Helena Ariño

Cerebellar Ataxia and Glutamic Acid Decarboxylase Antibodies: Immunologic Profile and Long-term Effect of Immunotherapy

IMPORTANCE Current clinical and immunologic knowledge on cerebellar ataxia (CA) with glutamic acid decarboxylase 65 antibodies (GAD65-Abs) is based on case reports and small series with short-term follow-up data. OBJECTIVE To report the symptoms, additional antibodies, prognostic factors, and long-term outcomes in a cohort of patients with CA and GAD65-Abs. DESIGN, SETTING, AND PARTICIPANTS Retrospective cohort study and laboratory investigations at a center for autoimmune neurologic disorders among 34 patients with CA and GAD65-Abs, including 25 with long-term follow-up data (median, 5.4 years; interquartile range, 3.1-10.3 years). MAIN OUTCOMES AND MEASURES Analysis of clinicoimmunologic features and predictors of response to immunotherapy. Immunochemistry on rat brain, cultured neurons, and human embryonic kidney cells expressing GAD65, GAD67, α1-subunit of the glycine receptor, and a repertoire of known cell surface autoantigens were used to identify additional antibodies. Twenty-eight patients with stiff person syndrome and GAD65-Abs served as controls. RESULTS The median age of patients was 58 years (range, 33-80 years); 28 of 34 patients (82%) were women. Nine patients (26%) reported episodes of brainstem and cerebellar dysfunction or persistent vertigo several months before developing CA. The clinical presentation was subacute during a period of weeks in 13 patients (38%). Nine patients (26%) had coexisting stiff person syndrome symptoms. Systemic organ-specific autoimmunities (type 1 diabetes mellitus and others) were present in 29 patients (85%). Twenty of 25 patients with long-term follow-up data received immunotherapy (intravenous immunoglobulin in 10 and corticosteroids and intravenous immunoglobulin or other immunosuppressors in 10), and 7 of them (35%) improved. Predictors of clinical response included subacute onset of CA (odds ratio [OR], 0.50; 95% CI, 0.25-0.99; P = .047) and prompt immunotherapy (OR, 0.98; 95% CI, 0.96-0.99; P = .01). Similar frequencies of serum GAD67-Abs were found in patients with CA (24 of 34 patients [71%]) and in patients with stiff person syndrome (20 of 28 patients [71%]). However, GAD67-Abs were found in all of the cerebrospinal fluid samples examined (22 samples from patients with CA and 17 samples from patients with stiff person syndrome). Glycine receptor antibodies but not other cell surface antibodies were identified in 4 patients with CA. The presence of glycine receptor antibodies did not correlate with any specific clinical feature. CONCLUSIONS AND RELEVANCE In patients with CA and GAD65-Abs, subacute onset of symptoms and prompt immunotherapy are associated with good outcome. Persistent vertigo or brainstem and cerebellar episodes can herald CA and should lead to GAD65-Ab testing, particularly in patients with systemic organ-specific autoimmunities.

Antibodies to inhibitory synaptic proteins in neurological syndromes associated with glutamic acid decarboxylase autoimmunity.

Antibodies to glutamic acid decarboxylase (GAD-ab) associate to different neurological syndromes. It is unknown if the diversity in syndrome association represents epitopes in different immunodominant domains or co-existence of antibodies to other proteins of the inhibitory synapsis. We examined the serum and CSF of 106 patients with anti-GAD related syndromes (39 cerebellar ataxia, 32 stiff-person syndrome [SPS], 18 epilepsy, and 17 limbic encephalitis [LE]). GAD65-ab titres were quantified by ELISA. Immunoblot was used to determine if the antibody-targeted epitopes of GAD65 and GAD67 were linear. A cell-based assay (CBA) with HEK293 cells expressing the GAD65 N-terminal, central catalytic domain, or C-terminal was used to investigate the immunodominant domains. Antibodies to GAD67, gamma-aminobutyric acid A receptor (GABAaR), glycine receptor (GlyR), GABAaR-associated protein (GABARAP), and gephyrin were determined with CBA. GAD-ab internalization was investigated using cultured rat hippocampal neurons. CSF GAD65-ab titres were higher in patients with cerebellar ataxia and LE compared to those with SPS (p = 0.02). GAD67-ab were identified in 81% of sera and 100% of CSF. GAD65-ab recognized linear epitopes in 98% of the patients and GAD67-ab in 42% (p<0.001). The GAD65 catalytic domain was recognized by 93% of sera, and the three domains by 22% of sera and 74% of CSF (p<0.001). Six patients had GABAaR-ab and another 6 had GlyR-ab without association to distinctive symptoms. None of the patients had gephyrin- or GABARAP-ab. GAD65-ab were not internalized by live neurons. Overall, these findings show that regardless of the neurological syndrome, the CSF immune response against GAD is more widespread than that of the serum and that there is no specific association between clinical phenotype and the presence of antibodies against other proteins of the inhibitory synapsis.

Paraneoplastic neurological syndromes in Hodgkin and non-Hodgkin lymphomas

Paraneoplastic neurological syndromes (PNSs) rarely associate with Hodgkin lymphoma (HL) and non-HLs (NHLs). Except for paraneoplastic cerebellar degeneration (PCD) in HL and dermato/ polymyositis in both HL and NHL, other PNSs are uncommon and have only been reported as isolated case reports or short series. There are several important differences in PNSs when occurring in association with HL and NHL compared with those associated with solid tumors. First, some PNSs such as sensory neuronopathy or Lambert-Eaton myasthenic syndrome rarely occur in lymphomas, whereas others, such as granulomatous angiitis, are only described in HL. Second, onconeural antibodies are absent in most PNSs associated with lymphomas with the exceptions of Tr (δ/notch-like epidermal growth factor-related receptor) in PCD and mGluR5 in limbic encephalitis (LE). The antigens recognized by these antibodies are not expressed in lymphoma cells, suggesting the tumor itself does not trigger the PNS. Third, unlike patients with solid tumors in patients with lymphoma, the PNSs often develops at advanced stages of the disease. Furthermore, the type and frequency of PNSs are different between HL and NHL; whereas LE and PCD occur almost exclusively in patients with HL, sensorimotor neuropathies and dermatomyositis are more frequent in NHL.

Anti-LGI1–associated cognitive impairment: Presentation and long-term outcome

Objective: We investigated a series of patients with LGI1 antibody (Ab)–related cognitive deterioration to determine the clinical presentation, long-term outcome, and LGI1 Ab evolution. Methods: We retrospectively analyzed the clinical information of 76 patients with LGI1 Ab–related cognitive deterioration. Presenting syndromes were classified as limbic encephalitis (LE), non-LE, or encephalopathy (normal MRI and no CSF pleocytosis). Frequency of relapses and clinical outcome were assessed in 48 patients with prolonged follow-up (median 39 months, range 18–200). Results: Sixty-three patients (83%) developed LE, 3 (4%) non-LE, and 10 (13%) encephalopathy. All patients received steroids, IV immunoglobulins (Ig), or both. At 2 years, 17 (35%; 95% CI 21%–49%) fully recovered, 17 (35%) became functionally independent but not at baseline or were unable to return to work, 11 (23%) required assistance because of moderate or severe cognitive deficits, and 3 (6%) died. Predictors of bad outcome included no response to initial immunotherapy (odds ratio 23.0, 95% CI 2.4–215.6, p = 0.006) and clinical relapses (odds ratio 10.2, 95% CI 1.0–100.1, p = 0.047) that occurred in 13 patients (27%). In all patients, the LGI1 Abs were IgG4 and usually detectable in both serum and CSF (only CSF, 8%). Abs remained positive in serum of 4 of 16 patients with long-term follow-up; 3 of these 4 patients fully recovered and none showed class switch to IgG1. Conclusions: Up to 13% of patients with LGI1 Abs develop cognitive impairment without criteria of encephalitis. After immunotherapy, only 35% of patients return to their baseline cognitive function. Serum LGI1 Abs may remain detectable after full clinical recovery.

Paraneoplastic Neurological Syndromes and Glutamic Acid Decarboxylase Antibodies

IMPORTANCE Little is known of glutamic acid decarboxylase antibodies (GAD-abs) in the paraneoplastic context. Clinical recognition of such cases will lead to prompt tumor diagnosis and appropriate treatment. OBJECTIVE To report the clinical and immunological features of patients with paraneoplastic neurological syndromes (PNS) and GAD-abs. DESIGN, SETTING, AND PARTICIPANTS Retrospective case series study and immunological investigations conducted in February 2014 in a center for autoimmune neurological disorders. Fifteen cases with GAD65-abs evaluated between 1995 and 2013 who fulfilled criteria of definite or possible PNS without concomitant onconeural antibodies were included in this study. MAIN OUTCOMES AND MEASURES Analysis of the clinical records of 15 patients and review of 19 previously reported cases. Indirect immunofluorescence with rat hippocampal neuronal cultures and cell-based assays with known neuronal cell-surface antigens were used. One hundred six patients with GAD65-abs and no cancer served as control individuals. RESULTS Eight of the 15 patients with cancer presented as classic paraneoplastic syndromes (5 limbic encephalitis, 1 paraneoplastic encephalomyelitis, 1 paraneoplastic cerebellar degeneration, and 1 opsoclonus-myoclonus syndrome). When compared with the 106 non-PNS cases, those with PNS were older (median age, 60 years vs 48 years; P = .03), more frequently male (60% vs 13%; P < .001), and had more often coexisting neuronal cell-surface antibodies, mainly against γ-aminobutyric acid receptors (53% vs 11%; P < .001). The tumors more frequently involved were lung (n = 6) and thymic neoplasms (n = 4). The risk for an underlying tumor was higher if the presentation was a classic PNS, if it was different from stiff-person syndrome or cerebellar ataxia (odds ratio, 10.5; 95% CI, 3.2-34.5), or if the patient had coexisting neuronal cell-surface antibodies (odds ratio, 6.8; 95% CI, 1.1-40.5). Compared with the current series, the 19 previously reported cases had more frequent stiff-person syndrome (74% vs 13%; P = .001) and better responses to treatment (79% vs 27%; P = .005). Predictors of improvement in the 34 patients (current and previously reported) included presentation with stiff-person syndrome and the presence of a thymic tumor. CONCLUSIONS AND RELEVANCE Patients with GAD-abs must be screened for an underlying cancer if they have clinical presentations different from those typically associated with this autoimmunity or develop classic PNS. The risk for cancer increases with age, male sex, and the presence of coexisting neuronal cell-surface antibodies.

The Outcome of Patients with Mild Stroke Improves after Treatment with Systemic Thrombolysis

Introduction In up to one third of patients with mild stroke suitable to receive systemic thrombolysis the treatment is not administered because the treating physicians estimate a good spontaneous recovery. However, it is not settled whether the fate of these patients is equivalent to those who are thrombolysed. Methods We analyzed 203 consecutive patients (134 men and 69 women, mean age 69±14 years) without premorbid disability and a NIHSS score ≤5 at admission [median 3 (IQR 2–4)]. Intravenous thrombolysis was administered within 4.5 hours from stroke onset (n = 119), or it was withheld (n = 84) whenever the treating physician predicted a spontaneous recovery. The baseline risk factors, clinical course, infarction volume, bleeding complications, and functional outcome at 3 months were analyzed and declared to a Web-based registry which was accessible to the local Health Authorities. Results Expectedly, not thrombolysed patients had the mildest strokes at admission [median 2 (IQR 1–3.75)]. At day 2 to 5, the infarct volume on DWI-MRI was similar in both groups. There were no symptomatic cerebral bleedings in the study. An ordinal regression model adjusted for baseline stroke severity showed that thrombolysis was associated with a greater proportion of patients who shifted down on the modified Rankin Scale score at 3 months (OR 2.66; 95% CI 1.49–4.74, p = 0.001). Conclusions Intravenous thrombolysis seems to be safe in patients with mild stroke and may be associated with improved outcome compared with untreated patients. These results support the evaluation of the efficacy of intravenous thrombolysis in mild stroke patients in randomized clinical trials.

Clinical and Immunologic Investigations in Patients With Stiff-Person Spectrum Disorder

IMPORTANCE Symptoms of stiff-person syndrome (SPS), stiff-limb syndrome (SLS), or progressive encephalomyelitis with rigidity, myoclonus, or other symptoms (SPS-plus) can occur with several autoantibodies, but the relative frequency of each antibody, syndrome specificity, and prognostic implications are unclear. OBJECTIVE To report the clinical and immunologic findings of a large cohort of patients with stiff-person spectrum disorder (SPSD), including SPS, SLS, and SPS-plus. DESIGN, SETTING, AND PATIENTS This study retrospectively examined a case series (January 1, 1998, through December 31, 2014) of immunologic investigations performed in a neuroimmunology referral center. The study included 121 patients with clinical features of SPSD. Data analysis was performed from July 1, 2015, through November 1, 2015. MAIN OUTCOMES AND MEASURES Analysis of clinical-immunologic associations, including autoantibodies to 8 proteins expressed in inhibitory synapses. RESULTS The median age of the patients was 51 years (interquartile range, 40-61 years), and 75 (62.0%) were female. Fifty (41.3%) had SPS, 37 (30.6%) had SPS-plus, 24 (19.8%) had SLS, and 10 (8.3%) had SPS or SLS overlapping with ataxia, epilepsy, or encephalitis. Fifty-two patients (43.0%) had glutamic acid decarboxylase (GAD65) antibodies (2 with γ-aminobutyric acid-A [GABA-A] receptor antibodies), 24 (19.8%) had α1-subunit of the glycine receptor (GlyR) antibodies (2 with GAD65 antibodies), 5 (4.1%) had other antibodies, and 40 (33.1%) tested negative for antibodies. None had gephyrin or glycine transporter antibodies. Among the main immunologic groups (GAD65 antibodies, GlyR antibodies, and antibody negative), those with GAD65 antibodies were more likely to be female (45 [86.5%] of 52, 8 [36.4%] of 22, and 18 [45.0%] of 40, respectively; P < .001), have systemic autoimmunity (34 [65.4%] of 52, 7 [31.8%] of 22, and 13 [32.5%] of 40, respectively; P = .004), and have longer delays in being tested for antibodies (median, 3 vs 0.5 and 1 year; P < .001). Patients with GAD65 antibodies were more likely to develop SPS (27 [51.9%] of 52) or overlapping syndromes (8 [15.4%] of 52) than patients with GlyR antibodies (5 [22.7%] and 0 [0%] of 22, respectively), who more often developed SPS-plus (12 [54.5%] of 22 vs 7 [13.5%] in those with GAD65 antibodies); antibody-negative patients had an intermediate syndrome distribution. In multivariable analysis, symptom severity (P = .001) and immunologic group (P = .01) were independently associated with outcome. Compared with patients with GlyR antibodies, those with GAD65 antibodies (odds ratio, 11.1, 95% CI, 2.3-53.7; P = .003) had worse outcome. Patients without antibodies had similar outcome than patients with GlyR antibodies (odds ratio, 4.2, 95% CI, 0.9-20.0; P = .07). CONCLUSIONS AND RELEVANCE In SPSD, symptom severity and presence and type of antibodies are predictors of outcome.

Clinical and Immunological Features of Opsoclonus-Myoclonus Syndrome in the Era of Neuronal Cell Surface Antibodies

IMPORTANCE Most studies on opsoclonus-myoclonus syndrome (OMS) in adults are based on small case series before the era of neuronal cell surface antibody discovery. OBJECTIVE To report the clinical and immunological features of idiopathic OMS (I-OMS) and paraneoplastic OMS (P-OMS), the occurrence of antibodies to cell surface antigens, and the discovery of a novel cell surface epitope. DESIGN, SETTING, AND PARTICIPANTS Retrospective cohort study and laboratory investigations of 114 adult patients with OMS at a center for autoimmune neurological disorders done between January 2013 and September 2015. MAIN OUTCOMES AND MEASURES Review of clinical records. Immunohistochemistry on rat brain and cultured neurons as well as cell-based assays were used to identify known autoantibodies. Immunoprecipitation and mass spectrometry were used to characterize novel antigens. RESULTS Of the 114 patients (62 [54%] female; median age, 45 years; interquartile range, 32-60 years), 45 (39%) had P-OMS and 69 (61%) had I-OMS. In patients with P-OMS, the associated tumors included lung cancer (n = 19), breast cancer (n = 10), other cancers (n = 5), and ovarian teratoma (n = 8); 3 additional patients without detectable cancer were considered to have P-OMS because they had positive results for onconeuronal antibodies. Patients with I-OMS, compared with those who had P-OMS, were younger (median age, 38 [interquartile range, 31-50] vs 54 [interquartile range, 45-65] years; P < .001), presented more often with prodromal symptoms or active infection (33% vs 13%; P = .02), less frequently had encephalopathy (10% vs 29%; P = .01), and had better outcome (defined by a modified Rankin Scale score ≤ 2 at last visit; 84% vs 39%; P < .001) with fewer relapses (7% vs 24%; P= .04). Onconeuronal antibodies occurred in 13 patients (11%), mostly Ri/ANNA2 antibodies, which were detected in 7 of 10 patients (70%) with breast cancer. Neuronal surface antibodies were identified in 12 patients (11%), mainly glycine receptor antibodies (9 cases), which predominated in P-OMS with lung cancer (21% vs 5% in patients with OMS without lung cancer; P = .02); however, a similar frequency of glycine receptor antibodies was found in patients with lung cancer without OMS (13 of 65 patients [20%]). A novel cell surface epitope, human natural killer 1 (HNK-1), was the target of the antibodies in 3 patients with lung cancer and P-OMS. CONCLUSIONS AND RELEVANCE Patients with I-OMS responded better to treatment and had fewer relapses than those with P-OMS. Older age and encephalopathy, significantly associated with P-OMS, are clinical clues suggesting an underlying tumor. Glycine receptor antibodies occur frequently in P-OMS with lung cancer, but the sensitivity and specificity are low. The HNK-1 epitope is a novel epitope in a subset of patients with P-OMS and lung cancer.

DPPX antibody-associated encephalitis: Main syndrome and antibody effects.

Objective: To report the main syndrome of dipeptidyl-peptidase–like protein 6 (DPPX) antibody–associated encephalitis, immunoglobulin G (IgG) subclass, and the antibody effects on DPPX/Kv4.2 potassium channels. Methods: A retrospective analysis of new patients and cases reported since 2013 was performed. IgG subclass and effects of antibodies on cultured neurons were determined with described techniques. Results: Nine new patients were identified (median age 57 years, range 36–69 years). All developed severe prodromal weight loss or diarrhea followed by cognitive dysfunction (9), memory deficits (5), CNS hyperexcitability (8; hyperekplexia, myoclonus, tremor, or seizures), or brainstem or cerebellar dysfunction (7). The peak of the disease was reached 8 months (range 1–54 months) after onset. All patients had both IgG4 and IgG1 DPPX antibodies. In cultured neurons, the antibodies caused a decrease of DPPX clusters and Kv4.2 protein that was reversible on removal of the antibodies. Considering the current series and previously reported cases (total 39), 67% developed the triad: weight loss (median 20 kg; range 8–53 kg)/gastrointestinal symptoms, cognitive-mental dysfunction, and CNS hyperexcitability. Outcome was available from 35 patients (8 not treated with immunotherapy): 60% had substantial or moderate improvement, 23% had no improvement (most of them not treated), and 17% died. Relapses occurred in 8 of 35 patients (23%) and were responsive to immunotherapy. Conclusions: DPPX antibodies are predominantly IgG1 and IgG4 and associate with cognitive-mental deficits and symptoms of CNS hyperexcitability that are usually preceded by diarrhea, other gastrointestinal symptoms, and weight loss. The disorder is responsive to immunotherapy, and this is supported by the reversibility of the antibody effects in cultured neurons.

Antibody-associated CNS syndromes without signs of inflammation in the elderly.

Objective: To report the CNS syndromes of patients ≥60 years of age with antibodies against neuronal surface antigens but no evidence of brain MRI and CSF inflammatory changes. Methods: This was a retrospective clinical analysis of patients with antibodies against neuronal surface antigens who fulfilled 3 criteria: age ≥60 years, no inflammatory abnormalities in brain MRI, and no CSF pleocytosis. Antibodies were determined with reported techniques. Results: Among 155 patients ≥60 years of age with neurologic syndromes related to antibodies against neuronal surface antigens, 35 (22.6%) fulfilled the indicated criteria. The median age of these 35 patients was 68 years (range 60–88 years). Clinical manifestations included faciobrachial dystonic seizures (FBDS) in 11 of 35 (31.4%) patients, all with LGI1 antibodies; a combination of gait instability, brainstem dysfunction, and sleep disorder associated with IgLON5 antibodies in 10 (28.6%); acute confusion, memory loss, and behavioral changes suggesting autoimmune encephalitis (AE) in 9 (25.7%; 2 patients with AMPAR, 2 with NMDAR, 2 with GABAbR, 2 with LGI1, and 1 with CASPR2 antibodies); and rapidly progressive cognitive deterioration in 5 (14.3%; 3 patients with IgLON5 antibodies, 1 with chorea; 1 with DPPX antibody–associated cerebellar ataxia and arm rigidity; and 1 with CASPR2 antibodies). Conclusions: In patients ≥60 years of age, the correct identification of characteristic CNS syndromes (FBDS, anti-IgLON5 syndrome, AE) should prompt antibody testing even without evidence of inflammation in MRI and CSF studies. Up to 15% of the patients developed rapidly progressive cognitive deterioration, which further complicated the differential diagnosis with a neurodegenerative disorder.