Inherited focal, episodic neuropathies

Hereditary neuropathy associated with liability to pressure palsies: a 24-year experience with carpal and cubital tunnel surgery

The aim of this single-centre retrospective study was to evaluate the outcomes of carpal tunnel release surgery in patients with hereditary neuropathy with pressure palsies (HNPP). The secondary aims were to identify prognostic factors for the outcome of carpal tunnel release and to assess the outcome of cubital tunnel release. Our primary hypothesis was postoperative improvement. In total, 18 patients (26 carpal tunnel releases) with at least one symptomatic carpal tunnel syndrome were included. At a median follow-up of 8.5 years, more than 73% of the patients were satisfied with the results. The visual analogue scale (0 to 10) for discomfort decreased by 2.2 points (p < 0.001). The Boston Carpal Tunnel Questionnaire symptom severity scale decreased by 1.3 points (p < 0.001). The decrease in the Functional Status Scale was not significant. No significant prognostic factor for outcome was identified. A total of 12 patients also underwent cubital tunnel release, and three patients underwent just this procedure (23 procedures). Despite the lack of preoperative data, cubital tunnel release provided encouraging results. Level of evidence: III.

Efficacy of Spinal Cord Stimulation Using Differential Target Multiplexed Stimulation for Intractable Pain of Hereditary Neuropathy with Liability to Pressure Palsies: A Case Report

Hereditary neuropathy with liability to pressure palsies is an extremely rare genetic disorder; it is an autosomal dominant disorder with a high incidence of neuropathic and/or musculoskeletal pain. A case of achieving pain relief by spinal cord stimulation using differential target multiplexed stimulation for a 44-year-old female patient with hereditary neuropathy with liability to pressure palsies who was experiencing severe pain in her back, face, and all four limbs is presented. In her early teens, the initial symptoms were numbness and weakness of a limb after movement, which improved spontaneously. Transient pain in her back followed by systemic and persistent muscle weakness and pain developed. Deletion of the gene for peripheral myelin protein 22 was detected by peripheral nerve biopsy. The diagnosis of hereditary neuropathy with liability to pressure palsies was made in her early thirties. A spinal cord stimulation trial was performed because her severe pain continued despite administering many medications. Therefore, two spinal cord stimulation systems were implanted at the C3-5 and Th8-9 levels by two procedures. Pain in her back, arms, and legs decreased from 8 to 1, 5 to 1, and 6 to 2 on the numerical rating scale, respectively. Furthermore, opioid usage was tapered. The pain of hereditary neuropathy with liability to pressure palsies has a complicated pathogenesis and is resistant to pharmacological treatment. Spinal cord stimulation using differential target multiplexed stimulation may be a viable treatment option.

Tibial neuropathy, a rare manifestation of hereditary neuropathy with liability to pressure palsy: A case report

Hereditary neuropathy with liability to pressure palsy (HNPP) is characterized by acute, painless and recurrent mononeuropathies. Genetic testing shows PMP22 gene deletion of chromosome 17p11.2 can provide evidence for the diagnosis of HNPP. Reports on tibial neuropathy as the main manifestation of HNPP are very rare. We report a 14-year-old girl who was admitted to our hospital due to plantar foot numbness and plantar flexion weakness of her left foot. The patient had a history of lateral dorsal numbness and right foot drop when she was 3 years old. Clinical symptoms, and neurological examination demonstrated tibial neuropathy. Electromyography showed extensive peripheral nerve, including median nerve, ulnar nerve, tibial nerve and peroneal nerve, were involved. The diagnosis of HNPP was confirmed by genetic testing which disclosed a deletion of PMP22 gene. She was completely asymptomatic in one month after neurotrophic drug treatments.

[An 18-year-old man of hereditary neuropathy with liability to pressure palsies presenting with bilateral brachial plexopathy during military training]

An 18-year-old man without familial history of neuropathy developed motor and sensory disturbance of bilateral upper limbs after maintaining shoulder abduction/external rotation and elbow flection position of both upper limbs for an hour during military training. Neurological examination and electromyography studies suggested left brachial plexopathy, although a nerve conduction study (NCS) showed mild demyelination of bilateral median nerve and right ulnar nerve. Thoracic outlet syndrome (TOS) was firstly suspected because symptoms were induced by the specific position which narrows, costoclavicular and retropectoralis minor space and cause compression of the brachial plexus; however, no findings suggesting TOS were observed on computed tomography and magnetic resonance imaging. Hence, we suspected a diagnosis of hereditary neuropathy with liability to pressure palsies (HNPP) due to having episodes of bilateral acute brachial plexopathy and mild demyelination on NCS. The diagnosis of HNPP was confirmed by the deletion of the PMP22 gene deletion.

Adverse events following adenovirus type 4 and type 7 vaccine, live, oral in the Vaccine Adverse Event Reporting System (VAERS), United States, October 2011-July 2018

BACKGROUND

In March 2011, the U.S. Food and Drug Administration licensed adenovirus type 4 and type 7 vaccine, live, oral (Barr Labs, Inc.) (adenovirus vaccine) for use in military personnel 17 through 50 years of age. The vaccine was first universally administered to U.S. military recruits in October 2011. We investigated adverse event (AE) reports following the adenovirus vaccine submitted to the Vaccine Adverse Event Reporting System (VAERS).

METHODS

We searched the VAERS database for U.S. reports among persons who received adenovirus vaccine during October 2011 through July 2018 including participants in a military observational study. We reviewed all serious reports and accompanying medical records. We compared the proportion of serious reports in a proxy military recruit population and reviewed all reports of suspected allergic reactions following adenovirus vaccination.

RESULTS

During the analytic period, VAERS received 100 reports following adenovirus vaccination; 39 (39%) were classified as serious and of these, 17 (44%) were from the observational study. One death was reported. Males accounted for 72% of reports. Median age of vaccinees was 19 years (range 17-32). The most frequently reported serious AEs were Guillain Barré syndrome (GBS) (n = 12) and anaphylaxis (n = 8); of these, two GBS and all the anaphylaxis reports were reported in the observational study. Reports documented concurrent receipt of multiple other vaccines (95%) and penicillin G (IM Pen G) or other antibiotics (50%).

CONCLUSIONS

The reporting rate for serious AEs was higher than with other vaccines administered in the comparison military recruit population (39% vs 18%); however, we identified no unexpected or concerning pattern of adenovirus vaccine AEs. Co-administration of vaccines and IM Pen G was commonly reported in this military population. These exposures may have contributed to the GBS and anaphylaxis outcomes observed with the adenovirus vaccine. Future adenovirus vaccine safety studies in a population without these co-administrations would be helpful in clarifying the vaccine's safety profile.

Peripheral neuropathy in diabetes: it's not always what it looks like

BACKGROUND

Hereditary Neuropathy with liability to Pressure Palsies (HNPP) is an autosomal dominant neuropathy, associated with deletion of the Peripheral Myelin Protein-22 (PMP-22) gene, causing recurrent painless palsies with age of onset between 10 and 30 years old. Only a few cases of Type 2 Diabetes and HNPP have been described and the coexistence of HNPP and Type 1 diabetes has never been reported.

CASE REPORT

A 54-year old man with a history of Type 1 diabetes, managed with continuous subcutaneous insulin infusion (CSII), presented with deterioration of long-standing motor and sensory symptoms, previously attributed to golfer's elbow, diabetic neuropathy and spinal degenerative disease. He had multilevel severe spine degenerative changes and L4/L5 and L5/S1 root impingements with a L4/L5 discectomy performed when he was 25 years old. On physical examination he had normal power and distal hypoaesthesia of the digits and plantar aspect of the feet. Investigations revealed normal full blood count, liver and renal function, electrolytes, vitamin B12 and serum folate. He suffered from primary hypothyroidism and thyroid function tests indicated adequate levothyroxine replacement. Nerve conduction studies revealed a generalized demyelinating sensorimotor neuropathy, with more severe involvement of nerves over entrapment sites. Further history that his father suffered from episodes of weakness and numbness was elicited. Genetic analysis revealed one copy of the PMP22 gene at 17p11.2 confirming the diagnosis of HNPP.

CONCLUSION

In people with diabetes the evaluation of peripheral neuropathy should include a careful history, a comprehensive physical examination, blood tests and in some cases nerve conduction studies and genetic testing.

Characterisation of pain in people with hereditary neuropathy with liability to pressure palsy

Hereditary neuropathy with liability to pressure palsy (HNPP) has historically been considered a pain-free condition, though some people with HNPP also complain of pain. This study characterised persistent pain in people with HNPP. Participants provided cross-sectional demographic data, information on the presence of neurological and persistent pain symptoms, and the degree to which these interfered with daily life. The painDETECT and Central Sensitization Inventory questionnaires were used to indicate potential neuropathic, central sensitisation and musculoskeletal (nociceptive) pain mechanisms. Additionally, participants were asked if they thought that pain was related to/part of HNPP. 32/43 (74%) subjects with HNPP had persistent pain and experience this pain in the last week. Of those with pain, 24 (75%) were likely to have neuropathic pain and 27 (84%) were likely to have central sensitisation. All 32 participants felt that their pain could be related to/part of their HNPP. Significant negative impact of the pain was common. Pain characterisation identified neuropathic pain and/or central sensitisation as common, potential underlying processes. Pain may plausibly be directly related to the underlying pathophysiology of HNPP. Further consideration of including pain as a primary symptom of HNPP is warranted.

Whole-body MR neurography: Prospective feasibility study in polyneuropathy and Charcot-Marie-Tooth disease

PURPOSE

To evaluate the feasibility of whole-body magnetic resonance neurography (WBMRN) in polyneuropathy for technical feasibility, distribution of nerve abnormalities, and differentiation.

MATERIALS AND METHODS

Twenty WBMRN examinations were performed on a 3T scanner over 2 years. Patient demographics including history of hereditary and acquired neuropathy were recorded. The images were evaluated by two independent readers with nerve imaging experience for quality. The nerve signal and size alterations were measured in the brachial plexus, lumbosacral plexus, and femoral and sciatic nerves; diffusion tensor imaging parameters (fractional anisotropy [FA] and apparent diffusion coefficient [ADC]) were determined in plexuses, and tractography was performed. Nonparametric Wilcoxon rank sum test, receiver operating characteristic (ROC) analysis, and intraclass correlation coefficients (ICCs) were obtained.

RESULTS

Excellent image quality was obtained for the majority of lumbosacral (LS) plexus (18/20) and 50% of brachial plexus (10/20) regions. Qualitatively among cases, the nerve hyperintensity and/or thickening involved the brachial plexus (11/11), LS plexus (7/11), and both plexuses (7/11), with most nerve thickenings observed in Charcot-Marie-Tooth disease type 1. The nerve signal intensity alterations were significantly different for both brachial (P < 0.05) and LS (P < 0.05) plexuses in cases versus controls. The femoral and sciatic nerve size alterations were different (P < 0.05), while signal intensity differences were not significant (P = 0.1-0.97). Transverse dimensions of C8 (4 mm), L5 (6.2 mm) and S1 (5.1 mm) nerve roots, and sciatic nerves (10.2 mm) were the most accurate diagnostic performance measures in distinguishing cases from controls.

CONCLUSION

WBMRN is feasible for use in the clinical practice for the identification and potential characterization of polyneuropathy. J. Magn. Reson. Imaging 2016;44:1513-1521.

Congenital talipes equinovarus associated with hereditary congenital common peroneal nerve neuropathy: a literature review

We present a unique case of a congenital hereditary common peroneal nerve neuropathy with congenital idiopathic congenital talipes equinovarus that had been treated with the Ponseti method with satisfactory outcome at 5-year follow-up, along with a literature review.

Proximal arm weakness is the most common presentation in young Korean soldiers diagnosed as having hereditary neuropathy with liability to pressure palsy (HNPP)

OBJECTIVES

Because patients with hereditary neuropathy with liability to pressure palsy (HNPP) are diagnosed mostly in their 20s, they are likely to experience their first major neurological symptoms during military training. We aimed to analyse the clinical characteristics and electrodiagnostic study findings of patients diagnosed with HNPP during their military service.

METHODS

We identified patients diagnosed as having HNPP in 2011-2014 and investigated their initial symptom presentation, the location and severity of their weakness, the causative event, the results of electrodiagnostic studies and the results of the genetic analysis of the PMP-22 gene.

RESULTS

Among the 36 patients included in the study, 19 (52.8%) patients had upper extremity paraesthesia with proximal arm weakness caused by brachial plexus lesion. Distal upper extremity symptoms were found in 12 (33.3%) patients, and leg paraesthesia was present only in five (13.9%) patients. Among the 19 patients who had proximal arm weakness, the most common cause of weakness was the performance of push-ups as a punishment (36.8%), and strenuous push-up exercise was the second cause of this symptom (21.1%).

CONCLUSIONS

Brachial plexus lesion leading to proximal arm weakness and paraesthesia was the most common presentation in soldiers with HNPP, and strenuous push-up activity was the major leading causative event in this condition.

PMP22-Related neuropathies and other clinical manifestations in Chinese han patients with charcot-marie-tooth disease type 1

INTRODUCTION

Most cases of Charcot-Marie-Tooth (CMT) disease are caused by mutations in the peripheral myelin protein 22 gene (PMP22), including heterozygous duplications (CMT1A), deletions (HNPP), and point mutations (CMT1E).

METHODS

Single-nucleotide polymorphism (SNP) arrays were used to study PMP22 mutations based on the results of multiplex ligation-dependent probe amplification (MLPA) and polymerase chain reaction-restriction fragment length polymorphism methods in 77 Chinese Han families with CMT1. PMP22 sequencing was performed in MLPA-negative probands. Clinical characteristics were collected for all CMT1A/HNPP probands and their family members.

RESULTS

Twenty-one of 77 CMT1 probands (27.3%) carried duplication/deletion (dup/del) copynumber variants. No point mutations were detected. SNP array and MLPA seem to have similar sensitivity. Fifty-seven patients from 19 CMT1A families had the classical CMT phenotype, except for 1 with concomitant CIDP. Two HNPP probands presented with acute ulnar nerve palsy or recurrent sural nerve palsy, respectively.

CONCLUSIONS

The SNP array has wide coverage, high sensitivity, and high resolution and can be used as a screening tool to detect PMP22 dup/del as shown in this Chinese Han population.

Nerve entrapment: update

LEARNING OBJECTIVES

After reading this article, the participant should be able to: 1. Understand the pathophysiology of chronic nerve compression. 2. Describe the evaluation of a patient presenting with compression neuropathy. 3. Discuss the current controversies in the management of compression neuropathies. 4. Describe the treatment of common compression neuropathies, including carpal and cubital tunnel syndromes.

SUMMARY

Nerve entrapment syndromes are common in the general population, and are managed by a wide variety of medical and surgical specialists. A thorough understanding of the pathophysiology of nerve compression and appropriate clinical workup are critical in the overall management of these conditions. There remain several topics of controversy regarding the surgical management of nerve entrapment syndromes, including multiple points of nerve compression, carpal tunnel release under local anesthesia, open versus endoscopic decompression surgery, the "best" operation for primary cubital tunnel surgery, and revision decompression surgery. This article attempts to provide a concise summary of the advances in the basic and clinical science of peripheral nerve entrapment.

Characteristic features of hereditary neuropathy with liability to pressure palsy (HNPP) presenting with brachial plexopathy in soldiers

A brachial plexus lesion is not common in hereditary neuropathy with liability to pressure palsy (HNPP). We report the clinical and electrodiagnostic features of young soldiers with HNPP presenting with brachial plexopathy. By reviewing 2year medical records from Korean military hospitals, we identified soldiers with brachial plexus lesions. Among them, patients diagnosed with HNPP were determined and clinical and electrophysiological findings were compared between HNPP and non-HNPP patients with a brachial plexus lesion. Thirteen patients (6.8%) were diagnosed with HNPP among 189 patients with a brachial plexus lesion. Push-ups, as either a punishment or an exercise, was the most frequent preceding event in HNPP patients (76.9%), whereas it was rare in non-HNPP patients. The distal motor latency of the median nerve showed the highest sensitivity (90.9%) and specificity (100%) for HNPP in patients with a brachial plexus lesion. In conclusion, HNPP should be suspected in patients with brachial plexopathy if brachial plexopathy develops after push-ups or if the distal motor latency of median nerves is prolonged.

A novel locus for a hereditary recurrent neuropathy on chromosome 21q21

Hereditary recurrent neuropathies are uncommon. Disorders with a known molecular basis falling within this group include hereditary neuropathy with liability to pressure palsies (HNPP) due to the deletion of the PMP22 gene or to mutations in this same gene, and hereditary neuralgic amyotrophy (HNA) caused by mutations in the SEPT9 gene. We report a three-generation family presenting a hereditary recurrent neuropathy without pathological changes in either PMP22 or SEPT9 genes. We performed a genome-wide mapping, which yielded a locus of 12.4 Mb on chromosome 21q21. The constructed haplotype fully segregated with the disease and we found significant evidence of linkage. After mutational screening of genes located within this locus, encoding for proteins and microRNAs, as well as analysis of large deletions/insertions, we identified 71 benign polymorphisms. Our findings suggest a novel genetic locus for a recurrent hereditary neuropathy of which the molecular defect remains elusive. Our results further underscore the clinical and genetic heterogeneity of this group of neuropathies.

Magnetic resonance neurographic findings in classic idiopathic neuralgic amyotrophy in subacute stage: a report of four cases

Neuralgic amyotrophy (NA) is characterized by acute onset of severe pain, followed by muscular weakness and wasting of the shoulder girdle. While the diagnosis of NA mainly relies on the clinical history and examination, some investigations including electrophysiologic study and radiologic study may help to confirm the diagnosis. Magnetic resonance neurography (MRN), a new technique for the evaluation of peripheral nerve disorders, can be helpful in the diagnosis of NA. MRN presents additional benefits in comparison to conventional magnetic resonance imaging in the diagnosis of idiopathic NA (INA). In this report, we present the first four cases of classic INA diagnosed with MRN in subacute stage. MRN imaging modality should be considered in patients clinically suspected of INA.

The genetics of microdeletion and microduplication syndromes: an update

Chromosomal abnormalities, including microdeletions and microduplications, have long been associated with abnormal developmental outcomes. Early discoveries relied on a common clinical presentation and the ability to detect chromosomal abnormalities by standard karyotype analysis or specific assays such as fluorescence in situ hybridization. Over the past decade, the development of novel genomic technologies has allowed more comprehensive, unbiased discovery of microdeletions and microduplications throughout the human genome. The ability to quickly interrogate large cohorts using chromosome microarrays and, more recently, next-generation sequencing has led to the rapid discovery of novel microdeletions and microduplications associated with disease, including very rare but clinically significant rearrangements. In addition, the observation that some microdeletions are associated with risk for several neurodevelopmental disorders contributes to our understanding of shared genetic susceptibility for such disorders. Here, we review current knowledge of microdeletion/duplication syndromes, with a particular focus on recurrent rearrangement syndromes.

Early onset (childhood) monogenic neuropathies

Hereditary neuropathies (HN) with onset in childhood are categorized according to clinical presentation, pathogenic mechanism based on electrophysiology, genetic transmission and, in selected cases, pathological findings. Especially relevant to pediatrics are the items "secondary" versus "primary" neuropathy, "syndromic versus nonsyndromic," and "period of life." Different combinations of these parameters frequently point toward specific monogenic disorders. Ruling out a neuropathy secondary to a generalized metabolic disorder remains the first concern in pediatrics. As a rule, metabolic diseases include additional, orienting symptoms or signs, and their biochemical diagnosis is based on logical algorithms. Primary, motor sensory are the most frequent HN and are dominated by demyelinating autosomal dominant (AD) forms (CMT1). Other forms include demyelinating autosomal recessive (AR) forms, axonal AD/AR forms, and forms with "intermediate" electrophysiological phenotype. Peripheral motor neuron disorders are dominated by AR SMN-linked spinal muscular atrophies. (Distal) hereditary motor neuropathies represent <10% of HN but exhibit large clinical and genetic heterogeneity. Sensory/dysautonomic HN involves five classic subtypes, each one related to specific genes. However, genetic heterogeneity is larger than initially suspected. Syndromic HN distinguish "purely neurological syndromes", which are multisystemic, such as spinocerebellar atrophies +, spastic paraplegias +, etc. Peripheral neuropathy is possibly the presenting feature, including in childhood. Autosomal recessive forms, on average, start more frequently in childhood. "Multiorgan syndromes", on the other hand, are more specific to Pediatrics. AR forms, which are clearly degenerative, prompt the investigation of a large set of pleiotropic genes. Other syndromes expressed in the perinatal period are mainly developmental disorders, and can sometimes be related to specific transcription factors. Systematic malformative workup and ethical considerations are necessary. Altogether, >40 genes with various biological functions have been found to be responsible for primary HN. Many are responsible for various phenotypes, including some without the polyneuropathic trait, and some for various types of transmission.

Hereditary motor-sensory, motor, and sensory neuropathies in childhood

Hereditary neuropathies (HN) are categorized according to clinical presentation, pathogenic mechanism based on electrophysiology, genetic transmission, age of occurrence, and, in selected cases, pathological findings. The combination of these parameters frequently orients towards specific genetic disorders. Ruling out a neuropathy secondary to a generalized metabolic disorder remains the first pediatric concern. Primary, motor-sensory are the most frequent HN and are dominated by demyelinating AD forms (CMT1). Others are demyelinating AR forms, axonal AD/AR forms, and forms with "intermediate" electrophysiological phenotype. Pure motor HN represent<10% of HN but exhibit large clinical and genetic heterogeneity. Sensory/dysautonomic HN cover five classical subtypes, each one related to specific genes. However, genetic heterogeneity is largly greater than initially suspected. Syndromic HN distinguish: "purely neurological syndromes", which are multisystemic, usually AD disorders, such as spinocerebellar atrophies +, spastic paraplegias +, etc. Peripheral Neuropathy may be the presenting feature, including in childhood. Clearly degenerative, AR forms prompt to investigate a large set of pleiotropic genes. Other syndromes, expressed in the perinatal period and comprising malformative features, are mainly developmental disorders, sometimes related to specific transcription factors. Altogether, >40 genes with various biological functions have been found responsible for HN. Many are responsible for various phenotypes, including some without the polyneuropathic trait: for the pediatric neurologist, phenotype/genotype correlations constitute a permanent bidirectional exercise.

[Bilateral peroneal neuropathy following bariatric surgery]

We report the case of bilateral peroneal neuropathy following massive weight loss after bariatric surgery. A few months after a gastric by-pass, the patient developed sequentially within 6 months a L2-L3 herniated disc that required surgery, a severe right peroneal nerve palsy that led to decompressive surgery and finally contralateral peroneal nerve palsy also operated. The electrophysiological analysis confirmed the clinical suspicion of peroneal nerve compression at the fibular head. Postoperative course was favorable. Literature reports peroneal nerve palsy after slimming, mostly when weight loss is fast and marked although the issue is rarely bilateral.

Acute respiratory distress in an alpaca

An alpaca was presented with a history of respiratory difficulty and death. Histology of the phrenic nerves and diaphragm revealed degenerative changes consistent with denervation atrophy, and a diagnosis of diaphragmatic paralysis was established. No gross or histological abnormalities were observed in the spinal cord or other organs. The etiology of the phrenic nerve neuropathy could not be determined. The need to examine phrenic nerves and diaphragm in camelids with respiratory distress is emphasized, as failure to examine these samples will preclude a diagnosis of diaphragmatic paralysis.

The zinc finger protein ZPR1 is a potential modifier of spinal muscular atrophy

Spinal muscular atrophy (SMA) is caused by mutation of the Survival Motor Neurons 1 (SMN1) gene and is characterized by degeneration of spinal motor neurons. The severity of SMA is primarily influenced by the copy number of the SMN2 gene. Additional modifier genes that lie outside the SMA locus exist and one gene that could modify SMA is the Zinc Finger Protein (ZPR1) gene. To test the significance of ZPR1 downregulation in SMA, we examined the effect of reduced ZPR1 expression in mice with mild and severe SMA. We report that the reduced ZPR1 expression causes increase in the loss of motor neurons, hypermyelination in phrenic nerves, increase in respiratory distress and disease severity and reduces the lifespan of SMA mice. The deficiency of SMN-containing sub-nuclear bodies correlates with the severity of SMA. ZPR1 is required for the accumulation of SMN in sub-nuclear bodies. Further, we report that ZPR1 overexpression increases levels of SMN and promotes accumulation of SMN in sub-nuclear bodies in SMA patient fibroblasts. ZPR1 stimulates neurite growth and rescues axonal growth defects in SMN-deficient spinal cord neurons from SMA mice. These data suggest that the severity of disease correlates negatively with ZPR1 levels and ZPR1 may be a protective modifier of SMA.

Hereditary neuropathy with liability to pressure palsy: a brief review with a case report

Hereditary Neuropathy with Liability to Pressure Palsy (HNPP) is an autosomal dominant disorder and is usually characterized by episodes of recurrent and painless focal motor and sensory peripheral mononeuropathy. This condition is usually localized around areas of entrapment (predominantly the wrists, knees, elbows, and shoulders). The genetic locus of the disease is chromosome 17p12. A deletion of the PMP22 gene results in the lack of peripheral myelin protein, a key component to the myelin sheet of peripheral nerves. However, this disease may be completely asymptomatic until an event, such as a minor trauma, triggers these episodes, as seen in our presented case report. The diagnosis of HNPP can be somewhat challenging, as other diseases, such as Charcot-Marie-Tooth disease type 1A (CMT) and Hereditary Neuralgic Amyotrophy (HNA) must be included in the differential diagnosis due to their overlapping clinical features. There are currently no treatments to cure the disease, but therapies seek to alleviate the symptoms and recurring episodes.

EFNS guidelines for the molecular diagnosis of neurogenetic disorders: motoneuron, peripheral nerve and muscle disorders

OBJECTIVES

These EFNS guidelines on the molecular diagnosis of motoneuron disorders, neuropathies and myopathies are designed to summarize the possibilities and limitations of molecular genetic techniques and to provide diagnostic criteria for deciding when a molecular diagnostic work-up is indicated.

SEARCH STRATEGY

To collect data about planning, conditions and performance of molecular diagnosis of these disorders, a literature search in various electronic databases was carried out and original papers, meta-analyses, review papers and guideline recommendations reviewed.

RESULTS

The best level of evidence for genetic testing recommendation (B) can be found for the disorders with specific presentations, including familial amyotrophic lateral sclerosis, spinal and bulbar muscular atrophy, Charcot-Marie-Tooth 1A, myotonic dystrophy and Duchenne muscular dystrophy. For a number of less common disorders, a precise description of the phenotype, including the use of immunologic methods in the case of myopathies, is considered as good clinical practice to guide molecular genetic testing.

CONCLUSION

These guidelines are provisional and the future availability of molecular-genetic epidemiological data about the neurogenetic disorders under discussion in this article will allow improved recommendation with an increased level of evidence.

[Diagnostic pitfalls in carpal tunnel syndrome]

BACKGROUND

This review focuses on the main aspects of positive and differential diagnosis of carpal tunnel syndrome (CTS) in different clinical situations encountered in daily practice.

STATE OF THE ART

Authentic CTS can be discovered in situations, which alter the usual presentation or therapeutic management. This is the case for instance in pregnant women or in the elderly subject or with acute motor forms where CTS discloses a focal intratunnel disorder (neuroma, lipoma, arterial condition, bone disorder) or a general disease (hereditary neuropathy, amylosis). In certain situations, the clinical manifestations suggest a more proximal compression of the medial nerve (round pronator, Struthers arcade, or superficial flexor) or an inflammatory condition (mononeuritis, inflammatory demyelinising neuropathy). Locoregional disease may also be involved, for instance a plexus (thoracobrachial outlet syndrome, post-radiation plexitis) or radicular condition. The clinical presentation of diffuse polyneuropathy with initial manifestations involving the upper limb (ganglioneuropathies, polyradiculoneuritis, small-fiber neuropathies) may also be misleading. Finally central conditions can sometimes be confused with CTS.

CONCLUSION

A rigorous physical examination and an electroneuromyogram are determining to avoid diagnostic pitfalls.

A valuable non-invasive diagnostic investigation for paediatric idiopathic brachial neuritis

Idiopathic brachial neuritis (idiopathic neuralgic amyotrophy) in children is a well-recognized but rare condition. Although the precise aetiology is unknown, its usual occurrence after an infection suggests an immunological process. There is no specific test for brachial neuritis, and the diagnosis is one of exclusion with supportive evidence from nerve conduction studies, electromyography (EMG), and, in adults, changes in affected muscles on magnetic resonance imaging. Young children are often unable to tolerate EMG.

Not all neuropathy in diabetes is of diabetic etiology: differential diagnosis of diabetic neuropathy

Diabetic peripheral neuropathy is the most common peripheral neuropathy in the developed world; however, not all patients with diabetes and peripheral nerve disease have a peripheral neuropathy caused by diabetes. Several (although not all) studies have drawn attention to the presence of other potential causes of a neuropathy in individuals with diabetes; 10% to 50% of individuals with diabetes may have an additional potential cause of a peripheral neuropathy and some may have more than one cause. Neurotoxic medications, alcohol abuse, vitamin B(12) deficiency, renal disease, chronic inflammatory demyelinating neuropathy, inherited neuropathy, and vasculitis are the most common additional potential causes of a peripheral neuropathy in these series. The most common disorders in the differential diagnosis of a generalized diabetic peripheral neuropathy are discussed in this article. Prospective studies to investigate the prevalence of other disorders that might be responsible for a peripheral neuropathy in individuals with diabetes are warranted.

De novo footdrop resulting from an isolated acute repetitive strain injury

OBJECTIVES

To report a case of a teenage boy (N.K.) who had a peroneal nerve palsy after an isolated repetitive stain injury from an episode of sustained repetitive kicking and to explore the emergency physician's approach to footdrop or absent dorsiflexion.

METHODS

Chart review.

RESULTS

N.K. presented to the emergency department (ED) with right footdrop, inability to dorsiflex. Results of investigations in the ED, including radiographs of his lumbar spine and knees and a magnetic resonance imaging scan of the lumbar spine, were all normal. Electromyography showed that the extensor digitorum brevis muscle was borderline prolonged at 4.1 m/s for 65 mm, whereas the distal latency of the tibial nerve to abductor hallucis muscle was prolonged at 4.8 milliseconds for 7 cm. There were increased insertional activity and 2+ fibrillation potentials in EDB, but motor units were normal, as was recruitment. There was no conduction velocity slowing across the fibular head segment of the peroneal nerve. N.K. did not need any further follow-up because his function was completely regained.

CONCLUSIONS

Repetitive strain injury, even in acute settings may predispose one to developing a peroneal neuropathy. As in the case of N.K., most cases resolve in weeks to months, and electromyography studies are important to help definitively decide what type of neuronal injury has been sustained.

A new single-nucleotide deletion of PMP22 in an HNPP family without recurrent palsies

In this study we describe four patients from the same kindred who were affected by an autosomal-dominantly inherited peripheral neuropathy. They presented an unusual combination of clinical, electrophysiological, and pathological findings in association with a new mutation of the PMP22 gene. Clinically, three patients had carpal tunnel syndrome symptoms and one patient had late-onset peroneal atrophy. Motor and sensory nerve conduction velocities were reduced without focal slowing at entrapment sites. Nerve biopsy disclosed diffuse hypomyelination with focal thickening of the myelin sheath in some fibers. Sequence analysis of the PMP22 gene showed a single-nucleotide deletion (227delG) in the affected patients. This mutation, which has not been reported previously, leads to an open reading frame shift and probably to a truncated and unstable PMP22 protein. We conclude that this novel 227delG mutation of PMP22 gives a mild form of hereditary neuropathy with liability to pressure palsy with atypical clinical and electrophysiological findings.

Translational control of SEPT9 isoforms is perturbed in disease

A common feature of the mammalian septin gene family is complex genomic architecture with multiple alternate splice variants. Septin 9 has 18 distinct transcripts encoding 15 polypeptides, with two transcripts (SEPT9_v4 and v4*) encoding the same polypeptide. We have previously reported that the ratio of these distinct transcripts is altered in neoplasia, with the v4 transcript being the usual form in normal cells but v4* becoming predominant in tumours. This led us to ask what the functional differences between these two transcripts might be. The 5'-UTRs of v4 and v4* have distinct 5' ends encoded by exons 1beta (v4) and 1zeta and 2 (v4*) and a common 3' region and initiating ATG encoded within exon 3. Here we show that the two mRNAs are translated with different efficiencies and that cellular stress can alter this. A putative internal ribosome entry site can be identified in the common region of the v4 and v4* 5'-UTRs and translation is modulated by an upstream open-reading frame in the unique region of the v4 5'-UTR. Germline mutations in hereditary neuralgic amyotrophy (HNA) map to the region which is common to the two UTRs. These mutations dramatically enhance the translational efficiency of the v4 5'-UTR, leading to elevated SEPT9_v4 protein under hypoxic conditions. Our data provide a mechanistic insight into how the HNA mutations can alter the fine control of SEPT9_v4 protein and its regulation under physiologically relevant conditions and are consistent with the episodic and stress-induced nature of the clinical features of HNA.

A Family Harboring CMT1A Duplication and HNPP Deletion

Charcot-Marie-Tooth disease type 1A (CMT1A) is associated with duplication of chromosome 17p11.2-p12, whereas hereditary neuropathy with liability to pressure palsies (HNPP), which is an autosomal dominant neuropathy showing characteristics of recurrent pressure palsies, is associated with 17p11.2-p12 deletion. An altered gene dosage of PMP22 is believed to the main cause underlying the CMT1A and HNPP phenotypes. Although CMT1A and HNPP are associated with the same locus, there has been no report of these two mutations within a single family. We report a rare family harboring CMT1A duplication and HNPP deletion.