Strategy for genetic analysis in hereditary neuropathy.

Inherited neuropathies are a heterogeneous group of slowly progressive disorders affecting either motor, sensory, and/or autonomic nerves. Peripheral neuropathy may be the major component of a disease such as Charcot-Marie-Tooth disease or a feature of a more complex multisystemic disease involving the central nervous system and other organs. The goal of this review is to provide the clinical clues orientating the genetic diagnosis in a patient with inherited peripheral neuropathy. This review focuses on primary inherited neuropathies, amyloidosis, inherited metabolic diseases, while detailing clinical, neurophysiological and potential treatment of these diseases.

Neurological update: hereditary neuropathies.

In this update, we review the recent discovery of autosomal recessive variants in sorbitol dehydrogenase as one of the commonest and potentially treatable causes of hereditary motor neuropathy and CMT2. We also report on recent therapeutic advances in hereditary neuropathy including the use of lipid nanoparticle sequestered antisense oligonucleotides in CMT1A and lipid nanoparticle delivered CRISPR-Cas9 gene editing in ATTR amyloidosis.

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.

Inherited motor-sensory neuropathy with upper limb predominance associated with the tropomyosin-receptor kinase fused gene.

The Tropomyosin-receptor kinase fused gene (TFG) encodes TFG which is expressed in spinal motor neurons, dorsal root ganglia and cranial nerve nuclei, and plays a role in the dynamics of the endoplasmic reticulum. Two dominant missense TFG mutations have previously been reported in limited geographical areas (Far East, Iran, China) in association with hereditary motor sensory neuropathy with proximal involvement (HMSN-P) of the four limbs, or with Charcot-Marie-Tooth disease type 2 (CMT2). The 60-year-old female proband belonging to a three-generation Italian family presented with an atypical neuropathy characterized by diffuse painful cramps and prominent motor-sensory impairment of the distal upper limbs. Her sural nerve biopsy showed chronic axonal neuropathy without active degeneration or regeneration. Targeted next-generation sequencing of a panel with 98 genes associated with inherited peripheral neuropathies/neuromuscular disorders identified three candidate genes: TFG, DHTKD1 and DCTN2. In the family, the disease co-segregated with the TFG p.(Gly269Val) variant. TFG should be considered in genetic testing of patients with heterogeneous inherited neuropathy, independently of their ethnic origin.

Hereditary neuropathy with liability to pressure palsies.

Hereditary neuropathy with liability to pressure palsies (HNPP) is characterized by recurrent sensory and motor neuropathy in individual nerves starting in adolescence or young adulthood, focal conduction abnormalities at entrapment sites on nerve conduction studies, and sausage-like swellings (tomacula) of the myelin sheaths by nerve biopsy. It is characterized genetically by the deletion of the chromosome 17p11.2-p12 region including the peripheral myelin protein-22 gene in the overwhelming majority of cases. HNPP may be frequently underdiagnosed or misdiagnosed owing to the heterogeneity of clinical and electrophysiological appearance. The main objective of this review is to describe clinical manifestations, paraclinical features such as electrodiagnostic, pathological, radiological and genetics findings, and possible treatments.

Sural nerve pathology in TFG-associated motor neuron disease with sensory neuropathy.

The tropomyosin-receptor kinase fused gene (TFG) functions in vesicles formation and egress at the endoplasmic reticulum (ER). A heterozygous missense mutation c.854C > T (p.Pro285Leu) within TFG has been reported as causative for hereditary motor and sensory neuropathy with proximal predominance. Here, we describe two unrelated Chinese pedigrees with 13 affected members harboring the same variant. The clinical, electrophysiological and pathological findings are consistent with motor neuron disease with sensory neuropathy. The main symptoms were painful muscle cramps, slowly progressive proximal predominant weakness, muscle atrophy, fasciculation and distal sensory disturbance. Electromyography revealed widespread denervation and reinnervation. Sural nerve biopsy revealed severe loss of myelinated fibers. Electron microscopy revealed aggregation of ER with enlarged lumen and small vesicles in the remaining myelinated and unmyelinated axons. The mitochondria are smaller in Schwann cells and axons. Some unmyelinated axons showed disappearance of neurofilament and microtubular structures. This is the first report of c.854C > T mutation within TFG in Chinese population. Our findings not only extend the geographical and phenotypic spectrum of TFG-related neurological disorders, but also confirm the abnormalities of ER and mitochondria in sural nerves.

[Immune-mediated / inflammatory and hereditary neuropathies - overview and diagnostic algorithm]. / Immunvermittelte / inflammatorische und hereditäre Neuropathien ­ Übersicht und diagnostischer Algorithmus.

This paper is a practical survey of immune-mediated, inflammatory and hereditary neuropathies along with recommendations for diagnostic procedures. The large group of immune-mediated, inflammatory neuropathies includes the Guillain-Barré syndrome and chronic-inflammatory demyelinating polyradiculoneuropathy and their subtypes, vasculitic, paraneoplastic and paraproteinemic neuropathies as well as neuropathies resulting from connective tissue disorders. Besides clinical features such as time-dependent progression and distribution of sensorimotor deficits, characteristic electroneurographic findings and antibody profiles are considered. Recent studies in hereditary neuropathies reveal a prevalence of 10-28 out of 100 000 persons in Europe. Research into the genetic causes has made significant progress in the last 20 years; up to now more than 80 genes mutated in hereditary neuropathies have been identified. Besides classification into axonal, demyelinating or intermediate neuropathies based on electroneurography, distinguishing between sensorimotor, pure motor and (autonomous) sensory neuropathies as well as consideration of particular clinical features and ethnic origin can be helpful in orientating molecular genetic analysis.

Compression neuropathy of common peroneal nerve caused by a popliteal cyst: A case report.

RATIONALE: Popliteal cyst developing in the sheath of a peripheral nerve or joint capsule may cause compression neuropathy. Although popliteal cyst is very common lesion, it seldom causes serious complications. Common peroneal nerve compression is rarely caused by an extraneural popliteal cyst. PATIENT CONCERNS: We presented the case of a 52-year-old female with common peroneal nerve compression caused by an extraneural popliteal cyst. DIAGNOSES: Electromyography showed the damage of common peroneal nerve. MRI magnetic resonance imaging showed the lump to be a popliteal cyst. She was diagnosed as peroneal nerve injury and popliteal cyst. INTERVENTIONS: The patient was performed peroneal nerve decompression and popliteal cyst excision surgery. We excised the cyst completely and soluted the common peroneal nerve thoroughly. The cyst was filled with thick mucinous material. OUTCOMES: The pathological report showed that the excised mass was a popliteal cyst. There were no postoperative complications. Pain and hypoesthesia resolved 6 months after surgery. LESSONS: In this case, compression of the common peroneal nerve was due to an extraneural popliteal cyst, a situation rarely encountered. MRI can show in better detail their size and internal contents as well as their relation with surrounding anatomic structures. Patients with nerve entrapment caused by enlarged or ruptured cysts must be microsurgically excised if symptomatic.

Transthyretin familial amyloid polyneuropathy (TTR-FAP): Parameters for early diagnosis.

Background: Familial transthyretin amyloidosis is a life-threatening disease presenting with sensorimotor and autonomic polyneuropathy. Delayed diagnosis has a detrimental effect on treatment and prognosis. To facilitate diagnosis, we analyzed data patterns of patients with transthyretin familial amyloid polyneuropathy (TTR-FAP) and compared them to polyneuropathies of different etiology for clinical and electrophysiological discriminators. Methods: Twenty-four patients with TTR-FAP and 48 patients with diabetic polyneuropathy (dPNP) were investigated (neurological impairment score NIS; neurological disability score NDS) in a cross-sectional design. Both groups were matched for gender and presence of pain. Quantitative sensory testing (QST), sympathetic skin response (SSR), heart rate variability (HRV), and nerve conduction studies (NCV) were performed. Both groups were compared using univariate analysis. In a stepwise discriminant analysis, discriminators between both neuropathies were identified. These discriminators were validated comparing TTR-FAP patients with a cohort of patients with chemotherapy-induced polyneuropathy (CIN) and chronic inflammatory demyelinating neuropathy (CIDP). Results: TTR-FAP patients scored higher in NDS and NIS and had impaired cold detection (CDT, p = .024), cold-warm discrimination (TSL, p = .019) and mechanical hyperalgesia (MPT, p = .029) at the hands, SSR (upper limb, p = .022) HRV and ulnar and sural NCS (all p < .05) were more affected in TTR-FAP. Ulnar nerve sensory NCV, CDT, and the MPT but not the other parameters discriminated TTR-FAP from dPNP (82% of cases), from CIN (86.7%) and from CIDP (68%; only ulnar sNCV). Conclusion: Low ulnar SNCV, impaired cold perception, and mechanical hyperalgesia at the hands seem to characterize TTR-FAP and might help to differentiate from other polyneuropathies.

Hereditary Neuropathies.

BACKGROUND: Hereditary peripheral neuropathies constitute a large group of genetic diseases, with an overall prevalence of 1:2500. In recent years, the use of so-called next-generation sequencing (NGS) has led to the identification of many previously unknown involved genes and genetic defects that cause neuropathy. In this article, we review the procedures and utility of genetic evaluation for hereditary neurop - athies, while also considering the implications of the fact that causally directed treatment of these disorders is generally unavailable. METHODS: This review is based on pertinent publications retrieved by a PubMed search employing the search terms "hereditary neuropathy," "Charcot-Marie-Tooth disease," "hereditary sensory neuropathy," and "hereditary motor neuropathy." RESULTS: With rare exceptions, the diagnostic evaluation for hereditary neuropathies proceeds in stepwise fashion, beginning with the study of individual genes. If this fails to detect any abnormality, NGS analysis, which involves the sequencing of many different genes in parallel and has now become available for routine diagnosis, should be performed early on in the diagnostic work-up. Exome and genome analyses are currently performed only when considered to be indicated in the individual case. Whenever a hereditary neuropathy is suspected, other (including potentially treatable) causes of neuropathy should be ruled out. Mutations in neurop athy-associated genes may also be associated with other clinical entities such as spastic paraplegia or myopathy. Thus, interdisciplinary assessment is necessary. CONCLUSION: The molecular diagnosis of neuropathies has become much more successful through the use of NGS. Although causally directed treatment approaches still need to be developed, the correct diagnosis puts an end to the often highly stressful search for a cause and enables determination of the risk of disease in other members of the patient's family.

A case report of hereditary neuropathy with liability to pressure palsies accompanied by type 2 diabetes mellitus and psoriasis.

RATIONALE: Hereditary neuropathy with liability to pressure palsy (HNPP) is an episodic, multifocal neuropathy, with a typical clinical presentation of recurrent transient pressure palsies, which is induced by a PMP22 deletion. Another neuropathy caused by a PMP22 duplication is Charcot-Marie-Tooth disease type 1A (CMT1A). PMP22 is a gene coding a protein called peripheral myelin protein 22 (PMP22), which plays an essential role in the formation and maintenance of compact myelin. Coexistence of type 2 diabetes mellitus (T2DM) and CMT1A has been reported in many work, however HNPP patients with T2DM are rare, and comorbidity of HNPP and psoriasis has not been reported previously. Electrophysiological features of HNPP has been found progressing with aging. Patient concerns: Here we present a 20-year-old man who exhibited lower extremity weakness and foot drop as the initial manifestation. DIAGNOSES: HNPP was diagnosed on the basis of clinical features, positive sural nerve biopsy findings, and genetic testing results. Moreover, physical examination, blood/urine glucose test, and diabetes-related autoantibodies investigations demonstrated that he had psoriasis and T2DM. The electrophysiological manifestations revealed profound demyelinating injuries and axonal injuries in distal peripheral nerves and facial nerves, which were more severe than general HNPP cases. INTERVENTIONS: The young patient was treated with continuous subcutaneous insulin infusion and blood glucose monitoring, and then transferred to oral acarbose therapy. The psoriatic lesions were treated with calcipotriol ointment. OUTCOMES: In the follow-up, the right leg weakness was alleviated, and his gait was improved. LESSONS: The findings indicate that diabetes mellitus may have an impact on the severity of HNPP. Physicians should consider that worsening of symptoms might result from newly diagnosed diabetes mellitus while treating patients with HNPP.

Prevalence of thoracic spine lesions masquerading as cauda equina syndrome: yield of a novel magnetic resonance imaging protocol.

Our objective was to describe the yield of actionable thoracic spine lesions for a novel magnetic resonance imaging (MRI) protocol including evaluation of the thoracic spine among patients presenting to the Emergency Department (ED) with symptoms consistent with epidural compression syndrome. Our ED and Department of Radiology together designed a novel rapid MRI protocol entailing 3D volumetric T2 weighted sequences through both the thoracic and lumbar spine obtained in the sagittal plane to assess for both lumbar and thoracic spine lesions. We recorded study outcomes for all patients undergoing this protocol or conventional lumbar MRI during May 2014-May 2015 to determine the prevalence of actionable thoracic spine lesions. We defined an actionable thoracic lesion as any pathology requiring treatment (e.g., medication, admission, surgery) not otherwise indicated on the basis of lumbar spine findings. During the study period, 112 of 124 (90.3%) of ED patients undergoing MRI evaluation for epidural compression syndrome underwent the novel protocol. The remaining patients underwent evaluation of the lumbar spine using only a conventional MRI protocol. Of the 112 patients undergoing the novel protocol, 6 (5.4%) patients had thoracic spine lesions indicating therapy not otherwise indicated by lumbar spine findings. The etiologies of these six lesions were: neoplasms (2), de-myelination (2), compression fracture (1), and degeneration due to pernicious anemia (1). Emergency providers should strongly consider the routine use of MRI protocols including thoracic spine evaluation in patients presenting to the ED with symptoms consistent with epidural compression syndrome.

Pain in hereditary neuropathy with liability to pressure palsy: an association with fibromyalgia syndrome?

INTRODUCTION: This study characterizes the nature of pain in hereditary neuropathy with liability to pressure palsy (HNPP). METHODS: This retrospective study was performed to assess duration, nature, location, and intensity of pain on initial presentation of subjects with HNPP, including the degree and type of analgesic medication use and electrodiagnostic characteristics. Subjects who met the American College of Rheumatology criteria for fibromyalgia syndrome (FMS) were also identified. RESULTS: Of 32 HNPP subjects, 24 (75%) had symptoms of pain, and 4 (12%) had pain as an initial symptom. Of subjects who described pain, 9 (28%) reported only musculoskeletal pain, 10 (31%) only neuropathic pain, and 5 (16%) both musculoskeletal and neuropathic pain. All 9 subjects with only musculoskeletal pain met criteria for FMS. CONCLUSIONS: Neuropathic and musculoskeletal pain occur commonly in HNPP and may be a presenting symptom. Additionally, HNPP with predominantly musculoskeletal pain may meet criteria for FMS and potentially delay the diagnosis.

Distal tibial osteochondroma causing fibular deformity and deep peroneal nerve entrapment neuropathy: a case report.

Osteochondromas are the most common benign bone tumors, comprising 9% of all bone tumors and 35% of benign bone tumors. They are frequently diagnosed incidentally. Osteochondromas are mostly asymptomatic, but may cause mechanical findings depending on the location and size of the tumor. Rarely, they may originate from the interosseous surface of the tibia and affect the fibula. We report here a case of a rare osteochondroma originating from the distal tibial metaphysis and causing deep peroneal nerve entrapment syndrome with clinical and radiological findings. To our knowledge, this is the first case in the literature.

Intraneural perineurioma affecting multiple nerves: a case report and literature review.

Intraneural perineurioma is a neoplasm of perineurial cells, corresponding to WHO grade I. We present a case of intraneural perineurioma affecting multiple nerves, which usually involved one or two of major nerve trunks in one patient. We describe the clinical presentation, magnetic resonance (MR) neurography characteristics, and pathological characteristics. The differential diagnosis with other diseases, such as neurofibroma, Schwannomatosis and HNPP, will also be discussed. We also review the literature in efforts to highlight recent studies on intraneural perineurioma and heighten and awareness for the possible presentations of this disorder.

Clinical, electrophysiological, and molecular findings in early onset hereditary neuropathy with liability to pressure palsy.

INTRODUCTION: The first episode of hereditary neuropathy with liability to pressure palsy (HNPP) in childhood is rare. METHODS: We analyzed retrospectively the data of 7 patients with a deletion in PMP22 and onset of symptoms before age 18 years. Direct sequencing of the LITAF (lipopolysaccharide-induced tumor necrosis factor) gene was performed in patients and family members. RESULTS: Clinical presentations varied from mononeuropathies to brachial plexopathy, with recurrent episodes in 4 patients. Electrophysiological abnormalities characteristic for HNNP were found in most subjects. Analysis of the LITAF gene revealed an Ile92Val polymorphism in 6 of 7 (86%) probands and 5 of 7 (83%) family members, over 4 times greater frequency than in the general population. CONCLUSIONS: Clinical suspicion of HNPP even when nerve conduction study results do not fulfill HNPP criteria should indicate genetic testing. In our patients, early-onset HNPP was associated frequently with isoleucine92valine LITAF polymorphism.

Neuroblastoma with symptomatic epidural compression in the infant: the AIEOP experience.

BACKGROUND: Symptoms of epidural compression (SEC) in children with neuroblastoma (particularly infants) may be misinterpreted, leading to delay in diagnosis. PATIENTS AND METHODS: Clinical, imaging and follow-up data of 34 infants with neuroblastoma and SEC diagnosed between 2000 and 2011 at Italian AIEOP centers were retrieved and reviewed. RESULTS: Median age at initial SEC was 104 days (IQR 47-234). Main symptoms included motor deficit (85.3%), pain (38.2%), bladder and bowel dysfunctions (20.6% each). In the symptom-diagnosis interval (S-DI) (median, 12 days; IQR 7-34), the frequency of grade 3 motor deficit increased from 11.8% to 44.1% and that of bladder dysfunction from 20.6% to 32.4%. S-DI was significantly longer (P = 0.011) for patients developing grade 3 motor deficit. First treatment of SEC was neurosurgery in 14 patients, and chemotherapy in 20. SEC regressed in 11 patients (32.3%), improved in 9 (26.5%), and remained stable in 14 (41.2%), without treatment-related differences. Median follow-up was 82 months. At last visit, 11 patients (32.3%) were sequelae-free while 23 (67.7%) had sequelae, including motor deficit (55.9%), bladder (50.0%) and bowel dysfunctions (28.4%), and spinal abnormalities (38.2%). Sequelae were rated severe in 50% of patients. Severe sequelae scores were more frequent in patients presenting with spinal canal invasion >66% (P = 0.039) and grade 3 motor deficit (P = 0.084). CONCLUSIONS: Both neurosurgery and chemotherapy provide unsatisfactory results once paraplegia has been established. Sequelae developed in the majority of study patients and were severe in a half of them. Greater awareness by parents and physicians regarding SEC is warranted.