OBJECTIVE To examine the relative diagnostic sensitivity of various F wave parameters. METHODS Normal values for minimum, mean, and maximum F wave latency, chronodispersion, and persistence in the four major motor nerves were established and systematically applied to at least four separate categories of patients (radiculopathies, polyneuropathies, mononeuropathies, and others). F Waves were studied both isolated and in comparison with other motor nerve conduction parameters. RESULTS F Chronodispersion was the most often abnormal parameter, particularly in lumbosacral radiculopathies. Minimum F wave latency was more useful in polyneuropathies. Compared with minimum F wave latency, F chronodispersion was able to identify most additional cases. CONCLUSIONS F Wave studies should include minimum F wave latency and chronodispersion.

Hwang S, et al. Yonsei Med J. 2024 Feb;65(2):89-97. https://doi.org/10.3349/ymj.2022.0539

Lee KJ, et al. J Korean Med Sci. 2022 Aug;37(33):e254. https://doi.org/10.3346/jkms.2022.37.e254

Background: Reversible cerebral vasoconstriction syndrome (RCVS) is an uncommon and often underrecognized neurovascular disorder. We aimed to investigate the clinical presentations associated with extracerebral vasoconstriction in patients diagnosed with RCVS. Methods: In this cross-sectional study, we analyzed data from a single-center cohort of patients with RCVS in Korea. Extracerebral vasoconstriction in individuals diagnosed with RCVS was defined by the following criteria: (1) the presence of sudden and severe pain in extracerebral regions (primarily the chest or abdomen) coinciding with the onset of RCVS, (2) resolution of the pain following the administration of vasodilators, and (3) confirmation of vasoconstriction through imaging studies or, at a minimum, the exclusion of other potential causes associated with the pain. Results: Among the 80 eligible patients (median age, 53 years; female sex, 82.5%), 8 patients (10%) experienced extracerebral vasoconstriction. Regarding pain location, four patients reported chest pain, two reported abdominal pain, and two reported pains in both the chest and abdomen. When comparing visit route, the patients were associated with emergency department (odds ratio [OR]: 6; 95% confidence interval [CI]: 1.1–33; reference: outpatient) and inpatient consultation (OR: 25; 95% CI: 1.1–560) compared to those without extracerebral vasoconstriction. Patients with extracerebral vasoconstriction had no prior history of precipitating conditions or medication use before the onset of RCVS. The treatment response to vasodilators was excellent in all patients, and none reported neurovascular or extracerebral complications during the bout of RCVS. Conclusions: A co-occurrence of extracerebral vasoconstriction was not exceptionally uncommon among patients with RCVS. Our findings suggest that extracerebral vasoconstriction may be underrecognized in individuals with RCVS.

The Behavioural modelling of decision-making processes has advanced our understanding of impairments associated with various psychiatric conditions. While many studies have focused on models that best fit behavioural data, the extent to which such models reflect biologically plausible mechanisms remains underexplored. To bridge this gap, we developed a probabilistic two-armed bandit task model grounded in the active inference framework and evaluated its performance against established reinforcement learning (RL) models. Our model not only matched but outperformed conventional RL models in explaining individual variability in choice behaviour. A central feature of our model is the optimisation of policy precision based on previous outcomes. This process captures the dynamic balance between model-based predictions derived from the internal generative model and the influence of immediate past observations. Importantly, incorporating the temporal dynamics of policy precision significantly improved the model's capacity to explain large-scale brain network activity and inter-subject variability. We found that increases in policy precision were positively associated with default mode network dominance and negatively associated with states dominated by dorsal attention and frontoparietal networks. These opposing associations suggest functional coordination between these systems, as supported by the correlations between brain state transitions and behavioural parameters. Furthermore, prolonged dominance of another brain state, characterised by elevated ventral attention network activity and stronger inter-network connectivity, appeared to disrupt this coordination. Finally, we found that heightened sensitivity to negative outcomes in a loss-related context was associated with high suicidal risk among individuals with major depressive disorder.

Purpose: Neck pain is a leading musculoskeletal cause of disability in the United States. This study aimed to assess temporal, geographic, and demographic disparities in its burden across US states from 1990 to 2021.Methods: Global Burden of Disease 2021 data for all 50 US states and the District of Columbia were analyzed for 1990–2021. Counts and age-standardized rates per 100,000 population for prevalence, incidence, and years lived with disability (YLD) were compared by region, state, sex, age group, and sociodemographic index (SDI) level.Results: In 2021, neck pain accounted for 9,430,000 (95% uncertainty interval [UI], 7,400,000–11,590,000) prevalent cases, 1,900,000 (95% UI, 1,490,000–2,320,000) incident cases, and 920,000 (95% UI, 620,000–1,300,000) YLD, increases of 41.17%, 37.44%, and 38.72%, respectively, from 1990. Although age-standardized incidence increased globally by 1.18% (0.07%–2.39%) over 1990–2021, the United States had small declines in age-standardized incidence (−0.11%; 95% UI, −0.18% to −0.06%), prevalence (−0.20%; 95% UI, −0.32% to −0.10%), and YLD (−1.12%; 95% UI, −2.02% to −0.22%). Neck pain rates were highest in the District of Columbia, Georgia, and Delaware and lowest in North Carolina, Alaska, and Wyoming. The burden peaked at ages 40–49 years and was higher in females. Age-standardized YLD rates for neck pain were significantly positively correlated with the SDI (Spearman’s ρ=0.601, P<0.001).Conclusion: The geographic and demographic disparities in neck pain burden across US states indicate a need for targeted interventions.