Mutation-specific effects on thin filament length in thin filament myopathy

Objective

Thin filament myopathies are among the most common nondystrophic congenital muscular disorders, and are caused by mutations in genes encoding proteins that are associated with the skeletal muscle thin filament. Mechanisms underlying muscle weakness are poorly understood, but might involve the length of the thin filament, an important determinant of force generation.

Methods

We investigated the sarcomere length-dependence of force, a functional assay that provides insights into the contractile strength of muscle fibers as well as the length of the thin filaments, in muscle fibers from 51 patients with thin filament myopathy caused by mutations in NEB, ACTA1, TPM2, TPM3, TNNT1, KBTBD13, KLHL40, and KLHL41.

Results

Lower force generation was observed in muscle fibers from patients of all genotypes. In a subset of patients who harbor mutations in NEB and ACTA1, the lower force was associated with downward shifted force–sarcomere length relations, indicative of shorter thin filaments. Confocal microscopy confirmed shorter thin filaments in muscle fibers of these patients. A conditional Neb knockout mouse model, which recapitulates thin filament myopathy, revealed a compensatory mechanism; the lower force generation that was associated with shorter thin filaments was compensated for by increasing the number of sarcomeres in series. This allowed muscle fibers to operate at a shorter sarcomere length and maintain optimal thin–thick filament overlap.

Interpretation

These findings might provide a novel direction for the development of therapeutic strategies for thin filament myopathy patients with shortened thin filament lengths. 

Ann Neurol 2016

Advanced MRI and staging of multiple sclerosis lesions

Over the past few decades, MRI-based visualization of demyelinated CNS lesions has become pivotal to the diagnosis and monitoring of multiple sclerosis (MS). In this Review, we outline current efforts to correlate imaging findings with the pathology of lesion development in MS, and the pitfalls that are being encountered in this research. Multimodal imaging at high and ultra-high magnetic field strengths is yielding biologically relevant insights into the pathophysiology of blood–brain barrier dynamics and both active and chronic inflammation, as well as mechanisms of lesion healing and remyelination. Here, we parallel the results in humans with advances in imaging of a primate model of MS — experimental autoimmune encephalomyelitis (EAE) in the common marmoset — in which demyelinated lesions resemble their human counterparts far more closely than do EAE lesions in the rodent. This approach holds promise for the identification of innovative biological markers, and for next-generation clinical trials that will focus more on tissue protection and repair.

Nature Reviews Neurology 2016

Features of Patients With Nonfluent/Agrammatic Primary Progressive Aphasia With Underlying Progressive Supranuclear Palsy Pathology or Corticobasal Degeneration

Importance  We provide novel evidence of specific clinical and neuroimaging features that may help for the in vivo prediction of underlying pathology in patients with nonfluent/agrammatic primary progressive aphasia (nfvPPA) and progressive supranuclear palsy (PSP) or corticobasal degeneration (CBD) proved by autopsy.

Objective  To characterize the neurological, cognitive, and neuroimaging features of patients with nfvPPA—in whom either PSP or CBD was eventually confirmed at autopsy—at initial presentation and at 1-year follow-up.

Design, Setting, and Participants  A prospective longitudinal clinical-pathological study was conducted in a tertiary research clinic that specialized in cognitive disorders. Fourteen patients were evaluated between January 2002 and December 2014. Inclusion criteria for the study were a clinical diagnosis of nfvPPA; the availability of speech, language, and cognitive testing for at least 1 evaluation; magnetic resonance imaging within 6 months of initial evaluation; and a postmortem pathological diagnosis of PSP or CBD. Ten matched healthy control participants were also included.

Main Outcomes and Measures  Clinical, cognitive, and neuroimaging longitudinal data were analyzed to characterize the whole nfvPPA–4-repeat–tau group and identify differences between nfvPPA-PSP and nfvPPA-CBD both at presentation and longitudinally.

Results  Patient groups did not differ significantly in age, sex, or handedness (nfvPPA-PSP group: median [interquartile range (IQR)] age, 74 [67-76] years; 1 of 5 male [20%]; 1 of 5 left-handed [20%]; and nfvPPA-CBD group: mean [IQR] age, 65 [54-81] years; 3 of 9 male [33%]; 0 left-handed). Motor speech impairment and left frontal white matter atrophy were the most prominent common features. At presentation, dysarthria (Motor Speech Examination median [IQR] score: nfvPPA-PSP, 4 [2-7]; nfvPPA-CBD, 0 [0-4]; P = .02), depression (Geriatric Depression Scale median [IQR] score: nfvPPA-PSP, 19 [3-28]; nfvPPA-CBD, 4 [0-16];P = .04), and relatively selective white matter atrophy were typical of the nfvPPA-PSP group, while greater gray matter atrophy and a trend toward greater sentence comprehension deficits (median [IQR] sentence comprehension correct: nfvPPA-PSP, 98% [80-100]; nfvPPA-CBD, 81% [65-98]; P = .08) were found in the nfvPPA-CBD group. At follow-up after 1 year, we observed no significant differences in any speech or language measures. Furthermore, atrophy in patients with PSP progressed within the subcortical/brainstem motor system generating greater oculomotors deficits and swallowing difficulty; atrophy in patients with CBD spread anteriorly in prefrontal regions consistent with their greater working memory impairment and development of behavioral symptoms.

Conclusions and Relevance  In patients presenting with nfvPPA, presence of early severe dysarthria, relatively selective white matter atrophy at presentation, and a greater rate of change in the brainstem measured by longitudinal imaging may be useful for differentiating underlying PSP from CBD pathology during life.

JAMA Neurology 2016

A Clinical Approach to the Diagnosis of Traumatic Encephalopathy Syndrome A Review

Importance  Chronic traumatic encephalopathy (CTE) refers to pathologic changes that have been found in some individuals with a history of repetitive traumatic impact to the head (hereinafter referred to as head trauma). These changes cannot be assessed during the clinical evaluation of a living patient.

Observations  The neuropathologic features, taxonomy, history, role of biomarkers in diagnosis, and existing criteria of CTE are reviewed. Previous criteria have been proposed to approach the living patient; however, a unified, specific approach is needed for the practicing clinician. We propose a new diagnostic construct for the clinical syndrome associated with repetitive exposure to head trauma: traumatic encephalopathy syndrome. This clinical paradigm will provide the framework for a diagnosis of probable, possible, and unlikely traumatic encephalopathy syndrome, with included discussion regarding the minimum exposure, nature of the clinical course, and additional clinical features needed for diagnosis.

Conclusions and Relevance  While prospective longitudinal studies are ongoing to further elucidate the association of exposure to head trauma, clinical features, and the development of pathologic changes, a corresponding clinical construct for diagnosis is necessary.

JAMA Neurology 2016

Clinical, Genetic, and Radiological Features of Extrapyramidal Movement Disorders in Mitochondrial Disease

Importance  Extrapyramidal movement disorders associated with mitochondrial disease are difficult to treat and can lead to considerable disability. Moreover, potential new treatment trials on the horizon highlight the importance of genotype-phenotype associations and deep phenotyping of the movement disorders related to mitochondrial disease.

Objective  To describe the phenotype, genetic etiology, and investigation of extrapyramidal movement disorders in a large and well-defined mitochondrial disease cohort.

Design, Setting, and Participants  An observational cohort study at a single national referral center. Among 678 patients (87% adults) followed up at the Newcastle mitochondrial disease specialized referral center between January 1, 2000, and January 31, 2015, 42 patients (12 pediatric, 30 adult) with genetic or biochemical evidence of mitochondrial disease and with 1 or more predefined extrapyramidal movement disorders (parkinsonism, dystonia, tremor, chorea, and restless legs syndrome) were included.

Main Outcomes and Measures  We investigated the prevalence and genetic causes of dystonia and parkinsonism as well as radiological findings in the context of movement disorders in mitochondrial disease. All patients were interviewed and examined. All available medical notes and clinical, radiological, and genetic investigations were reviewed.

Results  Forty-two patients (mean [SD] age, 37 [25] years; 38% female) with mitochondrial disease (12 pediatric [age range, 4-14 years], 30 adult [age range, 20-81 years]) with extrapyramidal movement disorders were identified. Dystonia manifested in 11 pediatric patients (92%), often in the context of Leigh syndrome; parkinsonism predominated in 13 adult patients (43%), among whom 5 (38%) harbored either dominant (n = 1) or recessive (n = 4) mutations in POLG. Eleven adult patients (37%) manifested with either generalized or multifocal dystonia related to mutations in mitochondrial DNA, among which the most common were the m.11778G>A mutation and mutations in MT-ATP6 (3 of 11 patients [27%] each). Bilateral basal ganglia lesions were the most common finding in brain magnetic resonance imaging, usually associated with generalized dystonia or Leigh syndrome.

Conclusions and Relevance  Dystonia, often associated with Leigh syndrome, was the most common extrapyramidal movement disorder among pediatric patients with mitochondrial disease. Parkinsonism was the most prevalent extrapyramidal movement disorder in adults and was commonly associated with POLGmutations; dystonia was predominantly associated with mitochondrial DNA mutations. These findings may help direct genetic screening in a busy neurology outpatient setting.

JAMA Neurology 2016

Association of Progressive Cerebellar Atrophy With Long-term Outcome in Patients With Anti-N-Methyl-d-Aspartate Receptor Encephalitis

Importance  Anti-N-methyl-d-aspartate receptor (NMDAR) encephalitis is an immune-mediated disorder that occurs with IgG antibodies against the GluN1 subunit of NMDAR. Some patients develop reversible diffuse cerebral atrophy (DCA), but the long-term clinical significance of progressive brain and cerebellar atrophy is unknown.

Objective  To report the long-term clinical implications of DCA and cerebellar atrophy in anti-NMDAR encephalitis.

Design, Setting, and Participants  A retrospective observational study and long-term imaging investigation was conducted in the Department of Neurology at Kitasato University. Fifteen patients with anti-NMDAR encephalitis admitted to Kitasato University Hospital between January 1, 1999, and December 31, 2014, were included; data analysis was conducted between July 15, 2015, and January 18, 2016.

Exposures  Neurologic examination, immunotherapy, and magnetic resonance imaging (MRI) studies were performed.

Main Outcomes and Measures  Long-term MRI changes in association with disease severity, serious complications (eg, pulmonary embolism, septic shock, and rhabdomyolysis), treatment, and outcome.

Results  The clinical outcome of 15 patients (median age, 21 years, [range, 14-46 years]; 10 [67%] female) was evaluated after a median follow-up of 68 months (range, 10-179 months). Thirteen patients (87%) received first-line immunotherapy (intravenous high-dose methylprednisolone, intravenous immunoglobulin, and plasma exchange alone or combined), and 4 individuals (27%) also received cyclophosphamide; 2 patients (13%) did not receive immunotherapy. In 5 patients (33%), ovarian teratoma was found and removed. Serious complications developed in 4 patients (27%). Follow-up MRI revealed DCA in 5 patients (33%) that, in 2 individuals (13%), was associated with progressive cerebellar atrophy. Long-term outcome was good in 13 patients (87%) and poor in the other 2 individuals (13%). Although cerebellar atrophy was associated with poor long-term outcome (2 of 2 vs 0 of 13 patients; P = .01), other features, such as DCA without cerebellar atrophy, serious complications, ventilatory support, or prolonged hospitalization, were not associated with a poor outcome. Five patients with DCA had longer hospitalizations (11.1 vs 2.4 months; P = .002), required ventilatory support more frequently (5 of 5 vs 4 of 10 patients; P = .04), and developed more serious complications (4 of 5 vs 0 of 10 patients; P = .004) compared with those without DCA. Although DCA was reversible, cerebellar atrophy was irreversible.

Conclusions and Relevance  In anti-NMDAR encephalitis, DCA can be reversible and does not imply a poor clinical outcome. In contrast, cerebellar atrophy was irreversible and associated with a poor outcome. This observation deserves further study to confirm progressive cerebellar atrophy as a prognostic marker of poor outcome.

JAMA Neurology 2016

Neural correlates of consciousness in patients who have emerged from a minimally conscious state: a cross-sectional multimodal imaging study

Summary

Background

Between pathologically impaired consciousness and normal consciousness exists a scarcely researched transition zone, referred to as emergence from minimally conscious state, in which patients regain the capacity for functional communication, object use, or both. We investigated neural correlates of consciousness in these patients compared with patients with disorders of consciousness and healthy controls, by multimodal imaging.

Methods

In this cross-sectional, multimodal imaging study, patients with unresponsive wakefulness syndrome, patients in a minimally conscious state, and patients who had emerged from a minimally conscious state, diagnosed with the Coma Recovery Scale–Revised, were recruited from the neurology department of the Centre Hospitalier Universitaire de Liège, Belgium. Key exclusion criteria were neuroimaging examination in an acute state, sedation or anaesthesia during scanning, large focal brain damage, motion parameters of more than 3 mm in translation and 3° in rotation, and suboptimal segmentation and normalisation. We acquired resting state functional and structural MRI data and 18F-fluorodeoxyglucose (FDG) PET data; we used seed-based functional MRI (fMRI) analysis to investigate positive default mode network connectivity (within-network correlations) and negative default mode network connectivity (between-network anticorrelations). We correlated FDG-PET brain metabolism with fMRI connectivity. We used voxel-based morphometry to test the effect of anatomical deformations on functional connectivity.

Findings

We recruited a convenience sample of 58 patients (21 [36%] with unresponsive wakefulness syndrome, 24 [41%] in a minimally conscious state, and 13 [22%] who had emerged from a minimally conscious state) and 35 healthy controls between Oct 1, 2009, and Oct 31, 2014. We detected consciousness-level-dependent increases (from unresponsive wakefulness syndrome, minimally conscious state, emergence from minimally conscious state, to healthy controls) for positive and negative default mode network connectivity, brain metabolism, and grey matter volume (p<0·05 false discovery rate corrected for multiple comparisons). Positive default mode network connectivity differed between patients and controls but not among patient groups (F test p<0·0001). Negative default mode network connectivity was only detected in healthy controls and in those who had emerged from a minimally conscious state; patients with unresponsive wakefulness syndrome or in a minimally conscious state showed pathological between-network positive connectivity (hyperconnectivity; F test p<0·0001). Brain metabolism correlated with positive default mode network connectivity (Spearman's r=0·50 [95% CI 0·26 to 0·61]; p<0·0001) and negative default mode network connectivity (Spearman's r=–0·52 [–0·35 to −0·67); p<0·0001). Grey matter volume did not differ between the studied groups (F test p=0·06).

Interpretation

Partial preservation of between-network anticorrelations, which are seemingly of neuronal origin and cannot be solely explained by morphological deformations, characterise patients who have emerged from a minimally conscious state. Conversely, patients with disorders of consciousness show pathological between-network correlations. Apart from a deeper understanding of the neural correlates of consciousness, these findings have clinical implications and might be particularly relevant for outcome prediction and could inspire new therapeutic options.

Lancet Neurology 2016

Dementia risk after spontaneous intracerebral haemorrhage: a prospective cohort study

Background

Dementia occurs in at least 10% of patients within 1 year after stroke. However, the risk of dementia after spontaneous intracerebral haemorrhage that accounts for about 15% of all strokes has not been investigated in prospective studies. We aimed to determine the incidence of dementia and risk factors after an intracerebral haemorrhage.

Methods

We did a prospective observational cohort study in patients with spontaneous intracerebral haemorrhage from the Prognosis of Intracerebral Haemorrhage (PITCH) cohort who were admitted to Lille University Hospital, Lille, France. We included patients aged 18 years and older with parenchymal haemorrhage on the first CT scan. Exclusion criteria were pure intraventricular haemorrhage; intracerebral haemorrhage resulting from intracranial vascular malformation, intracranial venous thrombosis, head trauma, or tumour; haemorrhagic transformation within an infarct; and referral from other hospitals. Median follow-up was 6 years. We studied risk factors (clinical and neuroradiological [MRI] biomarkers) of new-onset dementia as per a prespecified subgroup analysis, according to intracerebral haemorrhage location. Dementia diagnosis was based on the National Institute on Aging-Alzheimer's Association criteria for all-cause dementia. We did multivariable analyses using competing risk analyses, with death during follow-up as a competing event.

Findings

From the 560 patients with spontaneous intracerebral haemorrhage enrolled in the PITCH cohort between Nov 3, 2004 and March 29, 2009, we included 218 patients (median age 67·5 years) without pre-existing dementia who were alive at 6 months follow-up. 63 patients developed new-onset dementia leading to an incidence rate of 14·2% (95% CI 10·0–19·3) at 1 year after intracerebral haemorrhage, and incidence reached 28·3% (22·4–34·5) at 4 years. The incidence of new-onset dementia was more than two times higher in patients with lobar intracerebral haemorrhage (incidence at 1 year 23·4%, 14·6–33·3) than for patients with non-lobar intracerebral haemorrhage (incidence at 1 year 9·2%, 5·1–14·7). Disseminated superficial siderosis (subhazard ratio [SHR] 7·45, 95% CI 4·27–12·99), cortical atrophy score (SHR per 1-point increase 2·61, 1·70–4·01), a higher number of cerebral microbleeds (SHR for >5 cerebral microbleeds 2·33, 1·38–3·94), and older age (SHR per 10-year increase 1·34, 1·00–1·79) were risk factors of new-onset dementia.

Interpretation

There is a substantial risk of incident dementia in dementia-free survivors of spontaneous intracerebral haemorrhage; our results suggest that underlying cerebral amyloid angiopathy is a contributing factor to the occurrence of new-onset dementia. Future clinical trials including patients with intracerebral haemorrhage should assess cognitive endpoints.

Lancet Neurology 2016

Distinct molecular mechanisms of HTRA1 mutants in manifesting heterozygotes with CARASIL

ABSTRACT

Objective: To elucidate the molecular mechanism of mutant HTRA1-dependent cerebral small vessel disease in heterozygous individuals.

Methods: We recruited 113 unrelated index patients with clinically diagnosed cerebral small vessel disease. The coding sequences of the HTRA1 gene were analyzed. We evaluated HTRA1 protease activities using casein assays and oligomeric HTRA1 formation using gel filtration chromatography.

Results: We found 4 heterozygous missense mutations in the HTRA1 gene (p.G283E, p.P285L, p.R302Q, and p.T319I) in 6 patients from 113 unrelated index patients and in 2 siblings in 2 unrelated families with p.R302Q. The mean age at cognitive impairment onset was 51.1 years. Spondylosis deformans was observed in all cases, whereas alopecia was observed in 3 cases; an autopsied case with p.G283E showed arteriopathy in their cerebral small arteries. These mutant HTRA1s showed markedly decreased protease activities and inhibited wild-type HTRA1 activity, whereas 2 of 3 mutant HTRA1s reported in cerebral autosomal-recessive arteriopathy with subcortical infarcts and leukoencephalopathy (CARASIL) (A252T and V297M) did not inhibit wild-type HTRA1 activity. Wild-type HTRA1 forms trimers; however, G283E and T319I HTRA1, observed in manifesting heterozygotes, did not form trimers. P285L and R302Q HTRA1s formed trimers, but their mutations were located in domains that are important for trimer-associated HTRA1 activation; in contrast, A252T and V297M HTRA1s, which have been observed in CARASIL, also formed trimers but had mutations outside the domains important for trimer-associated HTRA1 activation.

Conclusions: The mutant HTRA1s observed in manifesting heterozygotes might result in an impaired HTRA1 activation cascade of HTRA1 or be unable to form stable trimers.

Neurology 2016

The effect of 2 12-minute culturally targeted films on intent to call 911 for stroke

Objective: We assessed the behavioral effect of 2 12-minute culturally targeted stroke films on immediately calling 911 for suspected stroke among black and Hispanic participants using a quasi-experimental pretest-posttest design.

Methods: We enrolled 102 adult churchgoers (60 black and 42 Hispanic) into a single viewing of one of the 2 stroke films—a Gospel musical (English) or Telenovela (Spanish). We measured intent to immediately call 911 using the validated 28-item Stroke Action Test in English and Spanish, along with related variables, before and immediately after the intervention. Data were analyzed using repeated-measures analysis of variance.

Results: An increase in intent to call 911 was seen immediately following the single viewing. Higher self-efficacy for calling 911 was associated with intent to call 911 among Hispanic but not black participants. A composite measure of barriers to calling 911 was not associated with intent to call 911 in either group. A significant association was found between higher stroke symptom knowledge and intent to call 911 at baseline, but not immediately following the intervention. No sex associations were found; however, being older was associated with greater intent to call 911. The majority of participants would strongly recommend the films to others. One participant appropriately called 911 for a real-life stroke event.

Conclusions: Narrative communication in the form of tailored short films may improve intent to call 911 for stroke among the black and Hispanic population.

Neurology 2016

Natural history of cavernous malformation Systematic review and meta-analysis of 25 studies

Objective: We pooled the results of studies on natural history of cavernous malformations (CM) to calculate point estimates and investigate main sources of heterogeneity.

Methods: We searched MEDLINE, EMBASE, and ISI Web of Science for relevant studies published before May 2015. We used fixed or random effects models and meta-regression to pool the data.

Results: Twenty-five studies were entered into the meta-analysis (90–1,295 patients depending on the analysis). Bleeding was defined as symptomatic hemorrhage plus radiologic evidence of hemorrhage. Sources of heterogeneity were identified as mixture of hemorrhage and rehemorrhage, mixture of rehemorrhage before and after 2 years of first bleeding, brainstem vs other locations, and calculation method. The rehemorrhage rate was higher than the hemorrhage rate (incidence rate ratio 16.5, p < 0.001, 95% confidence interval [CI] 9.7–28.0). Rehemorrhage within 2 years of the first hemorrhage was higher than after that (incidence rate ratio 1.8, p = 0.042, 95% CI 1.5–2.0). In two metaregression models, rough estimate of the annual incidence rate of hemorrhage was 0.3% (95% CI 0.1%–0.5%) and 2.8% (2.5%–3.3%) per person year in nonbrainstem and brainstem lesions and rough estimate of annual rehemorrhage rate per person year was 6.3% (3%–13.2%) and 32.3% (19.8%–52.7%) in nonbrainstem and brainstem lesions. Median time to rehemorrhage was 10.5 months. Posthemorrhage full recovery was 38.8%/person-year (28.7%–48.8%). Posthemorrhage full recovery or minimal disability was 79.5%/person-year (74.3%–84.8%). Mortality after bleeding was 2.2%.

Conclusions: The incidence of symptomatic hemorrhage or rehemorrhage is higher in brainstem lesions. First symptomatic hemorrhage increases the chance of symptomatic rehemorrhage, which decreases after 2 years.

Neurology 2016

Rituximab versus fingolimod after natalizumab in multiple sclerosis patients

Objective

Many JC virus antibody-positive relapsing–remitting multiple sclerosis (RRMS) patients who are stable on natalizumab switch to other therapies to avoid progressive multifocal leukoencephalopathy.

Methods

We compared outcomes for all RRMS patients switching from natalizumab due to JC virus antibody positivity at 3 Swedish multiple sclerosis centers with different preferential use of rituximab and fingolimod (Stockholm, n = 156, fingolimod 51%; Gothenburg, n = 64, fingolimod 88%; Umeå, n = 36, fingolimod 19%), yielding a total cohort of N = 256 (fingolimod 55%).

Results

Within 1.5 years of cessation of natalizumab, 1.8% (rituximab) and 17.6% (fingolimod) of patients experienced a clinical relapse (hazard ratio for rituximab = 0.10, 95% confidence interval [CI] = 0.02–0.43). The hazard ratio (favoring rituximab) for adverse events (5.3% vs 21.1%) and treatment discontinuation (1.8% vs 28.2%) were 0.25 (95% CI = 0.10–0.59) and 0.07 (95% CI = 0.02–0.30), respectively. Furthermore, contrast-enhancing lesions were found in 1.4% (rituximab) versus 24.2% (fingolimod) of magnetic resonance imaging examinations (odds ratio = 0.05, 95% CI = 0.00–0.22). Differences remained when adjusting for possible confounders (age, sex, disability status, time on natalizumab, washout time, follow-up time, and study center).

Interpretation

Our findings suggest an improved effectiveness and tolerability of rituximab compared with fingolimod in stable RRMS patients who switch from natalizumab due to JC virus antibody positivity. Although residual confounding factors cannot be ruled out, the shared reason for switching from natalizumab and the preferential use of either rituximab or fingolimod in 2 of the centers mitigates these concerns. 

Ann Neurol 2016

Myasthenia gravis — autoantibody characteristics and their implications for therapy

Myasthenia gravis (MG) is an autoimmune disorder caused by autoantibodies that target the neuromuscular junction, leading to muscle weakness and fatigability. Currently available treatments for the disease include symptomatic pharmacological treatment, immunomodulatory drugs, plasma exchange, thymectomy and supportive therapies. Different autoantibody patterns and clinical manifestations characterize different subgroups of the disease: early-onset MG, late-onset MG, thymoma MG, muscle-specific kinase MG, low-density lipoprotein receptor-related protein 4 MG, seronegative MG, and ocular MG. These subtypes differ in terms of clinical characteristics, disease pathogenesis, prognosis and response to therapies. Patients would, therefore, benefit from treatment that is tailored to their disease subgroup, as well as other possible disease biomarkers, such as antibodies against cytoplasmic muscle proteins. Here, we discuss the different MG subtypes, the sensitivity and specificity of the various antibodies involved in MG for distinguishing between these subtypes, and the value of antibody assays in guiding optimal therapy. An understanding of these elements should be useful in determining how to adapt existing therapies to the requirements of each patient.

JAMA Neurology 2016

Association Between Anticholinergic Medication Use and Cognition, Brain Metabolism, and Brain Atrophy in Cognitively Normal Older Adults

Importance  The use of anticholinergic (AC) medication is linked to cognitive impairment and an increased risk of dementia. To our knowledge, this is the first study to investigate the association between AC medication use and neuroimaging biomarkers of brain metabolism and atrophy as a proxy for understanding the underlying biology of the clinical effects of AC medications.

Objective  To assess the association between AC medication use and cognition, glucose metabolism, and brain atrophy in cognitively normal older adults from the Alzheimer’s Disease Neuroimaging Initiative (ADNI) and the Indiana Memory and Aging Study (IMAS).

Design, Setting, and Participants  The ADNI and IMAS are longitudinal studies with cognitive, neuroimaging, and other data collected at regular intervals in clinical and academic research settings. For the participants in the ADNI, visits are repeated 3, 6, and 12 months after the baseline visit and then annually. For the participants in the IMAS, visits are repeated every 18 months after the baseline visit (402 cognitively normal older adults in the ADNI and 49 cognitively normal older adults in the IMAS were included in the present analysis). Participants were either taking (hereafter referred to as the AC+participants [52 from the ADNI and 8 from the IMAS]) or not taking (hereafter referred to as the AC−participants [350 from the ADNI and 41 from the IMAS]) at least 1 medication with medium or high AC activity. Data analysis for this study was performed in November 2015.

Main Outcomes and Measures  Cognitive scores, mean fludeoxyglucose F 18 standardized uptake value ratio (participants from the ADNI only), and brain atrophy measures from structural magnetic resonance imaging were compared between AC+ participants and AC− participants after adjusting for potential confounders. The total AC burden score was calculated and was related to target measures. The association of AC use and longitudinal clinical decline (mean [SD] follow-up period, 32.1 [24.7] months [range, 6-108 months]) was examined using Cox regression.

Results  The 52 AC+ participants (mean [SD] age, 73.3 [6.6] years) from the ADNI showed lower mean scores on Weschler Memory Scale–Revised Logical Memory Immediate Recall (raw mean scores: 13.27 for AC+ participants and 14.16 for AC− participants; P = .04) and the Trail Making Test Part B (raw mean scores: 97.85 seconds for AC+ participants and 82.61 seconds for AC− participants; P = .04) and a lower executive function composite score (raw mean scores: 0.58 for AC+ participants and 0.78 for AC−participants; P = .04) than the 350 AC− participants (mean [SD] age, 73.3 [5.8] years) from the ADNI. Reduced total cortical volume and temporal lobe cortical thickness and greater lateral ventricle and inferior lateral ventricle volumes were seen in the AC+ participants relative to the AC− participants.

Conclusions and Relevance  The use of AC medication was associated with increased brain atrophy and dysfunction and clinical decline. Thus, use of AC medication among older adults should likely be discouraged if alternative therapies are available.

JAMA Neurology 2016

Pharmacotherapy for Pain in a Family With Inherited Erythromelalgia Guided by Genomic Analysis and Functional Profiling

Importance  There is a need for more effective pharmacotherapy for chronic pain, including pain in inherited erythromelalgia (IEM) in which gain-of-function mutations of sodium channel NaV1.7 make dorsal root ganglion (DRG) neurons hyperexcitable.

Objective  To determine whether pain in IEM can be attenuated via pharmacotherapy guided by genomic analysis and functional profiling.

Design, Setting, and Participants  Pain in 2 patients with IEM due to the NaV1.7 S241T mutation, predicted by structural modeling and functional analysis to be responsive to carbamazepine, was assessed in a double-blind, placebo-controlled study conducted from September 2014 to April 21, 2015. Functional magnetic resonance imaging assessed patterns of brain activity associated with pain during treatment with placebo or carbamazepine. Multielectrode array technology was used to assess the effect of carbamazepine on firing of DRG neurons carrying S241T mutant channels.

Main Outcomes and Measures  Behavioral assessment of pain; functional magnetic resonance imaging; and assessment of firing in DRG neurons carrying S241T mutant channels.

Results  This study included 2 patients from the same family with IEM and the S241T NaV1.7 mutation. We showed that, as predicted by molecular modeling, thermodynamic analysis, and functional profiling, carbamazepine attenuated pain in patients with IEM due to the S241T NaV1.7 mutation. Patient 1 reported a reduction in mean time in pain (TIP) per day during the 15-day maintenance period, from 424 minutes while taking placebo to 231.9 minutes while taking carbamazepine (400 mg/day), and a reduction in total TIP over the 15-day maintenance period, from 6360 minutes while taking placebo to 3015 minutes while taking carbamazepine. Patient 2 reported a reduction in mean TIP per day during the maintenance period, from 61 minutes while taking placebo to 9.1 minutes while taking carbamazepine (400 mg then 200 mg/day), and a reduction in total TIP, from 915 minutes while taking placebo over the 15-day maintenance period to 136 minutes while taking carbamazepine. Patient 1 reported a reduction of mean episode duration, from 615 minutes while taking placebo to 274.1 minutes while taking carbamazepine, while patient 2 reported a reduction of the mean episode duration from 91.5 minutes while taking placebo to 45.3 minutes while taking carbamazepine. Patient 1, who had a history of night awakenings from pain, reported 101 awakenings owing to pain while taking placebo during the maintenance period and 32 awakenings while taking carbamazepine. Attenuation of pain was paralleled by a shift in brain activity from valuation and pain areas to primary and secondary somatosensory, motor, and parietal attention areas. Firing of DRG neurons expressing the S241T NaV1.7 mutant channel in response to physiologically relevant thermal stimuli was reduced by carbamazepine.

Conclusions and Relevance  Our results demonstrate that pharmacotherapy guided by genomic analysis, molecular modeling, and functional profiling can attenuate neuropathic pain in patients carrying the S241T mutation.

JAMA Neurology 2016