AQP4 autoantibody assay performance in clinical laboratory service.

OBJECTIVE: To compare performance of contemporary aquaporin-4-immunoglobulin (Ig) G assays in clinical service. METHODS: Sera from neurologic patients (4 groups) and controls were tested initially by service ELISA (recombinant human aquaporin-4, M1 isoform) and then by cell-based fluorescence assays: fixed (CBA, M1-aquaporin-4, observer-scored) and live (fluorescence-activated cell sorting [FACS], M1 and M23 aquaporin-4 isoforms). Group 1: all Mayo Clinic patients tested from January to May 2012; group 2: consecutive aquaporin-4-IgG-positive patients from September 2011 (Mayo and non-Mayo); group 3: suspected ELISA false-negatives from 2011 to 2013 (physician-reported, high likelihood of neuromyelitis optica spectrum disorders [NMOSDs] clinically); group 4: suspected ELISA false-positives (physician-reported, not NMOSD clinically). RESULTS: Group 1 (n = 388): M1-FACS assay performed optimally (areas under the curves: M1 = 0.64; M23 = 0.57 [p = 0.02]). Group 2 (n = 30): NMOSD clinical diagnosis was confirmed by: M23-FACS, 24; M1-FACS, 23; M1-CBA, 20; and M1-ELISA, 18. Six results were suspected false-positive: M23-FACS, 2; M1-ELISA, 2; and M23-FACS, M1-FACS, and M1-CBA, 2. Group 3 (n = 31, suspected M1-ELISA false-negatives): results were positive for 5 sera: M1-FACS, 5; M23-FACS, 3; and M1-CBA, 2. Group 4 (n = 41, suspected M1-ELISA false-positives): all negative except 1 (positive only by M1-CBA). M1/M23-cotransfected cells expressing smaller membrane arrays of aquaporin-4 yielded fewer false- positive FACS results than M23-transfected cells. CONCLUSION: Aquaporin-4-transfected CBAs, particularly M1-FACS, perform optimally in aiding NMOSD serologic diagnosis. High-order arrays of M23-aquaporin-4 may yield false-positive results by binding IgG nonspecifically.

Immunotherapy trial as diagnostic test in evaluating patients with presumed autoimmune gastrointestinal dysmotility.

BACKGROUND: Chronic gastrointestinal dysmotility greatly impacts the quality of life. Treatment options are limited and generally symptomatic. Neural autoimmunity is an under-recognized etiology. We evaluated immunotherapy as an aid to diagnosing autoimmune gastrointestinal dysmotility (AGID). METHODS: Twenty-three subjects evaluated at the Mayo Clinic for suspected AGID (August 2006-February 2014) fulfilled the following criteria: (1) prominent symptoms of gastrointestinal dysmotility with abnormalities on scintigraphy-manometry; (2) serological evidence or personal/family history of autoimmune disease; (3) treated by immunotherapy on a trial basis, 6-12 weeks (intravenous immune globulin, 16; or methylprednisolone, 5; or both, 2). Response was defined subjectively (symptomatic improvement) and objectively (gastrointestinal scintigraphy/manometry studies). KEY RESULTS: Symptoms at presentation: constipation, 18/23; nausea or vomiting, 18/23; weight loss, 17/23; bloating, 13/23; and early satiety, 4/23. Thirteen patients had personal/family history of autoimmunity. Sixteen had neural autoantibodies and 19 had extra-intestinal autonomic testing abnormalities. Cancer was detected in three patients. Preimmunotherapy scintigraphy revealed slowed transit (19/21 evaluated; gastric, 11; small bowel, 12; colonic, 11); manometry studies were abnormal in 7/8. Postimmunotherapy, 17 (74%) had improvement (both symptomatic and scintigraphic, five; symptomatic alone, eight; scintigraphic alone, four). Nine responders re-evaluated had scintigraphic evidence of improvement. The majority of responders who were re-evaluated had improvement in autonomic testing (six of seven) or manometry (two of two). CONCLUSIONS & INFERENCES: This proof of principle study illustrates the importance of considering an autoimmune basis for idiopathic gastrointestinal dysmotility and supports the utility of a diagnostic trial of immunotherapy.

Utility of an immunotherapy trial in evaluating patients with presumed autoimmune epilepsy.

OBJECTIVE: To evaluate a trial of immunotherapy as an aid to diagnosis in suspected autoimmune epilepsy. METHOD: We reviewed the charts of 110 patients seen at our autoimmune neurology clinic with seizures as a chief complaint. Twenty-nine patients met the following inclusion criteria: (1) autoimmune epilepsy suspected based on the presence of ≥ 1 neural autoantibody (n = 23), personal or family history or physical stigmata of autoimmunity, and frequent or medically intractable seizures; and (2) initiated a 6- to 12-week trial of IV methylprednisolone (IVMP), IV immune globulin (IVIg), or both. Patients were defined as responders if there was a 50% or greater reduction in seizure frequency. RESULTS: Eighteen patients (62%) responded, of whom 10 (34%) became seizure-free; 52% improved with the first agent. Of those receiving a second agent after not responding to the first, 43% improved. A favorable response correlated with shorter interval between symptom onset and treatment initiation (median 9.5 vs 22 months; p = 0.048). Responders included 14/16 (87.5%) patients with antibodies to plasma membrane antigens, 2/6 (33%) patients seropositive for glutamic acid decarboxylase 65 antibodies, and 2/6 (33%) patients without detectable antibodies. Of 13 responders followed for more than 6 months after initiating long-term oral immunosuppression, response was sustained in 11 (85%). CONCLUSIONS: These retrospective findings justify consideration of a trial of immunotherapy in patients with suspected autoimmune epilepsy. CLASSIFICATION OF EVIDENCE: This study provides Class IV evidence that in patients with suspected autoimmune epilepsy, IVMP, IVIg, or both improve seizure control.

Gastrointestinal hypomotility with loss of enteric nicotinic acetylcholine receptors: active immunization model in mice.

BACKGROUND: Autoimmune gastrointestinal dysmotility (AGID) is a limited form of dysautonomia. The only proven effector to date is IgG specific for ganglionic nicotinic-acetylcholine receptors containing α3 subunits [α3*- nicotinic acetylcholine receptor (nAChR)]. Rabbits immunized with recombinant α3-polypeptide produce α3*-nAChR autoantibodies, and profound AGID ensues. Human and rabbit α3*-nAChR-specific-IgGs induce transient hypomotility when injected into mice. Here, we describe success and problems encountered inducing gastrointestinal hypomotility in mice by active immunization. METHODS: We repeatedly injected young adult mice of seven different strains susceptible to autoimmunity (spontaneous diabetes or neural antigen immunization-induced myasthenia gravis or encephalomyelitis) with: (i) α3-polypeptide, intradermally or (ii) live α3*-nAChR-expressing xenogeneic cells, intraperitoneally. We measured serum α3*-nAChR-IgG twice monthly, and terminally assessed blue dye gastrointestinal transit, total small intestinal α3*-nAChR content (radiochemically) and myenteric plexus neuron numbers (immunohistochemically, ileal-jejunal whole-mount preparations). KEY RESULTS: Standard cutaneous inoculation with α3-polypeptide was minimally immunogenic, regardless of dose. Intraperitoneally injected live cells were potently immunogenic. Self-reactive α3*-nAChR-IgG was induced only by rodent immunogen; small intestinal transit slowing and enteric α3*-nAChR loss required high serum levels. Ganglionic neurons were not lost. CONCLUSIONS & INFERENCES: Autoimmune gastrointestinal dysmotility is inducible in mice by active immunization. Accompanying enteric α3*-nAChR reduction without neuronal death is consistent with an IgG-mediated rather than T cell-mediated pathogenesis, as is improvement of symptoms in patients receiving antibody-depleting therapies.

Serologic diagnosis of NMO: a multicenter comparison of aquaporin-4-IgG assays.

OBJECTIVES: Neuromyelitis optica (NMO) immunoglobulin G (IgG) (aquaporin-4 [AQP4] IgG) is highly specific for NMO and related disorders, and autoantibody detection has become an essential investigation in patients with demyelinating disease. However, although different techniques are now used, no multicenter comparisons have been performed. This study compares the sensitivity and specificity of different assays, including an in-house flow cytometric assay and 2 commercial assays (ELISA and transfected cell-based assay [CBA]). METHODS: Six assay methods (in-house or commercial) were performed in 2 international centers using coded serum from patients with NMO (35 patients), NMO spectrum disorders (25 patients), relapsing-remitting multiple sclerosis (39 patients), miscellaneous autoimmune diseases (25 patients), and healthy subjects (22 subjects). RESULTS: The highest sensitivities were yielded by assays detecting IgG binding to cells expressing recombinant AQP4 with quantitative flow cytometry (77; 46 of 60) or visual observation (CBA, 73%; 44 of 60). The fluorescence immunoprecipitation assay and tissue-based immunofluorescence assay were least sensitive (48%-53%). The CBA and ELISA commercial assays (100% specific) yielded sensitivities of 68% (41 of 60) and 60% (36 of 60), respectively, and sensitivity of 72% (43 of 60) when used in combination. CONCLUSIONS: The greater sensitivity and excellent specificity of second-generation recombinant antigen-based assays for detection of NMO-IgG in a clinical setting should enable earlier diagnosis of NMO spectrum disorders and prompt initiation of disease-appropriate therapies.

Paraneoplastic isolated myelopathy: clinical course and neuroimaging clues.

OBJECTIVE: To report the clinical phenotype and outcome of isolated paraneoplastic myelopathy. METHODS: We systematically reviewed clinical, serologic, and MRI data for 31 patients (20 female) who presented with an isolated myelopathy and coexisting cancer: carcinoma (lung, 9; breast, 7; kidney, 2; thyroid, 2; ovary/endometrium, 2), melanoma (2), or other cancer (3), or a paraneoplastic autoantibody with strong cancer association (amphiphysin-immunoglobulin G [IgG], 9; collapsin response-mediator protein 5-IgG, 9; Purkinje-cell cytoplasmic autoantibody type 1, 2; antineuronal nuclear autoantibody [ANNA]-1, 1; ANNA-3, 1). RESULTS: Of 31 patients who presented with a progressive myelopathy, symptom onset was subacute in 16 (52%). The median age was 62 years. CSF abnormalities included elevated protein (>45 mg/dL), 22; pleocytosis, 15; excess oligoclonal bands (normal <4), 7. MRI cord abnormalities identified in 20 patients were longitudinally extensive (>3 vertebral segments), 14; symmetric tract or gray matter-specific signal abnormality, 15 (enhancing in 13). Myelopathy preceded cancer diagnosis in 18 patients (median interval 12 months; range 2-44). After myelopathy onset, 26 patients underwent oncologic treatment, immunosuppressive treatment (median delay to commencing immunotherapy 9.5 months [range 1-54]), or both; only 8 improved (31%). At last neurologic evaluation (median interval after onset 17 months; range 1-165 months), 16 patients (52%) were wheelchair-dependent (median time from onset to wheelchair 9 months [range 1-21]). Ten patients died after a median of 38 months from symptom onset (range 7-152). CONCLUSION: Symmetric, longitudinally extensive tract or gray matter-specific changes on spinal MRI should raise suspicion for a paraneoplastic myelopathy. Resulting disability is often severe. Only a minority of patients improve with treatment.

Neuromyelitis optica unique area postrema lesions: nausea, vomiting, and pathogenic implications.

OBJECTIVE: To characterize the neuropathologic features of neuromyelitis optica (NMO) at the medullary floor of the fourth ventricle and area postrema. Aquaporin-4 (AQP4) autoimmunity targets this region, resulting in intractable nausea associated with vomiting or hiccups in NMO. METHODS: This neuropathologic study was performed on archival brainstem tissue from 15 patients with NMO, 5 patients with multiple sclerosis (MS), and 8 neurologically normal subjects. Logistic regression was used to evaluate whether the presence of lesions at this level increased the odds of a patient with NMO having an episode of nausea/vomiting. RESULTS: Six patients with NMO (40%), but no patients with MS or normal controls, exhibited unilateral or bilateral lesions involving the area postrema and the medullary floor of the fourth ventricle. These lesions were characterized by tissue rarefaction, blood vessel thickening, no obvious neuronal or axonal pathology, and preservation of myelin in the subependymal medullary tegmentum. AQP4 immunoreactivity was lost or markedly reduced in all 6 cases, with moderate to marked perivascular and parenchymal lymphocytic inflammatory infiltrates, prominent microglial activation, and in 3 cases, eosinophils. Complement deposition in astrocytes, macrophages, and/or perivascularly, and a prominent astroglial reaction were also present. The odds of nausea/vomiting being documented clinically was 16-fold greater in NMO cases with area postrema lesions (95% confidence interval 1.43-437, p = 0.02). CONCLUSIONS: These neuropathologic findings suggest the area postrema may be a selective target of the disease process in NMO, and are compatible with clinical reports of nausea and vomiting preceding episodes of optic neuritis and transverse myelitis or being the heralding symptom of NMO.

Absence of cortical demyelination in neuromyelitis optica.

OBJECTIVE: To asses the presence of cortical demyelination in brains of patients with neuromyelitis optica (NMO). NMO is an autoimmune inflammatory demyelinating disease that specifically targets aquaporin-4-rich regions of the CNS. Since aquaporin-4 is highly expressed in normal cortex, we anticipated that cortical demyelination may occur in NMO. METHODS: This is a cross-sectional neuropathologic study performed on archival forebrain and cerebellar tissue sections from 19 autopsied patients with a clinically and/or pathologically confirmed NMO spectrum disorder. RESULTS: Detailed immunohistochemical analyses of 19 archival NMO cases revealed preservation of aquaporin-4 in a normal distribution within cerebral and cerebellar cortices, and no evidence of cortical demyelination. CONCLUSIONS: This study provides a plausible explanation for the absence of a secondary progressive clinical course in NMO and shows that cognitive and cortical neuroimaging abnormalities previously reported in NMO cannot be attributed to cortical demyelination. Lack of cortical demyelination is another characteristic that further distinguishes NMO from MS.

Neurological autoimmunity targeting aquaporin-4.

Neuromyelitis optica (NMO) is the first inflammatory autoimmune demyelinating disease of the CNS for which a specific tissue target molecule has been identified--the astrocytic water channel aquaporin-4 (AQP4). Immunological insights have propelled significant advances in understanding the clinical, radiologic and immunopathologic characteristics of the disease in the last 5 years. In this review, we describe features distinguishing CNS AQP4 autoimmunity from classical multiple sclerosis (MS). In NMO, disease attacks preferentially involve the optic nerves and spinal cord (hence the name), but neurological signs in the initial attack of AQP4 autoimmunity in children commonly involve the brain. A clinically validated serum biomarker, NMO-IgG, distinguishes relapsing CNS inflammatory demyelinating disorders related to NMO from MS. The NMO-IgG autoantibody is AQP4-specific. Clinical, radiological and immunopathological data support its role in the pathogenesis of NMO spectrum disorders. Lesions characteristic of NMO are distinct from MS: AQP4 and its coupled glutamate transporter, excitatory amino acid transporter 2 (EAAT2), are lost, with and without associated myelin loss, IgG, IgM and complement are deposited in a vasculocentric pattern, edema and inflammation are prominent. In vitro studies demonstrate that binding of NMO-IgG to astrocytic AQP4 initiates multiple potentially neuropathogenic mechanisms: complement activation, AQP4 and EAAT2 downregulation with disruption of water and glutamate homeostasis, enhanced blood-brain barrier permeability, plasma protein and granulocyte influx, and antibody-dependent cell-mediated cytotoxicity. Development of effective, and potentially curative, therapies requires validated models of the disease, in animals and cell culture systems.

Neuromyelitis optica-IgG (aquaporin-4) autoantibodies in immune mediated optic neuritis.

The clinical course of immune mediated optic neuritis (ON) will depend on the specific underlying inflammatory disease. These disorders have traditionally been classified according to clinical and MRI findings. Aquaporin-4 (AQP4) autoantibodies (neuromyelitis optica-IgG (NMO-IgG)) may have diagnostic and prognostic value in patients who present with isolated ON. In this prospective study, NMO-IgG was evaluated in 114 patients with ON in the following contexts: neuromyelitis optica (NMO), multiple sclerosis (MSON), chronic relapsing inflammatory ON (CRION), relapsing isolated ON (RION) and single isolated ON (SION). The proportion seropositive was 56% for NMO (n = 9), 0% for MSON (n = 28) and 5% for the remaining diagnostic categories (CRION (n = 19), RION (n = 17) and SION (n = 41)). Testing for NMO-IgG in patients with recurrent or severe ON who lack convincing evidence of MS may identify patients who would benefit from immunosuppression rather than MS directed immunomodulatory therapies.

Posterior reversible encephalopathy syndrome in neuromyelitis optica spectrum disorders.

BACKGROUND: Posterior reversible encephalopathy syndrome (PRES) is characterized by vasogenic subcortical edema without infarction. It has been associated with hypertensive crises and with immunosuppressive medications but not with neuromyelitis optica (NMO). METHODS: We reviewed the clinical and neuroimaging features of five NMO-immunoglobulin G (IgG) seropositive white women who experienced an episode of PRES and had a coexisting NMO spectrum disorder (NMOSD). We also tested for the aquaporin-4 (AQP4) water channel autoantibody (NMO-IgG) in 14 patients from an independently ascertained cohort of individuals with PRES. RESULTS: All five patients developed abrupt confusion and depressed consciousness consistent with PRES. The encephalopathy resolved completely within 7 days. Comorbid conditions or interventions recognized to be associated with PRES included orthostatic hypotension with supine hypertension, plasma exchange, IV immunoglobulin treatment, and high-dose IV methylprednisolone. Brain MRI studies revealed bilateral T2-weighted (T2W) hyperintense signal abnormalities, primarily in frontal, parieto-occipital, and cerebellar regions. Three patients had highly symmetric lesions and three had gadolinium-enhancing lesions. Follow-up neuroimaging revealed partial or complete disappearance of T2W hyperintensity or gadolinium-enhancing lesions in all five patients. Patients with PRES without NMOSD were uniformly NMO-IgG seronegative. CONCLUSIONS: Brain lesions in some patients with neuromyelitis optica spectrum disorder (NMOSD) may be accompanied by vasogenic edema and manifest as posterior reversible encephalopathy syndrome (PRES). Water flux impairment due to aquaporin-4 autoimmunity may predispose to PRES in patients with NMOSD who experience blood pressure fluctuations or who are treated with therapies that can cause rapid fluid shifts.

Clinical spectrum of voltage-gated potassium channel autoimmunity.

OBJECTIVE: To document neurologic, oncologic, and serologic associations of patients in whom voltage-gated potassium channel (VGKC) autoantibodies were detected in the course of serologic evaluation for neuronal, glial, and muscle autoantibodies. METHODS: Indirect immunofluorescence screening of sera from 130,000 patients performed on a service basis for markers of paraneoplastic neurologic autoimmunity identified 80 patients whose IgG bound to the synapse-rich molecular layer of mouse cerebellar cortex in a pattern consistent with VGKC immunoreactivity. Antibody specificity was confirmed in all cases by immunoprecipitation of detergent-solubilized brain synaptic proteins complexed with (125)I-alpha-dendrotoxin. RESULTS: Clinical information was available for 72 patients: 51% women, median age at symptom onset 65 years, and median follow-up period 14 months. Neurologic manifestations were acute to subacute in onset in 71% and multifocal in 46%; 71% had cognitive impairment, 58% seizures, 33% dysautonomia, 29% myoclonus, 26% dyssomnia, 25% peripheral nerve dysfunction, 21% extrapyramidal dysfunction, and 19% brainstem/cranial nerve dysfunction. Creutzfeldt-Jakob disease was a common misdiagnosis (14%). Neoplasms encountered (confirmed histologically in 33%) included 18 carcinomas, 5 adenomas, 1 thymoma, and 3 hematologic malignancies. Hyponatremia was documented in 36%, other organ-specific autoantibodies in 49%, and a co-existing autoimmune disorder in 33% (including thyroiditis 21%, type 1 diabetes mellitus 11%). Benefit was reported for 34 of 38 patients (89%) receiving immunotherapy and was marked in 50%. CONCLUSIONS: The spectrum of neurologic manifestations and neoplasms associated with voltage-gated potassium channel (VGKC) autoimmunity is broader than previously recognized. Evaluation for VGKC antibodies is recommended in the comprehensive autoimmune serologic testing of subacute idiopathic neurologic disorders.

CNS aquaporin-4 autoimmunity in children.

BACKGROUND: In adult patients, autoantibodies targeting the water channel aquaporin-4 (AQP4) are a biomarker for a spectrum of CNS inflammatory demyelinating disorders with predilection for optic nerves and spinal cord (neuromyelitis optica [NMO]). Here we describe the neurologic, serologic, and radiographic findings associated with CNS AQP4 autoimmunity in childhood. METHODS: A total of 88 consecutive seropositive children were identified through service evaluation for NMO-IgG. Sera of 75 were tested for coexisting autoantibodies. Clinical information was available for 58. RESULTS: Forty-two patients (73%) were non-Caucasian, and 20 (34%) had African ethnicity. Median age at symptom onset was 12 years (range 4-18). Fifty-seven (98%) had attacks of either optic neuritis (n = 48; 83%) or transverse myelitis (n = 45; 78%), or both. Twenty-six (45%) had episodic cerebral symptoms (encephalopathy, ophthalmoparesis, ataxia, seizures, intractable vomiting, or hiccups). Thirty-eight (68%) had brain MRI abnormalities, predominantly involving periventricular areas (in descending order of frequency): the medulla, supratentorial and infratentorial white matter, midbrain, cerebellum, thalamus, and hypothalamus. Additional autoantibodies were detected in 57 of 75 patients (76%), and 16 of 38 (42%) had a coexisting autoimmune disorder recorded (systemic lupus erythematosus, Sjögren syndrome, juvenile rheumatoid arthritis, Graves disease). Attacks were recurrent in 54 patients (93%; median follow-up, 12 months). Forty-three of 48 patients (90%) had residual disability: 26 (54%) visual impairment and 21 (44%) motor deficits (median Expanded Disability Status Scale 4.0 at 12 months). CONCLUSIONS: Aquaporin-4 autoimmunity is a distinctive recurrent and widespread inflammatory CNS disease in children.

NMO-IgG predicts the outcome of recurrent optic neuritis.

OBJECTIVE: To determine the prognostic value of neuromyelitis optica (NMO)-immunoglobulin G (IgG) in patients with recurrent optic neuritis (ON). The aquaporin-4-specific serum autoantibody, NMO-IgG, is a biomarker for NMO and relapsing transverse myelitis. Recurrent ON may herald multiple sclerosis (MS) or NMO, or it may occur as an isolated syndrome. The prognosis and response to therapy differs in each of these contexts. METHODS: We evaluated 34 patients who were tested for NMO-IgG between 2000 and 2007 and who had two or more episodes of ON without satisfying a diagnosis of MS or NMO prior to serologic testing. Clinical data were available for 25 Mayo Clinic patients (5 NMO-IgG positive and 20 NMO-IgG negative) and for an additional 9 seropositive patients whose serum was referred to the Mayo Clinic Neuroimmunology laboratory for testing. RESULTS: Twenty percent of the patients with recurrent ON seen at Mayo Clinic were seropositive. All NMO-IgG-positive patients (vs 65% NMO-IgG-negative patients) had at least one attack with visual acuity in the affected eye worse than 20/200 (p = 0.05). In seropositive patients for whom long-term follow-up was possible (median 8.9 years after the initial ON), 6 of 12 (50%) experienced an episode of myelitis and fulfilled criteria for NMO. In contrast, 1 of 15 seronegative patients (6.7%) fulfilled McDonald criteria for MS (p = 0.03). Seropositive patients had a final visual score which was worse than that of seronegative patients (p = 0.02). CONCLUSIONS: Neuromyelitis optica (NMO)-immunoglobulin G seropositivity predicts poor visual outcome and development of NMO. Seropositive recurrent optic neuritis is a limited form of NMO.

Neuromyelitis optica-IgG in childhood inflammatory demyelinating CNS disorders.

OBJECTIVE: To determine seroprevalence of neuromyelitis optica (NMO)-IgG in childhood CNS inflammatory demyelinating disorders. METHODS: We analyzed demographic, clinical, and radiologic data in a blinded fashion and assessed serum NMO-IgG status for 87 children: 41 with relapsing-remitting multiple sclerosis (RRMS), 17 with NMO, 13 with monophasic/recurrent optic neuritis (ON), 13 with transverse myelitis, of whom 10 were longitudinally extensive on MRI spine (LETM), and another 3 with LETM in the context of acute disseminated encephalomyelitis (ADEM). RESULTS: Ten of the 87 children (11%) were seropositive. Eight of 17 with NMO (47%) were seropositive (7 of 9 with relapsing NMO [78%], 1 of 8 with monophasic NMO [12.5%]). Two other children were seropositive: 1 of 5 with recurrent ON and one child with recurrent LETM. No seropositive case was identified among 41 with RRMS (14% of whom had LETM at some point in their clinical course), 8 with monophasic ON, 9 with monophasic LETM, or 3 with LETM in the context of ADEM. CONCLUSIONS: The similar frequency of neuromyelitis optica (NMO)-IgG in both childhood and adult cases of NMO, and its rarity in relapsing-remitting multiple sclerosis, supports the concept that these diseases have a similar pathogenesis in childhood and adulthood. It is noteworthy that none of nine children with monophasic longitudinally extensive transverse myelitis (LETM) was NMO-IgG-seropositive. Furthermore, LETM does not appear to be as predictive of an NMO spectrum disorder in children as it is in adults. Longitudinal studies of larger pediatric LETM cohorts are required to ascertain whether the absence of NMO-IgG is a negative predictor for relapse in this childhood entity.

Bilateral autoimmune optic neuritis and vitreitis related to CRMP-5-IgG: intravitreal triamcinolone acetonide therapy of four eyes.

PURPOSE: To report the vision outcome following intravitreal triamcinolone acetonide (IVTA) as adjunctive therapy in four eyes of two patients with paraneoplastic autoimmune optic neuritis and vitreitis related to CRMP (Collapsin-Response-Mediator Protein)-5-IgG. DESIGN: Retrospective case series.MethodsChart review of four eyes. RESULTS: Preoperative visions were: patient 1, 20/50 OD, 20/25 OS; patient 2, counting fingers (CF) at two feet OD, and CF at three feet OS. At last follow-up, the postoperative visions were 20/40, 20/50 and 20/200, 20/60, respectively. All signs of optic disc swelling and vitreitis had abated. CONCLUSIONS: Use of IVTAin paraneoplastic autoimmune optic neuritis and vitreitis related to CRMP-5-IgG was followed by a marked decrease in inflammation and stabilization or improvement of vision. These observations support this form of adjunctive therapy in patients whose intraocular pathology is attributed to paraneoplastic autoimmunity.

Pathogenic potential of IgG binding to water channel extracellular domain in neuromyelitis optica.

BACKGROUND: Autoantibody specific for the aquaporin-4 astrocytic water channel is restricted to serum and CSF of patients with neuromyelitis optica (NMO) and related CNS inflammatory demyelinating disorders (relapsing optic neuritis and longitudinally extensive transverse myelitis). NMO-typical lesions are distinct from MS-typical lesions. Aquaporin-4 is lost selectively at vasculocentric sites of edema/inflammation coinciding with focal deposits of immunoglobulins (Ig) G, M, and terminal complement products, with and without myelin loss. Evidence for antigen-specific autoantibody pathogenicity is lacking. METHODS: We used confocal microscopy and flow cytometry to evaluate the selectivity and immunopathological consequences of Ig binding to surface epitopes of living target cells expressing aquaporin-4 fused at its cytoplasmic N-terminus with GFP. We tested serum, IgG-enriched and IgG-depleted serum fractions, and CSF from patients with NMO, neurologic control patients, and healthy subjects. We also analyzed aquaporin-4 immunoreactivity in myelinated adult mouse optic nerves and spinal cord, and plasma cell Ig isotypes in archived brain tissue from an NMO patient. RESULTS: Serum IgG from patients with NMO binds to the extracellular domain of aquaporin-4; it is predominantly IgG(1), and it initiates two potentially competing outcomes, aquaporin-4 endocytosis/degradation and complement activation. Serum and CSF lack aquaporin-4-specific IgM, and plasma cells in CNS lesions of NMO contain only IgG. Paranodal astrocytic endfeet highly express aquaporin-4. CONCLUSIONS: NMO patients' serum IgG has a selective pathologic effect on cell membranes expressing aquaporin-4. IgG targeting astrocytic processes around nodes of Ranvier could initiate demyelination.

A secondary progressive clinical course is uncommon in neuromyelitis optica.

We compared the clinical course of 96 patients with neuromyelitis optica (NMO) to multiple sclerosis (MS) natural history data. Based on the distribution of follow-up data (median 6.1 year), we estimated that 21 NMO patients would convert to a secondary progressive course, but we observed only two conversions (p = 0.00002; relative risk = 0.08). The disparate natural histories of MS and NMO suggest dissociation between relapses and clinical progression in CNS demyelinating diseases.

Revised diagnostic criteria for neuromyelitis optica.

BACKGROUND: The authors previously proposed diagnostic criteria for neuromyelitis optica (NMO) that facilitate its distinction from prototypic multiple sclerosis (MS). However, some patients with otherwise typical NMO have additional symptoms not attributable to optic nerve or spinal cord inflammation or have MS-like brain MRI lesions. Furthermore, some patients are misclassified as NMO by the authors' earlier proposed criteria despite having a subsequent course indistinguishable from prototypic MS. A serum autoantibody marker, NMO-IgG, is highly specific for NMO. The authors propose revised NMO diagnostic criteria that incorporate NMO-IgG status. METHODS: Using final clinical diagnosis (NMO or MS) as the reference standard, the authors calculated sensitivity and specificity for each criterion and various combinations using a sample of 96 patients with NMO and 33 with MS. The authors used likelihood ratios and logistic regression analysis to develop the most practical and informative diagnostic model. RESULTS: Fourteen patients with NMO (14.6%) had extra-optic-spinal CNS symptoms. NMO-IgG seropositivity was 76% sensitive and 94% specific for NMO. The best diagnostic combination was 99% sensitive and 90% specific for NMO and consisted of at least two of three elements: longitudinally extensive cord lesion, onset brain MRI nondiagnostic for MS, or NMO-IgG seropositivity. CONCLUSIONS: The authors propose revised diagnostic criteria for definite neuromyelitis optica (NMO) that require optic neuritis, myelitis, and at least two of three supportive criteria: MRI evidence of a contiguous spinal cord lesion 3 or more segments in length, onset brain MRI nondiagnostic for multiple sclerosis, or NMO-IgG seropositivity. CNS involvement beyond the optic nerves and spinal cord is compatible with NMO.