Action tremor is a relatively frequent motor sign in patients with Parkinson's disease staging 1-2 on the Hoehn-Yahr scale. Action tremor correlates with rest tremor and rigidity and may be associated with a lower burden of non-motor symptoms. These findings suggest a contribution of non-dopaminergic mechanisms to action tremor pathophysiology.

Background:Guillain-Barré syndrome (GBS) is the broad term used to describe a number of related acute autoimmune neuropathies, which together form a continuous spectrum of variable and overlapping syndromes. Bifacial weakness with paresthesias (BFP) is a rare variant of GBS, characterized by isolated facial diplegia in the absence of ophthalmoplegia, ataxia, or limb weakness, and it is usually associated with distal limb paresthesias.Case Description: An 8-year-old boy was brought to our attention; because 5 days before coming to the hospital, he noticed he could no longer smile. Bilateral facial droop and inability to close both eyes were evident along with slight paresthesias at the hands and feet and gait disturbances. He progressively developed hypophonia, dysarthria, dysphagia associated with dysmetria, and limb ataxia. Nerve conduction studies showed a demyelinating polyneuropathy. Brain and spine magnetic resonance imaging (MRI) revealed contrast enhancement of both facial nerves and cauda equina nerve roots along with a hyperintense signal of the periaqueductal gray matter, superior cerebellar peduncles, and pontine tegmentum. Because BFP is not typically associated with other cranial neuropathies or ataxia, these clinical features along with peculiar MRI findings supported the diagnosis of "BFP plus." Finally, it can be speculated that this case configures a rare overlap between BFP and the other GBS variants, such as Bickerstaff encephalitis. Conclusions:This atypical case underlines the potential role of MRI in contributing to refining the nosological classification of GBS spectrum and optimizing individual treatment, especially in children where unusual manifestations are not infrequent and neurological examination is more challenging.

Hereditary sensory and autonomic neuropathies (HSAN) encompass a group of peripheral nervous system disorders characterized by remarkable heterogeneity from a clinical and genetic point of view. Mutations in SPTLC1 gene are responsible for HSAN type IA, which usually starts from the second to fourth decade with axonal neuropathy, sensory loss, painless distal ulcerations, and mild autonomic features, while motor involvement usually occur later as disease progresses. Beyond the classic presentation of HSAN type IA, an exceedingly rare distinct phenotype related to SPTLC1 mutations at residue serine 331 (S331) has recently been reported, characterized by earlier onset, prominent muscular atrophy, growth retardation, oculo‐skeletal abnormalities, and possible respiratory complications. In this report, we describe clinical, instrumental, and genetic aspects of a 13‐year‐old Sri Lankan male carrying the rare de novo p.S331Y heterozygous mutation in SPTLC1 gene found by whole exome sequencing. Patient's phenotype partly overlaps with the first case previously reported, however with some additional features not described before. This work represent the second report about this rare mutation and our findings strongly reinforce the hypothesis of a clearly distinct “S331 syndrome”, thus expanding the spectrum of SPTLC1‐related disorders.

Neuroacanthocytosis (NA) syndromes are a group of genetically defined diseases characterized by the association of red blood cell acanthocytosis, progressive degeneration of the basal ganglia and neuromuscular features with characteristic persistent hyperCKemia. The main NA syndromes include autosomal recessive chorea-acanthocytosis (ChAc) and X-linked McLeod syndrome (MLS). A series of Italian patients selected through a multicenter study for these specific neurological phenotypes underwent DNA sequencing of the VPS13A and XK genes to search for causative mutations. Where it has been possible, muscle biopsies were obtained and thoroughly investigated with histochemical assays. A total of nine patients from five different families were diagnosed with ChAC and had mostly biallelic changes in the VPS13A gene (three nonsense, two frameshift, three splicing), while three patients from a single X-linked family were diagnosed with McLeod syndrome and had a deletion in the XK gene. Despite a very low incidence (only one thousand cases of ChAc and a few hundred MLS cases reported worldwide), none of the 8 VPS13A variants identified in our patients is shared by two families, suggesting the high genetic variability of ChAc in the Italian population. In our series, in line with epidemiological data, McLeod syndrome occurs less frequently than ChAc, although it can be easily suspected because of its X-linked mode of inheritance. Finally, histochemical studies strongly suggest that muscle pathology is not simply secondary to the axonal neuropathy, frequently seen in these patients, but primary myopathic alterations can be detected in both NA syndromes.