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Arthur Hosmann, Carmen Angelmayr, Andreas Hopf, Steffen Rauscher, Jonas Brugger, Lavinia Ritscher, Isabelle Bohl, Philipp Schnackenburg, Adrian Engel, Walter Plöchl, Markus Zeitlinger, Andrea Reinprecht, Karl Rössler, and Andreas Gruber

OBJECTIVE

Intrahospital transport for CT scans is routinely performed for neurosurgical patients. Particularly in the sedated and mechanically ventilated patient, intracranial hypertension and blood pressure fluctuations that might impair cerebral perfusion are frequently observed during these interventions. This study quantifies the impact of intrahospital patient transport on multimodality monitoring measurements, with a particular focus on cerebral metabolism.

METHODS

Forty intrahospital transports in 20 consecutive patients suffering severe aneurysmal subarachnoid hemorrhage (SAH) under continuous intracranial pressure (ICP), brain tissue oxygen tension (pbtO2), and cerebral microdialysis monitoring were prospectively included. Changes in multimodality neuromonitoring data during intrahospital transport to the CT scanner and the subsequent 10 hours were evaluated using linear mixed models. Furthermore, the impact of risk factors at transportation, such as cerebral vasospasm, cerebral hypoxia (pbtO2 < 15 mm Hg), metabolic crisis (lactate-pyruvate ratio [LPR] > 40), and transport duration on cerebral metabolism, was analyzed.

RESULTS

During the transport, the mean ICP significantly increased from 7.1 ± 3.9 mm Hg to 13.5 ± 6.0 mm Hg (p < 0.001). The ICP exceeded 20 mm Hg in 92.5% of patients; pbtO2 showed a parallel rise from 23.1 ± 13.3 mm Hg to 28.5 ± 23.6 mm Hg (p = 0.02) due to an increase in the fraction of inspired oxygen during the transport. Both ICP and pbtO2 returned to baseline values thereafter. Cerebral glycerol significantly increased from 71.0 ± 54.9 µmol/L to 75.3 ± 56.0 µmol/L during the transport (p = 0.01) and remained elevated for the following 9 hours. In contrast, cerebral pyruvate and lactate levels were stable during the transport but showed a significant secondary increase 1–8 hours and 2–9 hours, respectively, thereafter (p < 0.05). However, the LPR remained stable over the entire observation period. Patients with extended transport duration (more than 25 minutes) were found to have significantly higher levels of cerebral pyruvate and lactate as well as lower glutamate concentrations in the posttransport period.

CONCLUSIONS

Intrahospital transport and horizontal positioning during CT scans induce immediate intracranial hypertension and an increase in cerebral glycerol, suggesting neuronal injury. Afterward, sustained impairment of neuronal metabolism for several hours could be observed, which might increase the risk of secondary ischemic events. Therefore, intrahospital transport for neuroradiological imaging should be strongly reconsidered and only indicated if the expected benefit of imaging results outweighs the risks of transportation.

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Matthias Millesi, Barbara Kiesel, Vanessa Mazanec, Lisa I. Wadiura, Adelheid Wöhrer, Johannes Herta, Stefan Wolfsberger, Klaus Novak, Julia Furtner, Karl Rössler, Engelbert Knosp, and Georg Widhalm

OBJECTIVE

Gross-total resection (GTR) is the treatment of choice in the majority of patients suffering from spinal ependymal tumors. In such tumors, the extent of resection (EOR) is considered the key factor for tumor recurrence and thus patient prognosis. However, incomplete resection is not uncommon and leads to increased risk of tumor recurrence. One important cause of incomplete resection is insufficient intraoperative visualization of tumor tissue as well as residual tumor tissue. Therefore, the authors investigated the value of 5-aminolevulinic acid (5-ALA)–induced fluorescence in a series of spinal ependymal tumors for improved tumor visualization.

METHODS

Adult patients who underwent preoperative 5-ALA administration and surgery for a spinal ependymal tumor were included in this study. For each tumor, a conventional white-light microsurgical resection was performed. Additionally, the fluorescence status (strong, vague, or no fluorescence) and fluorescence homogeneity (homogenous or inhomogeneous) of the spinal ependymal tumors were evaluated during surgery using a modified neurosurgical microscope. In intramedullary tumor cases with assumed GTR, the resection cavity was investigated for potential residual fluorescing foci under white-light microscopy. In cases with residual fluorescing foci, these areas were safely resected and the corresponding samples were histopathologically screened for the presence of tumor tissue.

RESULTS

In total, 31 spinal ependymal tumors, including 27 intramedullary tumors and 4 intradural extramedullary tumors, were included in this study. Visible fluorescence was observed in the majority of spinal ependymal tumors (n = 25, 81%). Of those, strong fluorescence was noted in 23 of these cases (92%), whereas vague fluorescence was present in 2 cases (8%). In contrast, no fluorescence was observed in the remaining 6 tumors (19%). Most ependymal tumors demonstrated an inhomogeneous fluorescence effect (17 of 25 cases, 68%). After assumed GTR in intramedullary tumors (n = 15), unexpected residual fluorescing foci within the resection cavity could be detected in 5 tumors (33%). These residual fluorescing foci histopathologically corresponded to residual tumor tissue in all cases.

CONCLUSIONS

This study indicates that 5-ALA fluorescence makes it possible to visualize the majority of spinal ependymal tumors during surgery. Unexpected residual tumor tissue could be detected with the assistance of 5-ALA fluorescence in approximately one-third of analyzed intramedullary tumors. Thus, 5-ALA fluorescence might be useful to increase the EOR, particularly in intramedullary ependymal tumors, in order to reduce the risk of tumor recurrence.