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.

[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.

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.

Hand compression neuropathy: An assessment guide.

When a patient presents with pain or paresthesias of the hand and fingers, knowing what to ask, what to look for, and which tests to consider is essential.

Small amounts of functional ATP7A protein permit mild phenotype.

Mutations in ATP7A lead to at least three allelic disorders: Menkes disease (MD), Occipital horn syndrome and X-linked distal motor neuropathy. These disorders are mainly seen in male individuals, but a few affected females have been described. More than 400 different mutations have been identified in the ATP7A gene. We have conducted several studies in the hope of uncovering the relationship between genotype and phenotype. We have examined the X-inactivation pattern in affected females, the effect of exon-deletions and--duplications, and splice-site mutations on the composition and amount of ATP7A transcript, and we have examined the structural location of missense mutations. The X-inactivation pattern did not fully explain the manifestation of MD in a small fraction of carriers. Most of the affected females had preferential inactivation of the X-chromosome with the normal ATP7A gene, but a few individuals exhibited preferential inactivation of the X-chromosome with the mutated ATP7A gene. The observed mild phenotype in some patients with mutations that effect the composition of the ATP7A transcript, seems to be explained by the presence of a small amount of normal ATP7A transcript. The location of missense mutations on structural models of the ATP7A protein suggests that affected conserved residues generally lead to a severe phenotype. The ATP7A protein traffics within the cells. At low copper levels, ATP7A locates to the Trans-Golgi Network (TGN) to load cuproenzymes with copper, whereas at higher concentrations, ATP7A shifts to the post-Golgi compartments or to the plasma membrane to export copper out of the cell. Impaired copper-regulation trafficking has been observed for ATP7A mutants, but its impact on the clinical outcome is not clear. The major problem in patients with MD seems to be insufficient amounts of copper in the brain. In fact, prenatal treatment of mottled mice as a model for human MD with a combination of chelator and copper, produces a slight increase in copper levels in the brain which perhaps leads to longer survival and more active behavior. In conclusion, small amounts of copper at the right location seem to relieve the symptoms.

Hereditary neuropathy with liability to pressure palsies presenting with sciatic neuropathy.

Hereditary neuropathy with liability to pressure palsies (HNPP) is an autosomal-dominant disorder associated with recurrent mononeuropathies following compression or trivial trauma. Reports on sciatic neuropathy as the presenting manifestation of HNPP are very scarce. We report on a 21-year-old previously healthy man who was admitted with sensorimotor deficits in his left leg. He had no history of preceding transient episodes of weakness or sensory loss. Clinical and electrophysiological examinations were consistent with sciatic neuropathy. Cerebrospinal fluid investigation and MRI of the nerve roots, plexus, and sciatic nerve did not indicate the underlying aetiology. When extended electrophysiological tests revealed multiple subclinical compression neuropathies in the upper limbs, HNPP was contemplated and eventually confirmed by genetic testing.

PMP22 related neuropathies: Charcot-Marie-Tooth disease type 1A and Hereditary Neuropathy with liability to Pressure Palsies.

PMP22 related neuropathies comprise (1) PMP22 duplications leading to Charcot-Marie-Tooth disease type 1A (CMT1A), (2) PMP22 deletions, leading to Hereditary Neuropathy with liability to Pressure Palsies (HNPP), and (3) PMP22 point mutations, causing both phenotypes. Overall prevalence of CMT is usually reported as 1:2,500, epidemiological studies show that 20-64% of CMT patients carry the PMP22 duplication. The prevalence of HNPP is not well known. CMT1A usually presents in the first two decades with difficulty walking or running. Distal symmetrical muscle weakness and wasting and sensory loss is present, legs more frequently and more severely affected than arms. HNPP typically leads to episodic, painless, recurrent, focal motor and sensory peripheral neuropathy, preceded by minor compression on the affected nerve. Electrophysiological evaluation is needed to determine whether the polyneuropathy is demyelinating. Sonography of the nerves can be useful. Diagnosis is confirmed by finding respectively a PMP22 duplication, deletion or point mutation. Differential diagnosis includes other inherited neuropathies, and acquired polyneuropathies. The mode of inheritance is autosomal dominant and de novo mutations occur. Offspring of patients have a chance of 50% to inherit the mutation from their affected parent. Prenatal testing is possible; requests for prenatal testing are not common. Treatment is currently symptomatic and may include management by a rehabilitation physician, physiotherapist, occupational therapist and orthopaedic surgeon. Adult CMT1A patients show slow clinical progression of disease, which seems to reflect a process of normal ageing. Life expectancy is normal.

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.

Bilateral radial nerve compression neuropathy in the newborn.

PURPOSE: This study aims to discuss the diagnosis and management of radial nerve compression neuropathy in the newborn. METHODS: A personal case is presented, followed by a review and analysis of clinically similar cases identified via a PubMed search of published medical literature. RESULTS: We report a case of a term newborn with bilateral radial neuropathy at the humerus level. Despite severe axonal involvement in the electrophysiological evaluation, the patient showed complete bilateral recovery after 3 months of follow-up. CONCLUSIONS: Isolated radial nerve palsy is a rare event in the newborn. The condition does not require surgical treatment and usually proceeds to full and rapid spontaneous recovery.

Proximal median nerve entrapment caused by a distal biceps tendon cyst: an ultrasonographic diagnosis.

A 60-yr-old woman reported severe pain in the proximal part of her left forearm. The pain was also radiating toward the median nerve-innervated areas of the arm, especially during elbow flexion. Ultrasonographic imaging showed a well defined ganglion cyst around the distal biceps tendon close to the median nerve. Under ultrasound guidance, the cyst was aspirated and corticosteroid injection was performed. The patient's complaint improved 1 wk after the injection, and she started to flex her elbow without any pain. This case highlights the role of ultrasonography as a useful adjunctive tool not only to morphologically confirm a peripheral nerve entrapment but also to uncover the possible underlying etiology and to guide precisely during an intervention.

Treatment of chronic immune-mediated neuropathies: impact of the rare diseases centers network in Italy.

Chronic immune-mediated neuropathies represent a heterogeneous group of mostly demyelinating neuropathies thought to be caused by an autoimmune response to peripheral nerve antigens. They include chronic inflammatory demyelinating polyradiculoneuropathy (CIDP) and related variants, multifocal motor neuropathy (MMN) and neuropathy associated with an IgM monoclonal gammopathy with antibody activity against myelin-associated glycoprotein (MAG). Most of these neuropathies respond to immune therapy even though their response to therapy may be different, thereby confirming that their distinct characteristics have relevant clinical implications. While clinicians and scientists are intrigued by the desire to better clarify the cause and pathogenesis of these disorders, the need to allow affected patients to be reimbursed by insurance companies or the national health system can lead to the risk of lumping all these neuropathies under the umbrella term of 'CIDP' to facilitate patients' access to costly therapies.

Inherited neuropathies.

With a prevalence of 1 in 2500 people, inherited peripheral nerve diseases, collectively called Charcot-Marie-Tooth disease (CMT), are among the most common inherited neurologic disorders. Patients with CMT typically present with chronic muscle weakness and atrophy in limbs, sensory loss in the feet and hands, and foot deformities. Clinical similarities between patients often require genetic testing to achieve a precise diagnosis. In this article, the author reviews the clinical and pathologic features of CMT, and demonstrates how electrodiagnostic and genetic tools are used to assist in the diagnosis and symptomatic management of the diseases. Several cases are presented to illustrate the diagnostic processes.

[Wide spectrum of hereditary motor sensory neuropathy (HMSN)].

Hereditary neuropathies are classified into HMSN/Charcot-Marie-Tooth disease (CMT), familial amyloid polyneuropathy (FAP), hereditary motor neuropathies (HMN) and hereditary sensory (and autonomic) neuropathies (HSAN). The clinical features of HMSN are generally characterized as distal dominant motor and sensory involvements. However, we have reported a novel HMSN with proximal dominancy (HMSN-P) originated in Okinawa and Shiga prefectures, Japan. The gene locus is located in the centromere region of chromosome 3. In 2008, a new family with the HMSN-P was reported from Brazilians of Japanese ancestry. This Brazilian family was initially diagnosed as having "a familial ALS". The HMSN-P linked to ch.3 is not limited in Japan, but may be present in the worldwide. The overseas scientific research for the elucidation of the mechanism of HMSN-P supported by JSPS KAKENHI (21406026) is planning. Recently several other types of HMSN-P have been reported; HMSN-P with urinary disturbance and paroxysmal dry cough, a patient with both CMT 1A and mild spinal muscular atrophy and CMT1A with severe paresis of the proximal lower limb muscles. Therefore the clinical concept of HMSN is not limited as the disease with distal dominant motor sensory involvement. HMSN has the wider spectrum from distal to proximal and motor/sensory to autonomic neuropathies.

Diagnosis and new treatments in genetic neuropathies.

The genetic neuropathies are a clinically and genetically heterogeneous group of diseases of which the most common types are Charcot-Marie-Tooth disease (CMT), the hereditary sensory and autonomic neuropathies and the distal hereditary motor neuropathies. More than 30 causative genes have been described, making an accurate genetic diagnosis increasingly possible. Although no specific therapies are yet available, research into their pathogenesis has revolutionised our understanding of the peripheral nervous system and allowed the development of rational approaches to therapy. The first therapeutic trials in CMT are currently underway. This review will suggest an approach to the diagnosis of these disorders and provide an update on new therapies.

Experimental therapeutics in hereditary neuropathies: the past, the present, and the future.

Hereditary neuropathies represent approximately 40% of undiagnosed neuropathies in a tertiary clinic setting. The Charcot-Marie-Tooth neuropathies (CMT) are the most common. Mutations in more than 40 genes have been identified to date in CMT. Approximately 50% of CMT cases are accounted for by CMT type 1A, due to a duplication within the peripheral myelin protein 22 gene (PMP22). Mutations in the gap junction beta 1 gene (GJB1), the myelin protein zero gene (MPZ), and the mitofusin 2 gene (MFN2) account for a substantial proportion of other genetically definable CMT. Some 15% of demyelinating CMT and 70% of axonal CMT await genetic clarification. Other hereditary neuropathies include the hereditary sensory and autonomic neuropathies, the familial amyloid polyneuropathies, and multisystem disorders (e.g., lipid storage diseases and inherited ataxias) that have peripheral neuropathy as a major or minor component. This review surveys the challenges of developing effective therapies for hereditary neuropathies in terms of past, present, and future experimental therapeutics in CMT.

Inflammatory demyelinating neuropathies and neuropathies associated with monoclonal gammopathies: treatment update.

This review focuses on recent data regarding inflammatory demyelinating neuropathies and neuropathies associated with monoclonal gammopathies. We describe both acute and chronic inflammatory neuropathies, and we discuss conditions ranging from mostly cell-mediated to antibody-mediated disorders. These diseases are characterized by proximal and distal sensory motor involvement. Treatments are based on immune-modulation and/or immune-suppression. Work-up sequence and therapeutical modes are discussed in the light of recently published data, with a special interest on new treatment modalities.