Monoallelic variation in DHX9, the gene encoding the DExH-box helicase DHX9, underlies neurodevelopment disorders and Charcot-Marie-Tooth disease.

DExD/H-box RNA helicases (DDX/DHX) are encoded by a large paralogous gene family; in a subset of these human helicase genes, pathogenic variation causes neurodevelopmental disorder (NDD) traits and cancer. DHX9 encodes a BRCA1-interacting nuclear helicase regulating transcription, R-loops, and homologous recombination and exhibits the highest mutational constraint of all DDX/DHX paralogs but remains unassociated with disease traits in OMIM. Using exome sequencing and family-based rare-variant analyses, we identified 20 individuals with de novo, ultra-rare, heterozygous missense or loss-of-function (LoF) DHX9 variant alleles. Phenotypes ranged from NDDs to the distal symmetric polyneuropathy axonal Charcot-Marie-Tooth disease (CMT2). Quantitative Human Phenotype Ontology (HPO) analysis demonstrated genotype-phenotype correlations with LoF variants causing mild NDD phenotypes and nuclear localization signal (NLS) missense variants causing severe NDD. We investigated DHX9 variant-associated cellular phenotypes in human cell lines. Whereas wild-type DHX9 was restricted to the nucleus, NLS missense variants abnormally accumulated in the cytoplasm. Fibroblasts from an individual with an NLS variant also showed abnormal cytoplasmic DHX9 accumulation. CMT2-associated missense variants caused aberrant nucleolar DHX9 accumulation, a phenomenon previously associated with cellular stress. Two NDD-associated variants, p.Gly411Glu and p.Arg761Gln, altered DHX9 ATPase activity. The severe NDD-associated variant p.Arg141Gln did not affect DHX9 localization but instead increased R-loop levels and double-stranded DNA breaks. Dhx9-/- mice exhibited hypoactivity in novel environments, tremor, and sensorineural hearing loss. All together, these results establish DHX9 as a critical regulator of mammalian neurodevelopment and neuronal homeostasis.

Patient preference for virtual versus in-person visits in neuromuscular clinical practice.

INTRODUCTION/AIMS: It is unknown if patients with neuromuscular diseases prefer in-person or virtual telemedicine visits. We studied patient opinions and preference on virtual versus in-person visits, and the factors influencing such preferences. METHODS: Telephone surveys, consisting of 11 questions, of patients from 10 neuromuscular centers were completed. RESULTS: Five hundred and twenty surveys were completed. Twenty-six percent of respondents preferred virtual visits, while 50% preferred in-person visits. Sixty-four percent reported physical interaction as "very important." For receiving a new diagnosis, 55% preferred in-person vs 35% reporting no preference. Forty percent were concerned about a lack of physical examination vs 20% who were concerned about evaluating vital signs. Eighty four percent reported virtual visits were sufficiently private. Sixty eight percent did not consider expenses a factor in their preference. Although 92% were comfortable with virtual communication technology, 55% preferred video communications, and 19% preferred phone calls. Visit preference was not significantly associated with gender, diagnosis, disease severity, or symptom management. Patients who were concerned about a lack of physical exam or assessment of vitals had significantly higher odds of selecting in-person visits than no preference. DISCUSSION: Although neither technology, privacy, nor finance burdened patients in our study, more patients preferred in-person visits than virtual visits and 40% were concerned about a lack of physical examination. Interactions that occur with in-person encounters had high importance for patients, reflecting differences in the perception of the patient-physician relationship between virtual and in-person visits.

A National Cross-Sectional Survey of EMG Physician Volume.

Background and Objectives: This study presents results from a survey of physicians performing electrodiagnostic studies to assess average volume. We also assessed how different factors (trainees, technologists, age of the physician, and case complexity) affected volume. Productivity is an important factor for physicians across practice settings. However, unlike evaluation and management services for neurologists, there are no published data for benchmarks of average volume of electrodiagnostic studies. Methods: A 34-question survey was designed collecting information on demographics, electrodiagnostic study volume, technologists, trainees, referrals, and case complexity. The anonymous survey was disseminated through a QR code or hyperlink to multiple online neurology, physical medicine and rehabilitation, electromyography, and neuromuscular forums. The primary outcome was EMG volume including number of EMGs per half-day and EMG volume per year. We conducted bivariate association analysis between primary outcomes and respondent characteristics using the Pearson χ2 test. Multivariable regression models determined factors associated with each of our outcome variables. Results: A total of 201 respondents initiated the survey. 71% were certified in adult neurology, 19.6% in physical medicine and rehabilitation, and 2.7% in pediatric neurology. 37.5% practiced in academic medicine. The remaining respondents were from private practice, group, solo, hospital employed, or other. 83% of respondents allotted a dedicated half-day to performing EMGs. The median number of EMGs scheduled during a half-day was within 3-4 (45%). 30% and 7% scheduled 5-6 or more than 7 patients per half-day, respectively. The median number of EMGs performed per year was within 251-500 (37%). Discussion: This national, cross-sectional survey evaluates average metrics of EMG volume. Our survey showed that the median number of EMGs annually lies between 251 and 500 studies (37%). In addition, for those respondents who allotted a dedicated half-day to performing EMGs, the median number of EMG studies scheduled per half-day lies between 3 and 4 studies (45%). In multivariate analysis, respondent characteristics of age of the physician (older than 45), working with nerve conduction technologists, and holding the position of EMG director were associated with increased EMG volume.

Anesthesia for children with mitochondrial disorders: a national survey and review.

PURPOSE: Mitochondrial diseases are a heterogeneous group of disorders. Patients with such diseases often need general anesthesia for diagnostic procedures and surgery; guidelines are lacking for the anesthetic care of these patients. METHODS: We conducted a survey to investigate the current practices of pediatric anesthesiologists in the US in order to determine and document current practice. The survey consisted of twenty questions, including two demographic questions. A link to the survey was sent via email to members of the Society for Pediatric Anesthesia (2440), and was available online for 14 weeks. RESULTS: Only 503 completed the survey: a response rate of 20.61 %. Among the responders, 93.2 % had children with mitochondrial disorders among their patients, but only 11 % had institutional guidelines for such cases in place. Among the responders, 80.3 % used the standard nil per os (NPO) status guidelines, while the rest give intravenous dextrose solution once NPO was in effect. Only 18.3 % took precautions for malignant hyperthermia during treatment. The majority of the practitioners chose sevoflurane as the safest inhaled agent for induction and maintenance (89.7 and 78.5 %, respectively). Regional anesthesia was deemed safe by 97.3 % of the responders. Lactated Ringer's solution was considered safe for these children by 49 %; only 47.8 % used dextrose-containing fluids for fluid replacement. The blood glucose was monitored by 72.7 %, and the majority (85 %) of this monitoring was done in a postanesthesia care unit. CONCLUSION: Although the response rate was low, the majority of the responders provide care to these children routinely, so it can be inferred that the results of this survey are the closest published results to the true trend.

Guillain-Barré Syndrome and Other Acute Polyneuropathies.

Guillain-Barré syndrome (GBS) is an acute autoimmune neuropathy that can cause motor, sensory, and autonomic symptoms. Although GBS primarily is a neuropathic disorder, multiple organ systems can be affected during the disease course, and older patients may be more vulnerable to systemic complications. Close clinical monitoring and early interventions using pharmacologic and nonpharmacological treatments may lead to an improved long-term outcome.

Patient Assisted Intervention for Neuropathy: Comparison of Treatment in Real Life Situations (PAIN-CONTRoLS): Bayesian Adaptive Comparative Effectiveness Randomized Trial.

Importance: Cryptogenic sensory polyneuropathy (CSPN) is a common generalized slowly progressive neuropathy, second in prevalence only to diabetic neuropathy. Most patients with CSPN have significant pain. Many medications have been tried for pain reduction in CSPN, including antiepileptics, antidepressants, and sodium channel blockers. There are no comparative studies that identify the most effective medication for pain reduction in CSPN. Objective: To determine which medication (pregabalin, duloxetine, nortriptyline, or mexiletine) is most effective for reducing neuropathic pain and best tolerated in patients with CSPN. Design, Setting, and Participants: From December 1, 2014, through October 20, 2017, a bayesian adaptive, open-label randomized clinical comparative effectiveness study of pain in 402 participants with CSPN was conducted at 40 neurology care clinics. The trial included response adaptive randomization. Participants were patients with CSPN who were 30 years or older, with a pain score of 4 or greater on a numerical rating scale (range, 0-10, with higher scores indicating a higher level of pain). Participant allocation to 1 of 4 drug groups used the utility function and treatment's sample size for response adaptation randomization. At each interim analysis, a decision was made to continue enrolling (up to 400 participants) or stop the whole trial for success (80% power). Patient engagement was maintained throughout the trial, which helped guide the study and identify ways to communicate and disseminate information. Analysis was performed from December 11, 2015, to January 19, 2018. Interventions: Participants were randomized to receive nortriptyline (n = 134), duloxetine (n = 126), pregabalin (n = 73), or mexiletine (n = 69). Main Outcomes and Measures: The primary outcome was a utility function that was a composite of the efficacy (participant reported pain reduction of ≥50% from baseline to week 12) and quit (participants who discontinued medication) rates. Results: Among the 402 participants (213 men [53.0%]; mean [SD] age, 60.1 [13.4] years; 343 White [85.3%]), the utility function of nortriptyline was 0.81 (95% bayesian credible interval [CrI], 0.69-0.93; 34 of 134 [25.4%] efficacious; and 51 of 134 [38.1%] quit), of duloxetine was 0.80 (95% CrI, 0.68-0.92; 29 of 126 [23.0%] efficacious; and 47 of 126 [37.3%] quit), pregabalin was 0.69 (95% CrI, 0.55-0.84; 11 of 73 [15.1%] efficacious; and 31 of 73 [42.5%] quit), and mexiletine was 0.58 (95% CrI, 0.42-0.75; 14 of 69 [20.3%] efficacious; and 40 of 69 [58.0%] quit). The probability each medication yielded the highest utility was 0.52 for nortriptyline, 0.43 for duloxetine, 0.05 for pregabalin, and 0.00 for mexiletine. Conclusions and Relevance: This study found that, although there was no clearly superior medication, nortriptyline and duloxetine outperformed pregabalin and mexiletine when pain reduction and undesirable adverse effects are combined to a single end point. Trial Registration: ClinicalTrials.gov Identifier: NCT02260388.

Inflammatory Myopathies: Utility of Antibody Testing.

Inflammatory myopathies are a group of immune-mediated muscle disorders comprising dermatomyositis; polymyositis; overlap myositis, including antisynthetase syndromes and nonspecific myositis, immune-mediated necrotizing myopathies, and sporadic inclusion body myositis. They are now much more eloquently classified both pathologically and clinically because of the discovery of several myositis-specific and myositis-associated antibodies. These antibodies also aid in choosing the best treatment options in each case. Based on the initial classifications of inflammatory myopathies, inclusion body myositis, overlap myositis, and necrotizing myositis were all included in the polymyositis group. This article discusses cases, diagnostic tools, associated antibodies, and pathology.

Expanding Phenotype of VRK1 Mutations in Motor Neuron Disease.

OBJECTIVE: In the past decade, hereditary forms of motor neuron disease (spinal muscular atrophy and/or amyotrophic lateral sclerosis) are increasingly identified. As advanced genetic testing is performed, molecular diagnosis can be obtained. Identifying new gene mutations can lead to further understanding of disease. METHODS AND RESULTS: We report a single case of a patient with early-onset amyotrophic lateral sclerosis, evaluated at University of Texas Health Houston Science Center from 2011-2014. Initial genetic testing did not reveal an etiology in this patient. Through whole-exome sequencing, a VRK1 mutation was identified. CONCLUSIONS AND RELEVANCE: We identify a possible new cause of hereditary amyotrophic lateral sclerosis, VRK1 mutation. This case report also expands the phenotypic spectrum of this mutation in neurologic diseases.

POEMS Syndrome in a Juvenile Initially Diagnosed as Treatment Resistant Chronic Inflammatory Demyelinating Polyneuropathy.

POEMS (polyneuropathy, organomegaly, endocrinopathy, monoclonal protein, skin changes) is a disorder that mainly affects adults. We report a pediatric patient, initially considered to have Guillain-Barré syndrome, who continued to have progression of neuropathic disease leading to the diagnosis of chronic inflammatory demyelinating polyneuropathy. Diagnosis of POEMS was established by an abnormal bone marrow biopsy, prompted by laboratory and imaging findings, which became abnormal later in the course of the disease. POEMS syndrome is extremely rare in children, and neuropathic features in this age group have not been previously described. This case illustrates that "Guillain-Barré syndrome-like" initial presentation for POEMS, which has not been previously reported. It also emphasizes that in children with progressive acquired neuropathies that are treatment unresponsive, POEMS syndrome should be considered.

Occurrence of hemolytic anemia in patients with GBS treated with high-dose IVIg.

OBJECTIVE: We describe an underrecognized side effect of high-dose IV immunoglobulin (IVIg), hemolytic anemia. BACKGROUND: There are no established guidelines on treating patients with Guillain-Barré syndrome (GBS) who relapse or do not improve after a standard course of treatment (IVIg or plasma exchange). Some centers will opt for a second course of the initial treatment. There is an ongoing trial of a second course of IVIg in patients with severe GBS. METHODS: We retrospectively reviewed 4 patients with severe GBS who received high-dose IVIg. One patient inadvertently received a high dose of IVIg for Miller Fisher syndrome. All patients received a total of at least 2 courses of the standard dose of IVIg (total >4 g/kg). We review their clinical course and side effects. RESULTS: All patients with non-O blood types developed clinically significant hemolytic anemia requiring blood transfusion. CONCLUSION: Hemolytic anemia may limit doses of IVIg for treatment of severe GBS in patients with non-O blood types.

Dermatomyositis-associated sensory neuropathy: a unifying pathogenic hypothesis.

Neuropathy as extramuscular manifestation of dermatomyositis (DM) is controversial due to uncommon occurrence, heterogeneity of associated nerve pathology, and lack of unifying pathogenetic mechanism(s). We describe a patient with classic manifestations of DM and extramuscular manifestation of neuropathy. Nerve pathology showed deposits of terminal complement complex (C5b-9). Her examination showed mild proximal weakness, rash, and sensory impairment in fingertips, toes, and nose. EMG/NCS revealed irritable myopathy and mild sensory neuropathy. Muscle biopsy showed features suggestive of DM, including deposition of C5b-9. CK was elevated to 214 and ANA was positive at 1:160. Etiological work up for neuropathy, including diabetes, was negative. Sural nerve biopsy at light level revealed very mild large fiber sensory neuropathy. EM showed moderately severe involvement of small sensory fibers. Neuropathy may be an underrecognized manifestation of DM. Nerve pathology demonstrating complement-mediated damage could be a unifying mechanism of muscle and nerve injury.