Agnes van Sonderen

Anti-LGI1 encephalitis: Clinical syndrome and long-term follow-up

Objective: This nationwide study gives a detailed description of the clinical features and long-term outcome of anti–leucine-rich glioma-inactivated 1 (LGI1) encephalitis. Methods: We collected patients prospectively from October 2013, and retrospectively from samples sent to our laboratory from January 2007. LGI1 antibodies were confirmed with both cell-based assay and immunohistochemistry. Clinical information was obtained in interviews with patients and their relatives and from medical records. Initial MRI and follow-up MRI were revised blindly. Neuropsychological assessment was performed in those patients with follow-up over 2 years. Results: Annual incidence in the Netherlands was 0.83/million. A total of 34/38 patients had a limbic encephalitis. Subtle focal seizures (66%, autonomic or dyscognitive) and faciobrachial dystonic seizures (FBDS, 47%) mostly occurred before onset of memory disturbance. Later in the disease course, 63% had tonic-clonic seizures. Initial MRI showed hippocampal T2 hyperintensity in 74% of the patients. These lesions evolved regularly into mesial temporal sclerosis (44%). Substantial response to immunotherapy was seen in 80%, with early response of seizures and slow recovery of cognition. At follow-up ≥2 years, most surviving patients reported mild residual cognitive deficit with spatial disorientation. A total of 86% had persistent amnesia for the disease period. Relapses were common (35%) and presented up to 8 years after initial disease. Two-year case fatality rate was 19%. Conclusions: Anti-LGI1 encephalitis is a homogenous clinical syndrome, showing early FBDS and other focal seizures with subtle clinical manifestations, followed by memory disturbances. Better recognition will lead to earlier diagnosis, essential for prompt start of treatment. Long-term outcome of surviving patients is mostly favorable, but relapses are common.

The relevance of VGKC positivity in the absence of LGI1 and Caspr2 antibodies

Objective: To assess the clinical relevance of a positive voltage-gated potassium channel (VGKC) test in patients lacking antibodies to LGI1 and Caspr2. Methods: VGKC-positive patients were tested for LGI1 and Caspr2 antibodies. Patients lacking both antibodies were matched (1:2) to VGKC-negative patients. Clinical and paraclinical criteria were used to blindly determine evidence for autoimmune inflammation in both groups. Patients with an inconclusive VGKC titer were analyzed in the same way. Results: A total of 1,455 patients were tested by VGKC radioimmunoassay. Fifty-six patients tested positive, 50 of whom were available to be included. Twenty-five patients had antibodies to LGI1 (n = 19) or Caspr2 (n = 6) and 25 patients lacked both antibodies. Evidence for autoimmune inflammation was present in 7 (28%) of the VGKC-positive patients lacking LGI1 and Caspr2, compared to 9 (18%) of the VGKC-negative controls (p = 0.38). Evidence for autoimmune inflammation was mainly found in patients with limbic encephalitis/encephalomyelitis (57%), but not in other clinical phenotypes (5%, p < 0.01). VGKC titers were significantly higher in patients with antibodies to LGI1 or Caspr2 (p < 0.001). However, antibodies to Caspr2 could also be detected in patients with inconclusive low VGKC titer, while many VGKC-positive patients had no evidence for autoimmune inflammation. Conclusions: VGKC positivity in the absence of antibodies to LGI1 and Caspr2 is not a clear marker for autoimmune inflammation and seems not to contribute in clinical practice. No cutoff value for the VGKC titer was appropriate to discriminate between patients with and without autoimmune inflammation.

The value of LGI1, Caspr2 and voltage-gated potassium channel antibodies in encephalitis

The discovery, in 2010, of autoantibodies against the extracellular proteins LGI1 and Caspr2 facilitated a change of view regarding the clinical importance of voltage-gated potassium channel (VGKC) antibodies. Currently, these antibodies are all classified as VGKC-complex antibodies, and are commonly considered to have a similar clinical value. However, studies from the past few years show that the immune responses mediated by these antibodies have differing clinical relevance. Here, we review the clinical importance of these immune responses in three settings: patients with anti-LGI1 antibodies, patients with anti-Caspr2 antibodies, and patients with antibodies against the VGKC complex that lack LGI1 and Caspr2 specificity. Antibodies against LGI1 and Caspr2 are associated with different but well-defined syndromes, whereas the clinical importance of VGKC-complex antibodies without LGI1 and Caspr2 specificity is questionable. We describe each of these syndromes, discuss the function of the target antigens and review the limited paediatric literature on the topic. The findings emphasize the importance of defining these disorders according to the molecular identity of the targets (LGI1 or Caspr2), and caution against the use of VGKC-complex antibodies for the diagnosis and treatment of patients without further definition of the antigen.

Anti-LGI1 encephalitis is strongly associated with HLA-DR7 and HLA-DRB4.

Leucine‐rich glioma‐inactivated1 (LGI1) encephalitis is an antibody‐associated inflammation of the limbic area. An autoimmune etiology is suspected but not yet proven. We performed human leukocyte antigen (HLA) analysis in 25 nontumor anti‐LGI1 patients and discovered a remarkably strong HLA association. HLA‐DR7 was present in 88% compared to 19.6% in healthy controls (p = 4.1 × 10−11). HLA‐DRB4 was present in all patients and in 46.5% controls (p = 1.19 × 10−7). These findings support the autoimmune hypothesis. An exploratory analysis was performed in a small group of 4 tumor‐LGI1 patients. The strong HLA association seems not applicable in these patients. Therefore, the absence of HLA‐DR7 or HLA‐DRB4 could raise tumor suspicion in anti‐LGI1 patients. Ann Neurol 2017;81:193–198

Paraneoplastic syndromes of the neuromuscular junction: therapeutic options in myasthenia gravis, lambert-eaton myasthenic syndrome, and neuromyotonia.

Opinion statementMyasthenia gravis (MG), Lambert-Eaton myasthenic syndrome (LEMS) and neuromyotonia are neuromuscular transmission disorders occurring with or without associated malignancy. Due to the common antibody-mediated pathophysiology, immunosuppression has an important role in the treatment of each of these disorders. Symptomatic treatment is more variable. Pyridostigmine is first-line treatment in generalized MG. Response seems to be better in patients with acetylcholine receptor (AChR) antibodies than in patients with antibodies against muscle-specific tyrosine kinase (MuSK). Pyridostigmine can be sufficient in mild MG, although most patients need additional immunosuppressive therapy. If so, prednisolone is efficient in the majority of the patients, with a relatively early onset of clinical effect. High drug dosage and treatment duration should be limited as much as possible because of serious corticosteroid-related side effects. As long-term treatment is needed in most patients for sustainable remission, adding non-steroid immunosuppressive drugs should be considered. Their therapeutic response is usually delayed and often takes a period of several months. In the meantime, corticosteroids are continued and doses are tapered down over a period of several months. There are no trials comparing different immunosuppressive drugs. Choice is mainly based on the clinician’s familiarity with certain drugs and their side effects, combined with patients’ characteristics. Most commonly used is azathioprine. Alternatively, tacrolimus, cyclosporine A, mycophenolate mofetil or rituximab can be used. The use of cyclophosphamide is limited to refractory cases, due to serious side effects. Plasma exchange and intravenous immunoglobulin induce rapid but temporary improvement, and are reserved for severe disease exacerbations because of high costs of treatment. It is recommended that computed tomography (CT) of the thorax is performed in every AChR-positive MG patient, and that patients are referred for thymectomy in case of thymoma. In patients without thymoma, thymectomy can be considered as well, especially in younger, AChR-positive patients with severe disease. However, definite proof of benefit is lacking and an international randomized trial to clarify this topic is currently ongoing. When LEMS is suspected, always search for malignancy, especially small cell lung carcinoma with continued screening up to two years. In paraneoplastic LEMS, cancer treatment usually results in clinical improvement of the myasthenic symptoms. 3,4-Diaminopyridine is first-line symptomatic treatment in LEMS. It is usually well tolerated and effective. When immunosuppressive therapy is needed, the same considerations apply to LEMS as described for MG. Peripheral nerve hyperexcitability in neuromyotonia can be treated with anticonvulsant drugs such as phenytoin, valproic acid or carbamazepine. When response in insufficient, start prednisolone in mild disease and consider the addition of azathioprine. Plasma exchange or intravenous immunoglobulin is indicated in severe neuromyotonia and in patients with neuromyotonia combined with central nervous system symptoms, a clinical picture known as Morvan’s syndrome.

Autoimmune encephalitis with anti-leucine-rich glioma-inactivated 1 or anti-contactin-associated protein-like 2 antibodies (formerly called voltage-gated potassium channel-complex antibodies)

Purpose of review Twenty years since the discovery of voltage-gated potassium channel (VGKC)-related autoimmunity; it is currently known that the antibodies are not directed at the VGKC itself but to two closely associated proteins, anti-leucine-rich glioma-inactivated 1 (LGI1) and contactin-associated protein-like 2 (Caspr2). Antibodies to LGI1 and Caspr2 give well-described clinical phenotypes. Anti-LGI1 encephalitis patients mostly have limbic symptoms, and anti-Caspr2 patients have variable syndromes with both central and peripheral symptoms. A large group of patients with heterogeneous symptoms are VGKC positive but do not have antibodies against LGI1 or Caspr2. The clinical relevance of VGKC positivity in these ‘double-negative’ patients is questionable. This review focusses on these three essentially different subgroups. Recent findings The clinical phenotypes of anti-LGI1 encephalitis and anti-Caspr2 encephalitis have been described in more detail including data on treatment and long-term follow-up. A specific human leukocyte antigen (HLA) association was found in nontumor anti-LGI1 encephalitis, but not clearly in those with tumors. There has been increasing interest in the VGKC patients without LGI1/Caspr2 antibodies questioning its relevance in clinical practice. Summary Anti-LGI1 encephalitis and anti-Caspr2 encephalitis are separate clinical entities. Early recognition and treatment is necessary and rewarding. The term VGKC-complex antibodies, lumping patients with anti-LGI1, anti-Caspr2 antibodies or lacking both, should be considered obsolete.

Author response: The clinical spectrum of Caspr2 antibody-associated disease

We appreciate the comments of Dr. Chen. Our study was focused on the clinical picture associated with Caspr2 antibodies, showing a spectrum of symptoms that do not conform to specific syndromes but were present in most of the patients, leading to the terminology “Caspr2 core symptoms.”1 In some patients, Caspr2 antibodies associate with the syndrome described by Morvan.

Impact of the Haga Braincare Strategy on the burden of haemodynamic and embolic strokes related to cardiac surgery

OBJECTIVES This study prospectively evaluates the impact of the Haga Braincare Strategy (HBS) on the occurrence of haemodynamic and embolic stroke in a cohort of patients who underwent coronay artery bypass grafting (CABG), valve replacement of a combination of both types of surgery between 2012 and 2015 at the Haga Teaching Hospitals. METHODS The HBS is a dual strategy based on a preoperative vascular work-up of the cerebral circulation by transcranial Doppler and a perioperative monitoring of the cerebral circulation by cerebral oximetry. Duplex of the carotid arteries and/or computed tomography angiography prior to surgery was performed in high-risk patients. Patients with severe carotid artery stenosis were scheduled for carotid angioplasty prior to surgery or waived from surgery. RESULTS A total of 1065 patients were included. Poor cerebral haemodynamics were identified by transcranial Doppler in 2.1% of patients (n = 22). Based on the HBS, 3 patients were waived from surgery, 4 received preoperative carotid angioplasty followed by cardiac surgery and the remaining patients were operated while being monitored with bilateral cerebral oximetry sensors. In all, 2.2% of the study group experienced a stroke (n = 23), of which none were classified as haemodynamic. Most of the remaining presumed embolic strokes showed a minor to moderate stroke severity. CONCLUSIONS In this single-centre prospective follow-up study, surveillance of cerebral perfusion by the HBS eliminated the occurrence of haemodynamic stroke while most of the residual strokes had a good to favourable prognosis.

Predictive value of electroencephalography in anti-NMDA receptor encephalitis

Objectives Anti-N-methyl-D-aspartate receptor encephalitis (anti-NMDARE) is a severe, but treatable disease. This study aims to give a detailed description of electroencephalogram (EEG) results in paediatric and adult patients to improve disease recognition, and analyses the predictive value of the first EEG for the final clinical outcome. Methods This nationwide cohort study includes patients with N-methyl-D-aspartate receptor antibodies confirmed with cell-based assay and immunohistochemistry in serum and cerebrospinal fluid. EEG recordings were re-evaluated by two experienced neurophysiologists, mixed with control EEGs for blinding. Initial EEG as well as follow-up registrations were analysed. Results 35 adults and 18 children were included. Only two patients (4%) had a normal EEG. During the first recording, the majority of the patients had normal posterior rhythm (71%), which was associated with better modified Rankin Scale at final outcome (OR 4.74; 95% CI 1.56 to 14.47; p=0.006). In addition, EEGs showed focal (73%) or diffuse (67%) slowing. The first EEG was severely abnormal in 26%. However, 8 of 14 patients with a severely abnormal first EEG still had a favourable outcome. During the course of the disease, extreme delta brushes (EDBs) were present in 6 of 53(11%)patients. Conclusions The first EEG commonly shows normal posterior rhythm with focal or diffuse slowing. Although the sensitivity of an abnormal EEG is high (96%), normal EEG does not exclude anti-NMDARE. EDBs are only present in severely affected patients. The first EEG recording is predictive of the final clinical outcome.

Treatment options for Lambert--Eaton myasthenic syndrome

Introduction: Lambert–Eaton myasthenic syndrome (LEMS) is a rare autoimmune disorder of the neuromuscular junction. Antibody-mediated functional loss of voltage-gated calcium channels (VGCCs) on the presynaptic surface results in reduced neurotransmitter release. Muscle weakness starts in the proximal limbs and is accompanied by autonomic failure and areflexia. About 50 – 60% of the patients have small-cell lung cancer (SCLC), with antibodies produced in reaction to VGCC on tumor cells. In non-tumor LEMS, an autoimmune reaction causes antibody production. Knowledge of the pathophysiology of antibody production in SCLC-LEMS and non-tumor LEMS and a detailed understanding of the neuromuscular junction and its dysfunction in LEMS is needed for drug development. Areas covered: This review gives an overview of the clinical symptoms, diagnosis and pathophysiology of LEMS. Current treatment options and results of recent research on newly developed symptomatic treatment are described. Expert opinion: Extensive search for SCLC is needed in LEMS patients. Appropriate tumor treatment should be started in SCLC-LEMS. In both SCLC-LEMS and non-tumor LEMS, symptomatic treatment consists of 3,4-diaminopyridine. If insufficient, pyridostigmine can be added, although a small trial failed to prove its benefit in LEMS and it is probably only efficient in a subset of patients. In moderate-to-severe disease, immunosuppressive treatment with prednisolone and azathioprine should be started. Research on drugs in LEMS is complicated by the infrequency of the disorder. Future developments are mainly expected in the field of symptomatic treatment. Possibly, further studies on immunosuppression in myasthenia gravis will be meaningful for the therapeutic strategy in LEMS as well.