Transposition versus interposition method in microvascular decompression for trigeminal neuralgia: midterm analysis of both techniques in a single-center study

OBJECTIVE

Operative interposition of material between the trigeminal nerve and offending artery for surgical treatment of drug-resistant trigeminal neuralgia (TGN), following the Jannetta method, has been proven to be the most successful invasive treatment. Reexplorations of patients with recurrence of TGN have revealed nerve root irritations and scarring due to interposed material. To prevent these complications, modifications of microvascular decompression (MVD) aim at transposing the vessel away from the trigeminal nerve, without attachment of additional material to the nerve root. Given that both techniques (interposition and transposition) have been performed in the authors' institution, they decided to analyze them for the short- and midterm outcomes.

METHODS

All patients who had undergone MVD for drug-resistant TGN in the authors' institution between 2008 and 2022 were analyzed retrospectively. Outcome at discharge and follow-up was evaluated using the Barrow Neurological Institute pain intensity score. Additionally, complications and pain recurrence were assessed.

RESULTS

A total of 114 patients were operated on using transposition and 110 patients were treated using interposition. For transposition 102 patients were followed up for a median of 31.5 months, and for interposition 100 patients were followed up for a median of 95 months. At discharge 92.1% versus 94.5% of patients in the transposition and interposition groups, respectively, experienced a good outcome (Barrow Neurological Institute pain intensity scores I-III). At follow-up, 83.3% versus 85% of patients in the transposition and interposition groups, respectively, continued to demonstrate a good outcome. In 4.9% of patients in the transposition group and in 6% of patients in the interposition group, recurrence of pain occurred. Complications occurred in 24.6% of patients in the transposition and in 27.3% of those in the interposition group. The most frequent complications were facial hypesthesia (10.5% vs 11.8%, transposition vs interposition), followed by CSF leaks (2.6% vs 8.2%).

CONCLUSIONS

Transposition for MVD is an elegant way of solving vessel-nerve conflicts at the cerebellopontine angle. Similar to interposition, transposition shows positive short- and midterm outcomes for patients experiencing drug-resistant TGN. However, the main objective of transposition, which is improved prevention of recurrence and reduction of complications at the trigeminal nerve, could not be confirmed in this study.

White Matter Tract Density Index Prediction Model of Overall Survival in Glioblastoma

Importance

The prognosis of overall survival (OS) in patients with glioblastoma (GBM) may depend on the underlying structural connectivity of the brain.

Objective

To examine the association between white matter tracts affected by GBM and patients' OS by means of a new tract density index (TDI).

Design, Setting, and Participants

This prognostic study in patients with a histopathologic diagnosis of GBM examined a discovery cohort of 112 patients who underwent surgery between February 1, 2015, and November 30, 2020 (follow-up to May 31, 2023), in Italy and 70 patients in a replicative cohort (n = 70) who underwent surgery between September 1, 2012, and November 30, 2015 (follow-up to May 31, 2023), in Germany. Statistical analyses were performed from June 1, 2021, to May 31, 2023. Thirteen and 12 patients were excluded from the discovery and the replicative sets, respectively, because of magnetic resonance imaging artifacts.

Exposure

The density of white matter tracts encompassing GBM.

Main Outcomes and Measures

Correlation, linear regression, Cox proportional hazards regression, Kaplan-Meier, and prediction analysis were used to assess the association between the TDI and OS. Results were compared with common prognostic factors of GBM, including age, performance status, O6-methylguanine-DNA methyltransferase methylation, and extent of surgery.

Results

In the discovery cohort (n = 99; mean [SD] age, 62.2 [11.5] years; 29 female [29.3%]; 70 male [70.7%]), the TDI was significantly correlated with OS (r = -0.34; P < .001). This association was more stable compared with other prognostic factors. The TDI showed a significant regression pattern (Cox: hazard ratio, 0.28 [95% CI, 0.02-0.55; P = .04]; linear: t = -2.366; P = .02). and a significant Kaplan-Meier stratification of patients as having lower or higher OS based on the TDI (log-rank test = 4.52; P = .03). Results were confirmed in the replicative cohort (n = 58; mean [SD] age, 58.5 [11.1] years, 14 female [24.1%]; 44 male [75.9%]). High (24-month cutoff) and low (18-month cutoff) OS was predicted based on the TDI computed in the discovery cohort (accuracy = 87%).

Conclusions and Relevance

In this study, GBMs encompassing regions with low white matter tract density were associated with longer OS. These findings indicate that the TDI is a reliable presurgical outcome predictor that may be considered in clinical trials and clinical practice. These findings support a framework in which the outcome of GBM depends on the patient's brain organization.

TWMP-02. Supplementary motor area syndrome in glioma surgery - towards a classification system based on clinical and imaging data

OBJECTIVES

Surgical resection of gliomas involving the supplementary motor area (SMA) frequently results in a symptom complex commonly described as „SMA syndrome“, which is characterized by transient contralateral akinesia and mutism. As factors potentially influencing the severity and duration of symptoms still remain elusive, we aim to further investigate potential predictors in a multicentric cohort of glioma patients.

METHODS

Fifty patients with gliomas located in the superior frontal gyrus from 3 centers were included in this retrospective study. Patients with injury of M1 and/or the corticospinal tract were excluded. Early postoperative motor outcome, the occurrence of mutism and duration of acute symptoms in days were assessed. The long-term outcome was assessed in follow-up examinations 3 months after surgery. Atlas-based lesion-symptom mapping was performed using postoperative MR imaging estimating surgical grey matter damage as well as white matter disconnection severity. Associations between functional outcome and imaging findings were analyzed using group tests and correlation analyses.

RESULTS

Median duration of symptoms in the cohort was 3 days (range: 1 – 42 days). Persistent deficits concerning fine motor movements and speech after initial recovery were found in 27 patients (54%). Disconnection of the central segment of the corpus callosum was associated with longer symptom duration (FDR corr. p &lt; 0.05), while disconnection of the mid-posterior segment of the corpus callosum was associated with persistent deficits at follow-up (FDR corr. p &lt; 0.05).

CONCLUSIONS

The present study shows a high variability regarding the recovery time of postoperative SMA syndrome and a high prevalence of persistent deficits in fine motor movements and speech after initial recovery of acute symptoms. The pivotal role of interhemispheric connectivity in the recovery process is reinforced. These findings will help neurosurgeons in patient consultation and provide a foundation for future studies aiming to establish prediction models of the SMA syndrome.

Wound healing complications after revascularization for moyamoya vasculopathy with reference to different skin incisions

OBJECTIVEMoyamoya vasculopathy (MMV) is a steno-occlusive cerebrovascular disease that can be treated by a surgical revascularization. All the revascularization techniques influence the blood supply of the scalp, with a risk for wound healing disorders. The authors' aim was to analyze the wound healing process in the patients who underwent a direct or combined bypass surgery with a focus on different skin incisions.METHODSThe authors retrospectively identified all the patients with MMV who were treated surgically in their institution. Subsequently, they analyzed demographic data, clinical symptoms, surgical treatment, and detailed history of complications. Based on the evolution of their surgical techniques and the revascularization strategy to be used, the authors applied the following skin incisions: linear incision, curved incision, incomplete Y incision, and complete Y incision. Group comparisons regarding wound healing disorders were performed with significance testing using Fisher's exact test.RESULTSThe authors identified 172 patients with MMV (61.6% moyamoya disease, 7% unilateral moyamoya disease, 29.7% moyamoya syndrome, and 1.7% unilateral moyamoya syndrome), of whom 124 underwent bilateral operations. One-quarter of the patients were juveniles. A total of 236 hemispheres were included in the analysis, of which 27.9% were treated by a combined procedure with encephalomyosynangiosis. Overall, 5.1% major and 1.7% minor wound complications occurred. The overall wound complication rate was lower in direct revascularization compared to combined revascularization (3% vs 15.2%). The lowest incidence of wound healing disorders was found in the linear incision group for the parietal superficial temporal artery branch (1.6%), followed by the incomplete Y incision group for the frontal branch of the superficial temporal artery (3.8%) in the direct bypass group. In the combined revascularization cohort, major or minor wound disorders appeared in 14.3% and 4.8%, respectively, in the complete Y incision group and in 4.2% (for both major and minor) in the curved incision group. The complete Y incision caused significantly more wound healing disorders compared to the remaining incision types (17.1% vs 3.1%, p = 0.007).CONCLUSIONSWound healing disorders are one of the major complications of revascularization surgery. Their incidence depends on the revascularization strategy and skin incision applied, with a complete Y incision giving the worst results.

Bypass strategies for common carotid artery occlusion

BACKGROUND

Common carotid artery occlusion (CCA-occlusion) is a rare condition where standard revascularization is not feasible. Here, we analyzed our experience with surgical revascularization of CCA-occlusion to develop an algorithm for selection of the most suitable bypass strategy according to the Riles classification.

METHODS

During a 10-year period, 16 out of 288 patients with cerebrovascular disease and compromised hemodynamic reserve underwent revascularization for unilateral CCA-occlusion. The utilized bypass strategies included (1) a saphenous vein graft from the subclavian artery (SA) to the internal carotid artery (ICA), (2) a radial artery graft from the V3 segment of the vertebral artery (VA) to a superficial branch of the middle cerebral artery (MCA), or (3) a saphenous vein graft from the SA to a deep branch of the MCA.

RESULTS

In CCA-occlusion with maintained external carotid artery (ECA)/ICA patency (Riles type 1A), an SA-ICA bypass was performed (25%). In cases without ECA/ICA patency (Riles type 1B or 2) but suitable VA, a VA-MCA bypass was grafted (31%). In cases with unsuitable VA, a long SA-MCA interposition bypass was performed (38%). Transient postoperative neurological deficits occurred in 5 patients (31%) with 1 patient (6%) suffering permanent neurological worsening and 1 mortality (6%). Overall, no difference was found between the median preoperative mRS (2; range, 1-4) and the mRS at the time point of the last follow-up (2; range, 1-6; p = 0.75). The long-term graft patency was 94%.

CONCLUSIONS

Although surgical revascularization for CCA-occlusion is feasible, it is associated with a higher risk than standard bypass grafting. Considering the poor natural history of CCA-occlusion, however, this risk may be justified in carefully selected patients.

Manual for clinical language tractography

Background

We introduce a user-friendly, standardized protocol for tractography of the major language fiber bundles.

Method

The introduced method uses dMRI images for tractography whereas the ROI definition is based on structural T1 MPRAGE MRI templates, without normalization to MNI space. ROIs for five language-relevant fiber bundles were visualized on an axial, coronal, or sagittal view of T1 MPRAGE images. The ROIs were defined based upon the tracts’ obligatory pathways, derived from literature and own experiences in peritumoral tractography.

Results

The resulting guideline was evaluated for each fiber bundle in ten healthy subjects and ten patients by one expert and three raters.

Overall, 300 ROIs were evaluated and compared. The targeted language fiber bundles could be tracked in 88% of the ROI pairs, based on the raters’ result blinded ROI placements. The evaluation indicated that the precision of the ROIs did not relate to the varying experience of the raters.

Conclusions

Our guideline introduces a standardized language tractography method for routine preoperative workup and for research contexts. The ROI placement guideline based on easy-to-identify anatomical landmarks proved to be user-friendly and accurate, also in inexperienced test persons.

Hangman's Fracture Caused by Parachute Opening Deceleration Captured on Video

BACKGROUND

Nonlethal cervical spine injuries in skydiving are rare due to the associated high mortality. Here, we report an unusual pathomechanism leading to a Hangman fracture in a semiprofessional parachute athlete.

CASE DESCRIPTION

The moment of injury was captured on a first-person video and identified as a rough parachute opening deceleration during canopy deployment, caused by failure of the parachute inflation control device. Fractures of the C2 pars interarticularis with C2/C3 instability were treated by anterior cervical diskectomy and fusion, and the patient reached full recovery.

CONCLUSIONS

Excessive deceleration during canopy deployment may pose a risk for life-threatening cervical spine injuries in skydiving.