Use, tolerability, benefits and side effects of orthotic devices in Charcot-Marie-Tooth disease

BACKGROUND

Shoe inserts, orthopaedic shoes, ankle-foot orthoses (AFOs) are important devices in Charcot-Marie-Tooth disease (CMT) management, but data about use, benefits and tolerance are scanty.

METHODS

We administered to Italian CMT Registry patients an online ad hoc questionnaire investigating use, complications and perceived benefit/tolerability/emotional distress of shoe inserts, orthopaedic shoes, AFOs and other orthoses/aids. Patients were also asked to fill in the Quebec User Evaluation of Satisfaction with assistive Technology questionnaire, rating satisfaction with currently used AFO and related services.

RESULTS

We analysed answers from 266 CMT patients. Seventy per cent of subjects were prescribed lower limb orthoses, but 19% did not used them. Overall, 39% of subjects wore shoe inserts, 18% orthopaedic shoes and 23% AFOs. Frequency of abandonment was high: 24% for shoe inserts, 28% for orthopaedic shoes and 31% for AFOs. Complications were reported by 59% of patients and were more frequently related to AFOs (69%). AFO users experienced greater emotional distress and reduced tolerability as compared with shoe inserts (p<0.001) and orthopaedic shoes (p=0.003 and p=0.045, respectively). Disease severity, degree of foot weakness, customisation and timing for customisation were determinant factors in AFOs' tolerability. Quality of professional and follow-up services were perceived issues.

CONCLUSIONS

The majority of CMT patients is prescribed shoe inserts, orthopaedic shoes and/or AFOs. Although perceived benefits and tolerability are rather good, there is a high rate of complications, potentially inappropriate prescriptions and considerable emotional distress, which reduce the use of AFOs. A rational, patient-oriented and multidisciplinary approach to orthoses prescription must be encouraged.

Conduction slowing, conduction block and temporal dispersion in demyelinating, dysmyelinating and axonal neuropathies: Electrophysiology meets pathology

Nerve conduction studies are usually the first diagnostic step in peripheral nerve disorders and their results are the basis for planning further investigations. However, there are some commonplaces in the interpretation of electrodiagnostic findings in peripheral neuropathies that, although useful in the everyday practice, may be misleading: (1) conduction block and abnormal temporal dispersion are distinctive features of acquired demyelinating disorders; (2) hereditary neuropathies are characterized by uniform slowing of conduction velocity; (3) axonal neuropathies are simply diagnosed by reduced amplitude of motor and sensory nerve action potentials with normal or slightly slow conduction velocity. In this review, we reappraise the occurrence of uniform and non-uniform conduction velocity slowing, conduction block and temporal dispersion in demyelinating, dysmyelinating and axonal neuropathies attempting, with a translational approach, a correlation between electrophysiological and pathological features as derived from sensory nerve biopsy in patients and animal models. Additionally, we provide some hints to navigate in this complex field.

Clinical and pathology characterization of small nerve fiber neuro(no)pathy in cerebellar ataxia with neuropathy and vestibular areflexia syndrome

BACKGROUND AND PURPOSE

Biallelic mutation/expansion of the gene RFC1 has been described in association with a spectrum of manifestations ranging from isolated sensory neuro(no)pathy to a complex presentation as cerebellar ataxia with neuropathy and vestibular areflexia syndrome (CANVAS). Our aim was to define the frequency and characteristics of small fiber neuropathy (SFN) in RFC1 disease at different stages.

METHODS

RFC1 cases were screened for SFN using the Neuropathic Pain Symptom Inventory and Composite Autonomic Symptom Score 31 questionnaires. Clinical data were retrospectively collected. If available, lower limb skin biopsy samples were evaluated for somatic epidermal and autonomic subepidermal structure innervation and compared to healthy controls (HCs).

RESULTS

Forty patients, median age at onset 54 years (interquartile range [IQR] 49-61) and disease duration 10 years (IQR 6-16), were enrolled. Mild-to-moderate positive symptoms (median Neuropathic Pain Symptom Inventory score 12.1/50, IQR 5.5-22.3) and relevant autonomic disturbances (median Composite Autonomic Symptom Score 31 37.0/100, IQR 17.7-44.3) were frequently reported and showed scarce correlation with disease duration. A non-length-dependent impairment in nociception was evident in both clinical and paraclinical investigations. An extreme somatic denervation was observed in all patients at both proximal (fibers/mm, RFC1 cases 0.0 vs. HCs 20.5, p < 0.0001) and distal sites (fibers/mm, RFC1 cases 0.0 vs. HCs 13.1, p < 0.0001); instead only a slight decrease was observed in cholinergic and adrenergic innervation of autonomic structures.

CONCLUSIONS

RFC1 disease is characterized by a severe and widespread somatic SFN. Skin denervation may potentially represent the earliest feature and drive towards the suspicion of this disorder.

Daytime sleepiness and sleep quality in Charcot-Marie-Tooth disease

BACKGROUND

Sleep abnormalities have been reported in Charcot-Marie-Tooth disease (CMT), but data are scanty. We investigated their presence and correlation in a large CMT patients' series.

METHODS

Epworth Sleepiness Scale (ESS) and Pittsburgh Sleep Quality Index (PSQI) were administered to CMT patients of the Italian registry and controls. ESS score > 10 indicated abnormal daytime somnolence, PSQI score > 5 bad sleep quality. We analyzed correlation with disease severity and characteristics, Hospital Anxiety and Depression Scale (HADS), Modified Fatigue Impact Scale (MFIS), Body Mass Index, drug use.

RESULTS

ESS and PSQI questionnaires were filled by 257 and 253 CMT patients, respectively, and 58 controls. Median PSQI score was higher in CMT patients than controls (6 vs 4, p = 0.006), with no difference for ESS score. Abnormal somnolence and poor sleep quality occurred in 23% and 56% of patients; such patients had more frequently anxiety/depression, abnormal fatigue, and positive sensory symptoms than those with normal ESS/PSQI. Moreover, patients with PSQI score > 5 had more severe disease (median CMT Examination Score, CMTES, 8 vs 6, p = 0.006) and more frequent use of anxiolytic/antidepressant drugs (29% vs 7%, p < 0.001).

CONCLUSIONS

Bad sleep quality and daytime sleepiness are frequent in CMT and correlated with anxiety, depression and fatigue, confirming that different components affect sleep. Sleep disorders, such as sleep apnea and restless leg syndrome, not specifically investigated here, are other factors known to impact on sleep quality and somnolence. CMT patients' management must include sleep behavior assessment and evaluation of its correlated factors, including general distress and fatigue.

Leprosy Neuropathy in a Non-Endemic Area: A Clinical and Pathological Study

The extent of nerve involvement in leprosy is highly variable in distribution and clinical presentation. Mononeuropathies, multiple mononeuropathies, and polyneuropathies can present both in the context of a cutaneous and/or systemic picture and in the form of pure neuritic leprosy (PNL). The differential diagnosis of leprosy neuropathy remains challenging because it is a very rare condition and, especially in Western countries, is often overlooked. We report one case of the polyneuropathic form of PNL (P-PNL) and one case of multiple mononeuropathy in paucibacillary leprosy. In both cases, the diagnosis was achieved by performing a sural nerve biopsy, which showed subverted structure, severe infiltration of inflammatory cells in nerve fascicles, granulomatous abnormalities, and the presence of alcohol-acid-resistant, Ziehl-Neelsen-positive bacilli inside the nerve bundles. Leprosy remains an endemic disease in many areas of the world, and globalization has led to the spread of cases in previously disease-free countries. In this perspective, our report emphasizes that the diagnostic possibility of leprosy neuropathy should always be taken into account, even in Western countries, in the differential diagnostic process of an acquired sensory polyneuropathy or multineuropathy and confirms that nerve biopsy remains a useful procedure in working up neuropathies with unknown etiology.

Clinical spectrum and frequency of Charcot-Marie-Tooth disease in Italy: data from the national CMT registry

BACKGROUND

We report data from the Italian CMT Registry.

METHODS

The Italian CMT Registry is a dual registry where the patient registers, chooses a reference centre, where the attending clinician collects a minimal dataset of information and administers the CMT Examination/Neuropathy Score. Entered data are encrypted.

RESULTS

Overall, 1012 patients had registered (535 females) and 711 had received a genetic diagnosis. Demyelinating CMT (65.3%) was more common than axonal CMT2 (24.6%) and intermediate CMT (9.0%). The PMP22 duplication was the most frequent mutation (45.2%), followed by variants in GJB1 and MPZ (both ~10%) and MFN2 (3.3%) genes. We observed a relatively high mutation rate in some "rare" genes (HSPB1 1.6%, NEFL 1.5%, SH3TC2 1.5%) and the presence of multiple mutation clusters across Italy. CMT4A was the most disabling type, followed by CMT4C and CMT1E. Disease progression rate differed, depending on the CMT subtype. Foot deformities and walking difficulties were the main features. Shoe inserts and orthotic aids were used by almost one half of all patients. Scoliosis was present in 20% of patients, especially in CMT4C. Recessive forms had more frequently walking delay, walking support need and wheelchair use. Hip dysplasia occurred in early-onset CMT.

CONCLUSIONS

The Italian CMT Registry has proven to be a powerful data source to collect information about epidemiology and genetic distribution, clinical features and disease progression of CMT in Italy and is a useful tool for recruiting patients in forthcoming clinical trials.

Peripheral neuropathy as clinical onset of monoclonal IgM/k-related amyloidosis

AIM

Neuropathy is a frequent complication of Waldenström's macroglobulinemia (WM), the most common being a demyelinating polyneuropathy with anti-myelin associated glycoprotein (MAG) antibodies, but also cryoglobulins, vasculitis, neurolymphomatosis, and amyloidosis. We describe a patient with IgM/kappa WM who presented with a severe, not length-dependent, peripheral neuropathy as clinical onset of IgM/kappa-related amyloidosis.

METHODS

A 69-year-old woman came to our attention for weight loss, gait imbalance and sensory loss at upper limbs. In her medical history, she was in hematological follow-up for WM, and had undergone left carpal tunnel release. At neurological evaluation she had weakness and loss of sensation at upper limbs up to the elbows, more at the left side, gait was unsteady with right foot drop. Hypotrophy and areflexia were present at four limbs. Sensory loss and vibration sense were dramatically reduced. She underwent extensive diagnostic workup.

RESULTS

Laboratory workup revealed an IgM/kappa monoclonal paraprotein of 16 g/L and increased NT-proBNP; anti-MAG antibodies were absent. Bone marrow biopsy demonstrated a population of neoplastic B-lymphocytes. Total-body CT scan and echocardiogram were negative. Neurophysiology revealed a symmetric, no length dependent sensory-motor polyneuropathy Periumbilical fat biopsy was positive for amyloid. Sural nerve biopsy detected amyloid in the wall of an epineurial vein.

CONCLUSIONS

This case report describes a rare and unusual manifestation of IgM-related AL amyloidosis in WM. The patient presented with a subacute clinically asymmetric neuropathy with no pain or dysautonomic features as clinical onset of IgM/kappa-related amyloidosis. Sural nerve biopsy was crucial for the diagnosis.

Frequency, entity and determinants of fatigue in Charcot-Marie-Tooth disease

BACKGROUND AND PURPOSE

Fatigue, a disabling symptom in many neuromuscular disorders, has been reported also in Charcot-Marie-Tooth disease (CMT). The presence of fatigue and its correlations in CMT was investigated.

METHODS

The Modified Fatigue Impact Scale (MFIS) was administered to CMT patients from the Italian Registry and a control group. An MFIS score >38 indicated abnormal fatigue. The correlation with disease severity and clinical characteristics, the Hospital Anxiety and Depression Scale and Epworth Sleepiness Scale scores, and drug use was analysed.

RESULTS

Data were collected from 251 CMT patients (136 women) and 57 controls. MFIS total (mean ± standard deviation 32 ± 18.3, median 33), physical (18.9 ± 9.7, 20) and psychosocial (2.9 ± 2.4, 3) scores in CMT patients were significantly higher than controls. Abnormal fatigue occurred in 36% of the patients who, compared to patients with normal scores, had more severe disease (median CMT Examination Score 9 vs. 7), more frequent use of foot orthotics (22% vs. 11%), need of support for walking (21% vs. 8%), hand disability (70% vs. 52%) and positive sensory symptoms (56% vs. 36%). Patients with abnormal fatigue had significantly increased frequency of anxiety/depression/general distress (Hospital Anxiety and Depression Scale), somnolence (Epworth Sleepiness Scale), obesity (body mass index ≥ 30) and use of anxiolytic/antidepressant or anti-inflammatory/analgesic drugs.

CONCLUSIONS

Fatigue is a relevant symptom in CMT as 36% of our series had scores indicating abnormal fatigue. It correlated with disease severity but also with anxiety, depression, sleepiness and obesity, indicating different components in the generation of fatigue. CMT patients' management must include treatment of fatigue and of its different generators, including general distress, sleepiness and obesity.

Clinical and pathological findings in neurolymphomatosis: Preliminary association with gene expression profiles in sural nerves

Although inflammation appears to play a role in neurolymphomatosis (NL), the mechanisms leading to degeneration in the peripheral nervous system are poorly understood. The purpose of this exploratory study was to identify molecular pathways underlying NL pathogenesis, combining clinical and neuropathological investigation with gene expression (GE) studies. We characterized the clinical and pathological features of eight patients with NL. We further analysed GE changes in sural nerve biopsies obtained from a subgroup of NL patients (n=3) and thirteen patients with inflammatory neuropathies as neuropathic controls. Based on the neuropathic symptoms and signs, NL patients were classified into three forms of neuropathy: chronic symmetrical sensorimotor polyneuropathy (SMPN, n=3), multiple mononeuropathy (MN, n=4) and acute motor-sensory axonal neuropathy (AMSAN, n=1). Predominantly diffuse malignant cells infiltration of epineurium was present in chronic SMPN, whereas endoneurial perivascular cells invasion was observed in MN. In contrast, diffuse endoneurium malignant cells localization occurred in AMSAN. We identified alterations in the expression of 1266 genes, with 115 up-regulated and 1151 down-regulated genes, which were mainly associated with ribosomal proteins (RP) and olfactory receptors (OR) signaling pathways, respectively. Among the top up-regulated genes were actin alpha 1 skeletal muscle (ACTA1) and desmin (DES). Similarly, in NL nerves ACTA1, DES and several RPs were highly expressed, associated with endothelial cells and pericytes abnormalities. Peripheral nerve involvement may be due to conversion towards a more aggressive phenotype, potentially explaining the poor prognosis. The candidate genes reported in this study may be a source of clinical biomarkers for NL.

Neuropathic pain in Charcot-Marie-Tooth Disease

BACKGROUND

Pain, either nociceptive or neuropathic (NP), is a common symptom in Charcot-Marie-Tooth (CMT) disease.

METHODS

We investigated small fibers involvement and its correlation with pain in different CMT subtypes through a systematic clinical and neurophysiological study. We enrolled 50 patients: 19 with duplication of PMP22 (CMT1A), 11 with mutation of MPZ (CMT1B, CMT2I/J or CMTDID), 12 with mutation of GJB1 (CMTX1) and 8 with mutation of MFN2 (CMT2A and CMT2A2B). Pain was rated with the 11-point Numerical Rating Scale and characterized through Neuropathic Pain Symptoms Inventory). Laser evoked potentials (LEPs) were recorded after right foot and hand stimulation and N2-P2 complex amplitude and latency were compared with those of 41 controls.

RESULTS

Overall pain prevalence was 36%. NP was present in 14,6 % of patients, with a length-dependent distribution in 85,7% of cases and it was significantly more frequent in CMT1A (p<0,001). Aδ fibers involvement greatly varies between CMT subtypes, reflecting differences in molecular pathology and pathophysiologic mechanisms. Prolonged N2 latency from foot stimulation was noted in 11 CMT1A patients, 5 of which report NP. MPZ-CMTs displayed different neurophysiological phenotypes and a very low prevalence of NP. LEPs were normal in all but one CMTX1 patients, although lower limbs N2-P2 amplitude was significantly reduced in males (p=0,043). MFN2-CMTs were NP free and LEPs recordings were all normal. NP strictly correlated with LEPs alterations (p=0,017).

CONCLUSIONS

NP prevalence varies among CMTs subtypes and is mainly related to Aδ fibers impairment.

Hereditary neuropathies: A pathological perspective

Hereditary neuropathies may result from mutations in genes expressed by Schwann cells or neurons that affect selectively the peripheral nervous system (PNS) or may represent a minor or major component of complex inherited diseases that involve also the central nervous system and/or other organs and tissues. The chapter is constantly expanding and reworking, thanks to advances of molecular genetics; next-generation sequencing is identifying a plethora of new genes and is revolutionizing the diagnostic approach. In the past, diagnostic sural nerve biopsies paved the way to the discovery and elucidation of major genes and molecular pathways associated to most frequent hereditary motor-sensory neuropathies. Nowadays, a sural nerve biopsy may prove useful in selected cases for the differential diagnosis of an acquired neuropathy when clinical examination, nerve conduction studies, and molecular tests are not sufficiently informative. Skin biopsy has emerged as a minimally invasive window on the PNS, which may provide biomarkers of progression and clues to the physiopathology and molecular pathology of inherited neuropathies. The aim of our review is to illustrate the pathological features of more frequent and paradigmatic hereditary neuropathies and to highlight their correlations with the roles of the involved genes and functional consequences of related molecular defects.

RFC1 AAGGG repeat expansion masquerading as Chronic Idiopathic Axonal Polyneuropathy

BACKGROUND

A biallelic intronic AAGGG repeat expansion in the Replication Factor C subunit 1 (RFC1) gene has been recently associated with Cerebellar Ataxia, Neuropathy, Vestibular Areflexia Syndrome, a disorder often presenting as a slowly evolving sensory neuropathy at the onset. "Chronic Idiopathic Axonal Polyneuropathy" (CIAP) is a common indolent axonal neuropathy of adulthood which remains without an identifiable cause despite thorough investigations.

METHODS

We screened 234 probands diagnosed with CIAP for a pathogenic biallelic RFC1 AAGGG repeat expansion. Patients were selected from 594 consecutive patients with neuropathy referred to our tertiary-care center for a sural nerve biopsy over 10 years.

RESULTS

The RFC1 AAGGG repeat expansion was common in patients with pure sensory neuropathy (21/40, 53%) and less frequent in cases with predominantly sensory (10/56, 18%, P < 0.001) or sensorimotor (3/138, 2%, P < 0.001) neuropathy. The mutation was associated with sensory ataxia (τ_b = 0.254, P < 0.001), autonomic disturbances (35% vs 8%, Prevalence Odds Ratio-POR 6.73 CI 95% 2.79-16.2, P < 0.001), retained deep tendon reflexes (score 18.0/24 vs 11.5/24, R = 0.275, P < 0.001). On pathology, we observed absent/scant regenerative changes (τ_b = - 0.362, P < 0.001), concomitant involvement of large (100% and 99%, n.s.), small myelinated (97% vs 81%, POR 7.74 CI 95% 1.03-58.4, P = 0.02) and unmyelinated nerve fibers (85% vs 41%, POR 8.52 CI 95% 3.17-22.9, P < 0.001). Cerebellar or vestibular involvement was similarly rare in the two groups.

CONCLUSIONS

This study highlights the frequent occurrence of the RFC1 AAGGG repeat expansion in patients diagnosed with CIAP and characterizes the clinical and pathological features of the related neuro(no)pathy.

Alpha-synuclein seeds in olfactory mucosa and cerebrospinal fluid of patients with dementia with Lewy bodies

In patients with suspected dementia with Lewy bodies, the detection of the disease-associated α-synuclein in easily accessible tissues amenable to be collected using minimally invasive procedures remains a major diagnostic challenge. This approach has the potential to take advantage of modern molecular assays for the diagnosis of α-synucleinopathy and, in turn, to optimize the recruitment and selection of patients in clinical trials, using drugs directed at counteracting α-synuclein aggregation. In this study, we explored the diagnostic accuracy of α-synuclein real-time quaking-induced conversion assay by testing olfactory mucosa and CSF in patients with a clinical diagnosis of probable (n = 32) or prodromal (n = 5) dementia with Lewy bodies or mixed degenerative dementia (dementia with Lewy bodies/Alzheimer's disease) (n = 6). Thirty-eight patients with non-α-synuclein-related neurodegenerative and non-neurodegenerative disorders, including Alzheimer's disease (n = 10), sporadic Creutzfeldt-Jakob disease (n = 10), progressive supranuclear palsy (n = 8), corticobasal syndrome (n = 1), fronto-temporal dementia (n = 3) and other neurological conditions (n = 6) were also included, as controls. All 81 patients underwent olfactory swabbing while CSF was obtained in 48 participants. At the initial blinded screening of olfactory mucosa samples, 38 out of 81 resulted positive while CSF was positive in 19 samples out of 48 analysed. After unblinding of the results, 27 positive olfactory mucosa were assigned to patients with probable dementia with Lewy bodies, five with prodromal dementia with Lewy bodies and three to patients with mixed dementia, as opposed to three out 38 controls. Corresponding results of CSF testing disclosed 10 out 10 positive samples in patients with probable dementia with Lewy bodies and six out of six with mixed dementia, in addition to three out of 32 for controls. The accuracy among results of real-time quaking-induced conversion assays and clinical diagnoses was 86.4% in the case of olfactory mucosa and 93.8% for CSF. For the first time, we showed that α-synuclein real-time quaking-induced conversion assay detects α-synuclein aggregates in olfactory mucosa of patients with dementia with Lewy bodies and with mixed dementia. Additionally, we provided preliminary evidence that the combined testing of olfactory mucosa and CSF raised the concordance with clinical diagnosis potentially to 100%. Our results suggest that nasal swabbing might be considered as a first-line screening procedure in patients with a diagnosis of suspected dementia with Lewy bodies followed by CSF analysis, as a confirmatory test, when the result in the olfactory mucosa is incongruent with the initial clinical diagnosis.

Aberrant Splicing in GJB1 and the Relevance of 5' UTR in CMTX1 Pathogenesis

The second most common form of Charcot-Marie-Tooth disease (CMT) follows an X-linked dominant inheritance pattern (CMTX1), referring to mutations in the gap junction protein beta 1 gene (GJB1) that affect connexin 32 protein (Cx32) and its ability to form gap junctions in the myelin sheath of peripheral nerves. Despite the advances of next-generation sequencing (NGS), attention has only recently also focused on noncoding regions. We describe two unrelated families with a c.-17+1G>T transversion in the 5' untranslated region (UTR) of GJB1 that cosegregates with typical features of CMTX1. As suggested by in silico analysis, the mutation affects the regulatory sequence that controls the proper splicing of the intron in the corresponding mRNA. The retention of the intron is also associated with reduced levels of the transcript and the loss of immunofluorescent staining for Cx32 in the nerve biopsy, thus supporting the hypothesis of mRNA instability as a pathogenic mechanism in these families. Therefore, our report corroborates the role of 5' UTR of GJB1 in the pathogenesis of CMTX1 and emphasizes the need to include this region in routine GJB1 screening, as well as in NGS panels.

QTc Prolongation in Patients with Dementia and Mild Cognitive Impairment: Neuropsychological and Brain Imaging Correlations

The QTc interval is the electrocardiographic manifestation of ventricular depolarization and repolarization. This marker is often prolonged in acute and chronic neurological conditions. The cause of the cerebrogenic QT prolongation remains unclear. The aim of the study was to analyze the relation between QTc interval and the degree of cognitive impairment and structural brain imaging changes in patients with dementia and mild cognitive impairment (MCI). To this aim, 269 patients were screened, of whom 61 met one or more exclusion criteria. The remaining 208 patients (56 control subjects, 44 patients with MCI, and 108 with dementia) were recruited. Eighty-five patients using drugs causing prolongation of QT interval were further excluded. The QT interval was measured manually in all 12 leads by a single blinded observer, assuming the longest QT value adjusted for heart rate by using the Bazett's formula. All patients underwent a structural brain imaging and the following measures were obtained: the bicaudate ratio and the periventricular hyperintensity and deep white matter hyperintensity using the modified Fazekas scale. Prolonged QTc interval was prevalent in 1) patients with dementia, especially in those with moderate-severe degree; 2) subjects with impairment of praxis and attention, low functional status, and behavioral symptoms; 3) patients with global and temporal atrophy and with higher scores on the Fazekas or leukoaraiosis scales. Degenerative and vascular processes might play a main role in QTc interval prolongation because of the damage to brain areas involved in the control of the autonomic cardiac nervous system.

ATTRv amyloidosis Italian Registry: clinical and epidemiological data

INTRODUCTION

ATTRv amyloidosis is worldwide spread with endemic foci in Portugal and Sweden, Japan, Brazil, Maiorca, and Cyprus. A national Registry was developed to characterise the epidemiology and genotype-phenotype correlation of ATTRv amyloidosis in Italy and to allow a better planning of diagnostic and therapeutic services.

METHODS

Fifteen Italian referral centres for amyloidosis spread all over the country have contributed to the Registry.

RESULTS

Four-hundred-forty-seven subjects were enrolled, 187 asymptomatic carriers and 260 affected patients. Thirty-one different mutations were recorded. The seven most represented genetic variants were significantly different in terms of age at onset, clinical features and geographical distribution. National prevalence is 4.33/million with higher values in Southern Italy. Overall symptoms of polyneuropathy were present at disease onset in about half of the patients, symptoms of cardiomyopathy in a quarter of patients, the rest referring carpal tunnel syndrome, dysautonomia or lumbar spinal stenosis. 52.6% of patients were in FAP stage 1, 20.4% in stage 2 and 13.5% in stage 3, while 13.5% patients had no neuropathy, presenting only cardiological symptoms.

CONCLUSIONS

We presented an epidemiological study based on collaboration among referral centres for ATTRv amyloidosis spread in all the Italian territory, using web-based Registry. It provided a detailed map of the regional distribution of the disease. The increased awareness of the disease among general practitioners and medical specialists has contributed to reduce the diagnostic delay and the rate of misdiagnosis. The Registry will allow to collect also future information about clinical and instrumental follow-up.

Convergent pathological and ultrasound features in hereditary syndromic and non-syndromic minifascicular neuropathy related to DHH

Minifascicular neuropathy (MN) is a rare, autosomal recessive disease with prominent structural changes of peripheral nerves. So far, it has been observed in females with a 46,XY karyotype and mutations of the Desert Hedgehog (DHH) gene, thus linking MN to gonadal dysgenesis (GD) and disorders of sex development (DSD). However, a 46,XX proband with normal female sex and gender development underwent clinical evaluations, nerve conduction studies and genetic screening for a severe motor-sensory neuropathy with a pathological phenotype that hinted at MN. Indeed, sural nerve biopsy revealed a profound disturbance of perineurium development with a thin and loose structure. High-resolution ultrasound (HRUS) also disclosed diffuse changes of nerve echotexture that visibly correlated with the pathological features. After extensive genetic testing, a novel homozygous DHH null mutation (p.Ser185*) was identified in the proband and in her sister, who was affected by a similar motor-sensory neuropathy, but was eventually found to be a 46,XY patient according to a late diagnosis of DSD with complete GD. DHH should therefore be considered as a possible cause of rare non-syndromic hereditary motor-sensory neuropathies, regardless of DSD. Furthermore, HRUS could effectively smooth the complex diagnostic workup as it demonstrated a high predictive power to detect MN, providing the same detailed correlations to the pathologic features of the nerve biopsy and Dhh-/- mice in both sisters. Hence, HRUS may assume a pivotal role in guiding molecular analysis in individuals with or without DSD.

CIDP, CMT1B, or CMT1B plus CIDP?

Charcot-Marie-Tooth disease type 1 (CMT1) and chronic inflammatory demyelinating polyradiculoneuropathy (CIDP) have distinct clinical and neurophysiological features that result from dysmyelination in CMT1 and macrophage-mediated segmental demyelination in CIDP. CMT1 may occur in genetically isolated cases with atypical presentations that converge phenotypically with CIDP; in rare cases, however, CMT1 may be complicated by superimposed CIDP. We report the case of a patient harboring a de novo heterozygous null mutation of the myelin protein zero (MPZ) gene and affected by subclinical CMT1B who became symptomatic due to superimposed CIDP. Peripheral nerve high-resolution ultrasound (HRUS) aided in establishing the coexistence of CMT1B and CIDP; the diagnosis was further supported by favorable clinical, neurophysiological, and ultrasound responses to immunoglobulin therapy.

Pregnancy in Charcot-Marie-Tooth disease: Data from the Italian CMT national registry

OBJECTIVE

To collect information on frequency of pregnancy and delivery complications in Charcot-Marie-Tooth (CMT) disease and on CMT course during pregnancy.

METHODS

Through an ad hoc online questionnaire, we investigated pregnancy and neuropathy course in women with CMT adhering to the Italian CMT Registry. Data were compared to those of controls (recruited among friends and unaffected relatives) and the Italian (or other reference) population.

RESULTS

We collected data on 193 pregnancies from 86 women with CMT (age 20-73 years) with 157 deliveries (81.4%) after a mean of 38.6 gestational weeks. In women with CMT, there were no differences compared to controls (59 pregnancies and 46 deliveries from 24 controls) and the reference population for miscarriages (11.4%) and planned (21.0%) and emergency (14.0%) cesarean sections. We found a significantly higher frequency of placenta previa (1.6% vs 0.4%), abnormal fetal presentations (8.4% vs 4.5%), and preterm deliveries (20.3% vs 6.9%; most in week 34-36 of gestation) compared to reference populations. Excluding twins, newborn weight did not differ from the reference population. Postpartum bleeding rate in patients with CMT (2.1%) was similar to that of the general population (2.4%). CMT status worsened during 18 of 193 pregnancies (9.3%) with no recovery in 16 of them and with similar figures in the CMT1A and non-CMT1A subtypes.

CONCLUSIONS

We observed higher rates of placenta previa, abnormal presentations, and preterm deliveries in CMT, but pregnancy outcome and newborn weight and health were similar to those of the reference populations. Worsening of CMT is not infrequent and occurs not only in CMT1A. Pregnant women with CMT should be monitored with particular care.

Nerve ultrasound in hereditary transthyretin amyloidosis: red flags and possible progression biomarkers

Background

Diagnostic delay of hereditary transthyretin amyloidosis (ATTRv, v for variant) prevents timely treatment and, therefore, concurs to the mortality of the disease. The aim of the present study was to explore with nerve ultrasound (US) possible red flags for early diagnosis in ATTRv patients with carpal tunnel syndrome (CTS) and/or polyneuropathy and in pre-symptomatic carriers.

Methods

Patients and pre-symptomatic carriers with a TTR gene mutation were enrolled from seven Italian centers. Severity of CTS was assessed with neurophysiology and clinical evaluation. Median nerve cross-section area (CSA) was measured with US in ATTRv carriers with CTS (TTR-CTS). One thousand one hundred ninety-six idiopathic CTS were used as controls. Nerve US was also performed in several nerve trunks (median, ulnar, radial, brachial plexi, tibial, peroneal, sciatic, sural) in ATTRv patients with polyneuropathy and in pre-symptomatic carriers.

Results

Sixty-two subjects (34 men, 28 women, mean age 59.8 years ± 12) with TTR gene mutation were recruited. With regard to CTS, while in idiopathic CTS there was a direct correlation between CTS severity and median nerve CSA (r = 0.55, p < 0.01), in the subgroup of TTR-CTS subjects (16 subjects, 5 with bilateral CTS) CSA did not significantly correlate with CTS severity (r = − 0.473). ATTRv patients with polyneuropathy showed larger CSA than pre-symptomatic carriers in several nerve sites, more pronounced at brachial plexi (p < 0.001).

Conclusions

The present study identifies nerve morphological US patterns that may help in the early diagnosis (morpho-functional dissociation of median nerve in CTS) and monitoring of pre-symptomatic TTR carriers (larger nerve CSA at proximal nerve sites, especially at brachial plexi).

Neurolymphomatosis, a rare manifestation of peripheral nerve involvement in lymphomas: Suggestive features and diagnostic challenges

Neurolymphomatosis, the infiltration of the peripheral nervous system from lymphoid cells, represents an uncommon manifestation of lymphomas. We describe the challenging diagnostic work-up in a patient with neurolymphomatosis. A 58-year-old woman with previous breast diffuse large B-cell lymphoma treated with chemo- and radiation-therapy, presented with dysesthesias, neuropathic pain at left abdomen and thigh, and weakness at left lower limb 9 years after disease remission. Neurophysiology revealed left T10-L4 radiculo-plexopathy with no abnormalities at cerebrospinal fluid (CSF), nerve ultrasound, and ¹⁸ fluorodeoxyglucose positron emission tomography/computed tomography (FDG PET/CT). MR-neurography disclosed left rectus abdominis muscle atrophy, neurogenic edema, and denervation. Radiation-induced damage, paraneoplastic, infectious radiculo-plexopathies, and atypical chronic inflammatory demyelinating polyradiculoneuropathy were ruled out. Neurolymphomatosis was suspected, and the patient treated with rituximab with improvement. Despite treatment, the radiculo-plexopathy eventually extended to the right side and sacral roots. Later in the disease course, sural nerve biopsy confirmed the diagnosis. Maintenance therapy was continued, until cutaneous localizations occurred, requiring salvage therapy and autologous stem cell transplant. Although rare, neurolymphomatosis should be considered in all patients with lymphomas and unexplained peripheral nervous system involvement. Hematological, CSF, and neuroimaging findings may be unremarkable, and a high index of suspicion required in order to achieve the diagnosis.

Sural nerve biopsy: current role and comparison with serum neurofilament light chain levels

The diagnosis of peripheral neuropathies can be challenging with consequent difficulties in patients' management. The aim of this study was to explore the current diagnostic role of sural nerve biopsy and to compare pathological findings with serum neurofilament light chain levels (NfL) as biomarkers of axonal damage. We collected demographic, clinical, and paraclinical data of patients referred over 1 year to the Neurology Unit, University of Verona, Italy, to perform nerve biopsy for diagnostic purposes, and we analyzed NfL levels in available paired sera using a high sensitive technique (Quanterix, Simoa). Eighty-two patients were identified (37.8% females, median age 65.5 years). Neuropathy onset was frequently insidious (68.3%) with a slowly progressive course (76.8%). Lower limbs were usually involved (81.7%), with a predominance of sensory over motor symptoms (74.4% vs 42.7%). The most common neuropathological findings were a demyelinating pattern (76.8%), clusters of regenerations (58.5%), and unmyelinated fibers involvement on ultrastructural evaluation (52.4%). A definite pathological diagnosis was achieved in 29 cases, and in 20.7% of patients, the referral clinical diagnosis was modified. Coexistent hematological conditions and hepatitis were diagnostic confounding factors (p = 0.012 and 0.034, respectively). In the analyzed paired sera (n = 37), an inverse despite not significant relationship between NfL values and fiber density was observed (Spearman's rho - 0.312, p = 0.056). In addition, we noted increased serum NfL values of patients with active axonal degeneration. Nerve biopsy remains a useful diagnostic investigation to achieve a correct diagnosis and guide patients' management in selected cases of peripheral neuropathy. Serum NfL is an accessible and potential valuable marker of axonal damage in these conditions.

Pharmacological treatment for familial amyloid polyneuropathy

BACKGROUND

Disease-modifying pharmacological agents for transthyretin (TTR)-related familial amyloid polyneuropathy (FAP) have become available in the last decade, but evidence on their efficacy and safety is limited. This review focuses on disease-modifying pharmacological treatment for TTR-related and other FAPs, encompassing amyloid kinetic stabilisers, amyloid matrix solvents, and amyloid precursor inhibitors.

OBJECTIVES

To assess and compare the efficacy, acceptability, and tolerability of disease-modifying pharmacological agents for familial amyloid polyneuropathies (FAPs).

SEARCH METHODS

On 18 November 2019, we searched the Cochrane Neuromuscular Specialised Register, the Cochrane Central Register of Controlled Trials, MEDLINE, and Embase. We reviewed reference lists of articles and textbooks on peripheral neuropathies. We also contacted experts in the field. We searched clinical trials registries and manufacturers' websites.

SELECTION CRITERIA

We included randomised clinical trials (RCTs) or quasi-RCTs investigating any disease-modifying pharmacological agent in adults with FAPs. Disability due to FAP progression was the primary outcome. Secondary outcomes were severity of peripheral neuropathy, change in modified body mass index (mBMI), quality of life, severity of depression, mortality, and adverse events during the trial.

DATA COLLECTION AND ANALYSIS

We followed standard Cochrane methodology.

MAIN RESULTS

The review included four RCTs involving 655 people with TTR-FAP. The manufacturers of the drugs under investigation funded three of the studies. The trials investigated different drugs versus placebo and we did not conduct a meta-analysis. One RCT compared tafamidis with placebo in early-stage TTR-FAP (128 randomised participants). The trial did not explore our predetermined disability outcome measures. After 18 months, tafamidis might reduce progression of peripheral neuropathy slightly more than placebo (Neuropathy Impairment Score (NIS) in the lower limbs; mean difference (MD) -3.21 points, 95% confidential interval (CI) -5.63 to -0.79; P = 0.009; low-certainty evidence). However, tafamidis might lead to little or no difference in the change of quality of life between groups (Norfolk Quality of Life-Diabetic Neuropathy (Norfolk QOL-DN) total score; MD -4.50 points, 95% CI -11.27 to 2.27; P = 0.19; very low-certainty evidence). No clear between-group difference was found in the numbers of participants who died (risk ratio (RR) 0.65, 95% CI 0.11 to 3.74; P = 0.63; very low-certainty evidence), who dropped out due to adverse events (RR 1.29, 95% CI 0.30 to 5.54; P = 0.73; very low-certainty evidence), or who experienced at least one severe adverse event during the trial (RR 1.16, 95% CI 0.37 to 3.62; P = 0.79; very low-certainty evidence). One RCT compared diflunisal with placebo (130 randomised participants). At month 24, diflunisal might reduce progression of disability (Kumamoto Score; MD -4.90 points, 95% CI -7.89 to -1.91; P = 0.002; low-certainty evidence) and peripheral neuropathy (NIS plus 7 nerve tests; MD -18.10 points, 95% CI -26.03 to -10.17; P < 0.001; low-certainty evidence) more than placebo. After 24 months, changes from baseline in the quality of life measured by the 36-Item Short-Form Health Survey score showed no clear difference between groups for the physical component (MD 6.10 points, 95% CI 2.56 to 9.64; P = 0.001; very low-certainty evidence) and the mental component (MD 4.40 points, 95% CI -0.19 to 8.99; P = 0.063; very low-certainty evidence). There was no clear between-group difference in the number of people who died (RR 0.46, 95% CI 0.15 to 1.41; P = 0.17; very low-certainty evidence), in the number of dropouts due to adverse events (RR 2.06, 95% CI 0.39 to 10.87; P = 0.39; very low-certainty evidence), and in the number of people who experienced at least one severe adverse event (RR 0.77, 95% CI 0.18 to 3.32; P = 0.73; very low-certainty evidence) during the trial. One RCT compared patisiran with placebo (225 randomised participants). After 18 months, patisiran reduced both progression of disability (Rasch-built Overall Disability Scale; least-squares MD 8.90 points, 95% CI 7.00 to 10.80; P < 0.001; moderate-certainty evidence) and peripheral neuropathy (modified NIS plus 7 nerve tests - Alnylam version; least-squares MD -33.99 points, 95% CI -39.86 to -28.13; P < 0.001; moderate-certainty evidence) more than placebo. At month 18, the change in quality of life between groups favoured patisiran (Norfolk QOL-DN total score; least-squares MD -21.10 points, 95% CI -27.20 to -15.00; P < 0.001; low-certainty evidence). There was little or no between-group difference in the number of participants who died (RR 0.61, 95% CI 0.21 to 1.74; P = 0.35; low-certainty evidence), dropped out due to adverse events (RR 0.33, 95% CI 0.13 to 0.82; P = 0.017; low-certainty evidence), or experienced at least one severe adverse event (RR 0.91, 95% CI 0.64 to 1.28; P = 0.58; low-certainty evidence) during the trial. One RCT compared inotersen with placebo (172 randomised participants). The trial did not explore our predetermined disability outcome measures. From baseline to week 66, inotersen reduced progression of peripheral neuropathy more than placebo (modified NIS plus 7 nerve tests - Ionis version; MD -19.73 points, 95% CI -26.50 to -12.96; P < 0.001; moderate-certainty evidence). At week 65, the change in quality of life between groups favoured inotersen (Norfolk QOL-DN total score; MD -10.85 points, 95% CI -17.25 to -4.45; P < 0.001; low-certainty evidence). Inotersen may slightly increase mortality (RR 5.94, 95% CI 0.33 to 105.60; P = 0.22; low-certainty evidence) and occurrence of severe adverse events (RR 1.48, 95% CI 0.85 to 2.57; P = 0.16; low-certainty evidence) compared to placebo. More dropouts due to adverse events were observed in the inotersen than in the placebo group (RR 8.57, 95% CI 1.16 to 63.07; P = 0.035; low-certainty evidence). There were no studies addressing apolipoprotein AI-FAP, gelsolin-FAP, and beta-2-microglobulin-FAP.

AUTHORS' CONCLUSIONS

Evidence on the pharmacological treatment of FAPs from RCTs is limited to TTR-FAP. No studies directly compare disease-modifying pharmacological treatments for TTR-FAP. Results from placebo-controlled trials indicate that tafamidis, diflunisal, patisiran, and inotersen may be beneficial in TTR-FAP, but further investigations are needed. Since direct comparative studies for TTR-FAP will be hampered by sample size and costs required to demonstrate superiority of one drug over another, long-term non-randomised open-label studies monitoring their efficacy and safety are needed.

Myelin uncompaction and axo-glial detachment in chronic ataxic neuropathy with monospecific IgM antibody to ganglioside GD1b

To describe clinical features, disease course, treatment response, and sural nerve biopsy findings in a patient with chronic sensory ataxic neuropathy, Binet stage A chronic lymphocytic leukemia, and monoclonal IgMλ paraprotein against ganglioside GD1b. During 9 months of hospitalization at two neurologic centers, the patient underwent serial neurologic examinations, neurophysiologic studies, imaging investigations, extensive laboratory work-up, bone marrow, and sural nerve biopsies. The patient had a severe progressive sensory neuropathy accompanied by motor involvement, dysautonomia, and marked bulbar weakness with preserved ocular movements. Conduction studies were characterized by prolonged F-wave minimal latencies, prolonged distal latencies, reduction of compound motor action potentials, and absence of sensory nerve action potentials. Sural nerve biopsy showed endoneurial edema, axonal degeneration, and regeneration, in the absence of cellular inflammation, macrophagic activation, and B-lymphocyte infiltration; no IgM or complement deposition was detected. Myelinated fibers showed redundant/abnormally thickened myelin, myelin vacuolation, and frank intramyelinic edema with condensed axoplasm. Ultrastructural features included axo-glial detachment, disruption of membrane integrity, and myelin uncompaction. This study shows that monospecific anti-GD1b IgM paraprotein is associated with non-inflammatory nerve damage. We suggest that the loss of myelin and axonal integrity reflects antibody-induced disruption of membrane lipid rafts.

Peripheral nervous system involvement in lymphomas

The peripheral nervous system may be involved at any stage in the course of lymphoproliferative diseases. The different underlying mechanisms include neurotoxicity secondary to chemotherapy, direct nerve infiltration (neurolymphomatosis), infections, immune-mediated, paraneoplastic or metabolic processes and nutritional deficiencies. Accordingly, the clinical features are heterogeneous and depend on the localization of the damage (ganglia, roots, plexi, and peripheral nerves) and on the involved structures (myelin, axon, and cell body). Some clinical findings, such a focal or diffuse involvement, symmetric or asymmetric pattern, presence of pain may point to the correct diagnosis. Besides a thorough medical history and neurological examination, neurophysiological studies, cerebrospinal fluid analysis, nerve biopsy (in selected patients with suspected lymphomatous infiltration) and neuroimaging techniques (magnetic resonance neurography and nerve ultrasound) may be crucial for a proper diagnostic workup.

Novel Familial Variant of the Desert Hedgehog Gene: Clinical Findings in Two Sisters with 46,XY Gonadal Dysgenesis or 46,XX Karyotype and Literature Review

BACKGROUND

In humans, Desert Hedgehog (DHH) gene mutations are a very rare cause of 46,XY gonadal dysgenesis (GD), eventually associated with peripheral neuropathy.

PATIENTS AND METHODS

Clinical records of 12 patients with 46,XY GD and unknown genetic background were reviewed and a 46,XY woman with peripheral neuropathy was individuated. Her 46,XX sister affected by similar neuropathy was also investigated. Genomic DNA was extracted and DHH exons sequenced and analyzed. A comparative genomic hybridization array was also performed.

RESULTS

In both the 46,XY and 46,XX sisters, a homozygous c.554C>A mutation in exon 2 of the DHH gene was found, determining a premature termination codon (p.Ser 185*). Heterozygous consanguineous carrier parents showed neither reproductive problems nor peripheral neuropathy. In the proband and her sister, a 499-kb duplication in 9p22.1 was also found.

CONCLUSION

A 46,XY European woman with 46,XY GD and a novel homozygous DHH pathogenic variant is reported, confirming that this gene plays a key role in male gonadal development. Her 46,XX sister, harboring the same mutation, showed normal internal and external female phenotype. Thus, DHH seems not to be involved in the ovarian development pathway or its postpubertal function. Homozygous DHH mutations cause a specific peripheral neuropathy in humans with both 46,XY and 46,XX karyotypes.

The spectrum of Charcot-Marie-Tooth disease due to myelin protein zero: An electrodiagnostic, nerve ultrasound and histological study

OBJECTIVE

Nerve ultrasound (US) data on myelin protein zero (MPZ)-related Charcot-Marie-Tooth disease (CMT) are lacking. To offer a comprehensive perspective on MPZ-related CMTs, we combined nerve US with clinics, electrodiagnosis and histopathology.

METHODS

We recruited 36 patients (12 MPZ mutations), and correlated nerve US to clinical, electrodiagnostic measures, and sural nerve biopsy.

RESULTS

According to motor nerve conduction velocity (MNCV) criteria, nine patients were categorized as "demyelinating" CMT1B, 17 as "axonal" CMT2I/J, and 10 as dominant "intermediate" CMTDID. Sural nerve biopsy showed hypertrophic de-remyelinating neuropathy with numerous complex onion bulbs in one patient, de-remyelinating neuropathy with scanty/absent onion bulbs in three, axonal neuropathy in two, mixed demyelinating-axonal neuropathy in five. Electrodiagnosis significantly differed in CMT1B vs. CMT2I/J and CMTDID subgroups. CMT1B had slightly enlarged nerve cross sectional area (CSA) especially at proximal upper-limb (UL) sites. CSA was negatively correlated to UL MNCV and not increased at entrapment sites. Major sural nerve pathological patterns were uncorrelated to UL nerve US and MNCV.

CONCLUSIONS

Sural nerve biopsy confirmed the wide pathological spectrum of MPZ-CMT. UL nerve US identified two major patterns corresponding to the CMT1B and CMT2I/J-CMTDID subgroups.

SIGNIFICANCE

Nerve US phenotype of MPZ-CMT diverged from those in other demyelinating peripheral neuropathies and may have diagnostic value.

Predictive role of early milestones-related psychomotor profiles and long-term neurodevelopmental pitfalls in preterm infants

BACKGROUND

Developmental milestones are useful signposts developed to assess the pace and the trajectory of maturation occurring during specific time-windows called critical periods. The predictive role of their clinical assessment in premature infants is challenging, however, it actually represents an easy and reliable tool at follow-up.

AIM AND STUDY DESIGN

Relying on a milestone-based neurological examination, we aimed to detect the interdependence between time of achievement of each milestone with long-term neuropsychological and neurodevelopmental outcomes. The influence of pre-perinatal events was also considered.

PATIENTS & METHODS

Two-hundred-eighty patients (53.2% M) were serially assessed by classic neurological examination during the first 18months and subsequently evaluated by Griffiths Developmental Mental Scale. Children were sorted by ranges of gestational age and compared according to their different profiles.

RESULTS

The Extremely PreTerms appeared to have a globally delayed development with subsequent attentional and behavioral troubles. Differently, the older peers, from Moderately to Full Term ones, although did not show significant differences in achievement of gross motor skills, had a stable delay of visual and social skills across the age ranges. This gap was not evidenced at the long-term evaluation, except for the Extremely PreTerm children. Pre-perinatal factors played a significant role on short and long term neurodevelopmental outcome.

CONCLUSIONS

Early assessed classic neurological examination might address neurodevelopmental trajectories in PreTerm children in which visual and social skills appear to be the mostly affected. It remains the easiest and most reliable tool of evaluation throughout the follow-up programs.

Loss-of-function mutations in the SIGMAR1 gene cause distal hereditary motor neuropathy by impairing ER-mitochondria tethering and Ca2+ signalling

Distal hereditary motor neuropathies (dHMNs) are clinically and genetically heterogeneous neurological conditions characterized by degeneration of the lower motor neurons. So far, 18 dHMN genes have been identified, however, about 80% of dHMN cases remain without a molecular diagnosis. By a combination of autozygosity mapping, identity-by-descent segment detection and whole-exome sequencing approaches, we identified two novel homozygous mutations in the SIGMAR1 gene (p.E138Q and p.E150K) in two distinct Italian families affected by an autosomal recessive form of HMN. Functional analyses in several neuronal cell lines strongly support the pathogenicity of the mutations and provide insights into the underlying pathomechanisms involving the regulation of ER-mitochondria tethering, Ca2+ homeostasis and autophagy. Indeed, in vitro, both mutations reduce cell viability, the formation of abnormal protein aggregates preventing the correct targeting of sigma-1R protein to the mitochondria-associated ER membrane (MAM) and thus impinging on the global Ca2+ signalling. Our data definitively demonstrate the involvement of SIGMAR1 in motor neuron maintenance and survival by correlating, for the first time in the Caucasian population, mutations in this gene to distal motor dysfunction and highlight the chaperone activity of sigma-1R at the MAM as a critical aspect in dHMN pathology.

Nerve conduction velocity in CMT1A: what else can we tell?

BACKGROUND AND PURPOSE

Charcot-Marie-Tooth disease (CMT) type 1A is characterized by uniformly reduced nerve conduction velocity (NCV) that is fully penetrant since the first years of life, remains fairly stable through the life and does not correlate with disability whereas compound muscular action potential (CMAP) amplitude does. The aim of the present study was to analyze the large amount of electrophysiological data collected in the ascorbic acid trial in Italy and the UK (CMT-TRIAAL/CMT-TRAUK) and to use these data to gain insights into the pathophysiology of NCV in CMT1A.

METHODS

Baseline electrophysiological data from 271 patients were analysed. Electrophysiological recordings were taken from the motor ulnar, median and peroneal nerves and the sensory ulnar nerve. Distal motor latency (DML), motor (MNCV) and sensory (SNCV) nerve conduction velocity, and amplitudes of CMAPs and sensory action potentials were assessed. Electrophysiological findings were correlated with age of patients at examination and the Charcot-Marie-Tooth Examination Score (CMTES).

RESULTS

NCV was markedly and uniformly reduced. CMAP amplitudes were overall reduced but more severely in lower limbs. DML decreased and MNCV and SNCV increased with age of the patients, whereas CMAP amplitudes worsened with age and also correlated with CMTES.

CONCLUSIONS

This is the largest sample of electrophysiological data obtained so far from CMT1A patients. Axonal degeneration as assessed by means of CMAP amplitude reflected clinical impairment and was consistent with a slowly progressive length-dependent neuropathy. All patients typically had markedly slowed NCV that did, however, slightly increase with age of the patients. The improvement of NCV might depend on myelin thickness remodelling that occurs during the adult life of CMT1A patients.

Novel outcome measures for Charcot-Marie-Tooth disease: validation and reliability of the 6-min walk test and StepWatch(™) Activity Monitor and identification of the walking features related to higher quality of life

BACKGROUND AND PURPOSE

Charcot-Marie-Tooth (CMT) disease is the most common inherited neuropathy, but therapeutic options have been limited to symptom management. Past pharmacological trials have failed, possibly due to insensitive outcome measures (OMs). The aim of the current study was to evaluate the validity and reliability of the 6-min walk test (6MWT) and StepWatch(™) Activity Monitoring (SAM) with other previously validated OMs in CMT disease.

METHODS

A prospective multicenter study was performed, consecutively enrolling 168 CMT patients (104 with CMT1A, 27 with CMT1B, 37 with X-linked CMT) from Italian centers specializing in CMT care.

RESULTS

Statistical analysis showed that the 6MWT was highly related with all previously used OMs. Some, but not all, SAM parameters were related to commonly used OMs but may provide more information about quality of life.

CONCLUSIONS

The current study demonstrated the validity and reliability of the 6MWT and SAM as OMs for CMT. Moreover, SAM provides data that correlate better with quality of life measures, making it useful in future rehabilitation trials.

Charcot-Marie-Tooth disease: New insights from skin biopsy

OBJECTIVE

To evaluate, by skin biopsy, dermal nerve fibers in 31 patients with 3 common Charcot-Marie-Tooth (CMT) genotypes (CMT1A, late-onset CMT1B, and CMTX1), and rarer forms of CMT caused by mutations in RAB7 (CMT2B), TRPV4 (CMT2C), and GDAP1 (AR-CMT2K) genes.

METHODS

We investigated axonal loss by quantifying Meissner corpuscles and intrapapillary myelinated endings and evaluated morphometric changes in myelinated dermal nerve fibers by measuring fiber caliber, internodal, and nodal gap length.

RESULTS

The density of both Meissner corpuscles and intrapapillary myelinated endings was reduced in skin samples from patients with CMT1A and all the other CMT genotypes. Nodal gaps were larger in all the CMT genotypes though widening was greater in CMT1A. Perhaps an altered communication between axons and glia may be a common feature for multiple forms of CMT. Internodal lengths were shorter in all the CMT genotypes, and patients with CMT1A had the shortest internodes of all our patients. The uniformly shortened internodes in all the CMT genotypes suggest that mutations in both myelin and axon genes may developmentally impede internode formation. The extent of internodal shortening and nodal gap widening are likely both important in determining nerve conduction velocities in CMT.

CONCLUSIONS

This study extends the information gained from skin biopsies on morphologic abnormalities in various forms of CMT and provides insights into potential pathomechanisms of axonal and demyelinating CMT.