[Postoperative cognitive dysfunction. Possible neuronal mechanisms and practical consequences for clinical routine]

Biomechanical comparison of acetabular fracture fixation with stand-alone THA or in combination with plating

PURPOSE

A common surgical treatment in anterior column acetabular fractures with preexisting osteoarthritis is THA, which is commonly combined with plate osteosynthesis. Implantation of a solitary revision cup cranially fixed to the os ilium is less common. The purpose of this study was to compare the stabilization of anterior column acetabular fractures fixed with a cranial socket revision cup with flange and iliac peg or with a suprapectineal plate osteosynthesis combined with an additional revision cup.

METHODS

In 20 human hemipelves, an anterior column fracture was stabilized by either a cranial socket revision cup with integrated flange (CF = Cup with Flange) or by a suprapectineal plate combined with a revision cup (CP = Cup and Plate). Each specimen was loaded under a stepwise increasing dynamic load protocol. Initial construct stiffness, interfragmentary movements along the fracture line, as well as femoral head movement in relation to the acetabulum were analyzed.

RESULTS

Both groups showed comparable initial construct stiffness (CP: 3180 ± 1162 N/mm and CF: 3754 ± 668 N/mm; p = 0.158). At an applied load of 1400 N, interfragmentary movements at the acetabular (p = 0.139) and the supraacetabular region (p = 0.051) revealed comparable displacement for both groups and remained below 1 mm. Femoral head movement in relation to the acetabulum also remained below 1 mm for both test groups (p = 0.260).

CONCLUSION

From a biomechanical point of view, both surgical approaches showed comparable fracture reduction in terms of initial construct stiffness and interfragmentary movement. The potential benefit of the less-invasive cranial socket revision cup has to be further investigated in clinical studies.

[Perioperative Management: From the Operating Room to Postanesthesia Care Unit/to the Normal Ward]

The early postoperative period is of increasing importance in modern operative medicine with a continuously increasing surgical spectrum and patients with increasingly complex comorbidities. Even with optimal preoperative evaluation and intraoperative care, postoperative complications are not uncommon. The fastest possible diagnosis, including possible differential diagnoses and any combined disorders, is essential in order to initiate the indicated therapeutic measures. The spatial correlate of the postoperative phase is the post-anaesthesia care unit (PACU). The qualification of the medical staff and spatial structure must meet the recommended minimum and must be in line with the existing operational structures. Good interdisciplinary and interprofessional communication reduces the loss of information and a good error reporting culture helps to reduce critical incidents.

Preoperative cognitive intervention reduces cognitive dysfunction in elderly patients after gastrointestinal surgery: a randomized controlled trial

BACKGROUND

Preoperative conditions may play a significant role in postoperative cognitive dysfunction (POCD) development in elderly patients. We aimed to investigate whether preoperative cognitive training could lower the incidence of POCD one week after surgery.

MATERIAL AND METHODS

A total of 141 ASA I-III elderly patients who underwent gastrointestinal surgery were enrolled into the study. Patients were randomized into either the Intervention group (69 analyzed) or the Control group (72 analyzed). Patients in the intervention group were instructed and trained in a cognition mnemonic skill for a total of three 1-hour sessions with the method of loci (MoL). Controls did not receive any cognitive training during hospitalization. All patients were tested using neuropsychological battery tests (NPTs) on admission and one week after surgery.

RESULTS

The incidence of POCD in the intervention group (15.9%) was significantly lower than in the controls (36.1%) (P<0.05). Patients' performance in Brief Visuospatial Memory Test-Revised and Symbol-Digit Modalities Test were improved by the cognitive training. Increasing age, longer length of anesthesia and surgery, and lack of cognitive training were associated with a significantly higher risk of POCD (P<0.05).

CONCLUSIONS

Cognitive training with MoL can reduce the decline of early postoperative cognitive function in elderly patients undergoing major gastrointestinal surgery.

Intracisternal administration of an interleukin-6 receptor antagonist attenuates surgery-induced cognitive impairment by inhibition of neuroinflammatory responses in aged rats

Postoperative cognitive dysfunction (POCD) is common in elderly patients, and may persist or even evolve into Alzheimer's disease. It has been hypothesized that POCD is mediated by surgery-induced inflammatory processes. As a pro-inflammatory cytokine, the detailed role of interleukin (IL)-6 in POCD remains largely unknown. In this study, laparotomy was used to mimic human abdominal surgery in aged Sprague-Dawley rats. It was found that memory and learning were impaired following surgery, accompanied by the significant upregulation of the pro-inflammatory cytokines tumor necrosis factor α (TNF-α), IL-1β, IL-4, and IL-6. Moreover, the intracisternal administration of the IL-6 receptor (IL-6R) antagonist (tocilizumab, also know as MRA) at the time of surgery notably attenuated the surgery-induced cognitive deficit, and significantly inhibited the upregulated expression of pro-inflammatory cytokines. Further investigation indicated that the intracisternal administration of MRA inhibited the activation of the NF-κB signaling pathway in aged rats following surgery. In summary, the findings of this study suggest that IL-6 plays a crucial role in POCD, and that IL-6R antagonists may serve as novel agents for the prevention or treatment of POCD.

Protective effect of senegenin on splenectomy-induced postoperative cognitive dysfunction in elderly rats

Postoperative cognitive dysfunction (POCD) is common in elderly patients. Senegenin, an active component of extracts from Polygala tenuifolia root, a traditional Chinese medicine, has neuroprotective and neuroregenerative effects. However, the mechanism underlying the effects of senegenin against postoperative cognitive impairment in elderly individuals has yet to be elucidated. The aim of this study was to investigate the protective effects of senegenin on the cognitive functions of elderly rats with splenectomy-induced POCD. Results from a Morris water maze test suggested that splenectomy induced a transient cognitive deficiency in the elderly rats; however, when the rats were treated with senegenin, the cognitive impairment was notably attenuated. Further experiments showed that senegenin significantly inhibited the mRNA and protein expression of several key pro-inflammatory cytokines, specifically, tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β), IL-6 and IL-8, in the hippocampal tissues of elderly rats following splenectomy. In order to investigate the molecular mechanism involved, the expression and activity of the Toll-like receptor 4 (TLR4) signaling pathway was assessed. On day 1 postoperatively, it was observed that senegenin markedly suppressed the mRNA and protein expression of TLR4, myeloid differentiation factor 88 (MyD88) and TIR domain-containing adaptor-inducing interferon-β (TRIF). Furthermore, the phosphorylation levels of nuclear factor-κB (NF-κB) p65 and inhibitor of NF-κB (IκBα) were also decreased following senegenin treatment on the first day subsequent to surgery. These results suggest that senegenin suppressed splenectomy-induced transient cognitive impairment in elderly rats, possibly by downregulating two signaling pathways involved in inflammation, TLR4/MyD88/NF-κB and TLR4/TRIF/NF-κB, to further inhibit the expression of key pro-inflammatory cytokines, specifically, TNF-α, IL-1β, IL-6 and IL-8, and ultimately the neuroinflammation in the hippocampal tissues. In conclusion, the present study revealed that senegenin exhibited neuroprotective effects against splenectomy-induced transient cognitive impairment in elderly rats, which indicated that senegenin may be a promising agent for the treatment of POCD.

The role of the TLR4 signaling pathway in cognitive deficits following surgery in aged rats

Postoperative cognitive dysfunction (POCD), common in elderly patients, refers to a decline in cognitive function following surgery, which may persist or even evolve into Alzheimer's disease (AD). Despite great efforts, the mechanism of POCD remains unclear. In the present study, we tested the hypothesis that Toll-like receptor 4 (TLR4) on microglia contributes to POCD. Shortly after surgery, aged rats demonstrated significant deficits in memory and learning, accompanied by the activation of microglia, marked upregulation of TLR4 on microglia in the hippocampus, as well as an increased expression of two downstream factors [myeloid differentiation factor 88 (MyD88) and TIR-domain-containing adapter-inducing interferon-β (TRIF)] and pro-inflammatory cytokines [including tumor necrosis factor α (TNF-α) and interleukin 1β (IL-1β)]. With an increase in time following surgery, the expression of TLR4 and the aforementioned factors and pro-inflammatory cytokines gradually returned to normal, as did the cognitive function of the aged rats. In conclusion, our study suggests that the activation of TLR4 signaling on microglia may act as an underlying mechanism of POCD.