Management of Voltage-Gated Potassium Channel Antibody Disorders

Acquired hyperexcitable peripheral nerve disorders: Clinical and laboratory features, therapeutic responses, and long-term follow-up

INTRODUCTION/AIMS

Hyperexcitable peripheral nerve disorders (HPNDs) are rare. Although their clinical and laboratory features have been well studied, information on treatment and follow-up is limited. The aim of this study is to explore the long-term clinical, investigative, and therapeutic profile of patients with acquired HPNDs.

METHODS

This study retrospectively analyzed patients from a single tertiary care center with HPND (January 2012 to January 2022). Patients were recruited according to published inclusion and exclusion criteria. Details of clinical features, diagnostic tests, therapeutic interventions, and follow-up were recorded. This study included patients with follow-up of 2 or more years.

RESULTS

A total of 32 patients (M = 26, F = 6) were studied. The common clinical features included myokymia, neuropathic or shock-like pain, cramps, sleep disturbances, encephalopathy, cerebellar ataxia, and seizures. A total of 81.25% of patients responded favorably to corticosteroids and membrane stabilizers. Among the nonresponders, five received intravenous immunoglobulin (IVIG), and one received plasma exchange (PLEX). Two patients required rituximab due to poor responses to the above treatments. The mean duration of response was 6 weeks (4-24 weeks) from the initiation of treatment. All patients had favorable outcomes, reaching clinical remission within 1-5 years from the initiation of treatment. Only two patients had relapses. Immunotherapy could be stopped in 78% of patients within 3 years and 100% by 5 years.

DISCUSSION

Chronic immunosuppression starting with corticosteroids is required for satisfactory outcomes of HPNDs. These disorders usually run a monophasic course, and relapses are uncommon.

Autoimmune neuromyotonia

PURPOSE OF REVIEW

Autoimmune neuromyotonia encompasses a group of rare immune-mediated neurological disorders frequently associated with anti-contactin-associated protein-like 2 (CASPR2) antibodies and featuring clinical and electrical signs of peripheral nerve hyperexcitability (PNH). We aim to summarize the current knowledge on immune-mediated neuromyotonia, focusing on clinical presentations, pathophysiology, and management.

RECENT FINDINGS

Neuromyotonia is a major feature of several autoimmune neurological syndromes characterized by PNH with or without central neurological system involvement. Experimental and clinical evidence suggest that anti-CASPR2 antibodies are directly pathogenic in autoimmune neuromyotonia patients.

SUMMARY

Neuromyotonia, a form of PNH, is a major feature in several syndromes associated with anti-CASPR2 antibodies, including cramp-fasciculation syndrome, Isaacs syndrome, Morvan syndrome, and autoimmune limbic encephalitis. Diagnosis relies on the identification of motor, sensory, and autonomic signs of PNH along with other neurological symptoms, anti-CASPR2 antibody-positivity, and of characteristic electroneuromyographic abnormalities. Paraneoplastic associations with thymoma are possible, especially in Morvan syndrome. Patients usually respond to immune-active treatments, including steroids, intravenous immunoglobulins, plasma exchanges, and rituximab.

Fasciculations in Children

Fasciculations are the most common form of spontaneous muscle contraction. They frequently occur in healthy individuals. However, there are a minority of situations that fasciculations are observed in association with specific neurologic disorders. Publications concerning the evaluation of pediatric patients experiencing fasciculations are limited. These children may undergo invasive or expensive diagnostic investigations that are unnecessary. Moreover, without careful consideration of differential diagnoses, rare neuromuscular disorders that present with fasciculations in the pediatric age group can be under-recognized by pediatric neurologists. This review examines the most important pediatric disorders presenting with fasciculations and other spontaneous muscle contractions to guide pediatric neurologists in evaluating these children.

Electrodiagnostic Assessment of Hyperexcitable Nerve Disorders

Peripheral nerve hyperexcitability (PNH) typically presents with complaints of muscle twitching, cramps, and muscle stiffness. Symptoms and signs indicating central and/or autonomic nervous system dysfunction also may be reported. An electroclinical spectrum exists, spanning from the milder cramp-fasciculation syndrome to more severe syndromes characterized by continuous muscle fiber activity. It is important to recognize that PNH may be an autoimmune phenomenon associated with antibodies targeting proteins of the voltage-gated potassium channel-complex and, in some patients, a paraneoplastic phenomenon. Symptomatic therapies include medicines that reduce neuronal excitability and in severe disease immunomodulatory treatments may be indicated.

Caspr2 autoantibody-associated Morvan syndrome predating thymoma relapse by 30 months

Morvan's syndrome (MoS) is a rare autoimmune disorder characterized by central nervous system involvement, autonomic dysfunction and peripheral nerve hyperexcitability. MoS is believed to be caused by autoantibodies targeting contactin-associated protein 2 (Caspr2), a subunit of the neuronal voltage-gated potassium channel (VGKC) complex, usually in association with thymoma, less commonly with other malignancies. This case highlights an exceptional case of severe sleep disturbances and behavioural changes due to MoS, in a patient who would present with and be treated successfully for a second relapse of thymoma 30 months later. Originally he suffered from ocular myasthenia, another autoimmune disorder, which led to diagnosis of his original thymoma and first relapse.

Utility of stimulus induced after discharges in the evaluation of peripheral nerve hyperexcitability: Old wine in a new bottle?

Limited literature is available on stimulus induced after discharges (SIAD) in patients with peripheral nerve hyperexcitability (PNH). The aim of the study was to examine the diagnostic utility of SIAD in the diagnosis and monitoring of primary PNH disorders. In this retrospective study, we studied 26 patients who were admitted with a diagnosis of primary PNH to the department of Neurology from January 2013 to April 2019. Their clinical profile, immunological characteristics were extracted from the database and nerve conduction studies were relooked for the presence of SIAD. 76% of patients in the primary PNH cohort had SIAD with 90% of them being voltage-gated potassium channel complex antibody positive; predominantly against contactin-associated protein-2 antigen and rest being paraneoplastic. There was also resolution of SIAD following treatment indicating reversible hyperexcitability. SIAD is a sensitive marker for Primary PNH syndrome with monitoring and diagnostic implications.

Guidelines on the Use of Therapeutic Apheresis in Clinical Practice - Evidence-Based Approach from the Writing Committee of the American Society for Apheresis: The Eighth Special Issue

The American Society for Apheresis (ASFA) Journal of Clinical Apheresis (JCA) Special Issue Writing Committee is charged with reviewing, updating and categorizing indications for the evidence-based use of therapeutic apheresis (TA) in human disease. Since the 2007 JCA Special Issue (Fourth Edition), the committee has incorporated systematic review and evidence-based approaches in the grading and categorization of apheresis indications. This Eighth Edition of the JCA Special Issue continues to maintain this methodology and rigor in order to make recommendations on the use of apheresis in a wide variety of diseases/conditions. The JCA Eighth Edition, like its predecessor, continues to apply the category and grading system definitions in fact sheets. The general layout and concept of a fact sheet that was introduced in the Fourth Edition, has largely been maintained in this edition. Each fact sheet succinctly summarizes the evidence for the use of TA in a specific disease entity or medical condition. The Eighth Edition comprises 84 fact sheets for relevant diseases and medical conditions, with 157 graded and categorized indications and/or TA modalities. The Eighth Edition of the JCA Special Issue seeks to continue to serve as a key resource that guides the utilization of TA in the treatment of human disease.

A case study: Therapeutic plasma exchange in voltage-gated potassium channel autoimmune encephalitis

INTRODUCTION

Neurological syndromes associated with voltage-gated potassium channels (VGKC) affect the nerve and muscle physiology. Presence of antibodies to VGKC are associated with three main neurologic syndromes namely neuromyotonia (NMT), limbic encephalitis (LE) and Morvan's syndrome(MVS) LE is a variably treatable neurologic syndrome associated with high levels of antibodies to the voltage-gated potassium channel (VGKC) complex. These antibodies are directed against protein antigens that bind to the VGKC complex. These antigens are usually leucine-rich, glioma inactivated 1 (LGI1), and contactin associated protein-like 2 (CASPR2).

CASE DESCRIPTION

A 58-year-old female and with a known case of auto immune encephalitis (voltage gated potassium channel) and steroid induced diabetes mellitus presented with progressive worsening of vertigo, recurrent myoclonic jerks and post ictal confusion for last 7 days. She had memory impairment since last few months. She was on treatment with steroids which were gradually tapered off 11 months back. CSF was tested for presence of VGKC antibodies and the test was positive for LGI (leucine-rich glioma inactivated 1) antibody. Therapeutic plasma exchange (TPE) was scheduled every day for 6 consecutive days based upon the recommendations from the ASFA guidelines for the treatment of neurologic syndromes.

CONCLUSION

TPE done every day in patient diagnosed LE with VGKC antibodies had shown rapid improvement in controlling the symptoms.

Current Treatment Options for Peripheral Nerve Hyperexcitability Syndromes

PURPOSE OF REVIEW

Peripheral nerve hyperexcitability (PNH) syndromes are divided into primary and secondary groups based on the presence or absence of demonstrable peripheral nerve disease. In this review, we systematically evaluate the evidence for current therapies and supportive managements based on autoimmune, paraneoplastic, and genetic components in pathophysiology reported in the literature.

RECENT FINDINGS

Current therapy options are based on symptomatic management as well as focusing the underlying immune/genetic/paraneoplastic pathology by immunosuppressants, chemotherapy, and surgery. Further research is desired to provide treatment options geared specifically towards addressing PNH. Supportive care can also be an area for future research.

Evaluation and Management of Autoimmune Encephalitis: A Clinical Overview for the Practicing Child Psychiatrist

Medical conditions that present with psychiatric symptoms are becoming increasingly well-recognized in response to the emergence of the field of neuroimmunology. As the availability of testing for novel antineuronal antibodies has increased, so too has the clinical awareness of this diagnostic spectrum. Psychiatrists may have little exposure to this area of expertise, yet may be called on to assist in the diagnosis and treatment of patients with complex neuropsychiatric syndromes secondary to autoimmune encephalitis. This article summarizes the evaluation and management of patients with autoimmune encephalitis and describes emerging patterns in phenotype recognition.

Guidelines on the Use of Therapeutic Apheresis in Clinical Practice-Evidence-Based Approach from the Writing Committee of the American Society for Apheresis: The Seventh Special Issue

The American Society for Apheresis (ASFA) Journal of Clinical Apheresis (JCA) Special Issue Writing Committee is charged with reviewing, updating, and categorizing indications for the evidence-based use of therapeutic apheresis in human disease. Since the 2007 JCA Special Issue (Fourth Edition), the Committee has incorporated systematic review and evidence-based approaches in the grading and categorization of apheresis indications. This Seventh Edition of the JCA Special Issue continues to maintain this methodology and rigor to make recommendations on the use of apheresis in a wide variety of diseases/conditions. The JCA Seventh Edition, like its predecessor, has consistently applied the category and grading system definitions in the fact sheets. The general layout and concept of a fact sheet that was used since the fourth edition has largely been maintained in this edition. Each fact sheet succinctly summarizes the evidence for the use of therapeutic apheresis in a specific disease entity. The Seventh Edition discusses 87 fact sheets (14 new fact sheets since the Sixth Edition) for therapeutic apheresis diseases and medical conditions, with 179 indications, which are separately graded and categorized within the listed fact sheets. Several diseases that are Category IV which have been described in detail in previous editions and do not have significant new evidence since the last publication are summarized in a separate table. The Seventh Edition of the JCA Special Issue serves as a key resource that guides the utilization of therapeutic apheresis in the treatment of human disease. J. Clin. Apheresis 31:149-162, 2016. © 2016 Wiley Periodicals, Inc.

Fatal Morvan Syndrome Associated With Myasthenia Gravis

INTRODUCTION

Morvan syndrome is a rare and complex autoimmune disorder affecting multiple sites of neuraxis.

CASE REPORT

We present fulminant Morvan syndrome, developing on a background of chronic myasthenia gravis. A 54-year-old gentleman presented with fluctuating ophthalmoplegia and proximal muscles weakness of 7 years duration that remitted with pyridostigmine and prednisolone. He developed insomnia of 2 months duration, worsening of myasthenic symptoms and respiratory distress, dysautonomia, encephalopathy, and peripheral nerve hyperexcitability. Antibodies against contactin-associated protein (CASPR) 2 were detected in serum. Computed tomography of thorax showed a thymic mass. He received intravenous methyl prednisolone and plasmapheresis. Antibodies against CASPR and thymic lesion reduced with immunotherapy. However, he developed persistent hypotension and expired after 11 weeks of hospital stay.

CONCLUSIONS

Clinical clues for diagnosis of Morvan syndrome and therapeutic changes faced by the treating team are highlighted in this report. Increased awareness and prompt testing for CASPR2 antibody is warranted so that early immunotherapy can be initiated.

Autoimmune encephalitis in psychiatric institutions: current perspectives

Autoimmune encephalitis is a rare and newly described group of diseases involving autoantibodies directed against synaptic and neuronal cell surface antigens. It comprises a wide range of neuropsychiatric symptoms. Sensitive and specific diagnostic tests such as cell-based assay are primordial for the detection of neuronal cell surface antibodies in patients' cerebrospinal fluid or serum and determine the treatment and follow-up of the patients. As neurological symptoms are fairly well described in the literature, this review focuses on the nature of psychiatric symptoms occurring at the onset or during the course of the diseases. In order to help the diagnosis, the main neurological symptoms of the most representative synaptic and neuronal cell surface autoantibodies were detailed. Finally, the exploration of these autoantibodies for almost a decade allowed us to present an overview of autoimmune encephalitis incidence in psychiatric disease and the general guidelines for the management of psychiatric manifestations. For the majority of autoimmune encephalitis, the prognosis depends on the rapidity of the detection, identification, and the management of the disease. Because the presence of pronounced psychiatric symptoms drives patients to psychiatric institutions and can hinder the diagnosis, the aim of this work is to provide clues to help earlier detection by physicians and thus provide better medical care to patients.

Leucine-Rich Glioma Inactivated-1 and Voltage-Gated Potassium Channel Autoimmune Encephalitis Associated with Ischemic Stroke: A Case Report

Autoimmune encephalitis is associated with a wide variety of antibodies and clinical presentations. Voltage-gated potassium channel (VGKC) antibodies are a cause of autoimmune non-paraneoplastic encephalitis characterized by memory impairment, psychiatric symptoms, and seizures. We present a case of VGKC encephalitis likely preceding an ischemic stroke. Reports of autoimmune encephalitis associated with ischemic stroke are rare. Several hypotheses linking these two disease processes are proposed.

Isaacs' syndrome in a patient with dermatomyositis: case report and review of the literature

This is a case report of Isaacs' syndrome in dermatomyositis. The patient presented with proximal muscle weakness, rash, elevated muscle enzyme, myopathic electromyograph and typical muscle biopsy. Ultimately he developed typical symptoms of Isaacs' syndrome which is an autoimmune channelopathy from voltage gated potassium channel antibody (anti-VGKC) leading to dysfunction of axonal discharge at neuromuscular junctions. It shares some similar characteristics with dermatomyositis such as autoimmunity, its association with malignancy and the response to treatment.

A case study of voltage-gated potassium channel antibody-related limbic encephalitis with PET/MRI findings

Preclinical and clinical studies have demonstrated the significance of inflammation and autoantibodies in epilepsy, and the use of immunotherapies in certain situations has become an established practice. Temporal lobe epilepsy can follow paraneoplastic or nonparaneoplastic limbic encephalitis associated with antibodies directed against brain antigens. Here, we focus on a patient with worsening confusion and temporal lobe seizures despite treatment with antiepileptic medications. Serial brain MRIs did not conclusively reveal structural abnormalities, so the patient underwent brain PET/MRI to simultaneously evaluate brain structure and function, revealing bitemporal abnormalities. The patient was diagnosed with voltage-gated potassium channel antibody-related limbic encephalitis based on clinical presentation, imaging findings, and antibody testing. Treatment included the addition of a second antiepileptic agent and oral steroids. His seizures and cognitive deficits improved and stabilized.

Neuromyotonia with polyneuropathy, prominent psychoorganic syndrome, insomnia, and suicidal behavior without antibodies: a case report

Introduction

Peripheral nerve hyperexcitability disorders are characterized by constant muscle fiber activity. Acquired neuromyotonia manifests clinically in cramps, fasciculations, and stiffness. In Morvan’s syndrome the signs of peripheral nerve hyperexcitability are accompanied by autonomic symptoms, sensory abnormalities, and brain disorders.

Case presentation

A 70-year-old Caucasian man developed, in the course of 3 months, polyneuropathy with unpleasant dysesthesia of lower extremities and gradually increasing fasciculations, muscle stiffness and fatigue. Subsequently, he developed a prominent insomnia with increasing psychological changes and then he attempted a suicide. Electromyography confirmed a sensory-motor polyneuropathy of a demyelinating type. The findings included fasciculations as well as myokymia, doublets and multiplets, high frequency discharges, and afterdischarges, following motor nerve stimulation. No auto-antibodies were found either in his blood or cerebrospinal fluid. Magnetic resonance imaging of his brain showed small, unspecific, probably postischemic changes. A diagnosis of Morvan’s syndrome was confirmed; immunoglobulin (2g/kg body weight) was applied intravenously, and, subsequently, carbamazepine 2×200mg, venlafaxine 150mg, and mirtazapine each night were prescribed. His sleep improved, suicidal tendencies stopped, less fasciculations occurred, and muscle hypertonia also improved. Hyperexcitation also partially remitted including the electromyography finding.

Conclusions

We described here the case of a patient with Morvan’s syndrome; his case is rare because of severe psychical changes with a suicide attempt, short admission to a psychiatric ward, prominent electromyographic changes, and because antibodies were not detected. After therapy with immunoglobulins followed by corticosteroids with sodium channel blocker, his motor, autonomic, psychical signs and symptoms, and electromyography changes substantially improved.

Isaacs syndrome: A review

Isaacs syndrome is a peripheral nerve hyperexcitability (PNH) syndrome that presents as continuous motor activity. Clinical findings include cramps, fasciculations, and myokymia. Electrodiagnosis plays a key role in diagnosis by demonstrating after-discharges on nerve conduction studies, and fasciculation potentials, myokymic discharges, neuromyotonic discharges, and other types of abnormal spontaneous activity on needle examination. Etiopathogenesis involves the interaction of genetic, autoimmune, and paraneoplastic factors, which requires a broad-ranging evaluation for underlying causes. Initial treatment is symptomatic, but immune therapy is often needed and can be effective. The purpose of this review is to describe the syndrome and its pathogenesis, assist the reader in evaluating patients with suspected Isaacs syndrome and distinguishing it from other disorders of PNH, and suggest an approach to management, including both symptomatic and immunomodulating therapy.

[A case of Isaacs' syndrome causing various central nervous symptoms successfully treated with high-dose intravenous methylprednisolone therapy]

A 44-year-old man with a bilateral hand tremor suffered from a decline in concentration and abnormal vision for several months. He also complained of easily falling down because of muscle stiffness and cramps in his lower limbs. On admission, he demonstrated lower limb stiffness, muscle cramps, diplopia, hyperhidrosis, left upper limb ataxia and dysesthesia in all limbs. Laboratory examination showed a marked elevation in his serum creatine kinase level (26,890 U/l), and needle electromyography demonstrated myokymic discharges in the muscles of his lower extremities. Isaacs' syndrome was diagnosed based on a positive voltage-gated potassium channel antibody titer of 1,007 pM. Administration of an anticonvulsant (phenytoin, 200 mg/day) did not resolve his symptoms; however, high-dose intravenous methylprednisolone therapy (1 g/day for 3 days) resulted in marked clinical improvement. This case suggests that high-dose intravenous methylprednisolone therapy for Isaacs' syndrome might be as effective as other immunosuppressive therapies such as plasma exchange or intravenous immunoglobulin.

Immunomodulation in Adult Epilepsy: The Role of IVIG

Much of the research for intravenous immunoglobulins (IVIG) use in epilepsy has focused on childhood epilepsies and the results have been inconclusive. As evidence for inflammation in epilepsy and epileptogenesis is accumulating, IVIG might have a role to play in adult epilepsy. Our literature review focuses on the purported mechanisms of IVIG, the link between inflammation and the various causes of adult epilepsy and the different steps of epileptogenesis at which inflammation might play a role. We also review the current clinical evidence supporting IVIG as a treatment for epilepsy in the adult population. Though there is interesting theoretical potential for treatment of refractory epilepsy in adults with IVIG, insufficient evidence exists to support its standard use. The question remains if IVIG should still be considered as an end-of-the-line option for patients with epilepsy poorly responsive to all other treatments.

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

OPINION STATEMENT

Myasthenia 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.

Plasma exchange as a therapeutic option in patients with neurologic symptoms due to antibodies to voltage-gated potassium channels: a report of five cases and review of the literature

Antibodies to voltage-gated potassium channels (VGKC) are associated with acquired neuromyotonia, limbic encephalitis, and Morvan's syndrome. The antibodies are often not associated with malignancy and have shown good clinical response to immunomodulatory therapies. A record review identified five patients with laboratory evidence of antibodies to VGKC who underwent plasma exchange (PE) as part of their immunosuppressive therapy for neurologic disease. Four of the patients presented with limbic encephalitis and one with neuromyotonia. Symptoms included memory impairment, seizures, and personality changes. All PE were 1.0 volume and were performed on an every-other-day schedule. Replacement fluid was 5% normal serum albumin except when a bleeding risk was identified and then fresh frozen plasma was added. Four of five patients were also receiving concurrent immunosuppressive therapy including corticosteroids. Of the five patients treated with PE, three had sustained improvement in symptoms for 6-17 months following PE. Two patients did not have signs of improvement at a limited follow-up. One patient had recurrence of her symptoms, which responded to additional PE. These cases, as well as the reports in the literature, suggest that PE could be a useful adjunctive therapy for patients with VGKC antibodies and neurologic symptoms.

Paraneoplastic encephalitis associated with myasthenia gravis and malignant thymoma

We present a patient with type B2 thymoma (World Health Organization Thymoma Classification) with the complications of anti-muscle acetylcholine receptor antibody-positive myasthenia gravis and anti-voltage-gated potassium channel antibodies associated with paraneoplastic encephalitis. A timing difference between the onset of these neurological disorders and a dissociation of clinical symptoms was observed during the disease. This report alerts clinicians that long-term follow-up is needed where patients have a residual thymoma and attention should be paid to other concomitant autoimmune disorders.

Immune mediated diseases and immune modulation in the neurocritical care unit

This chapter will review the spectrum of immune-mediated diseases that affect the nervous system and may result in an admission to the neurological intensive care unit. Immunomodulatory strategies to treat acute exacerbations of neurological diseases caused by aberrant immune responses are discussed, but strategies for long-term immunosuppression are not presented. The recommendations for therapeutic intervention are based on a synthesis of the literature, and include recommendations by the Cochrane Collaborative, the American Academy of Neurology, and other key organizations. References from recent publications are provided for the disorders and therapies in which randomized clinical trials and large evidenced-based reviews do not exist. The chapter concludes with a brief review of the mechanisms of action, dosing, and side effects of commonly used immunosuppressive strategies in the neurocritical care unit.

Sleep-related movement disorders

Several movement disorders may occur during nocturnal rest disrupting sleep. A part of these complaints is characterized by relatively simple, non-purposeful and usually stereotyped movements. The last version of the International Classification of Sleep Disorders includes these clinical conditions (i.e. restless legs syndrome, periodic limb movement disorder, sleep-related leg cramps, sleep-related bruxism and sleep-related rhythmic movement disorder) under the category entitled sleep-related movement disorders. Moreover, apparently physiological movements (e.g. alternating leg muscle activation and excessive hypnic fragmentary myoclonus) can show a high frequency and severity impairing sleep quality. Clinical and, in specific cases, neurophysiological assessments are required to detect the presence of nocturnal movement complaints. Patients reporting poor sleep due to these abnormal movements should undergo non-pharmacological or pharmacological treatments.

VGKC positive autoimmune encephalopathy mimicking dementia

Voltage gated potassium channel antibodies (VGKC Abs) are known to cause three rare neurological syndromes- neuromyotonia, Morvan's syndrome and limbic encephalitis although an increasing array of other associated neurological symptoms are becoming recognised. The authors describe the case of a 60-year-old female who presented to the neurology clinic with an apparent early onset dementing process. She was noted to have both extrapyramidal and frontal release signs on examination and was admitted for further evaluation. Her dementia investigation including a neoplastic screen was negative except for VGKC antibody positivity. Her symptoms dramatically improved with commencement of immunosuppression. A non-paraneoplastic VGKC antibody associated dementia-like syndrome has rarely been described. The authors add to the few existing reports of what represents an important reversible cause of cognitive impairment.