Defining SOD1 ALS natural history to guide therapeutic clinical trial design.

IMPORTANCE: Understanding the natural history of familial amyotrophic lateral sclerosis (ALS) caused by SOD1 mutations (ALSSOD1) will provide key information for optimising clinical trials in this patient population. OBJECTIVE: To establish an updated natural history of ALSSOD1. DESIGN, SETTING AND PARTICIPANTS: Retrospective cohort study from 15 medical centres in North America evaluated records from 175 patients with ALS with genetically confirmed SOD1 mutations, cared for after the year 2000. MAIN OUTCOMES AND MEASURES: Age of onset, survival, ALS Functional Rating Scale (ALS-FRS) scores and respiratory function were analysed. Patients with the A4V (Ala-Val) SOD1 mutation (SOD1A4V), the largest mutation population in North America with an aggressive disease progression, were distinguished from other SOD1 mutation patients (SOD1non-A4V) for analysis. RESULTS: Mean age of disease onset was 49.7±12.3 years (mean±SD) for all SOD1 patients, with no statistical significance between SOD1A4V and SOD1non-A4V (p=0.72, Kruskal-Wallis). Total SOD1 patient median survival was 2.7 years. Mean disease duration for all SOD1 was 4.6±6.0 and 1.4±0.7 years for SOD1A4V. SOD1A4V survival probability (median survival 1.2 years) was significantly decreased compared with SOD1non-A4V (median survival 6.8 years; p<0.0001, log-rank). A statistically significant increase in ALS-FRS decline in SOD1A4V compared with SOD1non-A4V participants (p=0.02) was observed, as well as a statistically significant increase in ALS-forced vital capacity decline in SOD1A4V compared with SOD1non-A4V (p=0.02). CONCLUSIONS AND RELEVANCE: SOD1A4V is an aggressive, but relatively homogeneous form of ALS. These SOD1-specific ALS natural history data will be important for the design and implementation of clinical trials in the ALSSOD1 patient population.

Myelinated and unmyelinated endoneurial axon quantitation and clinical correlation.

INTRODUCTION: Different disease patterns result from loss of myelinated and unmyelinated axons, but quantitation to define their loss has been difficult. METHODS: We measured large and small endoneurial axons in axonal neuropathies by staining them with peripherin and comparing their area to that of nonmyelinating Schwann cells stained with neural cell adhesion molecule (NCAM). RESULTS: Loss of myelinated and unmyelinated axons was typically proportional, with predominant myelinated or unmyelinated axon loss in a few patients. Myelinated axon loss was associated with loss of distal vibration sense and sensory potentials (P < 0.0001) and was selective in patients with bariatric and bowel resection surgery (P < 0.001). Unmyelinated axon measurements correlated with skin (ankle P = 0.01; thigh P = 0.02) and vascular (nerve P < 0.0001; muscle P = 0.01) innervation. CONCLUSIONS: Myelinated and unmyelinated axons can be quantitated by comparing areas of axons and nonmyelinating Schwann cells. Clinical features correlate with myelinated axon loss, and unmyelinated axon loss correlates with skin and vascular denervation.

Myovascular innervation: axon loss in small-fiber neuropathies.

INTRODUCTION: Vascular denervation occurs in some neuropathies, but measurement of small perivascular axons has been difficult. METHODS: We evaluated 31 consecutive patients who had both muscle and skin biopsies. We quantitated myovascular innervation by staining unmyelinated axons with peripherin and non-myelinating Schwann cells with neural cell adhesion molecule and comparing their areas. RESULTS: Perivascular unmyelinated axon-Schwann (UAS) ratios correlated with axon density in skin (r = 0.679; P < 0.0001). Low UAS ratios (≤0.25) had a sensitivity of 90% and specificity of 91% for a clinical diagnosis of small-fiber neuropathy (P < 0.0001). Autonomic features were more common in patients with low perivascular UAS ratios (P = 0.002). A patient subgroup with myovascular, but not skin, denervation commonly had muscle discomfort and autonomic features. CONCLUSIONS: UAS ratio measurements, comparing axons and associated non-myelinating Schwann cells, can quantitate perivascular innervation. Small-fiber neuropathies are often associated with myovascular denervation. Some patients with muscle discomfort have selective myovascular denervation.

Exome sequencing reveals DNAJB6 mutations in dominantly-inherited myopathy.

OBJECTIVE: To identify the causative gene in an autosomal dominant limb-girdle muscular dystrophy (LGMD) with skeletal muscle vacuoles. METHODS: Exome sequencing was used to identify candidate mutations in the studied pedigree. Genome-wide linkage was then used to narrow the list of candidates to a single disease-associated mutation. Additional pedigrees with dominant or sporadic myopathy were screened for mutations in the same gene (DNAJB6) using exome sequencing. Skeletal muscle from affected patients was evaluated with histochemistry and immunohistochemical stains for dystrophy-related proteins, SMI-31, TDP43, and DNAJB6. RESULTS: Exome analysis in 3 affected individuals from a family with dominant LGMD and vacuolar pathology identified novel candidate mutations in 22 genes. Linkage analysis excluded all variants except a Phe93Leu mutation in the G/F domain of the DNAJB6 gene, which resides within the LGMD locus at 7q36. Analysis of exome sequencing data from other pedigrees with dominant myopathy identified a second G/F domain mutation (Pro96Arg) in DNAJB6. Affected muscle showed mild dystrophic changes, vacuoles, and abnormal aggregation of proteins, including TDP-43 and DNAJB6 itself. INTERPRETATION: Mutations within the G/F domain of DNAJB6 are a novel cause of dominantly-inherited myopathy. DNAJB6 is a member of the HSP40/DNAJ family of molecular co-chaperones tasked with protecting client proteins from irreversible aggregation during protein synthesis or during times of cellular stress. The abnormal accumulation of several proteins in patient muscle, including DNAJB6 itself, suggest that DNAJB6 function is compromised by the identified G/F domain mutations.

Cramps and small-fiber neuropathy.

INTRODUCTION: Muscle cramps are a common complaint and are thought to arise from spontaneous discharges of the motor nerve terminal. Polyneuropathy is often causative, but small-fiber neuropathy (SFN) has not been assessed. METHODS: We performed skin biopsies on consecutive patients with cramps but without neuropathic complaints. Twelve patients were biopsied, 8 with normal small-fiber sensation. RESULTS: Seven patients had decreased intraepidermal nerve fiber density (IENFD), 2 with non-length-dependent loss. A cause for neuropathy was found in 1 patient with cramp-fasciculation syndrome. Creatine kinase was elevated in 8 patients, 4 with decreased IENFD. Muscle biopsy, performed in 8 patients, but was diagnostic in only 1, with McArdle disease. CONCLUSIONS: Our data show that 60% of patients with muscle cramps who lack neuropathic complaints have SFN, as documented by decreased IENFD. Cramps may originate as local mediators of inflammation released by damaged small nerve that excite intramuscular nerves.

Inflammatory demyelinating neuropathies.

OPINION STATEMENT: The primary goal of therapy in patients with the Guillain-Barré syndrome (GBS) and chronic inflammatory demyelinating polyradiculoneuropathy (CIDP) is improved strength and functional ability. Improvement in pain, sensory loss, gait disorder, and autonomic instability are other goals of therapy. Patients with very mild symptoms that do not interfere with activities of daily living can be observed for deterioration without treatment. For GBS, standard care includes plasma exchange (PE) or human immune globulin (HIG), both of which have similar efficacy. Supportive care in the intensive care unit may be needed for those patients with severe bulbar or respiratory weakness. We treat most patients with PE, usually performing an exchange every other day for a total of five exchanges. We use HIG in children, if there are antiglycolipid antibodies (eg, anti-GM1 or anti-GQ1b) or if there is a contraindication to PE, such as hemodynamic instability; severe renal, hepatic, or cardiac disease; or poor venous access. For CIDP, there are no guidelines concerning the initial choice of therapy. Corticosteroids, HIG, and PE have all been shown to be effective in prospective, randomized controlled trials, and comparison trials have shown equal efficacy among these three immunomodulating therapies. The choice of therapy depends on several factors including disease severity, concomitant illnesses, side-effect profile, potential drug interactions, venous access, age-related risks, and cost of treatment. In patients with moderate to severe symptoms, treatment with corticosteroids or HIG should be used. We usually use high-dose, intermittent methylprednisolone as the initial drug of choice. We believe intermittent corticosteroids are better than HIG because of their good safety profile, low cost, ease of administration (can be given intravenously or by mouth), and proven efficacy. If there is a major contraindication to corticosteroids, then HIG is offered. PE is less well tolerated and is primarily used as a third choice and only for a few weeks to months to induce initial improvement. Once symptoms are improving, the dose of corticosteroids or HIG should be tapered with the goal of eventual discontinuation depending on patient response. Patients who do not respond to initial therapy, experience adverse effects from the initial immunomodulating agent, or require chronic treatment can be treated with another first-line agent or one of several second-line agents.

Familial ALS with extreme phenotypic variability due to the I113T SOD1 mutation.

We describe a large family with amyotrophic lateral sclerosis (ALS) caused by an I113T mutation in superoxide dismuatse type 1 (SOD1). The proband developed symptoms typical for ALS at age 39 years and is still walking five years later. Marked phenotypic variability is manifested by her mother with onset of gait difficulty and decision-making problems at age 67 years and a five-year course marked by progressive mild upper motor neuron weakness, frontotemporal dementia and chorea. An aunt's initial symptoms included foot numbness and an uncle with the mutation is asymptomatic. Penetrance is only 50% at age 60 years and 88% at age 80 years with an 86-year-old woman harboring the mutation and having a normal neurologic examination. This family highlights the extreme variability in age of onset, clinical manifestations, disease progression and penetrance due to the I113T SOD1 mutation.

Prevalence of Axonal Sensory Neuropathy With IgM Binding to Trisulfated Heparin Disaccharide in Patients With Fibromyalgia.

OBJECTIVE: To assess the intraepidermal nerve fiber density in patients diagnosed with fibromyalgia (FM) and to evaluate the role of IgM binding to trisulfated heparin disaccharide (TS-HDS) in these patients. METHODS: FM is a poorly understood pain disorder with several proposed pathophysiologic mechanisms. It is characterized by widespread pain, fatigue, and sleep abnormalities. Small fiber neuropathy (SFN) has been proposed as an underlying mechanism, and patients with FM have been shown to have a reduction in the intraepidermal nerve fiber density. An underlying inflammatory process that could be a result of autoimmune phenomena has also been suggested. Non-length-dependent SFN (NLDSFN) has been shown to have a higher incidence of autoimmune disease. Twenty-two patients with established diagnosis of FM underwent skin biopsy at 2 sites; 10 cm above the lateral malleolus and 10 cm above the patella. Serum IgM binding to TS-HDS was assayed using an ELISA method. RESULTS: A total of 5/22 patients had positive TS-HDS antibodies; of these, 4 had NLDSFN (P = 0.0393). Comparison with a control group at Washington University showed no significant difference in percentage with TS-HDS antibodies (P = 0.41). When compared with Washington University database of skin biopsy, there was a trend for an increased percentage of NLDSFN in patients with FM (P = 0.06). CONCLUSIONS: This study further supports the hypothesis that a subgroup of patients with FM has SFN. We suggest a correlation between the presence of NLDSFN and TS-HDS antibodies.

CANOMAD and other chronic ataxic neuropathies with disialosyl antibodies (CANDA).

INTRODUCTION: CANOMAD/CANDA are syndromes characterized by ataxic neuropathy, ophthalmoplegia, monoclonal gammopathy, cold agglutinins and disialosyl antibodies. METHODS: A retrospective review of our neuromuscular autoantibody panel database was performed. Anti-GD1b seropositive patients with ataxia were included. RESULTS: Eleven patients were identified. Median age at onset was 56 years. Median disease duration was 6 years. All patients had gait disorders. Nine had ocular motility abnormalities. Most had a monoclonal protein and all had elevated serum IgM. Electrodiagnostic studies showed a mixed axonal/demyelinating pattern (6), an axonal pattern (4), or a pure demyelinating pattern (1). Ultrasounds showed nerve enlargement patterns consistent with acquired demyelination. A nerve biopsy showed near complete loss of myelinated axons with preservation of smaller axons. Rituximab was the most effective immunotherapy. CONCLUSION: CANOMAD/CANDA are rare and debilitating disorders with characteristic clinical and diagnostic findings. In our cohort, nerve ultrasound showed regional nerve enlargement and rituximab was the most effective immunomodulatory therapy.

Treatment of chronic inflammatory demyelinating polyneuropathy with high-dose intermittent intravenous methylprednisolone.

BACKGROUND: Chronic inflammatory demyelinating polyradiculoneuropathy (CIDP) causes progressive disability due to weakness but responds to immunomodulating medication, including oral prednisone and intravenous (IV) immunoglobulin (IVIg). However, there is no consensus on initial therapy, and both of these treatments have drawbacks with long-term treatment. OBJECTIVE: To review the efficacy and safety of high-dose, intermittent IV methylprednisolone (IVMP) as initial and long-term maintenance therapy for patients with CIDP. DESIGN: A retrospective medical record review between 1992 and 2003 of outcomes in CIDP, comparing patients in 3 cohorts depending on whether their primary treatment was IVMP, IVIg, or oral immunosuppression with prednisone or cyclosporine. SETTING: Washington University Neuromuscular Disease Center (St Louis, Mo), outpatient and inpatient records. PATIENTS: Patients with clinical and electrophysiologic evidence of CIDP were identified. Of 57 patients, 39 had sufficient data for full analysis. MAIN OUTCOME MEASURES: Quantitative muscle testing with a handheld dynamometer. Medication profiles and adverse effects were also recorded. RESULTS: There was no significant difference in the mean improvement in quantitative muscle testing at 6 months or at the last clinic visit (an average of 4.5 years later) among the 3 groups. Fewer patients treated with oral immunosuppression improved at 6 months, but at the last visit, 81% to 88% improved in all 3 groups. Less weight gain and fewer cushingoid features affected patients treated with IVMP (19%) compared with patients treated with oral prednisone (58%). CONCLUSIONS: Treatment of patients with CIDP using high-dose intermittent IVMP results in improved strength equal to that with IVIg and oral prednisone. The frequency of occurrences of weight gain and cushingoid features with IVMP is less than that with oral prednisone. Intravenous methylprednisolone should be considered for initial and long-term therapy in CIDP when patients have disability due to weakness.

Autophagic vacuolar pathology in desminopathies.

Autophagic vacuolar myopathies are an emerging group of muscle diseases with common pathologic features. These include autophagic vacuoles containing both lysosomal and autophagosomal proteins sometimes lined with sarcolemmal proteins such as dystrophin. These features have been most clearly described in patients with Danon's disease due to LAMP2 deficiency and X-linked myopathy with excessive autophagy (XMEA) due to mutations in VMA21. Disruptions of these proteins lead to lysosomal dysfunction and subsequent autophagic vacuolar pathology. We performed whole exome sequencing on two families with autosomal dominantly inherited myopathies with autophagic vacuolar pathology and surprisingly identified a p.R454W tail domain mutation and a novel p.S6W head domain mutation in desmin, DES. In addition, re-evaluation of muscle tissue from another family with a novel p.I402N missense DES mutation also identified autophagic vacuoles. We suggest that autophagic vacuoles may be an underappreciated pathology present in desminopathy patient muscle. Moreover, autophagic vacuolar pathology can be due to genetic etiologies unrelated to primary defects in the lysosomes or autophagic machinery. Specifically, cytoskeletal derangement and the accumulation of aggregated proteins such as desmin may activate the autophagic system leading to the pathologic features of an autophagic vacuolar myopathy.

Targeted sequencing and identification of genetic variants in sporadic inclusion body myositis.

Sporadic inclusion body myositis (sIBM) has clinical, pathologic and pathomechanistic overlap with some inherited muscle and neurodegenerative disorders. In this study, DNA from 79 patients with sIBM was collected and the sequencing of 38 genes associated with hereditary inclusion body myopathy (IBM), myofibrillar myopathy, Emery-Dreifuss muscular dystrophy, distal myopathy, amyotrophic lateral sclerosis and dementia along with C9orf72 hexanucleotide repeat analysis was performed. No C9orf72 repeat expansions were identified, but; 27 rare (minor allele frequency <1%) missense coding variants in several other genes were identified. One patient carried a p.R95C missense mutation in VCP and another carried a previously reported p.I27V missense mutation in VCP. Mutations in VCP cause IBM associated with Paget's disease of the bone (PDB) and fronto-temporal dementia (IBMPFD). Neither patient had a family history of weakness or manifested other symptoms reported with VCP mutations such as PDB or dementia. In vitro analysis of these VCP variants found that they both disrupted autophagy similar to other pathogenic mutations. Although no clear genetic etiology has been implicated in sIBM pathogenesis, our study suggests that genetic evaluation in sIBM may be clinically meaningful and lend insight into its pathomechanism.

Motor neuron disease associated with copper deficiency.

Copper deficiency in humans is a rare cause of myeloneuropathy that usually presents with a spastic ataxic gait, hyperreflexia, and distal sensory loss similar to that seen in patients with subacute combined degeneration. We describe three copper-deficient patients, two of whom were referred with a presumptive diagnosis of amyotrophic lateral sclerosis, who had progressive asymmetric weakness or electrodiagnostic findings of proximal and distal denervation suggestive of lower motor neuron disease. Copper replacement resulted in stabilization or mild improvement in weakness. The clinical spectrum of human copper deficiency should include lower motor neuron disease in addition to a syndrome of spastic ataxia.

Brachio-cervical inflammatory myopathies: clinical, immune, and myopathologic features.

OBJECTIVE: To characterize patients with inflammatory myopathies who present with weakness in the proximal regions of the arms. METHODS: Clinical, laboratory, and myopathologic features were evaluated in 10 patients, identified consecutively over 12 years, with inflammatory myopathies and weakness that was most severe in the proximal regions of the arms. The features of these brachio-cervical inflammatory myopathy (BCIM) syndromes were compared with those of other inflammatory and immune-mediated myopathies evaluated during the same period. RESULTS: Patients with BCIM developed progressive weakness at ages 24-82 years (mean +/- SD age 55 +/- 9 years). Posterior neck weakness occurred in 60% of patients, while motor neuron disease was the referring diagnosis in 30%. All patients had other systemic autoimmune disorders, including myasthenia gravis (40%) and rheumatoid arthritis (20%). Antinuclear antibodies were present in all patients. Serum creatine kinase levels were usually moderately high (mean 910 IU/liter). Active myopathy was identified in muscle biopsy samples from the patients. Focal collections of mononuclear cells, some predominantly B cells, were present in perivascular and perimysial regions. MxA- and CD123-positive dendritic cells were present in the endomysium. C5b-9 components of complement were present diffusely in endomysial connective tissue. Most patients improved in strength after receiving corticosteroids. CONCLUSION: Patients with BCIM syndromes have progressive weakness in the proximal regions of the arms and neck. The predominant myopathologic findings are active myopathy, C5b-9 staining of endomysium, focal perivascular and perimysial inflammation, often with a prominent B cell component, and endomysial dendritic cells. Corticosteroid treatment of BCIM is often followed by improvement in strength.

Peripheral neuropathy in an outpatient cohort of patients with Sjögren's syndrome.

Peripheral neuropathy is common in patients with Sjögren's syndrome (SS), but its precise prevalence is unknown. Most prior studies were conducted at neurology or rheumatology specialty clinics and likely selected for a more severely affected population. We evaluated 22 SS patients and 10 controls for evidence of neuropathy in an outpatient setting at a regional meeting of the Sjögren's Syndrome Foundation. We performed neurological examinations and nerve conduction studies (NCSs) and measured serum antinuclear antibody (ANA) and SS-A and SS-B antibody levels. Participants filled out a questionnaire pertaining to symptoms, diagnosis, and treatment. We found that signs and symptoms related to small axons were more common in patients with SS than in controls. Complaints of painful distal paresthesias in the feet were noted in 59% of patients but in only 10% of controls, and of abnormal sweating in 41% and 0%, respectively. Examination revealed decreased pinprick sensation in 64% of patients with SS, but in only 30% of controls. Overall, 45% of the patients but none of the controls were thought to have an isolated small-fiber neuropathy. Large-fiber dysfunction (as measured by testing vibration, deep tendon reflexes, and NCSs) was similar between the two groups. We conclude that small-fiber neuropathy is common in patients with SS.

Severe sensory ataxia and demyelinating polyneuropathy with IgM anti-GM2 and GalNAc-GD1A antibodies.

Several polyneuropathy syndromes have been described with polyclonal serum immunoglobulin G (IgG) or immunoglobulin M (IgM) binding to gangliosides GM2 and GalNAc-GD1a that contain the terminal trisaccharide moiety GalNAc(beta1-4)Gal(alpha2-3)NeuAc. We describe the clinical and electrodiagnostic features in two patients with serum IgM monoclonal anti-GM2 and anti-GalNAc-GD1a antibodies. These patients had slowly progressive, panmodal sensory loss with severe sensory ataxia. Electrodiagnostic testing showed demyelinating features. Prominent improvement in gait ataxia occurred after treatment with human immune globulin but not after other immunomodulating therapies. Enzyme-linked immunoabsorbent assay and thin-layer chromatography demonstrate that the patient's serum monoclonal IgM bound to gangliosides GM2 and GalNac-GD1a but not to gangliosides without the GalNAc(beta1-4)Gal(alpha2-3)NeuAc moiety. This neuropathy differs from previously reported neuropathy syndromes associated with polyclonal GM2 and GalNAc-GD1a antibodies and from other chronic demyelinating polyneuropathies. We conclude that a distinct syndrome of chronic demyelinating neuropathy with sensory ataxia, unresponsive to corticosteroids, is associated with monoclonal IgM binding to gangliosides with a terminal GalNAc(beta1-4)Gal(alpha2-3)NeuAc trisaccharide moiety. Diagnosis of this syndrome is important to direct appropriate treatment.