42 months). We evaluated the survival and the outcome of the patients with respect to pain relief and neurological status, and the surgical risk and complications. RESULTS: At the last follow-up, three patients were alive with disease, and 21 patients were dead with disease. Overall median survival was 14.8 months (range 1-47 months). A posterior approach was performed in 15 patients, an anterior approach with corpectomy and fusion in eight patients, and a two-stage combined approach in one patient. Overall, 21 patients experienced complete or almost complete, two patients mild, and one patient no pain relief; seven patients experienced complete neurological improvement, two patients moderate, while four patients remained stable. Overall, five patients experienced six complications including residual pain, sagittal malalignment with instability, and wound dehiscence; in five complications, a reoperation was necessary. CONCLUSIONS: Palliative surgical treatment is usually performed in patients with metastatic bone disease of the cervical spine. Appropriate selection of the surgical technique is mandatory. However, the survival of the patients is dismal, and complications should be expected.

A Unique Case of Cervical Myelopathy in an Adult Patient with Scheie Syndrome.

INTRODUCTION: Scheie syndrome is an extremely rare systematic disease that represents the most attenuated form of mucopolysaccharidosis Type I disorder. Although associated with a variety of manifestations, Scheie syndrome leading to the development of cervical myelopathyis yet to be reported. Our purpose was to present a unique case of a Scheie syndrome patient, who underwent surgery due to cervical myelopathy, and to discuss the clinical and imaging findings, as well as the challenges and outcomes of surgical treatment. CASE REPORT: A 33-year-old man with Scheie syndrome presented with neck and radicular pain, upper extremity weakness, and insecure gait. The workup studies revealedcervical spine stenosis at multiple levels, caused by accumulation of soft tissue, within the cervical spinal canal. D espite the high risks of anesthesia, and the patient's inherent poor bone quality that could lead to failure of spinal fusion, we decided to proceed with surgery; indeed, decompressive laminectomies combined with C1-7 posterior stabilization led to immediate pain relief. Despite counter advised, the patient returned to sports rather early, and 6months after index procedure neck pain relapsed, while screw breakage and cutout occurred at the level of C7. Consequently, the initial instrumentation was revised and extended at T2 level. At 2years follow-up, the patient remained continuously pain-free and ambulatory. CONCLUSION: Although cervical myelopathy in Scheie syndrome represents an extremely rare entity, it can make a severe impact on patients' quality of life. If timely managed though, these patients can be offered a significant relief from symptoms. Surgery is rather challenging and treating physicians should be aware of the high risks of anesthesia. Especially spine surgeons should be aware of the nature of the disease, since it may not allow for fusion, causing instrumentation to fail.