Revisiting a Telencephalic Extent of the Ascending Reticular Activating System.

Is the cerebrum involved in its own activation to states of attention or arousal? "Telencephalon" is a term borrowed from embryology to identify not only the cerebral hemispheres of the forebrain, but also the basal forebrain. We review a generally undercited literature that describes nucleus basalis of Meynert, located within the substantia innominata of the ventrobasal forebrain, as a telencephalic extension of the ascending reticular activating formation. Although that formation's precise anatomical definition and localization have proven elusive over more than 70 years, a careful reading of sources reveals that there are histological features common to certain brainstem neurons and those of the nucleus basalis, and that a largely common dendritic architecture may be a morphological aspect that helps to define non-telencephalic structures of the ascending reticular activating formation (e.g., in brainstem) as well as those parts of the formation that are telencephalic and themselves responsible for cortical activation. We draw attention to a pattern of dendritic arborization described as "isodendritic," a uniform (isos-) branching in which distal dendrite branches are significantly longer than proximal ones. Isodendritic neurons also differ from other morphological types based on their heterogeneous, rather than specific afferentation. References reviewed here are consistent in their descriptions of histology, particularly in studies of locales rich in cholinergic neurons. We discuss the therapeutic implications of a basal forebrain site that may activate cortex. Interventions that specifically target nucleus basalis and, especially, the survival of its constituent neurons may benefit afflictions in which higher cortical function is compromised due to disturbed arousal or attentiveness, including not only coma and related syndromes, but also conditions colloquially described as states of cognitive "fog" or of "long-haul" mental compromise.

Neurologic disease activity in people with multiple sclerosis treated with immune checkpoint inhibitors.

BACKGROUND: There is concern that immune checkpoint inhibitors (ICPIs) can provoke relapses in people with multiple sclerosis (pwMS). OBJECTIVE: Analyze outcomes of pwMS who received ICPI treatment for malignancy. METHODS: We electronically identified pwMS who received ICPI treatment at Mass General Brigham hospital system. We retrospectively obtained information about patients' MS, cancer, treatment, and outcomes. RESULTS: Sixteen patients were identified with an average (standard deviation (SD)) age of 67.4 (11.9) years. Eleven (68.8%) had no relapses since MS diagnosis. None had MS relapses after ICPI treatment or new MS lesions. CONCLUSION: ICPI use was not associated with increased clinical disease activity in this cohort of older patients with inactive MS.

Fluorescein Angiography Findings in Susac Syndrome: A Multicenter Retrospective Case Series.

BACKGROUND: Susac syndrome is a vasculopathy, resulting in the classic triad of branch retinal artery occlusion (BRAO), inner ear ischemia, and brain ischemia. In this retrospective chart review, we characterize fluorescein angiography (FA) findings and other ancillary studies in Susac syndrome, including the appearance of persistent disease activity and the occurrence of new subclinical disease on FA. METHODS: This multicenter, retrospective case series was institutional review board-approved and included patients with the complete triad of Susac syndrome evaluated with FA, contrasted MRI of the brain, and audiometry from 2010 to 2020. The medical records were reviewed for these ancillary tests, along with demographics, symptoms, visual acuity, visual field defects, and findings on fundoscopy. Clinical relapse was defined as any objective evidence of disease activity during the follow-up period after initial induction of clinical quiescence. The main outcome measure was the sensitivity of ancillary testing, including FA, MRI, and audiometry, to detect relapse. RESULTS: Twenty of the 31 (64%) patients had the complete triad of brain, retinal, and vestibulocochlear involvement from Susac syndrome and were included. Median age at diagnosis was 43.5 years (range 21-63), and 14 (70%) were women. Hearing loss occurred in 20 (100%), encephalopathy in 13 (65%), vertigo in 15 (75%), and headaches in 19 (95%) throughout the course of follow-up. Median visual acuity at both onset and final visit was 20/20 in both eyes. Seventeen (85%) had BRAO at baseline, and 10 (50%) experienced subsequent BRAO during follow-up. FA revealed nonspecific leakage from previous arteriolar damage in 20 (100%), including in patients who were otherwise in remission. Of the 11 episodes of disease activity in which all testing modalities were performed, visual field testing/fundoscopy was abnormal in 4 (36.4%), MRI brain in 2 (18.2%), audiogram in 8 (72.7%), and FA in 9 (81.8%). CONCLUSIONS: New leakage on FA is the most sensitive marker of active disease. Persistent leakage represents previous damage, whereas new areas of leakage suggest ongoing disease activity that requires consideration of modifying immunosuppressive therapy.

Development of a Definition of Postacute Sequelae of SARS-CoV-2 Infection.

Importance: SARS-CoV-2 infection is associated with persistent, relapsing, or new symptoms or other health effects occurring after acute infection, termed postacute sequelae of SARS-CoV-2 infection (PASC), also known as long COVID. Characterizing PASC requires analysis of prospectively and uniformly collected data from diverse uninfected and infected individuals. Objective: To develop a definition of PASC using self-reported symptoms and describe PASC frequencies across cohorts, vaccination status, and number of infections. Design, Setting, and Participants: Prospective observational cohort study of adults with and without SARS-CoV-2 infection at 85 enrolling sites (hospitals, health centers, community organizations) located in 33 states plus Washington, DC, and Puerto Rico. Participants who were enrolled in the RECOVER adult cohort before April 10, 2023, completed a symptom survey 6 months or more after acute symptom onset or test date. Selection included population-based, volunteer, and convenience sampling. Exposure: SARS-CoV-2 infection. Main Outcomes and Measures: PASC and 44 participant-reported symptoms (with severity thresholds). Results: A total of 9764 participants (89% SARS-CoV-2 infected; 71% female; 16% Hispanic/Latino; 15% non-Hispanic Black; median age, 47 years [IQR, 35-60]) met selection criteria. Adjusted odds ratios were 1.5 or greater (infected vs uninfected participants) for 37 symptoms. Symptoms contributing to PASC score included postexertional malaise, fatigue, brain fog, dizziness, gastrointestinal symptoms, palpitations, changes in sexual desire or capacity, loss of or change in smell or taste, thirst, chronic cough, chest pain, and abnormal movements. Among 2231 participants first infected on or after December 1, 2021, and enrolled within 30 days of infection, 224 (10% [95% CI, 8.8%-11%]) were PASC positive at 6 months. Conclusions and Relevance: A definition of PASC was developed based on symptoms in a prospective cohort study. As a first step to providing a framework for other investigations, iterative refinement that further incorporates other clinical features is needed to support actionable definitions of PASC.

Myelopathy: A Clinical Approach.

Myelopathy is a clinical diagnosis with many causes. A focused history and neurologic exam can help identify a myelopathic syndrome that guides a targeted workup. Though an exact cause may not always be identified, a thoughtful clinical approach can narrow down the differential diagnosis enough to treat the patient.

Acute Neurologic Manifestations of Systemic Immune-Mediated Diseases.

Systemic autoimmune diseases can affect the peripheral and central nervous system. In this review, we outline the common inpatient consultations for patients with neurological symptoms from rheumatoid arthritis, Sjogren's syndrome, systemic lupus erythematosus, sarcoidosis, immunoglobulin G4-related disease, Behçet's disease, giant cell arteritis, granulomatosis with polyangiitis, microscopic polyangiitis, eosinophilic granulomatosis, polyarteritis nodosa, and ankylosing spondylitis. We discuss the symptoms, diagnostic strategies, and treatment options.

Emerging Cases of Powassan Virus Encephalitis in New England: Clinical Presentation, Imaging, and Review of the Literature.

BACKGROUND: Powassan virus (POWV) is a rarely diagnosed cause of encephalitis in the United States. In the Northeast, it is transmitted by Ixodes scapularis, the same vector that transmits Lyme disease. The prevalence of POWV among animal hosts and vectors has been increasing. We present 8 cases of POWV encephalitis from Massachusetts and New Hampshire in 2013-2015. METHODS: We abstracted clinical and epidemiological information for patients with POWV encephalitis diagnosed at 2 hospitals in Massachusetts from 2013 to 2015. We compared their brain imaging with those in published findings from Powassan and other viral encephalitides. RESULTS: The patients ranged in age from 21 to 82 years, were, for the most part, previously healthy, and presented with syndromes of fever, headache, and altered consciousness. Infections occurred from May to September and were often associated with known tick exposures. In all patients, cerebrospinal fluid analyses showed pleocytosis with elevated protein. In 7 of 8 patients, brain magnetic resonance imaging demonstrated deep foci of increased T2/fluid-attenuation inversion recovery signal intensity. CONCLUSIONS: We describe 8 cases of POWV encephalitis in Massachusetts and New Hampshire in 2013-2015. Prior to this, there had been only 2 cases of POWV encephalitis identified in Massachusetts. These cases may represent emergence of this virus in a region where its vector, I. scapularis, is known to be prevalent or may represent the emerging diagnosis of an underappreciated pathogen. We recommend testing for POWV in patients who present with encephalitis in the spring to fall in New England.

Oral Inosine Persistently Elevates Plasma antioxidant capacity in Parkinson's disease.

INTRODUCTION: Higher serum urate predicts slower progression in PD. The aim of this work was to assess whether oral inosine alters antioxidant capacity of plasma or CSF or urinary markers of oxidative injury in early PD. METHODS: We assayed plasma and CSF antioxidant capacity by ferric-reducing antioxidant power and measured DNA oxidation adduct 8-hydroxydeoxyguanosine from urine in Safety of URate Elevation in PD, a randomized, placebo-controlled trial of oral inosine assessing safety of elevating serum urate from <6 mg/dL to 6.1-7.0 or 7.1-8.0 mg/dL in patients with early PD. RESULTS: At 6 months, antioxidant capacity was 29% higher among mild and 43% higher among moderate group participants compared to placebo and correlated with change in serum urate (r = 0.86) and inversely with rate of clinical decline (r = -0.26). CSF antioxidant capacity and urine 8-hydroxydeoxyguanosine did not differ. CONCLUSIONS: The findings demonstrate a dose-dependent, persistent elevation of plasma antioxidant capacity from oral inosine of potential therapeutic relevance.

Primary angiitis of the central nervous system: avoiding misdiagnosis and missed diagnosis of a rare disease.

Primary angiitis of the central nervous system (PACNS) is an extremely rare condition, defined as a vasculitis limited to the CNS with no identifiable cause. Its presentation is non-specific and includes headache, cognitive dysfunction and focal neurological signs. Laboratory studies, neuroimaging and angiography are neither sufficiently sensitive nor specific for diagnosis; a definitive diagnosis requires brain biopsy. As a result, PACNS is commonly misdiagnosed. Here, we review its clinical, laboratory and radiological features, and focus on avoiding common diagnostic pitfalls.

Ataxia induced by a thymic neuroblastoma in the elderly patient.

Thymic neuroblastoma is a rare tumor with only few reports in modern literature. Whereas most data is taken from childhood neuroblastoma, little is known about the characteristics of the disease in the adult and elderly population. There are significant differences between adult and childhood neuroblastoma which are reviewed below. We report a case of a 62-year-old male who presented with neurological symptoms of ataxia and opsoclonus and an anterior mediastinal mass. Ultimately, the patient underwent a resection of the mass and pathologic review identified a thymic neuroblastoma. This is the first case of thymic neuroblastoma associated with symptomatic central nervous system disease; it is presented with an up-to-date review of the previous cases in the field as well with a review of the literature of post adolescent neuroblastoma.

Neurologic complications of systemic lupus erythematosus, sjögren syndrome, and rheumatoid arthritis.

Neurologic complications are frequent and often morbid in systemic lupus erythematosus, Sjögren syndrome, and rheumatoid arthritis. Although all are systemic inflammatory syndromes, each disease affects the nervous system distinctly, such as peripheral neuropathy in Sjögren syndrome, cerebrovascular disease in lupus, and cervical spine subluxation in rheumatoid arthritis. Some neurologic complications share convergent pathophysiology across diseases, such as neuromyelitis optica spectrum disorders in both Sjögren syndrome and lupus. Ill-defined cognitive complaints are especially common in lupus and Sjögren syndrome. For the majority of the complications, evidence for treatment efficacy is limited and requires further investigation.

Infectious Myelopathies.

OBJECTIVE: Infectious myelopathy of any stage and etiology carries the potential for significant morbidity and mortality. This article details the clinical presentation, risk factors, and key diagnostic components of infectious myelopathies with the goal of improving the recognition of these disorders and guiding subsequent management. LATEST DEVELOPMENTS: Despite our era of advanced multimodal imaging and laboratory diagnostic technology, a causative organism often remains unidentified in suspected infectious and parainfectious myelopathy cases. To improve diagnostic capability, newer technologies such as metagenomics are being harnessed to develop diagnostic assays with a greater breadth of data from each specimen and improvements in infection identification. Conventional assays have been optimized for improved sensitivity and specificity. ESSENTIAL POINTS: Prompt recognition and treatment of infectious myelopathy decreases morbidity and mortality. The key diagnostic tools include serologies, CSF analysis, and imaging; however clinical presentation, epidemiologic risk factors, and history of recent illness are all vital to making the proper diagnosis because current laboratory and imaging modalities are often inconclusive. The cornerstone of recommended treatment is targeted antimicrobials with appropriate immune modulation, surgical intervention, supportive care, and interdisciplinary involvement, all of which further improve outcomes for patients with infectious myelopathy.

Stroke associated with sarcoidosis: A systematic review of reported cases.

BACKGROUND: Sarcoidosis can be associated with stroke. Whether granulomatous vasculitis directly causes stroke in patients with sarcoidosis remains unclear. This systematic review aims to consolidate reports of concurrent sarcoidosis and stroke. METHODS: Medline and Embase were searched for terms encompassing sarcoidosis and stroke with a censoring date of March 25, 2023. Cases were reviewed by two authors, with the inclusion criteria: biopsy-confirmed systemic sarcoidosis, stroke confirmed by imaging or pathology, clinical description of individual patient history, and English language publications. RESULTS: Of 1628 articles screened, 51 patients from 49 articles were included (65% male, mean age 41 years). Seventy-one percent of strokes were ischemic and 29% were hemorrhagic. Lesions were supratentorial in 78% of cases, infratentorial in 34%, and multifocal in 45%. Presenting symptoms were variable, with the most common being headache (38%) followed by weakness (35%). 10 patients had recurrent strokes. Stroke was the presenting symptom of sarcoidosis in 65%. 21 patients had brain biopsies. The most common neuropathologic findings were perivascular (33%) or intramural (33%) non-caseating granulomas. On imaging, 32 patients had findings suggestive of neurosarcoidosis, including 35% with evidence of meningeal enhancement. 63% of patients were treated with corticosteroids and/or other immunomodulatory therapy, with varying clinical improvement. CONCLUSIONS: Stroke associated with sarcoidosis generally follows trends in stroke incidence, with infarction being more common than hemorrhage and male sex carrying a higher risk. Most patients were diagnosed with sarcoidosis during or following their stroke episode. Brain biopsy infrequently shows clear granulomatous vasculitis.

Disease modifying therapy in the treatment of tumefactive multiple sclerosis: A retrospective cohort study.

Tumefactive multiple sclerosis (TMS) is characterized by large demyelinating brain lesions. This was a retrospective cohort study of 67 patients with TMS between January 2015-2023, examining different disease modifying therapy impact on expanded disability scale score change at follow-up. Median age was 36 with a female predominance. Mean EDSS was 3.3 ± 2.3 at TMS onset, 2.1 ± 1.9 at year one, and 2.1 ± 1.9 at last follow-up. A multilinear regression model found higher presentation EDSS and post-diagnosis non-B-cell high efficacy therapies were each independently associated with higher EDSS at last follow up. Further research is needed to determine the value of B-cell therapy in TMS.