Faculty Bibliography

BACKGROUND AND OBJECTIVES/OBJECTIVE:Superficial temporal artery to middle cerebral artery (STA-MCA) bypass is the workhorse for flow augmentation surgery. Although either interrupted or running sutures can be used to complete the anastomosis with high intraoperative patency rates, no previous study in the cranial bypass literature has compared long-term patency and maturity of end-to-side STA-MCA anastomoses. We compared STA-MCA anastomoses performed with running vs interrupted sutures by evaluating bypass flow and anastomotic maturation on follow-up vascular imaging. METHODS:Ninety-six STA-MCA anastomoses were performed from 1/2019 to 6/2024. Forty-seven anastomoses (40 patients) with long-term vascular imaging were retrospectively analyzed. All anastomoses were intraoperatively patent on initial revascularization. Patient demographics, clinical course, and imaging were reviewed. All images were reviewed by a neuroradiologist or a cerebrovascular neurosurgeon. RESULTS:Twenty-five anastomoses were performed with interrupted sutures and compared with 22 anastomoses performed with running sutures. All patients underwent a preoperative perfusion assessment confirming a significant hypoperfusion state. There were no significant differences between cohorts in demographics, bypass indication, or time to follow-up. Formal digital subtraction angiography was performed for 35 anastomoses (21 interrupted, 14 running). On digital subtraction angiography follow-up, there was no difference in STA caliber between cohorts (P = .204), but there was a difference in anastomotic growth (P = .014), with 5/21 (23.8%) anastomoses stable or enlarged in the interrupted cohort vs 9/14 (64.3%) stable or enlarged in the running cohort. Notably, of the 47 total anastomoses, there was no difference in long-term bypass patency between interrupted and running anastomoses (22/25 (88.0%) vs 22/22 (100.0%), respectively, P = .380). CONCLUSION/CONCLUSIONS:No significant differences in patency or STA caliber on follow-up imaging were observed between STA-MCA anastomoses performed with interrupted vs running sutures although a difference in anastomotic maturity was observed, with the running suture cohort having a higher proportion of enlarged or stable anastomoses. Further studies are needed for validation.

BACKGROUND:The choroid plexus (ChP), a highly vascularized structure within the ventricles, is essential for cerebrospinal fluid (CSF) production and metabolic waste clearance, crucial for neurofluid homeostasis and cognitive function. ChP enlargement is seen in normal aging and neurodegenerative diseases like Alzheimer's disease (AD). Despite its key role of in the blood-CSF barrier (BCSFB), detailed studies on age-related changes in its perfusion and microstructure remain limited. METHODS:We analyzed data from 641 healthy individuals aged between 36 and 90, using the Human Connectome Project Aging (HCP-A) dataset. Volumetric, perfusion, and diffusion metrics of the ChP were derived from structural MRI, arterial spin labeling (ASL), and diffusion-weighted imaging (DWI), respectively. Partial correlations were used to explore age-related ChP changes, and independent t-tests to examine sex differences across age decades. One-way ANOVA was employed to compare perfusion characteristics among ChP, gray matter (GM), and white matter (WM). Relationships between volume, perfusion, and diffusion were investigated, adjusting for age and sex. Additionally, the distribution of cyst-like structures within the ChP and their diffusion/perfusion MRI characteristics were analyzed across different age groups. RESULTS: = 0.16, P < 0.001). Perfusion characteristics showed significant differences between the ChP, GM, and WM (P < 0.001). Both the ChP and GM exhibited age-related declines in CBF, with a more pronounced decline in the ChP. A negative correlation was observed between the age-related increase in ChP volume and the decrease in CBF, suggesting compensatory dystrophic hyperplasia in response to perfusion decline. Cyst-like structures in ChP, characterized by lower MD and reduced CBF, were found to be more prevalent in older individuals. CONCLUSIONS:Our findings provide a detailed quantitative assessment of age-related changes in ChP perfusion and diffusion, which may affect CSF production and circulation, potentially leading to waste solute accumulation and cognitive impairment. GRANT SUPPORT/UNASSIGNED:This work was supported in part by the NIH U01AG052564, P30AG066512, P01AG060882, RF1 NS110041, R01 NS108491, U24 NS135568.

INTRODUCTION/BACKGROUND:Recent new advances in myoclonus characterization and etiology justify an update of the 40-year-old respected classification of myoclonus proposed by Marsden, Hallett, and Fahn. New advances include genetic studies and clinical neurophysiology characterization. METHODS:The IAPRD appointed an expert panel to develop a new myoclonus classification. The Delphi Method of consensus determination was employed using a panel of fifteen international experts in myoclonus. In an in-person meeting, an Axis approach, previously used for dystonia and tremor was ratified by the panel: Axis I included clinical and neurophysiology features, Axis II included etiology categories. As a unique part of our Axis approach, Clinical Neurophysiology was included as Axis Ib. The first Delphi survey round queried agreement on major headings in Axes Ia and Ib, myoclonus clinical syndromes, and Axis II. In the second round, the full expert panel was surveyed on constituents and specific characteristics of each feature that had consensus in the first round. RESULTS:In the first round, the percentage of agreement for the fifty-three out of the 56 items was greater than 60.0 %, indicating strong consensus among expert panel members. In the second round, for Axis Ia, Axis Ib, and Axis II, strong agreement was also achieved. For both rounds, Physiological Myoclonus had the lowest agreement. Comments from the whole panel were incorporated into the consensus results. CONCLUSION/CONCLUSIONS:This Myoclonus Classification, which reached consensus using the Delphi Method, will facilitate a collaborative effort among myoclonus investigators to find better diagnostics and treatment for myoclonus patients.

White matter hyperintensities of presumed vascular origin (WMH) are associated with cognitive impairment and are a key imaging marker in evaluating brain health. However, WMH volume alone does not fully account for the extent of cognitive deficits and the mechanisms linking WMH to these deficits remain unclear. Lesion network mapping (LNM) enables us to infer if brain networks are connected to lesions and could be a promising technique for enhancing our understanding of the role of WMH in cognitive disorders. Our study employed LNM to test the following hypotheses: (i) LNM-informed markers surpass WMH volumes in predicting cognitive performance; and (ii) WMH contributing to cognitive impairment map to specific brain networks. We analysed cross-sectional data of 3485 patients from 10 memory clinic cohorts within the Meta VCI Map Consortium, using harmonized test results in four cognitive domains and WMH segmentations. WMH segmentations were registered to a standard space and mapped onto existing normative structural and functional brain connectome data. We employed LNM to quantify WMH connectivity to 480 atlas-based grey and white matter regions of interest (ROI), resulting in ROI-level structural and functional LNM scores. We compared the capacity of total and regional WMH volumes and LNM scores in predicting cognitive function using ridge regression models in a nested cross-validation. LNM scores predicted performance in three cognitive domains (attention/executive function, information processing speed, and verbal memory) significantly better than WMH volumes. LNM scores did not improve prediction for language functions. ROI-level analysis revealed that higher LNM scores, representing greater connectivity to WMH, in grey and white matter regions of the dorsal and ventral attention networks were associated with lower cognitive performance. Measures of WMH-related brain network connectivity significantly improve the prediction of current cognitive performance in memory clinic patients compared to WMH volume as a traditional imaging marker of cerebrovascular disease. This highlights the crucial role of network integrity, particularly in attention-related brain regions, improving our understanding of vascular contributions to cognitive impairment. Moving forward, refining WMH information with connectivity data could contribute to patient-tailored therapeutic interventions and facilitate the identification of subgroups at risk of cognitive disorders.

After corticospinal tract (CST) stroke, several motor deficits can emerge in the upper extremity (UE), including diminished muscle strength, motor control, and muscle individuation. Both the ipsilesional CST and contralesional corticoreticulospinal tract (CReST) innervate the paretic UE, but their relationship to motor behaviors after stroke remains uncertain. In this cross-sectional study of 14 chronic stroke and 27 healthy subjects, we examined two questions: whether the ipsilesional CST and contralesional CReST differentially relate to chronic motor behaviors in the paretic arm and hand and whether the severity of motor deficits differs by proximal versus distal location. In the paretic biceps and first dorsal interosseous muscles, we used transcranial magnetic stimulation to measure the projection strengths of the ipsilesional CST and contralesional CReST. We also used quantitative testing to measure strength, motor control, and muscle individuation in each muscle. We found that stroke subjects had muscle strength comparable to healthy subjects but poorer motor control and muscle individuation. In both paretic muscles, stronger ipsilesional CST projections related to better motor control, whereas stronger contralesional CReST projections related to better muscle strength. Stronger CST projections related to better individuation in the biceps alone. The severity of motor control and individuation deficits was comparable in the arm and hand. These findings suggest that the ipsilesional CST and contralesional CReST have specialized but complementary roles in motor behaviors of the paretic arm and hand. They also suggest that deficits in motor control and muscle individuation are not segmentally biased, underscoring the functional extent and efficacy of these pathways.NEW & NOTEWORTHY The corticospinal (CST) and corticoreticulospinal (CReST) tracts are two major descending motor pathways. We examined their relationships to motor behaviors in paretic arm and hand muscles in chronic stroke. Stronger ipsilesional CST projections related to better motor control, whereas stronger contralesional CReST projections related to better muscle strength. Stronger CST projections are also uniquely related to better biceps individuation. These findings support the notion of specialized but complementary contributions of these pathways to human motor function.

The effects of subthalamic nucleus deep brain stimulation (STN-DBS) on anxiety in Parkinson"™s disease (PD) are understudied. We identified clinical predictors of STN-DBS effects on anxiety in this study. In this prospective, open-label, multicentre study, we assessed patients with anxiety undergoing STN-DBS for PD preoperatively and at 6-month follow-up postoperatively. We assessed the Hospital Anxiety and Depression Scale (HADS-anxiety and depression subscales), Unified PD Rating Scale-motor examination, Scales for Outcomes in PD-motor (SCOPA-M)-activities of daily living (ADL) and -motor complications, Non-Motor Symptom Scale (NMSS), PDQuestionnaire-8 (PDQ-8), and levodopa-equivalent daily dose. We tested changes at follow-up with Wilcoxon signed-rank test and corrected for multiple comparisons (Bonferroni method). We identified patients with a clinically relevant anxiety improvement of anxiety based on a designated threshold of ½ standard deviation of baseline HADS-anxiety. Moreover, we investigated predictors of HADS-anxiety changes with correlations and linear regressions. We included 50 patients with clinically relevant baseline anxiety (i.e., HADS-anxiety ≥ 8) aged 63.1 years ± 8.3 with 10.4 years ± 4.5 PD duration. HADS-anxiety improved significantly at 6-month follow-up as 80% of our cohort experienced clinically relevant anxiety improvement. In predictor analyses, worse baseline SCOPA-ADL and NMSS-urinary domain were associated with greater HADS-anxiety improvements. HADS-anxiety and PDQ-8 changes correlated moderately. Worse preoperative ADL and urinary symptoms predicted favourable postoperative anxiety outcome, which in turn was directly proportionate to greater QoL improvement. This study highlights the importance of detailed anxiety assessments alongside other non-motor and motor symptoms when advising and monitoring patients undergoing STN-DBS for PD.