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Bob S. Carter

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Jens Rachinger, Stefan Rampp, Julian Prell, Christian Scheller, Alex Alfieri, and Christian Strauss

Object

Preservation of cochlear nerve function in vestibular schwannoma (VS) removal is usually dependent on tumor size and preoperative hearing status. Tumor origin as an independent factor has not been systematically investigated.

Methods

A series of 90 patients with VSs, who underwent surgery via a suboccipitolateral route, was evaluated with respect to cochlear nerve function, tumor size, radiological findings, and intraoperatively confirmed tumor origin. All patients were reevaluated 12 months after surgery.

Results

Despite comparable preoperative cochlear nerve status and larger tumor sizes, hearing preservation was achieved in 42% of patients with tumor originating from the superior vestibular nerve, compared with 16% of those with tumor originating from the inferior vestibular nerve.

Conclusions

Tumor origin is an important prognostic factor for cochlear nerve preservation in VS surgery.

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Christian Scheller, Jens Rachinger, Julian Prell, Malte Kornhuber, and Christian Strauss

The intermediate nerve is seldom identified as the site of tumor origin in cerebellopontine angle schwannomas. A 29-year-old man presented with a 6-month history of slowly progressive hearing loss and dizziness; facial nerve weakness was not observed clinically. Magnetic resonance imaging revealed a tumor in the left cerebellopontine angle region extending up to the geniculate ganglion and along the course of the superficial petrosal nerve. A CT scan showed enlargement of the facial nerve canal. Microsurgery was performed via an extended retrosigmoid approach. Intraoperative and electrophysiological findings identified the intermediate nerve as the site of tumor origin.

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Julian Prell, Grit Schenk, Bettina-Maria Taute, Christian Scheller, Christian Marquart, Christian Strauss, and Stefan Rampp

OBJECTIVE

The term “venous thromboembolism” (VTE) subsumes deep venous thrombosis (DVT) and pulmonary embolism. The incidence of DVT after craniotomy was reported to be as high as 50%. Even clinically silent DVT may lead to potentially fatal pulmonary embolism. The risk of VTE is correlated with duration of surgery, and it appears likely that it develops during surgery. The present study aimed to evaluate intraoperative use of intermittent pneumatic compression (IPC) of the lower extremity for prevention of VTE in patients undergoing craniotomy.

METHODS

A total of 108 patients undergoing elective craniotomy for intracranial pathology were included in a single-center controlled randomized prospective study. In the control group, conventional compression stockings were worn during surgery. In the treatment group, IPC of the calves was used in addition. The presence of DVT was evaluated by Doppler sonography pre- and postoperatively.

RESULTS

Intraoperative use of IPC led to a significant reduction of VTE (p = 0.029). In logistic regression analysis, the risk of VTE was approximately quartered by the use of IPC. Duration of surgery was confirmed to be correlated with VTE incidence (p < 0.01); every hour of surgery increased the risk by a factor of 1.56.

CONCLUSIONS

Intraoperative use of IPC significantly lowers the incidence of potentially fatal VTE in patients undergoing craniotomy. The method is easy to use and carries no additional risks.

■ CLASSIFICATION OF EVIDENCE Type of question: therapeutic; study design: randomized controlled trial; evidence: class I.

Clinical trial registration no.: DRKS00011783 (https://www.drks.de)

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Julian Prell, Stefan Rampp, Jens Rachinger, Christian Scheller, Alex Alfieri, Liane Marquardt, Christian Strauss, and Viktoria Bau

Object

High-grade postoperative facial nerve paresis after surgery for vestibular schwannoma with insufficient eye closure involves a risk for severe ocular complications. When conservative measurements are not sufficient, conventional invasive treatments include tarsorrhaphy and eyelid loading. In this study, injection of botulinum toxin into the levator palpebrae muscle was investigated as an alternative for temporary iatrogenic eye closure.

Methods

Injection of botulinum toxin was indicated by an interdisciplinary decision (neurosurgery and ophthalmology) in patients with a postoperative facial nerve paresis corresponding to a House-Brackmann Grade of IV or greater and documented abnormalities concerning corneal status such as keratopathia or conjunctival redness. Twenty-five IUs of botulinum toxin were injected transcutaneously and transconjunctivally.

Results

Six of 11 patients with high-grade paresis showed abnormal corneal findings in the early postoperative period. In 4 of these patients, botulinum toxin was injected; 1 patient declined the treatment, and in 1 patient it was not performed because of contralateral blindness. Temporary eye closure was achieved for 2 to 6 months in all cases. In all cases, facial nerve function had recovered sufficiently in terms of eye closure when the effect of botulinum toxin subsided.

Conclusion

The application of botulinum toxin for temporary iatrogenic eye closure is an excellent low-risk and temporary alternative to other invasive measures for the treatment of postoperative high-grade facial nerve paresis when the facial nerve is anatomically intact.

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Stefan Rampp, Christian Scheller, Julian Prell, Tobias Engelhorn, Christian Strauss, and Jens Rachinger

Object

Efficacy of radiosurgery in vestibular schwannoma (VS) is usually documented by changes of tumor size and by loss of contrast enhancement in MR imaging within the central portion of the lesion. Until now, however, correlation between contrast enhancement and timing of image acquisition in nontreated VS has not been analyzed systematically. The authors undertook this study to investigate changes in contrast enhancement with respect to latency of image acquisition after contrast agent administration.

Methods

The dynamics of contrast medium uptake were evaluated with T1-weighted VIBE MR imaging sequences performed immediately and 1.5, 3.5, 4.5, 9.5, and 11.5 minutes after administration of single dose of Gd in 21 patients with nontreated medium- to large-sized VSs. Signal-to-noise (SNR) and contrast-to-noise ratio (CNR) of tumors were evaluated, and volumes of central nonenhancing areas (NEAs) were determined.

Results

The interior appearance of the tumors changed considerably over time. The NEA significantly diminished in size (p < 0.0001, Friedman test) and almost completely disappeared in all but 2 patients. Compared to images at 1.5 minutes, NEA volumes decreased to a median of 36% at 3.5 minutes and 34% at 4.5 minutes, showing smaller changes after that—9% at 9.5 minutes and 3% at 11.5 minutes. Tumor SNR and CNR increased over time. The maximum change in the median values for SNR and CNR were a 72% increase and 117% increase, respectively; both occurred at 1.5 minutes after Gd administration.

Conclusions

Contrast enhancement in VS MR imaging varies according to the duration of the delay between contrast agent administration and image acquisition. Postradiotherapy changes in contrast enhancement of VS can therefore not be attributed only to effective radiotherapy. So-called “loss of central contrast enhancement” may be falsely detected because of timing. A standardized protocol with defined timing of image acquisition may increase comparability of contrast uptake in VS.

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Maximilian Scheer, Bruno Griesler, Elisabeth Ottlik, Christian Strauss, Christian Mawrin, Christian Kunze, Julian Prell, Stefan Rampp, Sebastian Simmermacher, Jörg Illert, Heike Kielstein, and Christian Scheller

OBJECTIVE

The background for this investigation was the dramatic course of a 14-year-old girl with a spontaneous hemorrhage in the area of the conus medullaris resulting in a complete cross-sectional syndrome with bladder and bowel dysfunction. Despite immediate surgical treatment, the patient showed close to no postoperative improvement. Subsequent histopathological examination of the removed masses revealed a cavernoma. To better understand the link between the site and symptoms of conus medullaris lesions, the authors performed a literature search and then histological examination of the conus medullaris of 18 cadaveric specimens from body donors.

METHODS

After a literature search regarding the histological features of the structure of the conus medullaris did not lead to satisfying results, the authors performed histological examination of the conus medullaris in 18 cadaveric specimens from body donors. The largest (a) and smallest (b) diameters of the conus medullaris were measured, noting individual variations in the distance from the caudal ending of the gray matter to the macroscopically visible end of the conus medullaris. Correlations of these differences with sex, body height, gray matter transverse diameter, and cross-sectional area at the end of the gray matter were analyzed.

RESULTS

Gray matter displayed in the form of a butterfly figure was found along almost the entire length of the conus medullaris. The specific slide containing the end of the gray matter was noted. The distance between the caudal ending of the gray matter in the conus and the macroscopical end of the conus medullaris was defined as the gray matter to cone termination (GMCT) distance. There were great individual variations in the distance from the caudal ending of the gray matter to the macroscopically visible end of the conus medullaris. Analysis of the correlations of these differences with sex, body height, gray matter transverse diameter, and cross-sectional area at the end of the gray matter showed no significant sex-specific differences in the GMCT distance. Patient body height and transverse diameter at the end of the gray matter were found to be correlated positively with the GMCT distance. Moreover, greater height also correlated positively with the cross-sectional area at the end of the gray matter.

CONCLUSIONS

This report is, to the authors’ knowledge, the first published description of the histological structure of the conus medullaris and can serve as the basis for a better understanding of neurological deficits in patients with a conus medullaris syndrome. Findings that gray matter can be detected far into the conus medullaris, with large individual differences in the endpoint of the gray matter, are important for operative care of intramedullary masses and vascular malformations in this area. It is therefore important to use electrophysiological monitoring during these operations.

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Maximilian Scheer, Bruno Griesler, Elisabeth Ottlik, Christian Strauss, Christian Mawrin, Christian Kunze, Julian Prell, Stefan Rampp, Sebastian Simmermacher, Jörg Illert, Heike Kielstein, and Christian Scheller

OBJECTIVE

The background for this investigation was the dramatic course of a 14-year-old girl with a spontaneous hemorrhage in the area of the conus medullaris resulting in a complete cross-sectional syndrome with bladder and bowel dysfunction. Despite immediate surgical treatment, the patient showed close to no postoperative improvement. Subsequent histopathological examination of the removed masses revealed a cavernoma. To better understand the link between the site and symptoms of conus medullaris lesions, the authors performed a literature search and then histological examination of the conus medullaris of 18 cadaveric specimens from body donors.

METHODS

After a literature search regarding the histological features of the structure of the conus medullaris did not lead to satisfying results, the authors performed histological examination of the conus medullaris in 18 cadaveric specimens from body donors. The largest (a) and smallest (b) diameters of the conus medullaris were measured, noting individual variations in the distance from the caudal ending of the gray matter to the macroscopically visible end of the conus medullaris. Correlations of these differences with sex, body height, gray matter transverse diameter, and cross-sectional area at the end of the gray matter were analyzed.

RESULTS

Gray matter displayed in the form of a butterfly figure was found along almost the entire length of the conus medullaris. The specific slide containing the end of the gray matter was noted. The distance between the caudal ending of the gray matter in the conus and the macroscopical end of the conus medullaris was defined as the gray matter to cone termination (GMCT) distance. There were great individual variations in the distance from the caudal ending of the gray matter to the macroscopically visible end of the conus medullaris. Analysis of the correlations of these differences with sex, body height, gray matter transverse diameter, and cross-sectional area at the end of the gray matter showed no significant sex-specific differences in the GMCT distance. Patient body height and transverse diameter at the end of the gray matter were found to be correlated positively with the GMCT distance. Moreover, greater height also correlated positively with the cross-sectional area at the end of the gray matter.

CONCLUSIONS

This report is, to the authors’ knowledge, the first published description of the histological structure of the conus medullaris and can serve as the basis for a better understanding of neurological deficits in patients with a conus medullaris syndrome. Findings that gray matter can be detected far into the conus medullaris, with large individual differences in the endpoint of the gray matter, are important for operative care of intramedullary masses and vascular malformations in this area. It is therefore important to use electrophysiological monitoring during these operations.

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Julian Prell, Jens Rachinger, Robert Smaczny, Bettina-Maria Taute, Stefan Rampp, Joerg Illert, Gershom Koman, Christian Marquart, Alexandra Rachinger, Sebastian Simmermacher, Alex Alfieri, Christian Scheller, and Christian Strauss

Object

The incidence of deep venous thrombosis (DVT) after craniotomy is reported to be as high as 50%. In outpatients, D-dimer levels of more than 0.5 mg/L indicate venous thromboembolism (VTE, which subsumes DVT and pulmonary embolism [PE]) with a sensitivity of 99.4% and a specificity of 38.2%. However, D-dimer levels are believed to be unreliable in postoperative patients. The authors undertook the present study to test the hypothesis that D-dimer levels would be systematically raised in a postoperative population and to define a feasible threshold for identification of VTE.

Methods

Doppler ultrasonography of the lower extremity was performed pre- and postoperatively to evaluate for DVT in 101 patients who underwent elective craniotomy. D-dimer levels were assessed preoperatively and on the 3rd, 7th, and 10th days after surgery. Statistical analysis was carried out to define a feasible threshold for D-dimer levels.

Results

D-dimer plasma levels were found to be systematically raised postoperatively, and they differed between patients with and without VTE in a highly significant way. On the 3rd day after surgery, D-dimer levels of more than 2 mg/L indicated VTE with a sensitivity of 95.3% and a specificity of 74.1%, allowing for the definition of a feasible threshold. D-dimer levels of more than 4 mg/L were observed in all patients who had PE during the postoperative period (n = 9). Ventilation time and duration of surgery were identified as highly significant risk factors for the development of VTE.

Conclusions

Using a threshold of 2 mg/L, D-dimer levels will indicate VTE with a high degree of sensitivity and specificity in patients who have undergone craniotomy. Pulmonary embolism seems to be indicated by even higher D-dimer levels. Given that the development of D-dimer plasma levels in the postoperative period follows a principle that can be predicted and that deviations from it indicate VTE, this principle might be applicable to other types of surgery.

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Christian Scheller, Stefan Rampp, Marcos Tatagiba, Alireza Gharabaghi, Kristofer F. Ramina, Oliver Ganslandt, Barbara Bischoff, Cordula Matthies, Thomas Westermaier, Maria Teresa Pedro, Veit Rohde, Kajetan von Eckardstein, and Christian Strauss

OBJECTIVE

Patient positioning in vestibular schwannoma (VS) surgery is a matter of ongoing discussion. Factors to consider include preservation of cranial nerve functions, extent of tumor resection, and complications. The objective of this study was to determine the optimal patient positioning in VS surgery.

METHODS

A subgroup analysis of a randomized, multicenter trial that investigated the efficacy of prophylactic nimodipine in VS surgery was performed to investigate the impact of positioning (semisitting or supine) on extent of resection, functional outcomes, and complications. The data of 97 patients were collected prospectively. All procedures were performed via a retrosigmoid approach. The semisitting position was chosen in 56 patients, whereas 41 patients were treated while supine.

RESULTS

Complete resection was obtained at a higher percentage in the semisitting as compared to the supine position (93% vs 73%, p = 0.002). Logistic regression analysis revealed significantly better facial nerve function in the early postoperative course in the semisitting group (p = 0.004), particularly concerning severe facial nerve paresis (House-Brackmann grade IV or worse; p = 0.002). One year after surgery, facial nerve function recovered. However, there was still a tendency for better facial nerve function in the semisitting group (p = 0.091). There were no significant differences between groups regarding hearing preservation rates. Venous air embolism with the necessity to terminate surgery occurred in 2 patients in the semisitting position (3.6%). Supplementary analysis with a 2-tailed permutation randomization with 10,000 permutations of treatment choice and a propensity score matching showed either a tendency or significant results for better facial nerve outcomes in the early postoperative course and extent of resection in the semisitting group.

CONCLUSIONS

Although the results of the various statistical analyses are not uniform, the data indicate better results concerning both a higher rate of complete removal (according to the intraoperative impression of the surgeon) and facial nerve function after a semisitting as compared to the supine position. These advantages may justify the potential higher risk for severe complications of the semisitting position in VS surgery. The choice of positioning has to consider all individual patient parameters and risks carefully.