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Background and Objectives: The RFC1 spectrum has become considerably expanded as multisystemic features beyond the triad of cerebellar ataxia, neuropathy, and vestibular areflexia syndrome (CANVAS) have started to be unveiled, although many still require clinical replication. Here, we aimed to clinically characterize a cohort of RFC1 -positive patients by addressing both classic and multisystemic features. In a second part of this study, we prospectively assessed small nerve fibers (SNF) and autonomic function in a subset of these RFC1 -related patients., Methods: We retrospectively enrolled 67 RFC1-positive patients from multiple neurologic centers in Portugal. All patients underwent full neurologic and vestibular evaluation, as well as neuroimaging and neurophysiologic studies. For SNF and autonomic testing (n = 15), we performed skin biopsies, quantitative sensory testing, sudoscan, sympathetic skin response, heart rate deep breathing, and tilt test., Results: Multisystemic features beyond CANVAS were present in 82% of the patients, mainly chronic cough (66%) and dysautonomia (43%). Other features included motor neuron (MN) affection and motor neuropathy (18%), hyperkinetic movement disorders (16%), sleep apnea (6%), REM and non-REM sleep disorders (5%), and cranial neuropathy (5%). Ten patients reported an inverse association between cough and ataxia severity. A very severe epidermal denervation was found in skin biopsies of all patients. Autonomic dysfunction comprised cardiovascular (67%), cardiovagal (54%), and/or sudomotor (50%) systems., Discussion: The presence of MN involvement, motor neuropathy, small fiber neuropathy, or extrapyramidal signs should not preclude RFC1 testing in cases of sensory neuronopathy. Indeed, the RFC1 spectrum can overlap not only with multiple system atrophy but also with hereditary motor and sensory neuropathy, hereditary sensory and autonomic neuropathy, and feeding dystonia phenotypes. Some clinical-paraclinical dissociations can pose diagnostic challenges, namely large and small fiber neuropathy and sudomotor dysfunction which are usually subclinical., Competing Interests: The authors report no relevant disclosures. Full disclosure form information provided by the authors is available with the full text of this article at Neurology.org/cp., (© 2023 American Academy of Neurology.)

Hereditary transthyretin amyloidosis (ATTRv amyloidosis) is predominantly a disease of the peripheral nerves, heart, kidney, and eye. CNS involvement has been a marginal issue in research and the clinical setting until recently. Growing evidence shows that leptomeningeal amyloid accumulation is frequent and present from early stages of ATTRv amyloidosis. Several recent studies show CNS symptoms arise as a common late complication in patients with the V30M mutation after at least 14 years of symptomatic peripheral nerve disease. Conversely, in non-V30M patients, there are several descriptions, mostly case reports, of patients presenting with severe phenotypes of ocular and CNS dysfunction (oculoleptomeningeal amyloidosis), with little systemic involvement. This phenotype is found in rare families worldwide, associated with at least 14 mutations. In both patients with late and early onset CNS dysfunction, symptoms include transient focal neurologic episodes, hemorrhagic and ischemic stroke, cognitive decline, and cranial nerve dysfunction. Pathologically, there is severe amyloid deposition in the leptomeninges and cerebral amyloid angiopathy of leptomeningeal and penetrating vessels. These amyloid aggregates are formed mostly by CSF-produced transthyretin (TTR) and seem resistant to the available ATTRv therapies that increase the stability or reduce the production of plasma TTR. This indicates that CNS involvement will become a meaningful issue in patient management in upcoming years., (© 2021 American Academy of Neurology.)

Background: Gliomatosis cerebri is a specific entity defined as a diffuse neoplastic glial cell infiltration of the brain, preserving the architecture of the normal surrounding tissues, involving more than 2 cerebral lobes. Clinical symptoms or radiologic features are nonspecific, and patients are often misdiagnosed with other neurologic diseases., Review Summary: Here, we report the diagnostic workup of 2 patients with gliomatosis cerebri, discussing the clinical, radiologic, and pathologic findings. Case 1: a 64-year-old woman who presented with an intracranial hypertension syndrome and had symmetrical white matter T2-weighted and fluid-attenuated inversion recovery hyperintensities pattern on magnetic resonance imaging; and case 2: a 54-year-old man with the diagnosis of multiple sclerosis for 8 years who presented with de novo cognitive impairment and focal deficits., Conclusions: This report highlights the difficulty of this differential diagnosis and the need of considering it also in the presence of a symmetrical pattern of white matter involvement. Cerebral biopsy remains crucial for the correct diagnosis and treatment approach.