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Anthony T. Lee, Claire Faltermeier, Ramin A. Morshed, Jacob S. Young, Sofia Kakaizada, Claudia Valdivia, Anne M. Findlay, Phiroz E. Tarapore, Srikantan S. Nagarajan, Shawn L. Hervey-Jumper, and Mitchel S. Berger

OBJECTIVE

Gliomas are intrinsic brain tumors with the hallmark of diffuse white matter infiltration, resulting in short- and long-range network dysfunction. Preoperative magnetoencephalography (MEG) can assist in maximizing the extent of resection while minimizing morbidity. While MEG has been validated in motor mapping, its role in speech mapping remains less well studied. The authors assessed how the resection of intraoperative electrical stimulation (IES)–negative, high functional connectivity (HFC) network sites, as identified by MEG, impacts language performance.

METHODS

Resting-state, whole-brain MEG recordings were obtained from 26 patients who underwent perioperative language evaluation and glioma resection that was guided by awake language and IES mapping. The functional connectivity of an individual voxel was determined by the imaginary coherence between the index voxel and the rest of the brain, referenced to its contralesional pair. The percentage of resected HFC voxels was correlated with postoperative language outcomes in tasks of increasing complexity: text reading, 4-syllable repetition, picture naming, syntax (SYN), and auditory stimulus naming (AN).

RESULTS

Overall, 70% of patients (14/20) in whom any HFC tissue was resected developed an early postoperative language deficit (mean 2.3 days, range 1–8 days), compared to 33% of patients (2/6) in whom no HFC tissue was resected (p = 0.16). When bifurcated by the amount of HFC tissue that was resected, 100% of patients (3/3) with an HFC resection > 25% displayed deficits in AN, compared to 30% of patients (6/20) with an HFC resection < 25% (p = 0.04). Furthermore, there was a linear correlation between the severity of AN and SYN decline with percentage of HFC sites resected (p = 0.02 and p = 0.04, respectively). By 2.2 months postoperatively (range 1–6 months), the correlation between HFC resection and both AN and SYN decline had resolved (p = 0.94 and p = 1.00, respectively) in all patients (9/9) except two who experienced early postoperative tumor progression or stroke involving inferior frontooccipital fasciculus.

CONCLUSIONS

Imaginary coherence measures of functional connectivity using MEG are able to identify HFC network sites within and around low- and high-grade gliomas. Removal of IES-negative HFC sites results in early transient postoperative decline in AN and SYN, which resolved by 3 months in all patients without stroke or early tumor progression. Measures of functional connectivity may therefore be a useful means of counseling patients about postoperative risk and assist with preoperative surgical planning.

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Sudheesha Perera, Shawn L. Hervey-Jumper, Praveen V. Mummaneni, Ernest J. Barthélemy, Alexander F. Haddad, Dario A. Marotta, John F. Burke, Andrew K. Chan, Geoffrey T. Manley, Phiroz E. Tarapore, Michael C. Huang, Sanjay S. Dhall, Dean Chou, Katie O. Orrico, and Anthony M. DiGiorgio

OBJECTIVE

This study attempts to use neurosurgical workforce distribution to uncover the social determinants of health that are associated with disparate access to neurosurgical care.

METHODS

Data were compiled from public sources and aggregated at the county level. Socioeconomic data were provided by the Brookings Institute. Racial and ethnicity data were gathered from the Centers for Disease Control and Prevention Wide-ranging Online Data for Epidemiologic Research. Physician density was retrieved from the Health Resources and Services Administration Area Health Resources Files. Catchment areas were constructed based on the 628 counties with neurosurgical coverage, with counties lacking neurosurgical coverage being integrated with the nearest covered county based on distances from the National Bureau of Economic Research’s County Distance Database. Catchment areas form a mutually exclusive and collectively exhaustive breakdown of the entire US population and licensed neurosurgeons.

Socioeconomic factors, race, and ethnicity were chosen as independent variables for analysis. Characteristics for each catchment area were calculated as the population-weighted average across all contained counties. Linear regression analysis modeled two outcomes of interest: neurosurgeon density per capita and average distance to neurosurgical care. Coefficient estimates (CEs) and 95% confidence intervals were calculated and scaled by 1 SD to allow for comparison between variables.

RESULTS

Catchment areas with higher poverty (CE = 0.64, 95% CI 0.34–0.93) and higher prime age employment (CE = 0.58, 95% CI 0.40–0.76) were significantly associated with greater neurosurgeon density. Among categories of race and ethnicity, catchment areas with higher proportions of Black residents (CE = 0.21, 95% CI 0.06–0.35) were associated with greater neurosurgeon density. Meanwhile, catchment areas with higher proportions of Hispanic residents displayed lower neurosurgeon density (CE = −0.17, 95% CI −0.30 to −0.03). Residents of catchment areas with higher housing vacancy rates (CE = 2.37, 95% CI 1.31–3.43), higher proportions of Native American residents (CE = 4.97, 95% CI 3.99–5.95), and higher proportions of Hispanic residents (CE = 2.31, 95% CI 1.26–3.37) must travel farther, on average, to receive neurosurgical care, whereas people living in areas with a lower income (CE = −2.28, 95% CI −4.48 to −0.09) or higher proportion of Black residents (CE = −3.81, 95% CI −4.93 to −2.68) travel a shorter distance.

CONCLUSIONS

Multiple factors demonstrate a significant correlation with neurosurgical workforce distribution in the US, most notably with Hispanic and Native American populations being associated with greater distances to care. Additionally, higher proportions of Hispanic residents correlated with fewer neurosurgeons per capita. These findings highlight the interwoven associations among socioeconomics, race, ethnicity, and access to neurosurgical care nationwide.