The presigmoid approach (PSA) is selected to obtain more lateral access to cerebellopontine angle tumors, brainstem cavernous malformations, or vertebrobasilar artery aneurysms than the standard retrosigmoid approach. However, mastoidectomy for the PSA can be considered time-consuming and to carry a higher risk of complications due to the anatomical complexity of the region. The authors established a method of minimized mastoidectomy focused on exposing Trautmann’s triangle as the corridor for the PSA while maximizing procedural simplicity and safety and maintaining a sufficient operative view. The authors present their method of minimized mastoidectomy in a cadaver dissection and operative cases, showing potential as a useful option for the PSA.
Kuniaki Tanahashi, Kenji Uda, Yoshio Araki, Kazuhito Takeuchi, Jungsu Choo, Lushun Chalise, Kazuya Motomura, Fumiharu Ohka, Toshihiko Wakabayashi and Atsushi Natsume
Kazuya Motomura, Lushun Chalise, Fumiharu Ohka, Kosuke Aoki, Kuniaki Tanahashi, Masaki Hirano, Tomohide Nishikawa, Junya Yamaguchi, Hiroyuki Shimizu, Toshihiko Wakabayashi and Atsushi Natsume
Lower-grade gliomas (LGGs) are often observed within eloquent regions, which indicates that tumor resection in these areas carries a potential risk for neurological disturbances, such as motor deficit, language disorder, and/or neurocognitive impairments. Some patients with frontal tumors exhibit severe impairments of neurocognitive function, including working memory and spatial awareness, after tumor removal. The aim of this study was to investigate neurocognitive and functional outcomes of frontal LGGs in both the dominant and nondominant hemispheres after awake brain mapping.
Data from 50 consecutive patients with diffuse frontal LGGs in the dominant and nondominant hemispheres who underwent awake brain surgery between December 2012 and September 2018 were retrospectively analyzed. The goal was to map neurocognitive functions such as working memory by using working memory tasks, including digit span testing and N-back tasks.
Due to awake language mapping, the frontal aslant tract was frequently identified as a functional boundary in patients with left superior frontal gyrus tumors (76.5%). Furthermore, functional boundaries were identified while evaluating verbal and spatial working memory function by stimulating the dorsolateral prefrontal cortex using the digit span and visual N-back tasks in patients with right superior frontal gyrus tumors (7.1%). Comparing the preoperative and postoperative neuropsychological assessments from the Wechsler Adult Intelligence Scale–Third Edition (WAIS-III) and Wechsler Memory Scale–Revised (WMS-R), significant improvement following awake surgery was observed in mean Perceptual Organization (Z = −2.09, p = 0.04) in WAIS-III scores. Postoperative mean WMS-R scores for Visual Memory (Z = −2.12, p = 0.03) and Delayed Recall (Z = −1.98, p = 0.04) were significantly improved compared with preoperative values for every test after awake surgery. No significant deterioration was noted with regard to neurocognitive functions in a comprehensive neuropsychological test battery. In the postoperative course, early transient speech and motor disturbances were observed in 30.0% and 28.0% of patients, respectively. In contrast, late permanent speech and motor disturbances were observed in 0% and 4.0%, respectively.
It is noteworthy that no significant postoperative deterioration was identified compared with preoperative status in a comprehensive neuropsychological assessment. The results demonstrated that awake functional mapping enabled favorable neurocognitive and functional outcomes after surgery in patients with diffuse frontal LGGs.
Hiroyuki Shimizu, Kazuya Motomura, Fumiharu Ohka, Kosuke Aoki, Kuniaki Tanahashi, Masaki Hirano, Lushun Chalise, Tomohide Nishikawa, Junya Yamaguchi, Jun Yoshida, Atsushi Natsume and Toshihiko Wakabayashi
The current study aimed to evaluate the treatment outcomes and toxicities of patients with intracranial germ cell tumors (GCTs).
This study retrospectively included 110 consecutive patients (70 patients in the germinomatous group and 40 patients in the nongerminomatous GCT [NGGCT] groups) receiving surgery, platinum-based chemotherapy, and radiotherapy for newly diagnosed primary intracranial GCTs. In the authors’ protocol, patients with GCTs were further divided into the following four groups: the germinomatous group and the NGGCT groups (mature teratoma, intermediate prognosis, or poor prognosis).
The median overall survival (OS) and progression-free survival (PFS) rates of the patients in the germinomatous group were significantly higher than those in the NGGCT group (p < 0.001). The 5-, 10-, and 20-year OS rates in the germinomatous group were 97.1%, 95.7%, and 93.2%, respectively, with a median follow-up of 11.0 years. On the contrary, the 5-, 10-, and 20-year OS rates in the NGGCT group were 67.3%, 63.4%, and 55.4%, respectively. The 5-, 10-, and 20-year PFS rates were 91.4%, 86.6%, and 86.6%, respectively, in the germinomatous group, whereas those of the NGGCT group were approximately 67.4%, 60.2%, and 53.5%, respectively. Based on the four types of classification in our study, the 5-, 10-, and 20-year OS rates in the NGGCT intermediate prognosis group were 78.9%, 71.8%, and 53.8%, respectively. On the contrary, the 3- and 5-year OS rates in the NGGCT poor prognosis group were 42.9% and 34.3%, respectively. Moreover, toxicities with the treatment of intracranial GCTs were found to be tolerable in the present study population. The multivariate survival models for OS in the NGGCT intermediate prognosis and poor prognosis groups demonstrated that only the alpha-fetoprotein status was significantly associated with worsened OS (HR 3.88, 95% CI 1.29–11.66; p = 0.02).
The authors found that platinum-based chemotherapy and radiotherapy result in favorable survival outcomes in patients with germinomatous GCTs. Clinical outcomes were still unfavorable in the NGGCT intermediate prognosis and poor prognosis groups; therefore, a new protocol that increases the survival rate of patients belonging in both groups should be considered.