Giuseppe Lauria

European federation of neurological societies/peripheral nerve society guideline on the use of skin biopsy in the diagnosis of small fiber neuropathy. report of a joint task force of the european fe-deration of neurological societies and the peripheral nerve society

Background:u2002 Revision of the guidelines on the use of skin biopsy in the diagnosis of peripheral neuropathy, published in 2005, has become appropriate owing to publication of more relevant articles. Most of the new studies focused on small fiber neuropathy (SFN), a subtype of neuropathy for which the diagnosis was first developed through skin biopsy examination. This revision focuses on the use of this technique to diagnose SFN.

Does CMT1A homozygosity cause more severe disease with root hypertrophy and higher CSF proteins

Charcot-Marie-Tooth type 1A (CMT1A) is associated with a peripheral myelin protein-22 ( PMP22 ) gene duplication on chromosome 17p11.2.1 CMT1A patients have three PMP22 copies and a gene dosage effect, leading to increased PMP22 protein expression, is the hypothesized pathogenic mechanism. Homozygosity for the duplication has been reported in patients from three families, with both parents carrying the duplication and transmitting the mutation to their offspring, who had PMP22 tetrasomy and variable disease severity.1-3⇓⇓nnWe report a homozygous CMT1A patient with rather severe disease, high CSF proteins, and astonishing root hypertrophy.nnThe patient is a 45-year-old man born to first-cousin parents. His parents, two sisters, one brother, and two sons had pes cavus and lower limb weakness (see figure E-1A on the Neurology Web site). He developed pes cavus and walking difficulties at age 11 years, scoliosis at age 16, and slowly progressive lower limb weakness until age 42, when he had more rapid worsening with difficulty climbing stairs, loss of balance, and hand weakness. Hearing loss started at age 33 years. On admission, he had marked foot deformities (walking with support), moderate scoliosis, bilateral hearing loss, muscle wasting and weakness (severe distally in lower …

The diagnostic challenge of small fibre neuropathy: clinical presentations, evaluations, and causes

Small fibre neuropathies are a heterogeneous group of disorders affecting thinly myelinated Aδ-fibres and unmyelinated C-fibres. Although multiple causes of small nerve fibre degeneration have been reported, including via genetic mutations, the cause of small fibre neuropathy remains unknown in up to 50% of cases. The typical clinical presentation of small fibre neuropathy is that of a symmetrical, length-dependent polyneuropathy associated with sensory or autonomic symptoms. More rarely, the clinical presentation is characterised by non-length-dependent, focal, or multifocal symptoms. The diagnostic tests to identify small fibre neuropathy include skin biopsy, quantitative sensory, and autonomic testing. Additional tests, such as those measuring small fibre-related evoked potentials and corneal confocal microscopy, might contribute to a better understanding of these neuropathies. Biochemical markers can also help in screening patients for the presence of small fibre neuropathy and to assess disease progression.

Greater corneal nerve loss at the inferior whorl is related to the presence of diabetic neuropathy and painful diabetic neuropathy

We assessed whether a measure of more distal corneal nerve fibre loss at the inferior whorl(IW) region is better than proximal measures of central corneal nerve damage in relation to the diagnosis of diabetic peripheral neuropathy(DPN), painful DPN and quality of life(QoL). Participants underwent detailed assessment of neuropathy, QoL using the SF36 questionnaire, pain visual analogue score(VAS), and corneal confocal microscopy(CCM). Corneal nerve fibre density (CNFD), branch density (CNBD) and length (CNFL) at the central cornea and inferior whorl length (IWL) and average(ANFL) and total(TNFL) nerve fibre length were compared in patients with and without DPN and between patients with and without painful DPN and in relation to QoL. All CCM parameters were significantly reduced, but IWL was reduced ~three-fold greater than CNFL in patients with and without DPN compared to controls. IWL(pu2009=u20090.001), ANFL(pu2009=u20090.01) and TNFL(pu2009=u20090.02) were significantly lower in patients with painful compared to painless DPN. The VAS score correlated with IWL(ru2009=u2009−0.36, Pu2009=u20090.004), ANFL(ru2009=u2009−0.32, Pu2009=u20090.01) and TNFL(ru2009=u2009−0.32, Pu2009=u20090.01) and QoL correlated with CNFL(ru2009=u20090.35, Pu2009=u20090.01) and IWL(ru2009=u20090.4, Pu2009=u20090.004). Corneal nerve fibre damage is more prominent at the IW, lower in patients with painful compared to painless neuropathy and relates to their QoL. IWL may provide additional clinical utility for CCM in patients with DPN.

Cortical markers of cognitive syndromes in amyotrophic lateral sclerosis

Amyotrophic lateral sclerosis (ALS) can be associated with a spectrum of cognitive and behavioural symptoms, but the related patterns of focal cortical atrophy in non-demented ALS patients remain largely unknown. We enrolled 48 non-demented ALS patients and 26 healthy controls for a comprehensive neuropsychological assessment and a magnetic resonance exam. Behavioural and cognitive impairment was defined on the basis of a data-driven multi-domain approach in 21 ALS patients. Averaged cortical thickness of 74 bilateral brain regions was used as a measure of cortical atrophy. Cortical thinning in a fronto-parietal network, suggesting a disease-specific pattern of neurodegeneration, was present in all patients, independent of cognitive and behavioural status. Between-group and correlational analyses revealed that inferior frontal, temporal, cingular and insular thinning are markers for cognitive and behavioural deficits, with language impairment mainly related to left temporal pole and insular involvement. These specific correlates support the concept of a spectrum of deficits, with an overlap between the ALS cognitive phenotypes and the syndromes of frontotemporal dementia.

Adult leukoencephalopathies with prominent infratentorial involvement can be caused by Erdheim–Chester disease

BackgroundLeukoencephalopathies with prominent involvement of cerebellum and brainstem, henceforward called prominent infratentorial leukoencephalopathies (PILs), encompass a variety of inherited and acquired white matter diseases. Erdheim–Chester disease (ECD) is a rare non-Langerhans cell histiocytosis likely under-diagnosed as cause of adult PIL.MethodsWe reviewed the clinical and laboratory information of ten consecutive sporadic adult patients with PIL of unknown origin, who were investigated for ECD.ResultsThere were seven males and three females; mean age at clinical onset was 49.6xa0years (range 38–59); cerebellar ataxia with or without other neurological symptoms was the only or the main clinical manifestation; diabetes insipidus was present in three individuals. Eight patients had white matter focal supratentorial abnormalities, in addition to the infratentorial white matter changes. Six out of eight patients had spinal cord lesions. Thoraco-abdominal CT showed periaortic sheathing in two patients, whole-body FDG-PET revealed increased glucose uptake in the long bones of the legs in five patients, brain FDG-PET showed overt infratentorial hypermetabolism in one patient. In eight patients, ECD was confirmed by bone scintigraphy, pathological data, or both. Two ECD patients treated with vemurafenib showed a marked improvement of neurological symptoms and brain MRI abnormalities at 1 year follow-up.ConclusionsSymptoms of PIL can be the only clinical manifestation of ECD. Adult patients with PIL of unknown origin should undergo investigations aimed at unveiling ECD, including bone scintigraphy and whole-body FDG-PET. The early diagnosis allows starting disease-modifying therapies of an otherwise life-threatening disease.

A novel SCN9A splicing mutation in a compound heterozygous girl with congenital insensitivity to pain, hyposmia and hypogeusia

Congenital insensitivity to pain (CIP) is a rare autosomal recessive disorder presenting with a spectrum of clinical features caused by mutations in different genes. A 10‐year‐old girl with CIP, hyposmia and hypogeusia, and her unaffected twin and parents underwent next generation sequencing of SCN9A exons and flanking splice sites. Transcript analysis from whole blood successfully assayed the effect of the mutation on the mRNA splicing by polymerase chain reaction amplification on cDNA and Sanger sequencing. We identified the novel splicing variant c.1108‐2A>G compound with the p.Arg896Gln (c.2687G>A) missense mutation previously described in a homozygous patient. The new intronic variant was predicted to induce exon 10 skipping. Conversely, SCN9A mRNA assay demonstrated its partial deletion with a loss of 46 nucleotides causing a premature stop codon in position p.Gln369 (NP_002968). Genetic analysis showed that the two variants were biallelic, being the mother and brother heterozygous carriers of the missense mutation, and the father heterozygous for the splicing mutation. Skin biopsy showed lack of Meissners corpuscles, loss of epidermal nociceptors and normal autonomic organ innervation. We report a novel splicing mutation and provide clues on its pathogenic effect, broadening the spectrum of genotypes and phenotypes associated to CIP.

Bilateral Radiation-Induced Hypoglossal Nerve Palsy Responsive to Steroid Treatment

Dear Editor, A 63-year-old woman reported a 2-month history of neck pain followed by progressive deterioration of speech and swallowing and a weight loss of 3 kilograms. Six years ago, she had received radiotherapy for a lymphoepithelial rhinopharyngeal carcinoma. A neurological examination showed dysarthria, dysphagia, impaired tongue protrusion, and amyotrophy on the left side. Blood screening for autoantibodies (antinuclear antibodies, extractable nuclear antibodies, anti-neutrophil cytoplasmic antibodies, and anti-DNA), Lyme-disease serology, angiotensin-converting enzyme, anti-acetylcholine-receptor antibodies, and HIV produced negative findings. A cerebrospinal fluid (CSF) examination showed normal protein levels, the absence of malignant cells, and negativity for an immunoelectrofocusing reaction. A CSF search for viral genomes by PCR excluded active infections with herpes simplex virus types 1 and 2, varicella zoster virus, Epstein-Barr virus, and cytomegalovirus. An echo color Doppler study of the extracranial vessels produced normal findings. Magnetic resonance imaging of the brain, nasopharynx, and neck with gadolinium enhancement excluded locoregional tumor relapse and meningeal carcinomatosis. The findings of a sensorimotor nerve conduction study, F-wave examination, and highand low-frequency repetitive nerve stimulation were normal. In contrast, needle electromyography (EMG) disclosed active denervation of the tongue muscles (abundant fibrillations and positive sharp waves at rest in both genioglossus muscles with the absence of voluntary activity). Her motor evoked potentials were normal. A videofluoroscopic evaluation revealed severe dysphagia with a penetration-aspiration scale (PAS) score of 6 and a pooling score of 10. Percutaneous endoscopic gastrostomy was performed in order to assure adequate feeding and avoid the risk of aspiration. A putative diagnosis of postradiation bilateral hypoglossal palsy was made, and treatment with a steroid (1 mg/kg prednisone) was started and then slowly tapered. At the 7-month follow-up the patient reported improvements of speech and swallowing, while the videofluoroscopic re-evaluation confirmed the improvement of dysphagia (PAS score of 4 and pooling score of 8), and so the patient was allowed to consume semisolid food orally. An EMG evaluation disclosed the absence of spontaneous activity and chronic neurogenic changes associated with diffuse phenomena of collateral reinnervation in the genioglossus muscles, confirming the functional recovery of hypoglossal nerves. The differential diagnosis of bilateral hypoglossal palsy includes metastatic disease at the base of the skull, motor neuron disease, dissection of extracranial vessels, meningeal carcinomatosis, multiple mononeuritis of different etiologies (infective, vasculitic, and immune-mediated), and tumoral nerve infiltration. All of these conditions were ruled out in the present case. Cranial neuropathies are uncommon but well-recognized complications after head and neck radiotherapy, with an incidence ranging from 5% to 10%. The average latency period is reportedly 5 to 7 years.2,3 The hypoglossal nerve is the most frequently involved, often biAndrea Rigamonti Giuseppe Lauria Vittorio Mantero Lorenzo Stanzani Andrea Salmaggi

Laser capture microdissection for transcriptomic profiles in human skin biopsies

BackgroundThe acquisition of reliable tissue-specific RNA sequencing data from human skin biopsy represents a major advance in research. However, the complexity of the process of isolation of specific layers from fresh-frozen human specimen by laser capture microdissection, the abundant presence of skin nucleases and RNA instability remain relevant methodological challenges. We developed and optimized a protocol to extract RNA from layers of human skin biopsies and to provide satisfactory quality and amount of mRNA sequencing data.ResultsThe protocol includes steps of collection, embedding, freezing, histological coloration and relative optimization to preserve RNA extracted from specific components of fresh-frozen human skin biopsy of 14 subjects. Optimization of the protocol includes a preservation step in RNALater® Solution, the control of specimen temperature, the use of RNase Inhibitors and the time reduction of the staining procedure. The quality of extracted RNA was measured using the percentage of fragments longer than 200 nucleotides (DV200), a more suitable measurement for successful library preparation than the RNA Integrity Numberxa0(RIN). RNA was then enriched using the TruSeq® RNA Access Library Prep Kit (Illumina®) and sequenced on HiSeq®xa02500 platform (Illumina®). Quality control on RNA sequencing data was adequate to get reliable data for downstream analysis.ConclusionsThe described implemented and optimized protocol can be used for generating transcriptomics data on skin tissues, and it is potentially applicable to other tissues. It can be extended to multicenter studies, due to the introduction of an initial step of preservation of the specimen that allowed the shipment of biological samples.

Abstracts of the 8th Meeting of the Italian Peripheral Nerve Study Group: 75

Monoclonal IgM antibodies against myelin-associated glycoprotein (MAG) are associated with a chronic demyelinating neuropathy characterized by predominant involvement of large sensory fibers, although nerve conduction study reveals preferential demyelination of distal motor fibers. In sural nerve biopsy, deposits of monoclonal IgM are found at sites of MAG localization such as Schmidt-Lanterman incisures and paranodal loops, but also on the surface of myelinated nerve fibers (mesaxon). Distal involvement in sensory fibers cannot be assessed by routine studies. Therefore, we investigated sensory fibers by skin biopsy in 13 patients with anti-MAG neuropathy. Patients with CIDP (nxa0=xa08) and with IgM anti-MAG negative paraproteinemic neuropathy (nxa0=xa03) were used as diseased controls. Skin biopsy was performed using a 3xa0mm punch at the proximal thigh (nxa0=xa020), at the distal leg (nxa0=xa021), at the hand or arm or fingertip (nxa0=xa023). Specimens were processed to quantify the density of intra-epidermal nerve fibers (IENF) using the anti-protein gene product 9.5 (PGP 9.5). Both anti-MAG patients and CIDP patients showed a proximal-distal gradient in IENF density decrease, indicating a length-dependent fiber loss, as typically seen in other neuropathies. Further, we investigated anti-MAG immunoreactivity and the presence of IgM deposits in dermal myelinated fibers by confocal microscopy. IgM deposits were detected on the surface of MAG positive fibers in the dermis of 11 anti-MAG patients (85%), but not in diseased controls. IgM deposits were also located at paranodal loops. Our study shows that small myelinated fibers in the skin are involved in anti-MAG neuropathy, and that IgM deposits can be demonstrated in terminal sensory fibers. Skin biopsy provides a useful, minimally traumatic method for early diagnosis as well as for follow-up studies of anti-MAG neuropathy. Supported by a Fellowship of the European Neurological Society.