Evaluation of small fibre neuropathies.

Small fibre neuropathies (SFNs) are common and can significantly affect patients' lives due to debilitating pain and autonomic symptoms. We explain the tests that neurologists can use to diagnose SFNs and how neurophysiologists perform and interpret them. This review focuses on neurophysiological tests that can be used to investigate SFNs, their sensitivity, specificity and limitations.

Cortical myoclonus and epilepsy in a family with a new SLC20A2 mutation.

Idiopathic basal ganglia calcification (IBGC) or primary familial brain calcification is a rare genetic condition characterized by an autosomal dominant inheritance pattern and the presence of bilateral calcifications in the basal ganglia, thalami, cerebellum and cerebral subcortical white matter. The syndrome is genetically and phenotypically heterogeneous. Causal mutations have been identified in four genes: SLC20A2, PDGFRB, PDGFB and XPR1.

PDXK mutations cause polyneuropathy responsive to pyridoxal 5'-phosphate supplementation.

Objective: To identify disease-causing variants in autosomal recessive axonal polyneuropathy with optic atrophy and provide targeted replacement therapy.

Methods: We performed genome-wide sequencing, homozygosity mapping, and segregation analysis for novel disease-causing gene discovery. We used circular dichroism to show secondary structure changes and isothermal titration calorimetry to investigate the impact of variants on adenosine triphosphate (ATP) binding.

Brachial Neuritis After Botulinum Toxin Injections for Cervical Dystonia: A Need for a Reappraisal?

Background: Brachial neuritis has previously been described as a rare occurrence in patients receiving botulinum toxin for cervical or writing/focal arm dystonia.

Methods: We report four cases of patients with a long history of cervical dystonia treated with botulinum toxin injections.

Results: All patients developed pain and muscular weakness around the shoulder, with EMG studies suggesting brachial neuritis.

Adult Periodic Alternating Nystagmus Masked by Involuntary Head Movements.

Acquired periodic alternating nystagmus (PAN) describes a horizontal jerk nystagmus that reverses its direction with a predictable cycle, and is thought to arise from lesions involving the brainstem and cerebellum. We report a 20-year-old patient with PAN who presented with an acute vertiginous episode and developed an involuntary head movement that initially masked the PAN. The involuntary head movements were abolished with a subtherapeutic dose of botulinum toxin to the neck muscles.

A Pilot Study of Botulinum Toxin for Jerky, Position-Specific, Upper Limb Action Tremor.

Background: We aimed to investigate the efficacy and safety of botulinum toxin (BT) injections for jerky action tremor of the upper limb.

Methods: We performed an uncontrolled, prospective study of electromyography (EMG)-guided BT injections for jerky, position-specific, upper limb action tremor. The primary outcome was clinical global impression at 3-6 weeks after baseline.

Mental rotation and working memory in musicians' dystonia.

Background: Mental rotation of body parts engages cortical-subcortical areas that are actually involved in the execution of a movement. Musicians' dystonia is a type of focal hand dystonia that is grouped together with writer's cramp under the rubric of "occupational dystonia", but it is unclear to which extent these two disorders share common pathophysiological mechanisms. Previous research has demonstrated patients with writer's cramp to have deficits in mental rotation of body parts.

The long-term outcome of orthostatic tremor.

Objectives: Orthostatic tremor is a rare condition characterised by high-frequency tremor that appears on standing. Although the essential clinical features of orthostatic tremor are well established, little is known about the natural progression of the disorder. We report the long-term outcome based on the largest multicentre cohort of patients with orthostatic tremor.

Propriospinal myoclonus: clinical reappraisal and review of literature.

Objective: Propriospinal myoclonus (PSM) is a rare disorder with repetitive, usually flexor arrhythmic brief jerks of the trunk, hips, and knees in a fixed pattern. It has a presumed generation in the spinal cord and diagnosis depends on characteristic features at polymyography. Recently, a historical paradigm shift took place as PSM has been reported to be a functional (or psychogenic) movement disorder (FMD) in most patients.

Shaking on Standing: A Critical Review.

Orthostatic tremor is a rare condition, though its exact prevalence is unknown, which is clinically characterized by a feeling of unsteadiness or being about to fall on standing and which disappears on walking, sitting, or lying down. It is generally accepted that classic orthostatic tremor manifests with a high-frequency tremor (>13 Hz) of the legs when standing. However, a number of patients initially reported as orthostatic tremor did not actually have such electrophysiological features.

Facial tremor in dystonia.

Background: Tremor of the upper/middle part of the face, including the perinasal region and the forehead has been very rarely described in some patients with Parkinson's disease or Essential Tremor. It has not yet been reported in patients with idiopathic dystonia.

Methods: We describe here a series of 8 patients with common forms of idiopathic focal/segmental dystonia with tremor involving the upper/middle part of the face, along with demonstrative videos and electrophysiological recordings.

Psychogenic axial myoclonus: clinical features and long-term outcome.

Background: It has been increasingly recognized that the majority of patients with a diagnosis of idiopathic propriospinal myoclonus have either a subsequent clinical course or electrophysiological features indicating that the likely etiology is psychogenic. However, the clinical features of psychogenic axial myoclonus and the long-term outcome have not yet well characterized.

Patients And Methods: Here we describe clinical findings with representative videos and long term outcomes of 76 patients with an electrophysiologically established diagnosis of psychogenic axial myoclonus.

The phenotypic spectrum of DYT24 due to ANO3 mutations.

Genes causing primary dystonia are rare. Recently, pathogenic mutations in the anoctamin 3 gene (ANO3) have been identified to cause autosomal dominant craniocervical dystonia and have been assigned to the dystonia locus dystonia-24 (DYT24). Here, we expand on the phenotypic spectrum of DYT24 and provide demonstrative videos.

Rest and other types of tremor in adult-onset primary dystonia.

Introduction: Knowledge regarding tremor prevalence and phenomenology in patients with adult-onset primary dystonia is limited. Dystonic tremor is presumably under-reported, and we aimed to assess the prevalence and the clinical correlates of tremor in patients with adult-onset primary dystonia.

Methods: We enrolled 473 consecutive patients with different types of adult-onset primary dystonia.