Schwartz, J

OBJECTIVE Maximal safe resection of intra-axial brain tumors near the motor cortex is aided by intraoperative motor mapping. Here, the authors compared outcomes in patients undergoing either low-frequency bipolar stimulation (LFBS) or high-frequency monopolar stimulation (HFMS) for cortical and/or subcortical motor mapping during brain tumor resection. METHODS A retrospective analysis of patients undergoing an asleep craniotomy with motor mapping or an awake craniotomy with motor and speech mapping with a single surgeon was performed. Three cohorts were compared: 1) asleep LFBS (AsLFBS), 2) awake LFBS (AwLFBS; motor + speech mapping), and 3) asleep HFMS. HFMS mapping was not used for awake craniotomies. RESULTS A total of 284 patients who underwent 300 craniotomies with motor mapping were identified. No significant differences in permanent neurological deficits (p = 0.377) or extent of resection (EOR) of nonenhancing tumors (p = 0.453) were identified between LFBS or HFMS motor mapping cases. Both EOR (92.7% vs 83.5%, p = 0.035) and permanent neurological deficits (7.6% vs 3.3%) occurred more frequently in enhancing tumors with LFBS, although the latter was not statistically significant. HFMS was associated with higher rates of subcortical motor pathway identification (p = 0.001) and fewer total intraoperative seizures (p = 0.003) compared with LFBS. Previous resection (HR 0.46, p = 0.003) and a higher cortical threshold (HR 0.95, p = 0.023) were significantly associated with longer survival, while preoperative aphasia (HR 2.24, p = 0.022), hospital length of stay (HR 1.1, p = 0.005), an insular-based tumor (HR 3.5, p = 0.021), and a histological diagnosis of glioblastoma (HR 2.9, p = 0.001) were negative predictors. Interestingly, overall FLAIR EOR was significantly associated with a marginally decreased overall survival (HR 1.01, p = 0.011). CONCLUSIONS No significant differences in postoperative neurological deficits were found between LFBS and HFMS paradigms. HFMS may identify subcortical motor fibers more reliably while resulting in significantly fewer intraoperative seizures. Although LFBS was associated with greater EOR of contrast-enhancing tumors, it may also be associated with higher rates of postoperative deficits, perhaps reflecting less reliable identification of subcortical motor fibers.

Abstract A 71-year-old male with a history of progressive pulmonary fibrosis underwent bilateral lung transplantation via clamshell incision seven months prior to presenting with dyspnea and recurrent bilateral pleural effusions. His post-transplant course was complicated by lymphocytic myocarditis, leading to acute hypoxic respiratory failure and heart failure. Outpatient management with torsemide improved fluid status but was discontinued due to worsening renal function, resulting in effusion recurrence. Upon readmission, a right-sided 12 Fr pigtail thoracostomy tube was placed and left thoracentesis was done. Pleural fluid analysis revealed a serosanguineous, lymphocytic, exudative effusion on the right and a neutrophilic, transudative effusion on the left. Both had negative cytology and infectious studies. The left effusion initially seemed to be controlled. Persistent right-sided drainage prompted placement of a right indwelling tunneled pleural catheter (IPC). Pre-procedure imaging showed bilateral effusions, and ultrasound revealed a diminishing right effusion during setup, supporting interpleural communication. To aid IPC placement, one liter of lactated Ringer’s (LR) solution was infused into the right pleural space. Post-procedure imaging showed a large left-sided effusion and a small right effusion (Figure 1.), confirming buffalo chest physiology—fluid migration between pleural cavities due to the clamshell incision. Despite suction drainage and positional maneuvers, the left effusion persisted. Intrapleural administration of lytics via the right IPC failed to evacuate the left effusion. A subsequent left thoracentesis removed one liter of fluid, but recurrence necessitated placement of a left IPC one week later. Three weeks post-placement, the right IPC was removed, and continued drainage from the left IPC prevented recurrence of the right effusion. This case highlights the anatomical alterations following bilateral lung transplantation via clamshell incision, which can lead to atypical pleural fluid dynamics, including interpleural communication and buffalo chest physiology. Awareness of these changes is critical for effective management of pleural effusions in post-transplant patients. This abstract is funded by: None