Faculty Bibliography

Parsonage-Turner syndrome (PTS) is a spontaneous neuropathy characterized by severe upper extremity pain and muscle denervation and is considered to be a rare disease that is under-recognized. Quantitative MRI (qMRI) characterizes muscle denervation but has not been previously assessed in a longitudinal PTS cohort. The aims of this study are to prospectively and longitudinally characterize qMRI changes in PTS patients at baseline (< 6 months' symptom onset) and at follow-up timepoints (3, 6, and 12 months), to measure associations against electromyography (EMG) and muscle strength, and to predict muscle strength at follow-up. A total of 49 subjects (age = 47.2 ± 14.0 years, 31 M/18 F) underwent 3-Tesla qMRI with T2-mapping, diffusion-based muscle fiber diameter, volumetry, and fat fraction (FF) mapping. Image segmentation of involved muscles was performed by two raters. Linear regression between qMRI metrics and days from symptom onset (DSO) was performed. Pearson's correlation quantified correlations between qMRI metrics, and Kendall's tau assessed correlations between qMRI and EMG and muscle strength. For predictive modeling of muscle strength, a generalized linear model was used, and the coefficient of determination (r²) was compared for combinations of baseline inputs. Regression detected a mean T2 increase of 0.66 ms/week and a mean muscle fiber diameter decrease of 0.96 μm/week within DSO of 100. Muscle fiber diameter correlated with muscle volume (r = 0.850). T2 correlated with EMG (|τ| = 0.34-0.78) and muscle strength (|τ| = 0.40-0.83) in most muscles that could be analyzed. Muscle fiber diameter was correlated to EMG (|τ| = 0.43-0.72) and muscle strength in some muscles (|τ| = 0.39-0.56). The addition of baseline T2 values improved the prediction of muscle strength at 3-month (from r² = 0.57 to 0.67, with -0.057 to -0.068 muscle grade per ms T2), at 6-month (r² = 0.40-0.59, -0.057 to -0.071 grade per ms), and at 12-month follow-up (r² = 0.40-0.62, -0.053 to -0.080 grade per ms). Muscle qMRI measurements in PTS depict muscle denervation and provide complementary characterization of muscle quality for diagnosis and follow-up assessment.

BACKGROUND AND OBJECTIVES/OBJECTIVE:Epilepsy is a common neurologic disorder. Although antiseizure medications (ASMs) are the first-line treatment, identifying the most effective ASM for each individual remains a trial-and-error process. Genetic variation may influence treatment response. We aimed to develop and validate a multimodal deep learning model that integrates clinical and genomic features to predict response to the initial ASM in people with newly diagnosed epilepsy. METHODS:We used data from individuals with newly diagnosed epilepsy in Australia as the development cohort and participants from the Human Epilepsy Project 1 (recruited in the United States, Europe, and Australia) as the external validation cohort. All participants initiated ASM treatment and were followed prospectively for at least 1 year. We included 16 clinical factors and constructed 4 genomic feature types related to epilepsy and ASM pharmacogenomics, with and without functional impact annotations. We evaluated various machine learning architectures and multimodal fusion strategies to predict seizure freedom while taking the initial ASM at 1 year. RESULTS:< 0.05). Applying this model to the development cohort, if all participants took the highest ranked ASMs, the mean predicted seizure-free probability would be 68.05% (95% CI 65.79%-70.35%) compared with the observed seizure-free rate of 47.2% (95% CI 41.3%-53.2%). DISCUSSION/CONCLUSIONS:Integrating genomic data with clinical features enhances the ability of deep learning models in predicting ASM response in newly diagnosed epilepsy. This approach may support personalized treatment selection and improve clinical outcomes.

BACKGROUND AND OBJECTIVES/OBJECTIVE:Vascular dysfunction contributes to Alzheimer disease (AD) and related dementias (ADRDs), but the underlying mechanisms remain unclear. Previous studies link midlife hemostasis and platelet aggregation measures to late-life dementia risk. We aimed to determine whether platelet aggregation in midlife is associated with imaging markers of AD pathology. METHODS:F-flortaucipir) PET uptake in dementia-free, middle-aged adults from the Framingham Heart Study. Co-primary outcomes included amyloid and tau uptake in AD-vulnerable regions. We also examined an MRI-based cortical thickness signature of AD risk as a secondary outcome. We used multivariable regression models adjusted for demographic and clinical factors, considering potential nonlinear associations. RESULTS:< 0.035), consistent with a neurodegenerative pattern. DISCUSSION/CONCLUSIONS:Our findings indicate that platelet aggregation is linked to PET and MRI markers of AD pathology as early as midlife. These findings support further investigation of platelet-mediated mechanisms in AD pathogenesis.

This position statement provides updated member guidance from the American Academy of Neurology (AAN) regarding (1) communication with surrogate decision makers about brain death/death by neurologic criteria (BD/DNC), (2) management of surrogate decision-maker objections to BD/DNC, (3) the ethical considerations associated with BD/DNC determination in a pregnant person, and (4) enhancing public trust in BD/DNC. This position statement is intended to complement recommendations in the 2023 "Pediatric and Adult Brain Death/Death by Neurologic Criteria Consensus Guideline" published by the AAN, American Academy of Pediatrics, Child Neurology Society, and Society of Critical Care Medicine, as well as the 2021 AAN Code of Professional Conduct. It replaces the 2019 AAN position statement, "Brain death, the determination of brain death, and member guidance for brain death accommodation requests."

Differential mRNA translation efficiency (mTE) of codons is important in regulating protein synthesis and cellular states and can change in response to amino acid availability. While the mTE of codons is canonically associated with their corresponding transfer RNA (tRNA) isoacceptors, its regulation by amino acids in mammalian cells remains unexplored. We found that ELAC2, a 3' tRNA maturation endonuclease, decreases the mTE of UC[C/U] serine (Ser) codons in response to Ser limitation. Ablation of ELAC2 restored UC[C/U] mTE but reduced the mTE of AG[U/C] Ser codons. Among the tRNA^Ser isoacceptors, tRNA^Ser(GCU) decreased the most in ELAC2-deficient cells. Unexpectedly, tRNA^Ser(GCU) delivery restored AG[U/C] mTE and reduced UC[C/U] mTE in ELAC2-deficient cells. Last, we deciphered the effects of Ser-sensitive codons on mRNA translation and the human proteome. Our study revealed that in response to Ser limitation, regulation of tRNA^Ser(GCU) levels fine-tune the mTE of UC[C/U] or AG[U/C] Ser-sensitive codons and shapes the proteome.

Understanding consciousness remains a significant challenge in science. What distinguishes conscious beings from unconscious systems, such as organoids, artificial intelligence or other non-sentient entities? Research on consciousness often focuses on identifying brain activity associated with conscious and non-conscious states, primarily in neurotypical human adults. However, this approach is limited in scope when applied to entities with developmental or evolutionary trajectories different from our own. How do we investigate consciousness in infants, whose brains are still maturing or in non-human animals, shaped by diverse ecological and evolutionary pressures? This opinion piece encourages consciousness studies to adopt a neuroethological perspective, drawing on Tinbergen's framework for studying behaviour. By examining the (1) mechanisms, (2) development, (3) adaptive functions and (4) evolutionary origins of consciousness, we can move beyond a human-centric focus to explore its diversity across life forms. Most investigators now accept that consciousness is not confined to humans alone but that some other animals have it, and it is a continuum shaped by evolutionary pressures. By adopting this broader approach, consciousness studies can better investigate and understand consciousness in its various forms and contexts, with significant scientific, ethical and societal implications.This article is part of the theme issue 'Evolutionary functions of consciousness'.

Chronic progressive external ophthalmoplegia (CPEO), a genetic syndrome characterized by slowly progressive paresis of extraocular muscles, is often due to single large-scale deletions of the mitochondrial genome (mtDNA). Owing to heteroplasmy, mtDNA variants are often not uniformly expressed across tissues. This genetic variability affects clinical presentation and diagnostic testing. We report a case of a 34-year-old woman who presented with symptoms suspicious for a genetic myopathy: chronic asymmetric ptosis, slowly progressive asymmetric weakness, and external ophthalmoplegia. After initial nondiagnostic peripheral genetic testing, whole-exome and mitochondrial genome sequencing of muscle revealed a single large-scale mtDNA deletion, consistent with a diagnosis of mtDNA deletion-associated CPEO. Of interest, electrophysiologic studies showed myotonia in select muscles, a rarely reported finding. We discuss the clinical presentation and diagnostic approach in suspected CPEO, with an emphasis on common pitfalls in genetic testing for mitochondrial myopathies and the need for appropriate tissue and genetic testing modality selection.

IntroductionTraumatic intracranial aneurysms (TICAs) are rare, potentially fatal complications of traumatic brain injury (TBI) or iatrogenic insult. Often forming as pseudoaneurysms, TICAs result from direct arterial wall disruption. Their unique pathophysiology, delayed presentation, and high rupture risk pose diagnostic and therapeutic challenges. This review synthesizes current evidence on TICA pathogenesis, diagnosis, and treatment, with particular emphasis on the evolving role of angiographic diagnosis and endovascular intervention.MethodsA structured PubMed search was conducted, supplemented by manual citation screening. All study designs were considered with no date restrictions. Articles were included if they reported traumatic intracranial aneurysms in patients of any age and discussed diagnostic or therapeutic approaches. Data were synthesized thematically across epidemiology, pathophysiology, imaging, treatment (endovascular and surgical), and surveillance.ResultsTICAs typically arise at sites of direct injury or at fixed vessel segments (e.g., distal ACA, peripheral MCA, cavernous/supraclinoid ICA). Their delayed and subtle appearance necessitates high clinical suspicion and serial imaging. Digital subtraction angiography is the diagnostic gold standard, though immediate or early post-trauma studies may be negative. Endovascular techniques, particularly flow diversion, are increasingly favored for their minimally invasive nature and ability to achieve parent vessel reconstruction. Open surgery retains a role for lesions complicated by mass effect, intracerebral hematoma, or anatomy unsuitable for endovascular repair. Outcomes vary with aneurysm location, treatment timing, modality, and TBI severity.ConclusionTICAs represent a distinct, high-risk entity requiring timely diagnosis and individualized, multidisciplinary management. Endovascular approaches are increasingly favored. Further research is needed to guide optimal surveillance imaging protocols.

Chronic traumatic encephalopathy (CTE) is a neurodegenerative disease associated with exposure to repetitive head impacts (RHI). In CTE, hyperphosphorylated tau (p-tau) aggregates are found in neurons at the depth of cortical sulci close to the gray matter/white matter (GM/WM) boundary. To date, CTE can only be diagnosed postmortem by neuropathological examination. Traumatic encephalopathy syndrome (TES) is the clinical syndrome purported to be associated with CTE pathology. The aim of this study is to investigate microstructural properties at the GM/WM boundary in individuals with a history of exposure to RHI and clinical features of CTE (i.e., TES). Diffusion magnetic resonance imaging (dMRI), TES diagnoses, and cerebrospinal fluid (CSF) biomarkers were acquired from 165 male former American football players (age: 57.29 ± 8.23 years) from the DIAGNOSE CTE Research Project, a multicenter, observational cohort study. Fractional anisotropy (FA) was measured at the GM/WM boundary of the whole brain. In addition, a widely used method (tract-based spatial statistics [TBSS]) was applied to measure FA of central WM. We used analyses of covariance to test associations between FA and TES. Furthermore, we used linear regressions to test associations between FA and nine CSF biomarkers (i.e., p-tau-181, -217, -231, total tau, amyloid β [Aβ]_1-40, Aβ_1-42, glial fibrillary acidic protein [GFAP], neurofilament light [NfL], and soluble triggering receptor expressed on myeloid cells-2 [sTREM2]). We report an association between higher FA at the GM/WM boundary and higher levels of certainty for CTE pathology (F(1, 147) = 5.781, 95% confidence interval (CI) = 0.0003-0.003, p = 0.035) as well as neurobehavioral dysregulation (F(1, 148) = 7.559, 95% CI = 0.001-0.009, p = 0.020), and functional dependence/dementia (F(1, 148) = 5.046, 95% CI = 0.0004-0.006, p = 0.039). In addition, we report an association between higher FA at the GM/WM boundary and higher CSF p-tau-181 (β = 0.272, 95% CI = 0.078-0.466, p = 0.029) and p-tau-217 (β = 0.295, 95% CI = 0.102-0.488, p = 0.027). FA of the central WM was not associated with TES diagnoses. Taken together, these findings suggest that dMRI at the GM/WM boundary could be used to investigate microstructural alterations suggestive of tau pathology-associated neurodegeneration in individuals with TES, the clinical presentation of CTE. Future studies are needed to validate this approach and to identify clinically useful cutoff values for dMRI metrics.