Brain networks disconnection in early multiple sclerosis cognitive deficits: An anatomofunctional study

Severe cognitive impairment involving multiple cognitive domains can occur early during the course of multiple sclerosis (MS). We investigated resting state functional connectivity changes in large‐scale brain networks and related structural damage underlying cognitive dysfunction in patients with early MS. Patients with relapsing MS (3–5 years disease duration) were prospectively assigned to two groups based on a standardized neuropsychological evaluation: (1) cognitively impaired group (CI group, n = 15), with abnormal performances in at least 3 tests; (2) cognitively preserved group (CP group, n = 20) with normal performances in all tests. Patients and age‐matched healthy controls underwent a multimodal 3T magnetic resonance imaging (MRI) including anatomical T1 and T2 images, diffusion imaging and resting state functional MRI. Structural MRI analysis revealed that CI patients had a higher white matter lesion load compared to CP and a more severe atrophy in gray matter regions highly connected to networks involved in cognition. Functional connectivity measured by integration was increased in CP patients versus controls in attentional networks (ATT), while integration was decreased in CI patients compared to CP both in the default mode network (DMN) and ATT. An anatomofunctional study within the DMN revealed that functional connectivity was mostly altered between the medial prefrontal cortex (MPFC) and the posterior cingulate cortex (PCC) in CI patients compared to CP and controls. In a multilinear regression model, functional correlation between MPFC and PCC was best predicted by PCC atrophy. Disconnection in the DMN and ATT networks may deprive the brain of compensatory mechanisms required to face widespread structural damage. Hum Brain Mapp 35:4706–4717, 2014. © 2014 Wiley Periodicals, Inc .     

Upbeat nystagmus due to a small pontine lesion: evidence for the existence of a crossing ventral tegmental tract

We report a patient with an isolated large upbeat nystagmus (UBN) in the primary position of gaze. Eye movements were filmed and recorded using electro-oculography. The upward vestibulo-ocular reflex gain, evaluated by pitching the head forward, was markedly reduced compared to when pitching the head back. The lesion was a probable lacunar infarction located in the paramedian and posterior part of the basis pontis, at the upper pons level. This UBN case, with one of the smallest brainstem lesions reported so far, supports the existence in humans of the crossing ventral tegmental tract, described in the cat and transmitting excitatory upward vestibular signals to the third nerve nucleus. It is also suggested that the decussation of this tract lies at the same upper pons level as in the cat but in a slightly more ventral location, i.e. in the posterior basis pontis.     

Contribution of proton magnetic resonance spectroscopy to the diagnosis of Balo's concentric sclerosis

INTRODUCTION: Balo's concentric sclerosis is a neuropathological type of multiple sclerosis characterized by alternating rings of spared myelin and demyelination. Diagnosis is based on MRI, but very few data are available concerning the lesion features using serial proton magnetic resonance spectroscopy (1H-MRS). METHODS: We report 1H-MRS initial findings and disease course in one case of Balo's concentric sclerosis. RESULTS: The first 1H-MRS study of 2 concentric ring-enhanced lesions showed a decreased N-acetyl-aspartate (NAA) peak, an increased choline peak, 2 broad lactate peaks and the presence of a lipid peak at 0.9 ppm. Six months later, 1H-MRS showed a decrease of choline peak, whereas the lactate peak had disappeared. The NAA peak was still at a low level. CONCLUSION: These findings are similar to those reported in demyelinating disorders, such as multiple sclerosis. Thus, in Balo's concentric sclerosis, 1H-MRS may provide neurochemical arguments for inflammation and demyelination, and indicate the severity of axonal damage and recovery.     

MRI characteristics of MOG-Ab associated disease in adults: An update

Our knowledge of the radiological spectrum of myelin oligodendrocyte glycoprotein antibody associated disease (MOGAD) is growing rapidly. An update on the radiological features of the disease, and its evolution is thus necessary. Magnetic resonance imaging (MRI) has an increasingly important role in the differential diagnosis of MOGAD particularly from aquaporin-4 antibody-positive neuromyelitis optica spectrum disorder (AQP4-NMOSD), and multiple sclerosis (MS). Differentiating these conditions is of prime importance because the management is different between the three inflammatory diseases, and thus could prevent further attack-related disability. Therefore, identifying the MRI features suggestive of MOGAD has diagnostic and prognostic implications. We herein review optic nerve, spinal cord and the brain MRI findings from MOGAD adult patients, and compare them to AQP4-NMOSD and MS.     

Ophthalmoplegia as the presenting muscle-related manifestation of myotonic dystrophy

Introduction

Myotonic dystrophy type 1 (DM1) is a genetic disorder caused by expanded CTG repeats within the 3’ untranslated region of the dystrophia myotonia protein kinase (DMPK) gene on chromosome 19. Diplopia is rare in this disease and has only been reported in patients with diffuse neuromuscular disorders.

Observation

We report here on the case of a 58-year-old woman in whom ophthalmoplegia was the first neuromuscular manifestation of DM1 and led to the diagnosis. Among the multisystem abnormalities associated with DM1, muscle-related symptoms are prominent, and usually involve the facial and neck muscles early on in the disease. This case provides additional evidence of oculomotor muscle involvement in DM1.

Conclusion

DM1 should, therefore, be considered during the diagnostic workup of any unexplained ophthalmoplegia of muscle origin, especially if there has been a previous history of cataract, even in the absence of typical muscle-related features.     

"What" and "where" in word reading: ventral coding of written words revealed by parietal atrophy

The visual system of literate adults develops a remarkable perceptual expertise for printed words. To delineate the aspects of this competence intrinsic to the occipitotemporal "what" pathway, we studied a patient with bilateral lesions of the occipitoparietal "where" pathway. Depending on critical geometric features of the display (rotation angle, letter spacing, mirror reversal, etc.), she switched from a good performance, when her intact ventral pathway was sufficient to encode words, to severely impaired reading, when her parietal lesions prevented the use of alternative reading strategies as a result of spatial and attentional impairments. In particular, reading was disrupted (a) by rotating word by more than 50 degrees , providing an approximation of the invariance range for words encoding in the ventral pathway; (b) by separating letters with double spaces, revealing the limits of letter grouping into perceptual wholes; (c) by mirror-reversing words, showing that words escape the default mirror-invariant representation of visual objects in the ventral pathway. Moreover, because of her parietal lesions, she was unable to discriminate mirror images of common objects, although she was excellent with reversible pseudowords, confirming that the breaking of mirror symmetry was intrinsic to the occipitotemporal cortex. Thus, charting the display conditions associated with preserved or impaired performance allowed us to infer properties of word coding in the normal ventral pathway and to delineate the roles of the parietal lobes in single-word recognition.     

Anti-MOG associated disease with intracranial hypertension after COVID-19 vaccination

Journal of Neurology -