minimally-invasive-treatment-for-thoracolumbar-burst-fracture-using

Minimally Invasive Treatment for Thoracolumbar Burst Fracture Using Sagittal Alignment Screws and A Trauma Reduction Device

Thoracolumbar (TL) burst fracture is one of the most common indications for minimally invasive percutaneous pedicle screw fixation. Although the ...

Showa University School of Medicine

In the clinical setting, the use of QX-314 (a quaternary derivative of lidocaine) has been proposed to achieve the selective inhibition of nociceptors that express transient receptor potential vanilloid 1 (TRPV1) channels with fewer motor deficits. However, it has been also reported that QX-314 may produce systemic CNS toxicities with relative potencies that are approximately twice as high as those of lidocaine. There are no reports concerning the effects of extracellular QX-314 on the rhythm-generating neurons in the respiratory center. In the present study, we examined the effects of QX-314 on respiratory rhythm generation in brainstem-spinal cord preparations from newborn rats. The extracellular application of QX-314 (200μM) decreased the C4 burst rate, amplitude and slope during the initial rising phase, and the effects slowly developed with a half-decay time of approximately 20min. The combined application of capsaicin (10 or 100μM) with QX-314 (100μM) showed no additional effect. The intracellular application of QX-314 (100μM) to respiratory neurons depressed the action potentials with a half-decay time of around 5min. Our findings could explain one of the mechanisms underlying the central toxicities that occur after the systemic application of QX-314.

Effects of a quaternary lidocaine derivative, QX-314, on the respiratory activity in brainstem-spinal cord preparation from newborn rats.

The heat-sensitive transient receptor potential vanilloid 1 (TRPV1) channels are expressed in the peripheral and central nervous systems. However, there is no report on how the activation of TRPV1 causes the modulation of neuronal activity in the medullary respiratory center. We examined effects of capsaicin, a specific agonist of TRPV1 channels, on respiratory rhythm generation in brainstem-spinal cord preparation from newborn rats. Capsaicin induced a biphasic response in the respiratory rhythm (a transient decrease followed by an increase in the C4 rate). The second-phase excitatory effect (but not the initial inhibitory effect) in the biphasic response was partly blocked by capsazepine or AMG9810 (TRPV1 antagonists). Capsaicin caused strong desensitization. After its washout, the strength of C4 burst inspiratory activity was augmented once per four to five respiratory cycles. The preinspiratory and inspiratory neurons showed tonic firings due to membrane depolarization during the initial inhibitory phase. In the presence of TTX, capsaicin increased the fluctuation of the membrane potential of the CO-sensitive preinspiratory neurons in the parafacial respiratory group (pFRG), accompanied by slight depolarization. The C4 inspiratory activity did not stop, even 60-90 min after the application of 50/100 μM capsaicin. Voltage-sensitive dye imaging demonstrated that the spatiotemporal pattern of the respiratory rhythm generating networks after application of capsaicin (50 μM, 70-90 min) was highly similar to the control. A histochemical analysis using TRPV1 channel protein antibodies and mRNA demonstrated that the TRPV1 channel-positive cells were widely distributed in the reticular formation of the medulla, including the pFRG. Our results showed that the application of capsaicin in the medulla has various influences on the respiratory center: transient inhibitory and subsequent excitatory effects on the respiratory rhythm and periodical augmentation of the inspiratory burst pattern. The effects of capsaicin were partially blocked by TRPV1 antagonists but could be also induced at least partially via the non-specific action. Our results also suggested a minor contribution of the TRPV1 channels to central chemoreception.

Effects of a TRPV1 agonist capsaicin on respiratory rhythm generation in brainstem-spinal cord preparation from newborn rats.

Prospective feasibility study on consecutive patients.

A Novel Method for the Prediction of the Pedicle Screw Stability: Regional Bone Mineral Density Around the Screw.

There is growing interest in "osteosarcopenia" as the coexistence of osteoporosis and sarcopenia exacerbates negative outcomes. However, limited information is available regarding the risk factors of osteosarcopenia development in patients with osteoporosis. Therefore, we retrospectively reviewed 276 consecutive patients with postmenopausal osteoporosis who regularly visited Showa University Hospital. Patients were eligible for the study if they were ≥65 years of age and underwent dual-energy X-ray absorptiometry, blood sampling, and physical performance assessment. Patients were divided into the osteosarcopenia and osteoporosis alone groups according to the diagnostic criteria of the Asian Working Group for Sarcopenia. Of the 276 patients with osteoporosis, 54 patients (19.6%) had osteosarcopenia. Patients in the osteosarcopenia group had a greater risk of frailty than did those in the osteoporosis alone group (odds ratio 2.33; 95% confidence interval, 1.13-4.80, P = 0.028). Low body mass index seemed to be the strongest factor related to the development of osteosarcopenia, and none of the patients in the osteosarcopenia group were obese (BMI ≥27.5 kg/m2). Multiple logistic analyses revealed that patients aged 65-74 years who had comorbidities such as kidney dysfunction and high levels of HbA1c were at risk of developing osteosarcopenia. Thus, we strongly recommend the assessment of the key components of the diagnosis of osteosarcopenia in an osteoporosis clinic for patients with low body mass index. Furthermore, appropriate assessments, including comorbidities, will help in identifying patients at greater risk of developing osteosarcopenia.

Risk factors predicting osteosarcopenia in postmenopausal women with osteoporosis: A retrospective study.

Pedicle screw loosening is a major complication following spinal fixation associated with osteoporosis in elderly. However, denosumab is a promising treatment in patients with osteoporosis. The effect of denosumab on pedicle screw fixation is unknown. Therefore, we investigated whether denosumab treatment improves pedicle screw fixation in elderly patients with osteoporosis.

The effect of denosumab on pedicle screw fixation: a prospective 2-year longitudinal study using finite element analysis.

Atypical femoral fracture (AFF) is a rare complication in patients with osteoporosis undergoing long-term bisphosphonate therapy. The most common symptom of incomplete AFF is nonspecific thigh pain, which is often difficult to distinguish from other causes.

Atypical femoral fracture mimicking lumbar radiculopathy in two patients taking bisphosphonate long-term: A case report.

Proximal junctional kyphosis and failure is a common complication of adult spinal deformity surgery, with osteoporosis as a risk factor. This retrospective study investigated the influence of long thoracolumbar fusion with pelvic fixation on regional bone density of adjacent vertebrae (Hounsfield units on computed tomography) and evaluated the association between bone loss and the incidence of proximal junctional kyphosis and failure. Patients who underwent long thoracolumbar fusion (pelvis to T10 or above) or single-level posterior lumbar interbody fusion (control group) between 2016 and 2022 were recruited. Routine computed tomography preoperatively and within 1-2 weeks postoperatively was performed. Postoperative changes in Hounsfield unit values in the vertebrae at one and two levels above the uppermost instrumented vertebrae (UIV + 1 and UIV + 2) were evaluated. Overall, 127 patients were recruited: 45 long fusion (age, 73.9 ± 5.6 years) and 82 proximal junctional kyphosis and failure (age, 72.5 ± 9.3 years). Postoperative computed tomography was performed at a median [interquartile range] of 3.0 [1.0-7.0] and 4.0 [1.0-7.0] days, respectively. In both groups, Hounsfield unit values at UIV + 2 were significantly decreased postoperatively. In the long-fusion group, Hounsfield unit values at UIV + 1 and UIV + 2 were significantly lower in patients with proximal junctional kyphosis and failure (within 18 months postoperatively) than in those without proximal junctional kyphosis and failure. Proximal junctional kyphosis and failure and long thoraco-pelvic fusion negatively affect regional Hounsfield unit values at adjacent levels immediately after surgery. Patients with subsequent proximal junctional kyphosis and failure show greater postoperative bone loss at adjacent levels than those without.

Chikara Hayakawa

Department of Orthopaedic Surgery

Showa University School of Medicine

Minimally Invasive Treatment for Thoracolumbar Burst Fracture Using Sagittal Alignment Screws and A Trauma Reduction Device