Neglect scoring modifications in the National Institutes of Health Stroke Scale improve right hemisphere stroke lesion volume prediction.

BACKGROUND: The National Institutes of Health Stroke Scale (NIHSS) does not equitably assess stroke severity in the two cerebral hemispheres. By attributing a maximum of two points for neglect and seven for language, it undervalues right hemisphere deficits. We aimed to investigate if NIHSS equally predicts right hemisphere lesion volumes in patients with and without neglect, and if a modification of the neglect scoring rules could increase its predictive capacity. METHODS: We analyzed a prospective cohort of acute right middle cerebral artery ischemic stroke patients. First, we calculated the correlation between NIHSS scores and lesion volume and analyzed the partial correlation of neglect. Then, we applied different modifications in the neglect scoring rules and investigated how they interfered with lesion volume predictive capacity. RESULTS: A total of 162 ischemic stroke patients were included, 108 with neglect and 54 without. The correlation between lesion volume and NIHSS was lower in patients with neglect (r = 0.540 vs. r = 0.219, p = 0.004) and neglect was a statistically significant covariate in the partial correlation analysis between NIHSS and lesion volume (p = 0.017). With the neglect score tripled and with the duplication or triplication of all neglect modalities, the correlation was significantly higher than with the standard NIHSS (p = 0.043, p = 0.005, p = 0.001, respectively). With these modifications, neglect was no longer a significant covariable in the partial correlation between lesion volume and NIHSS. CONCLUSION: A modification of NIHSS neglect scoring might improve the scale's capacity to predict lesion volume.

An image is not always worth a thousand words: an image mimic of transient global amnesia.

Transient global amnesia (TGA) is a neurological syndrome with rather distinctive brain MRI features, namely hyperintense lesion in hippocampus on diffusion-weighted imaging (DWI) and fluid-attenuated inversion recovery (FLAIR) sequences. Post-traumatic amnesia is another amnestic syndrome which can also show hyperintense lesions in brain MRI due to cytotoxic oedema caused by traumatic brain injury. We present a case of a patient with post-traumatic amnesia with a brain MRI image mimic of TGA.

Structural disconnectome analysis of acute freezing of gait due to parietal stroke: implications for FOG pathogenesis.

Acute onset isolated freezing of gait (FOG) is a rare and defying diagnosis. Its pathophysiology is not yet totally understood and several brain regions seem to be involved. Postlesional FOG can help to shed light on the networks involved.We report a case of an 80-year-old woman who presented to the emergency department with acute onset impairment of gait. Her medical history was unremarkable. On neurological examination she was presented with difficulties in gait initiation, turning and progressing through narrow spaces. Her remaining neurological examination was unremarkable. Brain CT showed a subacute cortico-subcortical right parieto-occipital infarction. Acute isolated FOG due to parieto-occipital stroke was diagnosed. A structural disconnectome analysis showed that the lesion disrupted structural connections with the ipsilateral ventral striatum. This case highlights that acute onset FOG might be a consequence of a parietal cortical lesion.

The subcortical and neurochemical organization of the ventral and dorsal attention networks.

Attention is a core cognitive function that filters and selects behaviourally relevant information in the environment. The cortical mapping of attentional systems identified two segregated networks that mediate stimulus-driven and goal-driven processes, the Ventral and the Dorsal Attention Networks (VAN, DAN). Deep brain electrophysiological recordings, behavioral data from phylogenetic distant species, and observations from human brain pathologies challenge purely corticocentric models. Here, we used advanced methods of functional alignment applied to resting-state functional connectivity analyses to map the subcortical architecture of the Ventral and Dorsal Attention Networks. Our investigations revealed the involvement of the pulvinar, the superior colliculi, the head of caudate nuclei, and a cluster of brainstem nuclei relevant to both networks. These nuclei are densely connected structural network hubs, as revealed by diffusion-weighted imaging tractography. Their projections establish interrelations with the acetylcholine nicotinic receptor as well as dopamine and serotonin transporters, as demonstrated in a spatial correlation analysis with a normative atlas of neurotransmitter systems. This convergence of functional, structural, and neurochemical evidence provides a comprehensive framework to understand the neural basis of attention across different species and brain diseases.

An improved neuroanatomical model of the default-mode network reconciles previous neuroimaging and neuropathological findings.

The brain is constituted of multiple networks of functionally correlated brain areas, out of which the default-mode network (DMN) is the largest. Most existing research into the DMN has taken a corticocentric approach. Despite its resemblance with the unitary model of the limbic system, the contribution of subcortical structures to the DMN may be underappreciated. Here, we propose a more comprehensive neuroanatomical model of the DMN including subcortical structures such as the basal forebrain, cholinergic nuclei, anterior and mediodorsal thalamic nuclei. Additionally, tractography of diffusion-weighted imaging was employed to explore the structural connectivity, which revealed that the thalamus and basal forebrain are of central importance for the functioning of the DMN. The contribution of these neurochemically diverse brain nuclei reconciles previous neuroimaging with neuropathological findings in diseased brains and offers the potential for identifying a conserved homologue of the DMN in other mammalian species.