Neuromyotonia.

Neuromyotonia is continuous peripheral nerve hyper-excitability manifesting in muscle twitching at rest (myokymia), inducible cramps and impaired muscle relaxation, and characterized by EMG findings of spontaneous single motor unit discharges (with doublet, triplet, or multiplet morphology). The disorder may be genetic, acquired, and often in the acquired cases autoimmune. This chapter focuses on autoimmune acquired causes. Autoimmune associations include mainly contactin-associated protein-like 2 (CASPR2) antibody-associated disease (previously termed as VGKC or voltage-gated potassium channel antibody-associated neuromyotonia) (van Sonderen et al., 2016, p. 2), leucine-rich glioma-inactivated 1 (LGI1) antibody disease, the Guillain-Barré syndrome, NMDAR encephalitis (Varley et al., 2019), and IgLON5 (Gaig et al., 2021) disease. Nonimmune associations include radiation-induced plexopathy. An association with myasthenia gravis and other autoimmune disorders, response to plasma exchange (Newsom-Davis and Mills, 1993) and physiologically induced changes in mice injected with patient-derived immunoglobulins led to the discovery of autoantibodies to juxtaparanodal proteins complexed with potassium channels (Shillito et al., 1995). The target of the antibodies is most commonly the CASPR2 protein. The disorder may be paraneoplastic, and a search for and treatment of an underlying tumor is a necessary step. In cases in which there is evidence for an immune cause, then immune suppression, with an emerging role for B cell-depleting therapies, is associated with a good clinical outcome. In parallel, sodium channel blocking drugs remain effective symptomatic therapies.

Seasonality of presentation and birth in catatonia.

BACKGROUND: Catatonia is a neuropsychiatric syndrome associated with both psychiatric disorders and medical conditions. Understanding of the pathophysiology of catatonia remains limited, and the role of the environment is unclear. Although seasonal variations have been shown for many of the disorders underlying catatonia, the seasonality of this syndrome has not yet been adequately explored. METHODS: Clinical records were screened to identify a cohort of patients suffering from catatonia and a control group of psychiatric inpatients, from 2007 to 2016 in South London. In a cohort study, the seasonality of presentation was explored fitting regression models with harmonic terms, while the effect of season of birth on subsequent development of catatonia was analyzed using regression models for count data. In a case-control study, the association between month of birth and catatonia was studied fitting logistic regression models. RESULTS: In total, 955 patients suffering from catatonia and 23,409 controls were included. The number of catatonic episodes increased during winter, with a peak in February. Similarly, an increasing number of cases was observed during summer, with a second peak in August. However, no evidence for an association between month of birth and catatonia was found. CONCLUSIONS: The presentation of catatonia showed seasonal variation in accordance with patterns described for many of the disorders underlying catatonia, such as mood disorders and infections. We found no evidence for an association between season of birth and risk of developing catatonia. This may imply that recent triggers may underpin catatonia, rather than distal events.

The diagnosis and treatment of catatonia.

Catatonia is a severe neuropsychiatric syndrome that affects emotion, speech, movement and complex behaviour. It can occur in a wide range of psychiatric and neurological conditions, including depression, mania, schizophrenia, autism, autoimmune encephalitis (particularly NMDAR encephalitis), systemic lupus erythematosus, thyroid disease, epilepsy and medication-induced and -withdrawal states. This concise guideline highlights key recommendations from the British Association for Psychopharmacology (BAP) Catatonia Guideline, published in April 2023. Important investigations may include neuroimaging, electroencephalography and assessment for neuronal autoantibodies in serum and cerebrospinal fluid. First-line treatment comprises benzodiazepines and/or electroconvulsive therapy. The benzodiazepine of choice is lorazepam, which is sometimes used in very high doses. Multidisciplinary working between psychiatrists and physicians is often essential. The main limitation of the guidelines is the low quality of the underlying evidence, comprising mainly small observational studies and case reports or series.

Evidence-based consensus guidelines for the management of catatonia: Recommendations from the British Association for Psychopharmacology.

The British Association for Psychopharmacology developed an evidence-based consensus guideline on the management of catatonia. A group of international experts from a wide range of disciplines was assembled. Evidence was gathered from existing systematic reviews and the primary literature. Recommendations were made on the basis of this evidence and were graded in terms of their strength. The guideline initially covers the diagnosis, aetiology, clinical features and descriptive epidemiology of catatonia. Clinical assessments, including history, physical examination and investigations are then considered. Treatment with benzodiazepines, electroconvulsive therapy and other pharmacological and neuromodulatory therapies is covered. Special regard is given to periodic catatonia, malignant catatonia, neuroleptic malignant syndrome and antipsychotic-induced catatonia. There is attention to the needs of particular groups, namely children and adolescents, older adults, women in the perinatal period, people with autism spectrum disorder and those with certain medical conditions. Clinical trials were uncommon, and the recommendations in this guideline are mainly informed by small observational studies, case series and case reports, which highlights the need for randomised controlled trials and prospective cohort studies in this area.

Catatonia: demographic, clinical and laboratory associations.

BACKGROUND: Catatonia, a severe neuropsychiatric syndrome, has few studies of sufficient scale to clarify its epidemiology or pathophysiology. We aimed to characterise demographic associations, peripheral inflammatory markers and outcome of catatonia. METHODS: Electronic healthcare records were searched for validated clinical diagnoses of catatonia. In a case-control study, demographics and inflammatory markers were compared in psychiatric inpatients with and without catatonia. In a cohort study, the two groups were compared in terms of their duration of admission and mortality. RESULTS: We identified 1456 patients with catatonia (of whom 25.1% had two or more episodes) and 24 956 psychiatric inpatients without catatonia. Incidence was 10.6 episodes of catatonia per 100 000 person-years. Patients with and without catatonia were similar in sex, younger and more likely to be of Black ethnicity. Serum iron was reduced in patients with catatonia [11.6 v. 14.2 µmol/L, odds ratio (OR) 0.65 (95% confidence interval (CI) 0.45-0.95), p = 0.03] and creatine kinase was raised [2545 v. 459 IU/L, OR 1.53 (95% CI 1.29-1.81), p < 0.001], but there was no difference in C-reactive protein or white cell count. N-Methyl-d-aspartate receptor antibodies were significantly associated with catatonia, but there were small numbers of positive results. Duration of hospitalisation was greater in the catatonia group (median: 43 v. 25 days), but there was no difference in mortality after adjustment. CONCLUSIONS: In the largest clinical study of catatonia, we found catatonia occurred in approximately 1 per 10 000 person-years. Evidence for a proinflammatory state was mixed. Catatonia was associated with prolonged inpatient admission but not with increased mortality.

Clozapine as a treatment for catatonia: A systematic review.

Catatonia is a neuropsychiatric disorder characterised by altered movement, speech, and behaviour. Clozapine is an established therapy for treatment-resistant schizophrenia, but its role in catatonia has not been systematically examined. In this systematic review, we aimed to assess the evidence for clozapine as a treatment for catatonia. Full text original research articles in English where at least one patient with catatonia was treated with clozapine were included, provided catatonia did not occur solely in the context of neuroleptic malignant syndrome. Results were tabulated with calculations of summary statistics presented. Risk of bias was assessed with the Tool for Evaluating the Methodological Quality of Case Reports and Case Series. 182 patients were included, 81 from cohort studies and 101 from case reports or case series. 119/182 patients (65 %) had a specified underlying diagnosis of schizophrenia. Over 80 % of reported patients with catatonia had at least partial remission following treatment with clozapine across both cohort studies and case reports and case series. Among the case reports and series, 24/101 patients (23.8 %) followed clozapine withdrawal. Overall, 25 studies were of low quality, 60 of moderate quality and 8 of high quality. Our findings should be interpreted with caution, as the reliance on case reports, case series and small cohort studies is susceptible to reporting biases, regression to the mean and confounding by other treatments. Future research could use large healthcare databases to ascertain outcomes in those on clozapine with a history of catatonia given the difficulty and expense of conducting randomised controlled trials.

Clinical Neuroimaging Findings in Catatonia: Neuroradiological Reports of MRI Scans of Psychiatric Inpatients With and Without Catatonia.

OBJECTIVE: Catatonia is a debilitating psychomotor disorder. Previous neuroimaging studies have used small samples with inconsistent results. The authors aimed to describe the structural neuroradiological abnormalities in clinical magnetic resonance imaging (MRI) brain scans of patients with catatonia, comparing them with scans of psychiatric inpatients without catatonia. They report the largest study of catatonia neuroimaging to date. METHODS: In this retrospective case-control study, neuroradiological reports of psychiatric inpatients who had undergone MRI brain scans for clinical reasons were examined. Abnormalities were classified by lateralization, localization, and pathology. The primary analysis was prediction of catatonia by presence of an abnormal MRI scan, adjusted for age, sex, Black race-ethnicity, and psychiatric diagnosis. RESULTS: Scan reports from 79 patients with catatonia and 711 other psychiatric inpatients were obtained. Mean age was 36.4 (SD=17.3) for the cases and 44.5 (SD=19.9) for the comparison group. Radiological abnormalities were reported in 27 of 79 cases (34.2%) and in 338 of 711 in the comparison group (47.5%) (odds ratio [OR]=0.57, 95% confidence interval [CI]=0.35, 0.93; adjusted OR=1.11, 95% CI=0.58, 2.14). Among the cases, most abnormal scans had bilateral abnormalities (N=23, 29.1%) and involved the forebrain (N=25, 31.6%) and atrophy (N=17, 21.5%). CONCLUSIONS: Patients with catatonia were commonly reported to have brain MRI abnormalities, which largely consisted of diffuse cerebral atrophy rather than focal lesions. No evidence was found that these abnormalities were more common than in other psychiatric inpatients undergoing neuroimaging, after adjustment for demographic variables. Study limitations included a heterogeneous control group and selection bias in requesting scans.

Biomarkers Associated with Organ-Specific Involvement in Juvenile Systemic Lupus Erythematosus.

Juvenile systemic lupus erythematosus (JSLE) is characterised by onset before 18 years of age and more severe disease phenotype, increased morbidity and mortality compared to adult-onset SLE. Management strategies in JSLE rely heavily on evidence derived from adult-onset SLE studies; therefore, identifying biomarkers associated with the disease pathogenesis and reflecting particularities of JSLE clinical phenotype holds promise for better patient management and improved outcomes. This narrative review summarises the evidence related to various traditional and novel biomarkers that have shown a promising role in identifying and predicting specific organ involvement in JSLE and appraises the evidence regarding their clinical utility, focusing in particular on renal biomarkers, while also emphasising the research into cardiovascular, haematological, neurological, skin and joint disease-related JSLE biomarkers, as well as genetic biomarkers with potential clinical applications.

Clinical relevance of serum antibodies to extracellular N-methyl-D-aspartate receptor epitopes.

OBJECTIVE: There are now a large number of requests for N-methyl-D-aspartate receptor autoantibody (NMDAR-Ab) tests, and it is important to assess the clinical relevance of all results, particularly when they are reported as 'Low Positive'. METHODS: The clinical data of 56 patients found Positive or Low Positive by the Oxford live cell-based assay were reviewed. An autoimmune basis for the condition was assigned as 'Definite', 'Possible' or 'Unlikely'. The number of core features (encephalopathy, psychiatric, cognitive, epileptic, extrapyramidal and inflammatory cerebrospinal fluid (CSF)) was tabulated. RESULTS: Twenty-five (44.6%) patients had a Definite NMDAR-Ab encephalitis (eight ovarian teratomas, one Hodgkin's lymphoma), 18 (32.1%) a Possible NMDAR-Ab encephalitis and 13 (23.2%) an Unlikely autoimmune syndrome. Serum NMDAR-Ab levels were higher in patients with tumours. Positive NMDAR-Abs were found not only in patients with three or more core features and a Definite syndrome, but also in five patients classified as Possible. Conversely, Low Positive NMDAR-Abs were present in 7 Definite cases as well as in 13 Possible cases. Unlikely patients had mainly Low Positive antibodies and fewer core features. CSF NMDAR-Abs, only available in 11 pairs and at varying time points, broadly related to serum levels and were Positive in 3/3 patients with tumours but in only 2/5 Definite patients, and none of the Possible or Unlikely cases. INTERPRETATION: Using live cell-based assays, Positive and Low Positive antibodies can be of clinical significance. The number of core clinical features should help to select those patients in whom an immunotherapy intervention might be considered, irrespective of the antibody level.

Recent advances in the neuroimmunology of cell-surface CNS autoantibody syndromes, Alzheimer's disease, traumatic brain injury and schizophrenia.

In this update, we review recent advances in antibody-associated disorders of the central nervous system, and the immune mechanisms which may contribute to Alzheimer's disease, traumatic brain injury and schizophrenia. The field of neuroimmunology is rapidly developing and has concerned itself with an expanding portfolio of diseases. The core neuroimmunological diseases remain, multiple sclerosis, neuromyelitis optica, primary inflammatory and antibody-associated disorders of the central and peripheral nervous system (including Myasthenia Gravis and other disorders of neuromuscular junction and muscle, paraneoplastic syndromes, paraproteinaemic neuropathies), and the neurological involvement seen in systemic inflammatory diseases including lupus, sarcoidosis and vasculitis. But it is increasingly realised that immune mechanisms may contribute to the pathogenesis of degenerative diseases including Alzheimer's disease, traumatic brain disease and psychiatric diseases including schizophrenia and depression. These common and devastating disorders, often without effective disease-modifying therapies, are yet to be seen in a conventional neuroimmunology clinic, but the immune mechanisms identified have encouraged research into novel therapeutic approaches for them.

Long-term remission with rituximab in refractory leucine-rich glioma inactivated 1 antibody encephalitis.

Autoimmune encephalitis associated with antibodies to leucine-rich glioma inactivated 1 (LGI1) is recently described and there is a lack of detailed reports on the treatment of relapsing or refractory cases and long-term outcomes. Two case reports are presented. Both cases had faciobrachial dystonic seizures (FBDS) and received rituximab after relapsing or refractory disease. Both cases achieved sustained clinical remission of up to 15 and 56 months respectively. Rituximab use allowed withdrawal of corticosteroids and was well tolerated. Randomized clinical trials are needed in LGI1 encephalitis and other autoimmune encephalitides.

Clinical relevance of positive voltage-gated potassium channel (VGKC)-complex antibodies: experience from a tertiary referral centre.

BACKGROUND: Voltage-gated potassium channel (VGKC)-complex antibodies can be associated with a range of immunotherapy-responsive clinical presentations including limbic encephalitis, Morvan's syndrome and acquired neuromyotonia. However, there are patients with positive levels in whom the significance is uncertain. OBJECTIVE: To evaluate the clinical significance associated with positive (>100 pM) VGKC-complex antibodies. METHODS: Over a 4-year period, 1053 samples were sent for testing of which 55 were positive. The clinical presentations, final diagnoses and responses to immunotherapies, when given, were assessed retrospectively and the likelihood of autoimmunity was categorised as definite, possible, unlikely or undetermined (modified from Zuliani et al 2012). RESULTS: Only 4 of the 32 patients with low-positive (100-400 pM) levels were considered definitely autoimmune, 3 with peripheral nerve hyperexcitability and 1 with a thymoma; 3 were given immunotherapies. Of the remaining 28 with low-positive levels, 13 (3 of whom had tumours) were considered possibly autoimmune, and 15 were unlikely or undetermined; 1 was given immunotherapy unsuccessfully. Of the 23 patients with high-positive (>400 pM) levels, 12 were given immunotherapies, 11 of whom showed a good response. 11 were considered definitely autoimmune, 10 with limbic encephalitis (antibody specificity: 5 LGI1, 1 contactin2, 2 negative, 2 untested) and 1 with a tumour. In the remaining 12, autoimmunity was considered possible (n=9; most had not received immunotherapies), or unlikely (n=3). CONCLUSIONS: As antibody testing becomes more widely available, and many samples are referred from patients with less clear-cut diagnoses, it is important to assess the utility of the results. VGKC-complex antibodies in the range of 100-400 pM (0.1-0.4 nM) were considered clinically relevant in rare conditions with peripheral nerve hyperexcitability and appeared to associate with tumours (12.5%). By contrast high-positive (>400 pM; >0.4 nM) levels were considered definitely (38%) or possibly (49%) clinically relevant, but not all patients had a 'classical' limbic encephalitis and some did not receive immunotherapies.

Antibodies to the N-methyl-D-aspartate receptor and other synaptic proteins in psychosis.

This review concentrates on the evidence for autoantibodies to cell surface synaptic proteins in psychosis and schizophrenia. We and others have recently found antibodies to the N-methyl-D-aspartate receptor in first-episode psychosis. We describe the evidence for pathogenicity and disease-relevance of these antibodies, which builds on the novel field in neuroimmunology of cell surface antibody-associated central nervous system disorders. Relevant autoantibodies in psychosis and schizophrenia are likely to be those directed to cell surface proteins, in which the likelihood of pathogenicity is greater. We discuss the evidence for this from the field of paraneoplastic neurologic syndromes and the discovery of novel cell surface antigen central nervous system autoimmune syndromes.

A novel strategy to reduce the immunogenicity of biological therapies.

Biological therapies, even humanized mAbs, may induce antiglobulin responses that impair efficacy. We tested a novel strategy to induce tolerance to a therapeutic mAb. Twenty patients with relapsing-remitting multiple sclerosis received an initial cycle of alemtuzumab (Campath-1H), up to 120 mg over 5 d, preceded by 500 mg SM3. This Ab differs from alemtuzumab by a single point mutation and is designed not to bind to cells. Twelve months later, they received a second cycle of alemtuzumab, up to 72 mg over 3 d. One month after that, 4 of 19 (21%) patients had detectable serum anti-alemtuzumab Abs compared with 145 of 197 (74%) patients who received two cycles of alemtuzumab without SM3 in the phase 2 CAMMS223 trial (p < 0.001). The efficacy and safety profile of alemtuzumab was unaffected by SM3 pretreatment. Long-lasting "high-zone" tolerance to a biological therapy may be induced by pretreatment with a high i.v. dose of a drug variant, altered to reduce target-binding.

N-methyl-D-aspartate antibody encephalitis: temporal progression of clinical and paraclinical observations in a predominantly non-paraneoplastic disorder of both sexes.

Antibodies to the N-methyl-d-aspartate subtype of glutamate receptor have been associated with a newly-described encephalopathy that has been mainly identified in young females with ovarian tumours. However, the full clinical spectrum and treatment responses are not yet clear. We established a sensitive cell-based assay for detection of N-methyl-d-aspartate receptor antibodies in serum or cerebrospinal fluid, and a quantitative fluorescent immunoprecipitation assay for serial studies. Although there was marked intrathecal synthesis of N-methyl-d-aspartate receptor antibodies, the absolute levels of N-methyl-d-aspartate receptor antibodies were higher in serum than in cerebrospinal fluid. N-methyl-d-aspartate receptor antibodies were of the immunoglobulin G1 subclass and were able to activate complement on N-methyl d-aspartate receptor-expressing human embryonic kidney cells. From questionnaires returned on 44 N-methyl-d-aspartate receptor antibody-positive patients, we identified a high proportion without a detected tumour (35/44, 80%: follow-up 3.6-121 months, median 16 months). Among the latter were 15 adult females (43%), 10 adult males (29%) and 10 children (29%), with four in the first decade of life. Overall, there was a high proportion (29%) of non-Caucasians. Good clinical outcomes, as defined by reductions in modified Rankin scores, correlated with decreased N-methyl-d-aspartate receptor antibody levels and were associated with early (<40 days) administration of immunotherapies in non-paraneoplastic patients (P < 0.0001) and earlier tumour removal in paraneoplastic patients (P = 0.02). Ten patients (23%) who were first diagnosed during relapses had no evidence of tumours but had received minimal or no immunotherapy during earlier episodes. Temporal analysis of the onset of the neurological features suggested progression through two main stages. The time of onset of the early features, characterized by neuropsychiatric symptoms and seizures preceded by a median of 10-20 days, the onset of movement disorders, reduction in consciousness and dysautonomia. This temporal dichotomy was also seen in the timing of cerebrospinal fluid, electroencephalographic and in the rather infrequent cerebral imaging changes. Overall, our data support a model in which the early features are associated with cerebrospinal fluid lymphocytosis, and the later features with appearance of oligoclonal bands. The immunological events and neuronal mechanisms underlying these observations need to be explored further, but one possibility is that the early stage represents diffusion of serum antibodies into the cortical grey matter, whereas the later stage results from secondary expansion of the immunological repertoire within the intrathecal compartment acting on subcortical neurons. Four patients, who only had temporal lobe epilepsy without oligoclonal bands, may represent restriction to the first stage.