Investigating genotype-phenotype relationship of extreme neuropathic pain disorders in a UK national cohort.

The aims of our study were to use whole genome sequencing in a cross-sectional cohort of patients to identify new variants in genes implicated in neuropathic pain, to determine the prevalence of known pathogenic variants and to understand the relationship between pathogenic variants and clinical presentation. Patients with extreme neuropathic pain phenotypes (both sensory loss and gain) were recruited from secondary care clinics in the UK and underwent whole genome sequencing as part of the National Institute for Health and Care Research Bioresource Rare Diseases project. A multidisciplinary team assessed the pathogenicity of rare variants in genes previously known to cause neuropathic pain disorders and exploratory analysis of research candidate genes was completed.

Acute and chronic neuropathies.

Peripheral nerve disorders are common and often treatable. The 'default' presentation of a polyneuropathy is a chronic, length-dependent, sensorimotor axonopathy. Recognizing deviations from this default, informed by the clinical features and investigations, can help identify the cause of a neuropathy in most cases.

Vasculitis and the peripheral nervous system.

Peripheral neuropathy is a common feature of systemic vasculitis and can also occur when vessel wall inflammation is confined to the vasa nervorum, as a tissue-specific condition-non-systemic vasculitic neuropathy (NSVN). Typically, the clinical picture in both systemic and non-systemic cases is of a lower limb predominant, distal, asymmetric or multifocal neuropathy, which is painful and subacute in onset. For NSVN, nerve biopsy is required to make the diagnosis, and nerve biopsy also has a role when vasculitic neuropathy is suspected and a systemic process has not yet declared itself.

POEMS syndrome: clinical update.

POEMS syndrome (polyneuropathy, organomegaly, endocrinopathy, M-protein, skin changes) is a rare paraneoplastic syndrome, caused by a plasma cell proliferative disorder, which is most commonly lambda restricted. The neurological hallmark, which forms one of the mandatory criteria for diagnosis, is a subacute onset demyelinating neuropathy, which can be rapidly disabling and painful. A number of multi-system features are also characteristic of this disorder, and certainly not restricted to those included in its acronym, which though limited, remains a useful and memorable name, helping distinguish POEMS syndrome from other paraproteinaemic neuropathies.

Cryopyrin-Associated Periodic Fever Syndrome and the Nervous System.

Purpose Of Review: The purpose of this review is to highlight the molecular and clinical characteristics of the cryopyrin-associated periodic fever syndrome (CAPS) and its management. CAPS is an autosomal dominantly inherited autoinflammatory disorder associated with mutations in the NLRP3 gene, which ultimately lead to excessive production of interleukin-1β (IL-1β) and systemic inflammation. Typical systemic features include fever, urticarial rash and arthralgia, and ultimately amyloidosis.

Myelopathy: chameleons and mimics.

The diagnosis of spinal cord disease may be delayed or missed if the presentation does not conform to the expected pattern of a symmetrical spastic paraparesis with sphincter dysfunction and a sensory level. This may occur when a myelopathy has yet to evolve fully, or is highly asymmetrical, as in Brown-Séquard syndrome. Other potential distractions include fluctuating symptoms, as may accompany spinal cord demyelination, and pseudoneuropathic features, as seen acutely in spinal shock and in the chronic setting with some high cervical cord lesions.

The nerve biopsy: indications, technical aspects, and contribution.

This chapter discusses the indications for biopsying a peripheral nerve and the factors involved in justifying this decision and then deciding which nerve to take. There is a table summarizing some of the causes of neuropathy and attempting to relate these to the probability that nerve biopsy would be helpful in diagnosis. The surgical procedure for the nerve biopsy is described including aftercare and possible complications.

TRPA1 insensitivity of human sural nerve axons after exposure to lidocaine.

TRPA1 is an ion channel of the TRP family that is expressed in some sensory neurons. TRPA1 activity provokes sensory symptoms of peripheral neuropathy, such as pain and paraesthesia. We have used a grease gap method to record axonal membrane potential and evoked compound action potentials (ECAPs) in vitro from human sural nerves and studied the effects of mustard oil (MO), a selective activator of TRPA1.

Fabry International Prognostic Index: a predictive severity score for Anderson-Fabry disease.

Background: Anderson-Fabry disease (AFD) is a disorder of glycosphingolipid metabolism resulting from deficiency of α-galactosidase A and accumulation of globotriaosylceramide. Presentation is heterogeneous and, despite guidelines for initiation of therapy, there is no basis for defining subgroups that will progress more rapidly, whether treated or not. The authors of this study used clinical and pathological data recorded on 1483 patients in the Fabry Outcome Survey, a large international registry, to develop a prognostic severity score.

Neurologic manifestations of the cryopyrin-associated periodic syndrome.

Background: The cryopyrin-associated periodic syndrome (CAPS) is a rare but treatable hereditary autoinflammatory condition. Without treatment, one third of patients develop amyloidosis with consequent renal failure and death. CAPS encompasses 3 conditions: familial cold autoinflammatory syndrome, Muckle-Wells syndrome, and chronic infantile, neurologic, cutaneous, and articular syndrome.

The phenotype of Charcot-Marie-Tooth disease type 4C due to SH3TC2 mutations and possible predisposition to an inflammatory neuropathy.

Charcot-Marie-Tooth (CMT) disease is a heterogeneous group of inherited peripheral motor and sensory neuropathies. The locus responsible for CMT4C was previously assigned to the chromosome 5q23 region by homozygosity mapping and mutations in the SH3TC2 (KIAA1985) gene have been subsequently identified mainly in families around the Mediterranean basin but also frequently in European Gypsies. No English families have been reported to date.

Characterization of a novel TYMP splice site mutation associated with mitochondrial neurogastrointestinal encephalomyopathy (MNGIE).

Mitochondrial neurogastrointestinal encephalomyopathy is an autosomal recessive disorder caused by loss-of-function mutations in the thymidine phosphorylase gene (TYMP). We report here a patient compound heterozygous for two TYMP mutations: a novel g.4009G>A transition affecting the consensus splice donor site of intron 9, and a previously reported g.

CNS manifestations of Fabry's disease.

Background: Fabry's disease is a rare hereditary lysosomal storage disease with multiorgan involvement. Deficiency of alpha-galactosidase A activity leads to accumulation of neutral glycosphingolipids, especially in vascular endothelial and smooth-muscle cells. Along with progressive renal and cardiac dysfunction, stroke is a major and often life-threatening burden of the disease.

Magnetic resonance imaging changes in Fabry disease.

Unlabelled: Recognized magnetic resonance imaging (MRI) abnormalities in the brains of patients with Fabry disease include the consequences of infarction and haemorrhage, non-specific white and grey matter lesions, vascular anomalies, in particular dolicho-ectasia, and a characteristic appearance of the posterior thalamus. A preliminary analysis of MRI findings in patients registered in FOS, the Fabry Outcome Survey, indicates that most patients had abnormal scans (25/47). The commonest abnormality, in males and females, was the presence of cerebral white matter lesions, the number of which increased with patient age.

Brachial plexus hypertrophy in chronic inflammatory demyelinating polyradiculoneuropathy.

We present the clinical, imaging and neuropathological findings in three patients with predominant brachial plexus neuropathy. MR scanning was key to determining the brachial plexus involvement. Biopsy of the brachial plexus was performed in one patient.

A novel RAB7 mutation associated with ulcero-mutilating neuropathy.

There are two known autosomal dominant genes for the hereditary ulcero-mutilating neuropathies: SPTLC1 (hereditary sensory neuropathy type 1) and RAB7 (Charcot-Marie-Tooth disease type 2B). We report a family with autosomal dominant ulcero-mutilating neuropathy, developing in the teens and characterized by ulcers, amputations, sensory involvement in the feet but no motor features. Sequencing the RAB7 gene showed a novel heterozygous A to C mutation, changing asparagine to threonine at codon 161.

A clinical, genetic and biochemical study of SPG7 mutations in hereditary spastic paraplegia.

Mutations in the SPG7 gene, encoding the mitochondrial protein paraplegin, were the first to be identified in autosomal recessive hereditary spastic paraplegia (ARHSP). Four different SPG7 mutations have been described so far in association with both pure and complicated HSP phenotypes. Muscle biopsies from the most severely affected patients have shown histological evidence of an oxidative phosphorylation defect.