An infection-oriented approach for thoracic endovascular aortic repair in a SARS-CoV-2 positive patient. A case report.

CASE REPORT: A 64-year-old woman presented to our emergency department during the outbreak of the covid-19 emergency in Italy with syncope, anosmia, mild dyspnoea and atypical chest and dorsal pain. A chest CT scan showed an acute type B aortic dissection (ATBAD) and bilateral lung involvement with ground-glass opacity, compatible with interstitial pneumonia. Nasopharyngeal swabs resulted positive for SARS-CoV-2. For the persistence of chest pain, despite the analgesic therapy, we decided to treat her with a TEVAR. Patient's chest and back pain resolved during the first few days after the procedure. No surgical or respiratory complications occurred and the patient was discharged 14 days after surgery. DISCUSSION: By performing the operation under local anesthesia, it was possible to limit both the staff inside the operatory room and droplet/aerosol release. Since we had to perform the operation in a hemodynamics room, thanks to the limited extension of the endoprosthesis and the good caliber of the right vertebral artery we were able to reduce the risk of spinal cord ischemia despite the lack of a revascularization of the left subclavian artery. CONCLUSIONS: A minimally invasive total endovascular approach allows, through local anesthesia and percutaneous access, to avoid surgical cut down and orotracheal intubation. This, combined with a defined management protocol for infected patients, seems to be a reasonable way to perform endovascular aortic procedures in urgent setting, even in a SARSCoV- 2 positive patient. KEY WORDS: COVID-19, Dissection, TEVAR.

Evaluation of the neuroprotective effect of minocycline in a rabbit spinal cord ischemia model.

OBJECTIVE: To investigate whether postischemic administration of minocycline attenuates hind-limb motor dysfunction and gray and white matter injuries after spinal cord ischemia. DESIGN: A prospective, randomized, laboratory investigation. SETTING: Laboratory in university, single institution. PARTICIPANTS: Male New Zealand White rabbits. INTERVENTION: Spinal cord ischemia was induced by an occlusion of the infrarenal aorta for 15 minutes. The groups were administered minocycline 1 hour after reperfusion (M-1; n = 8), minocycline 3 hours after reperfusion (M-3; n = 8), saline 1 hour after reperfusion (control [C]; n = 8), or saline and no occlusion (sham; n = 4). Minocycline was administered intravenously at 10 mg/kg 6 times at 12-hour intervals until 60 hours after the initial administration. MEASUREMENT AND MAIN RESULTS: Hind-limb motor function was assessed using the Tarlov score. For histologic assessments, gray and white matter injuries were evaluated 72 hours after reperfusion using the number of normal neurons and the percentage of areas of vacuolation, respectively. Motor function 72 hours after reperfusion was significantly better in group M-1 than in group C. The number of neurons in the anterior horn was significantly larger in group M-1 than in groups M-3 or C but did not differ significantly between groups M-3 and C. No significant difference was noted in the percentage of areas of vacuolation among the ischemia groups. CONCLUSIONS: Minocycline administration beginning at 1 hour after reperfusion improved hind-limb motor dysfunction and attenuated gray matter injury in a rabbit spinal cord ischemia model.

Low-dose edaravone injection into the clamped aorta prevents ischemic spinal cord injury.

Previous studies have indicated that high-dose intravenous edaravone (3-10mg/kg) protects against ischemic spinal cord injury. This study examined whether direct injection of low-dose edaravone into the clamped segment of the aorta prevents ischemic spinal cord injury. Spinal cord ischemia was induced in rabbits by aortic clamping below the renal artery and above the aortic bifurcation for 15min at normothermia. In groups A and B, 3 and 1mg/kg of edaravone, respectively, was injected into the clamped segment of the aorta immediately following aortic clamping. In group C, saline was injected. Neurological function was assessed at 8, 24, and 48hr and 7 days after reperfusion with Tarlov criteria. The spinal cord was histologically examined at 7 days with hematoxylin-eosin staining and in situ terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end labeling (TUNEL) staining. The Tarlov score remained grade 4 throughout the period in groups A and B, whereas it dropped to grade 0 or 1 at 7 days in group C, significantly higher in the former two groups. The number of intact motor neurons was significantly greater in groups A and B with less necrotic motor neurons than in group C. There was no significant difference in terms of spinal cord protection between groups A and B. There was no TUNEL-positive neuron in any group, indicating the absence of apoptosis. Low-dose intra-aortic edaravone injection prevents immediate neuronal injury by reducing neuronal cell damage in the early stage as well as delayed neuronal injury at 7 days.

[Preface and comments: Protection of the brain and the spinal cord].

Basic and clinical investigations have been performed, focusing on the mechanism of ischemic brain and spinal cord injuries, and preventive measures against ischemic insults such as drug therapy, hypothermia, maintenace of blood flow to brain and spinal cord, preconditioning, and no use of high dose fentanyl. In this special issue, five experts have provided new relevant information concerning brain and spinal cord protection. Further research in brain and spinal cord protection will contribute to better understanding of ischemic central nervous system injuries and to the establishment of novel therapies for protection of central nervous system.

[Brain and spinal cord preconditioning for the protection against ischemic injury].

Recent studies have suggested that the brain preconditioning could induce tolerance to ischemia in humans. It has been believed that newly synthesized proteins are required for the acquisition of delayed tolerance in the brain and spinal cord. However, the mechanism other than the synthesis of neuroprotective proteins may also play a pivotal role. Preconditioning may reprogram the response to ischemic injury as seen during hibernation. Preconditioning with hyperbaric oxygen, volatile anesthetics, and xenon seems to be the focus of the attention from the standpoint of the clinical setting. Strong neuroprotection by the preconditioning with isoflurane and xenon is reported in animal experiments and may change the traditional idea of neuroprotection by anesthetics. The discovery that erythropoietin exerts neuroprotective properties has opened new therapeutic avenues. Erythropoietin is induced in the brain by hypoxic preconditioning and by the pharmacological preconditioning. In addition, the intravenous administration of erythropoietin has been shown to be safe and beneficial for acute stroke in humans. Therefore, erythropoietin is now one of the most promising neuroprotective agents. The research in the brain and spinal cord preconditioning will contribute to the elucidation of the mechanism of ischemic injury and to the establishment of new therapies for neuroprotection.

[Spinal cord protection and opioids].

Opioids, when administered in large doses, were reported to produce brain damage primarily in limbic system and association areas in animals. We recently found the result that intrathecal (IT) morphine after a short interval of aortic occlusion in the rodent model induced transient spastic paraparesis via opioid receptor-coupled effects in the spinal cord. Histopathological analysis revealed the possibility that IT morphine could induce degeneration of spinal ventral neurons even after a short lasting of spinal cord ischaemia in rats, and this degeneration was associated with the activation of spinal N-methyl-D-aspartate receptors by elevation of glutamate release in cerebrospinal fluid after IT morphine. Therefore, we would like to emphasize that all anesthesiologists should be aware of the possibility of morphine-induced paraplegia after thoracic aortic surgery and that we should carefully select appropriate analgesic agents from the several available opioids for these patients.

Extract EGb 761 pretreatment limits ubiquitin positive aggregates in rabbit spinal cord neurons after ischemia-reperfusion.

1. Ubiquitin immunohistochemistry was used for investigation of time dependent changes of ubiquitin in the nerve cells reacting to ischemic/reperfusion damage. In the rabbit spinal cord ischemia model a period of 30 min ischemia followed by 24 and 72 h of reperfusion caused neuronal degeneration selectively in the ventral horn motor neurons as well as interneurons of the intermediate zone. 2. Ubiquitin aggregates were accumulated in the neurons of lamina IX and the neurons of intermediate zone destined to die 72 h after 30 min of the spinal cord ischemia. 3. The activation of ubiquitin hydrolytic system is related to a defective homeostasis and could trigger different degenerative processes. Having in mind this, we used EGb 761 to rescue the motor neurons and interneurons against ischemia/reperfusion damage. Our results show that after 30 min of ischemia and 24 or 72 h of reperfusion with EGb 761 pre-treatment for 7 days the vulnerable neurons in the intermediate zone and lamina IX exhibit marked elevation of ubiquitin-positive granules in the cytoplasm, dendrites and nuclei. Abnormal protein aggregates have not been observed in these cells. 4. The rabbits were completely paraplegic after 30 min of ischemia and 24 or 72 h of reperfusion. However, after 7 days EGb 761 pre-treatment, 30 min of ischemia and 24 or 72 h of reperfusion the animals did not show paraplegia. 5. Evaluated ubiquitin-positive neurons of the L(5)-L(6) segments showed significant decrease in number and significant increase of density after 30 min of ischemia followed by 24 h and mainly 72 h of reperfusion. Ubiquitin immunohistochemistry confirmed the protective effect of EGb 761 against ischemia/reperfusion damage in the rabbit spinal cord.

Intra-aortic injection of propofol prevents spinal cord injury during aortic surgery.

OBJECTIVE: We investigated whether propofol, a widely used anesthetic, injected into clamped aortic segments quickly attenuated transcranial spinal motor-evoked potential (MEP) amplitudes and protected against spinal cord injury during thoracoabdominal aortic surgery. METHODS: Eighteen beagle dogs were divided into three groups (n=6, each group): group 1 (20 ml of saline, intra-aortic injection), group 2 (1.5 mg/kg of propofol, intravenous injection), and group 3 (1.5 mg/kg of propofol, intra-aortic injection). Aortic cross-clamping was performed for 30 min. In each group, MEP amplitudes were recorded before, during, and after aortic cross-clamping. Tarlov score and histopathological examination were used to evaluate the protective effects of intra-aortic propofol injections. RESULTS: MEP amplitudes in group 3 attenuated to a value that was 60% of the control in just a minute after aortic cross-clamping, but maintained 40% of the control value during aortic cross-clamping. However, MEP amplitudes in groups 1 and 2 gradually attenuated and almost disappeared. Groups 1 and 2 amplitudes were lower than those in group 3, 30 min after aortic cross-clamping (p<0.001). Twenty-four hours after ischemia, the Tarlov score in group 3 was 3.5+/-0.5 and was higher than scores from groups 1 and 2, which were 0.5+/-0.5 and 1.3+/-1.2 (mean+/-SD, p<0.001, and p<0.001), respectively. Histopathologically, normal spinal cord motor neurons in group 3 were preserved to a significantly greater extent than in groups 1 and 2 (p=0.0031, and p=0.0282, respectively). There was a strong correlation between Tarlov scores at 24h and the number of normal motor neurons in the anterior horns of spinal cords (r=0.897; p<0.001). CONCLUSIONS: Intra-aortic propofol injections produce the quick suppression of MEP amplitudes and protect spinal cords from ischemia during aortic cross-clamping.

Hyperbaric oxygen preconditioning induces tolerance against spinal cord ischemia by upregulation of antioxidant enzymes in rabbits.

The present study examined the hypothesis that spinal cord ischemic tolerance induced by hyperbaric oxygen (HBO) preconditioning is triggered by an initial oxidative stress and is associated with an increase of antioxidant enzyme activities as one effector of the neuroprotection. New Zealand White rabbits were subjected to HBO preconditioning, hyperbaric air (HBA) preconditioning, or sham pretreatment once daily for five consecutive days before spinal cord ischemia. Activities of catalase (CAT) and superoxide dismutase were increased in spinal cord tissue in the HBO group 24 h after the last pretreatment and reached a higher level after spinal cord ischemia for 20 mins followed by reperfusion for 24 or 48 h, in comparison with those in control and HBA groups. The spinal cord ischemic tolerance induced by HBO preconditioning was attenuated when a CAT inhibitor, 3-amino-1,2,4-triazole,1 g/kg, was administered intraperitoneally 1 h before ischemia. In addition, administration of a free radical scavenger, dimethylthiourea, 500 mg/kg, intravenous, 1 h before each day's preconditioning, reversed the increase of the activities of both enzymes in spinal cord tissue. The results indicate that an initial oxidative stress, as a trigger to upregulate the antioxidant enzyme activities, plays an important role in the formation of the tolerance against spinal cord ischemia by HBO preconditioning.

Neuroprotective effect of epidural electrical stimulation against ischemic spinal cord injury in rats: electrical preconditioning.

BACKGROUND: Electroconvulsion therapy is likely to serve as an effective preconditioning stimulus for inducing tolerance to ischemic brain injury. The current study examines whether electrical stimuli on the spinal cord is also capable of inducing tolerance to ischemic spinal cord injury by transient aortic occlusion. METHODS: Spinal cord ischemia was induced by occlusion of the descending thoracic aorta in combination with maintaining systemic hypotension (40 mmHg) during the procedure. Animals implanted with epidural electrodes were divided into four groups according to electrical stimulation and sham. Two groups consisted of rapid preconditioning (RE group, n = 8) and sham procedure (RC group, n = 8) 30 min before 9 min of spinal cord ischemia. In the two groups that underwent delayed preconditioning, rats were exposed to 9 min of aortic occlusion 24 h after either pretreatment with epidural electrical stimulation (DE group, n = 8) or sham (DC group, n = 8). In addition, rats were exposed to 6-11 min of spinal cord ischemia at 30 min or 24 h after epidural electrical stimulation or sham stimulation. The group P50 represents the duration of spinal cord ischemia associated with 50% probability of resultant paraplegia. RESULTS: Pretreatment with electrical stimulation in the DE group but not the RE group protected the spinal cord against ischemia, and this stimulation prolonged the P50 by approximately 15.0% in the DE group compared with the DC group. CONCLUSIONS: Although the optimal setting for this electrical preconditioning should be determined in future studies, the results suggest that epidural electrical stimulation will be a useful approach to provide spinal protection against ischemia.

Preoperative stress conditioning prevents paralysis after experimental aortic surgery: increased heat shock protein content is associated with ischemic tolerance of the spinal cord.

BACKGROUND: All forms of surgical therapy are stressful and injurious. The problems of paralysis, renal dysfunction, and colonic ischemia associated with aortic occlusion are due to acute ischemia-reperfusion injury at the cellular level. Acute-anterior spinal cord ischemia is the most devastating outcome of these iatrogenic-ischemic events. The majority of surgical procedures are performed electively and therefore provide an opportunity to preoperatively condition the patient to minimize these ischemia-related morbidities. OBJECTIVES: We sought to determine whether acute spinal cord injury associated with aortic occlusion can be prevented by induction of the cellular stress response by means of preoperative administration of whole-body hyperthermia or stannous chloride. METHODS: The study consisted of an experimental rabbit model of infrarenal aortic occlusion for 20 minutes at normothermic body temperature. RESULTS: Control rabbits experienced an 88% (7/8) incidence of paralysis after spinal cord ischemia induced by 20 minutes of aortic occlusion, whereas animals treated preoperatively with either whole-body hyperthermia (0/9) or stannous chloride (0/4) never became paralyzed (P <.001 for control vs treated groups). Ischemic protection of the spinal cord was associated with increased content of stress proteins within tissues of pretreated animals. CONCLUSION: Prior induction of the heat shock response in the whole animal will increase the content of stress proteins within the spinal cord and other tissues and result in the prevention of hind-limb paralysis associated with aortic occlusion. We have designated the preoperative induction of the cellular stress response for the prevention of ischemic tissue injury stress conditioning. We suggest that stress-conditioning protocols represent the opportunity to practice preventative medicine at the molecular level.

Adenovirus-mediated glial cell line-derived neurotrophic factor gene delivery reduces motor neuron injury after transient spinal cord ischemia in rabbits.

OBJECTIVE: Glial cell line-derived neurotrophic factor (GDNF) has protective effects on various injuries involving the central and peripheral nervous systems in vitro and vivo. However, the possible protective effect of GDNF on spinal cord ischemia and the exact mechanism involved in the ameliorative effect of GDNF on ischemic spinal cord injuries are not fully understood. Therefore, we investigated the possible protective effect of the adenovirus-mediated GDNF gene delivery on transient spinal cord ischemia in rabbits. METHODS: The adenoviral vector (lacZ gene as a control or GDNF gene contained) was injected directly into the lumbar spinal cord via a needle inserted into the dorsal spine 2 days before the animal was subjected to 15 minutes of spinal cord ischemia induced by infrarenal aortic occlusion. In situ terminal deoxynucleotidyl transferase (TdT)-mediated dUTP-biotin nick-end labeling (TUNEL staining) was performed, and temporal profiles of the GDNF and caspase-3 (caspase-3 is the marker of apoptotic change) immunoreactivity were investigated. RESULTS: In the control rabbit, the majority of motor neurons showed selective cell death at 7 days of reperfusion. Immunocytochemistry showed that in situ TUNEL staining was selectively detected at 2 days of reperfusion in motor neuron nuclei. GDNF and caspase-3 were selectively induced in the motor neuron cells at 8 hours of reperfusion. In the GDNF-treated group, a large population of motor neuron cells was still surviving at 7 days after having been subjected to 15 minutes of ischemia. Unlike the control group, the GDNF-treated group expressed GDNF persistently. Induction of TUNEL staining and immunoreactivity for caspase-3 were greatly reduced by the GDNF treatment. CONCLUSION: These results suggest that the reduction in motor neuron death by GDNF was greatly associated with a reduction in DNA fragmentation and apoptotic signals of the caspase-3 cascade; they further suggest a great potential for gene therapy for paraplegic patients in the future.