Novel Myocutaneous Hemicraniectomy Flap: Technical Note and Cadaveric Dissection Using the “Feng-Huang Technique”

Background: The hemicraniectomy is a common technique used in a variety of pathologies including some traumatic brain injury and malignant stroke. A novel technique of performing hemicraniectomies using a retro-auricular incision can avoid transgressing the temporalis muscle and superficial temporal artery while providing adequate hemicranial exposure. Method: This technique was reproduced in a skull base lab using a cadaveric head. The key steps of this approach were illustrated in step-by-step fashion. A post-approach CT scan of the cadaver was performed to evaluate the decompression exposure. Results: This approach is able to provide sufficient middle fossa decompression and area of exposure, while preserving the temporalis along with the superficial temporal artery. Conclusions: The altered retro-auricular flap (the “Feng-Huang” flap) is a novel technique for hemicraniectomy which can provide sufficient middle fossa decompression and exposure while sparing the temporalis muscle and superficial temporal artery during the approach. A step-by-step technical illustration is demonstrated in the present note.

A Comprehensive Approach To Alloplastic Cranioplasty: Novel Implant Design And Refinement of Soft Tissue Management

Background: Large scale craniectomy defects are commonly reconstructed with alloplastic implants, which can restore brain protection and promote cosmesis. However, esthetic outcomes can be subpar due to skin contour abnormalities and temporal hollowing. Herein we describe a senior craniofacial surgeon’s experience using a custom composite polyetheretherketone (PEEK) and porous polyethylene (Medpor) implant for alloplastic cranioplasty. Methods: A retrospective review was conducted of all PEEK-Medpor cranioplasty cases performed over the past 2 years. Patient characteristics, intraoperative information, surgical outcomes, and cosmetic outcomes were reviewed. Results: Sixteen patients (18-70 years of age) underwent surgery. Indications for cranioplasty included craniectomy due to trauma, stroke, or tumor, and bone resorption after a prior autologous cranioplasty. Augmentation of the temporalis area using alloderm or a muscle graft was performed in 7 cases. There were no intraoperative complications. Ultimately, all implants were maintained. One implant was temporarily removed due to infection, but successfully replaced. Three minor complications occurred. At an average follow-up of 9 months, 93.8% of surgical sites showed no significant temporal hollow. Conclusion: We describe a series of 16 implants using a composite PEEK Medpor implant for alloplastic cranioplasty, which resulted in a low infection rate and improved postoperative regional contour. Use of this implant with suspension of the temporalis muscle is a new technique that may allow for better adherence of the temporalis muscle to its anatomic position, while still providing good brain protection.

Deep learning-based quantification of temporalis muscle has prognostic value in patients with glioblastoma

Background Glioblastoma is the commonest malignant brain tumour. Sarcopenia is associated with worse cancer survival, but manually quantifying muscle on imaging is time-consuming. We present a deep learning-based system for quantification of temporalis muscle, a surrogate for skeletal muscle mass, and assess its prognostic value in glioblastoma. Methods A neural network for temporalis segmentation was trained with 366 MRI head images from 132 patients from 4 different glioblastoma data sets and used to quantify muscle cross-sectional area (CSA). Association between temporalis CSA and survival was determined in 96 glioblastoma patients from internal and external data sets. Results The model achieved high segmentation accuracy (Dice coefficient 0.893). Median age was 55 and 58 years and 75.6 and 64.7% were males in the in-house and TCGA-GBM data sets, respectively. CSA was an independently significant predictor for survival in both the in-house and TCGA-GBM data sets (HR 0.464, 95% CI 0.218–0.988, p = 0.046; HR 0.466, 95% CI 0.235–0.925, p = 0.029, respectively). Conclusions Temporalis CSA is a prognostic marker in patients with glioblastoma, rapidly and accurately assessable with deep learning. We are the first to show that a head/neck muscle-derived sarcopenia metric generated using deep learning is associated with oncological outcomes and one of the first to show deep learning-based muscle quantification has prognostic value in cancer.

Sarcopenia Measured by Temporalis Muscle Thickness Independently Predicts Early Relapse and Short Survival in Primary CNS Lymphoma

Introduction: Primary CNS lymphoma (PCNSL) outcomes diverge between a majority of patients who achieve long term remission and a smaller minority who have aggressive disease course and die in the first year. Sarcopenia is increasingly recognized as a powerful predictor of mortality in brain and systemic cancers. Temporalis muscle thickness (TMT) is a validated radiographic measure of sarcopenia. We hypothesized that patients with TMT less than one standard deviation below the mean (“very thin TMT”) would go on to have shorter survival. Methods: Two blinded operators retrospectively measured TMT in 99 consecutive pretreatment brain MRIs from patients that were subsequently diagnosed with PCNSL. Results: On univariate analysis TMT predicted early progression (HR 4.25, 95% CI 1.95 – 9.29, p<0.001) and early mortality (HR 4.38, 95% CI 2.25 – 8.53, p<0.001), and these effects were maintained in subgroups of patients both <65 and ³65 years of age. Very thin TMT predicted mortality more robustly than IELSG or MSKCC scores. Patients with very thin TMT received fewer cycles of high-dose methotrexate (HD-MTX) and were less likely to receive consolidation. On multivariate analysis which included the covariates age, sex, TMT, ECOG, BMI, lifetime doses of HD-MTX, and consolidation, very thin TMT was independently associated with both early progression (HR = 7.87, 95% CI = 3.55 – 17.45, p<0.001) and short survival (HR 4.49, 95% CI = 1.94 – 10.40, p<0.001). Conclusions: We conclude that PCNSL patients with very thin TMT are at high risk for relapse and early mortality. Future trials should stratify patients by TMT to avoid potential confounding.

The Influence of Visual Input on Electromyographic Patterns of Masticatory and Cervical Spine Muscles in Subjects with Myopia

This study aimed to analyze the change of visual input on electromyographic patterns of masticatory and cervical spine muscles in subjects with myopia. After applying the inclusion criteria, 50 subjects (18 males and 32 females) with myopia ranging from −0.5 to −5.75 Diopters (D), were included in the study. Four muscle pairs were analyzed: the anterior part of the temporalis muscle (TA), the superficial part of the masseter muscle (MM), the anterior belly of the digastric muscle (DA), and the middle part of the sternocleidomastoid muscle belly (SCM) during resting and functional activity. Statistical analysis showed a significant decrease within functional indices (FCI) for the sternocleidomastoid muscle (FCI SCM R, FCI SCM L, FCI SCM total) during clenching in the intercuspal position with eyes closed compared to eyes open. During maximum mouth opening, a statistically significant increase of functional opening index for the left temporalis muscle (FOI TA L) was observed. Within the activity index (AcI), there was a statistically significant decrease during clenching on dental cotton rollers with eyes closed compared to eyes open.

Suprafascial dissection for pterional craniotomy to preserve the frontotemporal branch of the facial nerve with less temporal hollowing

Background: To protect the frontotemporal branch of the facial nerve (FTFN) when performing pterional craniotomy, several reports suggest the subfascial or interfascial dissection technique. However, the reports of postoperative frontalis paralysis and temporal hollowing, which are common complications, were relatively limited. This study reports the incidence of postoperative frontalis paralysis and temporal hollowing after pterional craniotomy using the suprafascial and interfascial techniques. Methods: Patients who underwent pterional craniotomy, using the suprafascial technique (leaving the muscle cuff and not leaving the muscle cuff) and the interfascial technique, between November 2015 and September 2018 were retrospectively evaluated for postoperative frontalis paralysis and temporal hollowing using Chi-squared/ Fisher exact test. Results: Seventy-two patients underwent pterional craniotomy, using the suprafascial technique in 54 patients (leaving the muscle cuff in 21 patients and not leaving the muscle cuff in 33 patients) and the interfascial technique in 18 patients. Eleven patients (20.4%) in the suprafascial group and 1 patient (5.6%) in the interfascial group developed transient frontalis paralysis (P = 0.272). No permanent frontalis paralysis was observed. Obvious temporal hollowing occurred in 18.2% of patients in the suprafascial group without the muscle cuff, in 64.3% of patients in the suprafascial group with the muscle cuff, and in 72.7% of patients in the interfascial group (P = 0.003). Conclusion: The suprafascial dissection technique does not cause permanent injury of the FTFN, and this approach results in a significantly lower incidence of postoperative temporal hollowing than interfascial dissection, especially without leaving a temporalis muscle cuff.

NIMG-68. SARCOPENIA AS MEASURED BY TEMPORALIS MUSCLE WIDTH IS A PREDICTOR OF SURVIVAL IN PRIMARY CNS LYMPHOMA

Sarcopenia refers to a loss of skeletal muscle mass, which has been associated with increased risk of injury and decreased ability to perform activities of daily living. In multiple cancers including systemic lymphomas, sarcopenia has been strongly associated with survival and may be an important way to risk stratify patients in clinical trials as well as routine practice. Temporalis muscle width has been reported as an indicator of sarcopenia and independent predictor of outcomes in multiple settings including glioblastoma, brain metastases and subarachnoid hemorrhage. We evaluated temporalis width in primary CNS lymphoma (PCNSL) patients at presentation and outcomes. Using an institutional database of immunocompetent PCNSL patients treated at the University of Washington, two independent readers reviewed the initial MRIs for 104 patients who presented from 2011-2021 and measured the width of the temporalis muscle on axial T1 images. Median duration of follow up was 42.2 months (range 0.59-125.9 months). Median age at diagnosis was 65 (range 19-90 years), and patients were 42.8% male, 57.2% female. Interrater variability was acceptable with an average intraclass correlation coefficient of 0.934. Temporalis measurements were normally distributed, with mean 0.79 cm and standard deviation 0.18 cm. We divided patients into two groups, those with temporalis width less than or greater than 1 standard deviation below the mean (absolute value 0.60 cm). Temporalis width was strongly associated with survival among all patients (χ2=15.5, p&lt; 0.001) as well as patients 65 years or older (χ2=4.5, p=0.03). We conclude that sarcopenia as measured by temporalis muscle thickness is associated with survival in PCNSL and may be an important variable to consider in clinical trials and routine practice.