Patient satisfaction with televisit in chronic neurologic disorders during Covid-19 pandemic.

BACKGROUND: Covid-19 pandemic has boosted telemedicine in medical clinical practice. Experience in the management of chronic neurological disorders is limited as well as patient opinion. During Covid-19 pandemic, we evaluated patients' satisfaction and opinion about televisits in a large group of patients with chronic neurological disorders. METHODS: All patients with chronic neurological disorders who had a virtual visit during the first phase of pandemic were invited to fill an online anonymous questionnaire about their global satisfaction and satisfaction regarding continuity of care, possibility to stay at home, doctor-patient relationship, the future of teleconsultation after pandemic and the possibility of understanding medical information and instructions. RESULTS: We received 123 questionnaires among 232 e-mail (response rate 53%). Almost all (120 out of 121 patients, 99%) were satisfied with the overall experience with video-consultation. Comprehension of medical information was the same for 113 out of 122 patients (93%) and also the doctor-patient relationship was the same for 107 out of 122 respondents (88%) or better for 10 (8%). Ninety-three percent of patients (112 out of 120) were keen to integrate televisits with the traditional modality and only 11 out of 121 patients (9%) judged televisits as an option to discard. As a whole, 114 out of 122 respondents (93%) would suggest this modality to other patients. CONCLUSIONS: Our large cohort of patients with chronic neurologic disorders rated experience with televisits satisfactory. Comprehension of medical information and doctor-patient interaction was considered good. Eventually, patients are keen to integrate this modality with traditional follow-up visits.

Observational real-life study on regorafenib in recurrent glioblastoma: does dose reduction reduce toxicity while maintaining the efficacy?

PURPOSE: In the phase 2 REGOMA trial, regorafenib improved overall survival, as compared with lomustine, in glioblastoma (GBM) patients at first progression after chemoradiation. Recently, some real-life trials showed similar impact on survival but a higher rate of adverse events than in REGOMA, thus raising concerns over tolerability. The aim of this study was to assess the efficacy and tolerability of a lower intensity regorafenib regimen. PATIENTS AND METHODS: Regorafenib daily dose was gradually increased from 80 to 160 mg across the first 2 cycles. Progression-free survival (PFS) and overall survival (OS) were defined as time from regorafenib initiation and disease progression or death. RESULTS: Sixty-six GBM patients were included. Median age was 60.0 years. Median PFS and OS following regorafenib were 2.7 and 7.1 months, respectively. Best RANO response to regorafenib were partial response (PR) in 10 (15.1%), stable disease in 17 (25.8%), and progressive disease in 39 (59.1%) patients. Forty-six (69.7%) patients presented adverse events of any grade, and 21 (31.8%) grade 3-4 toxicity. In a multivariable analysis, higher age and absence of MGMTp methylation were significantly associated with poorer disease control after regorafenib. CONCLUSIONS: Our study is the largest observational real-life study on the use of regorafenib. Our lower intensity regimen proved as effective as the standard 160 mg daily schedule (mPFS and mOS being 2.7 vs 2.0 months and 7.1 vs 7.4 months in our study vs REGOMA, respectively). Moreover, we observed a higher rate of PRs as compared with REGOMA (15.0% vs 3.0%).

Virtual visits for chronic neurologic disorders during COVID-19 pandemic.

BACKGROUND: COVID-19 pandemic has boosted telemedicine in medical clinical practice. Experiences in the management of chronic neurological disorders are limited and scattered. The aim of the study was to evaluate feasibility and efficacy of virtual visit for chronic neurological disorders during COVID-19 pandemic. METHODS: All patients scheduled for a visit during the lockdown period were contacted. The patients fell into four categories: (1) long-term follow-up, the patient was re-scheduled; (2) visit was necessary, teleconsultation was accepted; (3) problem was solved by phone call; and (4) visit was necessary and teleconsultation was not feasible, then visit was maintained. Google Meet was used. During the virtual visit, neurological examination was performed, and demographic and clinical characteristics were recorded. RESULTS: At the end of May 2020, 184 virtual visits for 178 patients were performed for the following diseases: myasthenia gravis (47 patients), multiple sclerosis (79), epilepsy (12), headache (6), and parkinsonism (34). The patients were 70 males and 108 females with a mean age of 53.5 years (range 13-90). During virtual visit, we were able to obtain a satisfactory neurological examination. CONCLUSIONS: We demonstrated feasibility and effectiveness of virtual visit in the management of a large group of patients with common chronic neurological disorders.

Malingering Detection of Cognitive Impairment With the b Test Is Boosted Using Machine Learning.

Objective: Here we report an investigation on the accuracy of the b Test, a measure to identify malingering of cognitive symptoms, in detecting malingerers of mild cognitive impairment. Method: Three groups of participants, patients with Mild Neurocognitive Disorder (n = 21), healthy elders (controls, n = 21), and healthy elders instructed to simulate mild cognitive disorder (malingerers, n = 21) were administered two background neuropsychological tests (MMSE, FAB) as well as the b Test. Results: Malingerers performed significantly worse on all error scores as compared to patients and controls, and performed poorly than controls, but comparably to patients, on the time score. Patients performed significantly worse than controls on all scores, but both groups showed the same pattern of more omission than commission errors. By contrast, malingerers exhibited the opposite pattern with more commission errors than omission errors. Machine learning models achieve an overall accuracy higher than 90% in distinguishing patients from malingerers on the basis of b Test results alone. Conclusions: Our findings suggest that b Test error scores accurately distinguish patients with Mild Neurocognitive Disorder from malingerers and may complement other validated procedures such as the Medical Symptom Validity Test.

The possible involvement of mitochondrial dysfunctions in Lewy body dementia: a systematic review.

The hallmark of dementia with Lewy bodies (DLB) is the "Lewy body", an abnormal aggregation of alpha-synuclein found in some areas of the brain. The brain is the organ/system that is most vulnerable to this oxidative damage, and reactive oxygen species can cause neurodegenerative diseases. Different models of mitochondrial deregulation have been compared in DLB. The results are consistent with the hypothesis that alpha-synuclein affects the mitochondria themselves, increasing their sensitivity or leading to cell death through protective (neurosin) and accelerating (cytochrome c) factors. This systematic review suggests that mitochondria play an important role in neurodegeneration and a crucial role in the formation of Lewy bodies. DLB is a disease characterized by abnormal accumulation of alpha-synuclein that could result in the release of cytochrome c and subsequent activation of the apoptotic cascade.

Rapid onset of efficacy of rasagiline in early Parkinson's disease.

Rasagiline is a monoamine oxidase type-B inhibitor used as monotherapy or in addition to levodopa in the treatment of Parkinson's disease (PD). This naturalistic single-blind study was aimed at evaluating the rapidity of onset effect of rasagiline on motor symptoms in a cohort of early relatively elderly PD patients. 102 outpatients (55 males, median age 71 years) have been selected: 26 were PD therapy-naive and 76 received rasagiline as add-on therapy. The third section of the Unified Parkinson's Disease Rating Scale (UPDRSIII) and the Hoehn-Yahr (HY) scale were assessed at baseline and after 1 and 4 weeks thereafter. The mean UPDRS III total score (-6.7 at week 1 and -8.9 at week 4) and single items, as well as mean HY score (-0.40 at week 1 and -0.67 at week 4), significantly decreased from baseline (p < 0.001). Improvements were significant in both therapy-naive and add-on therapy patients: the mean decreases from baseline to week 4 in UPDRSIII and HY score were -8.8 and -0.46, and -9.0 and -0.74, respectively, in the two subgroups. The mean decrease from baseline in UPDRSIII and HY score did not significantly differ in patients aged > or ≤71 years. Rasagiline had a rapid therapeutic effect from the first week of therapy, which further improved at 4 weeks. The rapid onset of action and the absence of a dose titration are important issues in the management of the PD patient.

Treatment for paraneoplastic neuropathies.

BACKGROUND: It is not unusual to observe peripheral nervous system involvement in people with tumours outside the nervous system. Any part of the peripheral nervous system can be involved, from sensory and motor neurons to nerve roots and plexuses, from distal trunks to neuromuscular junctions. Pathogenesis also varies from direct infiltration by cancer cells, to treatment toxicity, to metabolic derangement, cachexia, infections and paraneoplastic syndromes.Paraneoplastic neurological syndromes are symptoms or signs resulting from damage to organs or tissues that are remote from the site of the malignancy or its metastases. The pathogenesis is thought to be immune-mediated as a result of a cross-reaction against antigens shared by the tumour and nervous system cells.Paraneoplastic neuropathies are the most frequently reported paraneoplastic syndromes. They are, however, heterogeneous and require several therapeutic approaches. This review was undertaken to systematically assess any data available from randomised controlled trials (RCTs) on the treatment of paraneoplastic syndromes of the peripheral nervous system and not the whole range of paraneoplastic neurological syndromes. OBJECTIVES: To assess the benefits and harms of treatments for paraneoplastic neuropathies. SEARCH METHODS: We searched the Cochrane Neuromuscular Disease Group Specialized Register (14 February 2012), CENTRAL (2012, Issue 1), MEDLINE (January 1966 to February 2012), EMBASE (January 1980 to February 2012) and LILACS (January 1982 to February 2012) for RCTs, quasi-RCTs, historically controlled studies and trials with concurrent controls.We adapted this strategy to search MEDLINE from 1966 and EMBASE from 1980 for comparative cohort studies, case-control studies and case series. SELECTION CRITERIA: We planned to include all RCTs and quasi-RCTs (in which allocation is not random but is intended to be unbiased, for example alternate allocation) of any treatment for paraneoplastic neuropathies. Since we expected there to be few or no included studies, we also planned to assess and summarise observational studies, prospective and retrospective comparative cohort studies, case-control studies and case series that met minimum criteria in the discussion. DATA COLLECTION AND ANALYSIS: Three review authors selected the trials for inclusion. When there was any disagreement we reached an agreement by discussion. Two review authors extracted data independently onto a specially designed data extraction form. We would have collected adverse event data from included studies. MAIN RESULTS: Despite many reports on paraneoplastic neuropathy, we identified no RCT or quasi-RCTs for inclusion in this review. We found only six studies, involving 54 participants, from among the non-randomised evidence that were judged by predefined criteria to be of suitable quality for inclusion in the discussion. These studies were not readily comparable. The treatments focused on tumour treatment and immunomodulation, mainly intravenous immunoglobulin. AUTHORS' CONCLUSIONS: At present there are no RCTs or quasi-RCTs of treatment for paraneoplastic neuropathies on which to base practice. There is only evidence from case series, case reports or expert opinion (class IV evidence) for the effect of immunomodulation (intravenous immunoglobulin, plasma exchange, steroid treatment or chemotherapy) on paraneoplastic neuropathy.  

Current approaches to the treatment of paraneoplastic encephalitis.

Paraneoplastic neurological syndromes (PNSs) cover a wide range of diseases and involve both the central nervous system (CNS) and peripheral nervous system. Paraneoplastic encephalitis comprises several diseases such as paraneoplastic cerebellar degeneration (PCD), limbic encephalitis (LE), paraneoplastic encephalomyelitis (PEM), brainstem encephalitis, opsomyoclonus syndrome, in addition to other even less frequently occurring entities. LE was the first historically identified CNS PNS, and similarities between other temporal lobe diseases such as herpes encephalitis have been elucidated. In the past few decades several autoantibodies have been described in association with LE. These encompass the classical 'onconeuronal' antibodies (abs) such as Hu, Yo, Ri and others, and now additionally abs towards either ion channels or surface antigens. The clinical core findings in LE are various mental changes such as amnesia or confusion, often associated with seizures. Careful characterization of psychiatric manifestations and/or associated neurological signs can help to characterize the syndrome and type of ab. The treatment options in LE depend on the aetiology. In LE caused by onconeuronal abs, the treatment options are poor. In two types of abs associated with LE, abs against ion channels and surface antigens (e.g. NMDA), immunomodulatory treatments seem effective, making these types of LE treatable conditions. However, LE can also occur without being associated with cancer, in which case only immunomodulation is required. Despite effective treatments, some patients' residual deficits remain, and recurrences have also been described.

Chorea and related movement disorders of paraneoplastic origin: the PNS EuroNetwork experience.

Chorea and other movement disorders are rarely described as paraneoplastic. The aim of this study was to describe 13 patients with paraneoplastic chorea and dystonia collected by the members of the paraneoplastic neurological syndrome (PNS) EuroNetwork and to review 29 cases from the literature. We analyzed neurological symptoms, severity of the neurological syndrome, delay in neurological diagnosis, associated cancer, oncological and neurological treatments received, and outcome. Eleven (1.2%) out of 913 patients with PNS were identified in the EuroNetwork register. Two more patients not included in the register were added. The overall population consisted of 13 patients with a median age of 75 years (range 49-82 years). In most patients, the movement disorder was classical choreoathetosis with symmetric involvement of the trunk, neck, and limbs. A minority of patients presented unilateral chorea, dystonia, and orobuccal dyskinesia. Associated symptoms, as polyneuropathy, encephalitis, psychiatric disturbances, or visual defects, were often present. The movement disorder usually had a subacute course. The most frequently associated cancer was small cell lung cancer (SCLC). Lymphoma, bowel, or kidney cancers were also reported. CV2/CRMP5 was the most frequently associated antibody, followed by Hu. Hyperintense lesions of the basal ganglia on T2-weighted images were seldom observed. Response to cancer therapy was observed in a minority of patients, but survival was short (17 months). As in other neurological diseases, movement disorders should also be suspected as paraneoplastic when they develop subacutely in older patients (usually over 50) and often in the presence of other ancillary neurological symptoms.

Spontaneous pain, pain threshold, and pain tolerance in Parkinson's disease.

The mechanisms underlying pain in Parkinson's disease (PD) are unclear. Although a few studies have reported that PD patients may have low pain threshold and tolerance, none could accurately assess whether there was a correlation between sensory thresholds and demographic/clinical features of PD patients. Thus, tactile threshold, pain threshold, and pain tolerance to electrical stimuli in the hands and feet were assessed in 106 parkinsonian patients (of whom 66 reported chronic pain) and 51 age- and sex-matched healthy subjects. Linear regression models determined relationships between psychophysical parameters and demographic/clinical features. Female gender, severity of disease, medical disease associated with painful symptoms, and dyskinesia were more frequently observed in PD patients experiencing pain, even though dyskinesia did not reach significance. Pain threshold and pain tolerance were significantly lower in PD patients than in control subjects, whereas the tactile threshold yielded comparable values in both groups. Multivariable linear regression analyses yielded significant inverse correlations of pain threshold and pain tolerance with motor symptom severity and Beck depression inventory. Pain threshold and pain tolerance did not differ between PD patients with and without pain. In the former group, there was no relationship between pain threshold and the intensity/type of pain, and number of painful body parts. These findings suggest that pain threshold and pain tolerance tend to decrease as PD progresses, which can predispose to pain development. Female gender, dyskinesia, medical conditions associated with painful symptoms, and postural abnormalities secondary to rigidity/bradikinesia may contribute to the appearance of spontaneous pain in predisposed subjects.

Paraneoplastic neurologic syndrome in the PNS Euronetwork database: a European study from 20 centers.

BACKGROUND: Paraneoplastic neurologic syndrome (PNS) represents the remote effects of cancer on the nervous system. Diagnostic criteria for the syndrome were published by the PNS Euronetwork and form the basis of a database to collect standardized clinical data from patients with PNS. OBJECTIVES: To analyze various types of PNS, frequent tumor and antibody associations, clinical characteristics of individual syndromes, and possible therapeutic and prognostic strategies. DESIGN: Prospective case series and database study. SETTING: Twenty European centers. Patients Patients were recruited from January 1, 2000, to December 31, 2008. MAIN OUTCOME MEASURES: Based on diagnostic criteria published by the PNS Euronetwork consortium, clinical characteristics of classic PNS and several other less well-characterized syndromes associated with cancer were assessed. RESULTS: Data from 979 patients were analyzed, representing the largest PNS investigation to date. The findings elucidate the clinical evolution of paraneoplastic cerebellar syndrome according to the onconeural antibodies present, the heterogeneity and prognosis of dysautonomic disorders, and the clinical variability of paraneoplastic limbic encephalitis. CONCLUSION: The study results confirm that PNS influences oncologic patient survival. Tumors are the main cause of death, but some types of PNS (such as dysautonomia) have a poorer prognosis than malignant neoplasms.

AMPA receptor antibodies in limbic encephalitis alter synaptic receptor location.

OBJECTIVE: To report the clinical and immunological features of a novel autoantigen related to limbic encephalitis (LE) and the effect of patients' antibodies on neuronal cultures. METHODS: We conducted clinical analyses of 10 patients with LE. Immunoprecipitation and mass spectrometry were used to identify the antigens. Human embryonic kidney 293 cells expressing the antigens were used in immunocytochemistry and enzyme-linked immunoabsorption assay. The effect of patients' antibodies on cultures of live rat hippocampal neurons was determined with confocal microscopy. RESULTS: Median age was 60 (38-87) years; 9 were women. Seven had tumors of the lung, breast, or thymus. Nine patients responded to immunotherapy or oncological therapy, but neurological relapses, without tumor recurrence, were frequent and influenced the long-term outcome. One untreated patient died of LE. All patients had antibodies against neuronal cell surface antigens that by immunoprecipitation were found to be the glutamate receptor 1 (GluR1) and GluR2 subunits of the alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor (AMPAR). Human embryonic kidney 293 cells expressing GluR1/2 reacted with all patients' sera or cerebrospinal fluid, providing a diagnostic test for the disorder. Application of antibodies to cultures of neurons significantly decreased the number of GluR2-containing AMPAR clusters at synapses with a smaller decrease in overall AMPAR cluster density; these effects were reversed after antibody removal. INTERPRETATION: Antibodies to GluR1/2 associate with LE that is often paraneoplastic, treatment responsive, and has a tendency to relapse. Our findings support an antibody-mediated pathogenesis in which patients' antibodies alter the synaptic localization and number of AMPARs.

Subacute onset of deafness and vertigo in a patient with leptomeningeal metastasis from ovarian cancer.

Ovarian carcinoma is a common gynecological malignancy. Distant metastases usually involve the liver and lung while neurological complications are rare. We describe the case of a 63-year-old woman diagnosed from an ovarian carcinoma with peritoneal seed, which was treated surgically and with chemotherapy. After 4 years she was admitted to our Department for the development of subacute right deafness, vertigo and imbalance. MRI revealed the presence of leptomeningeal carcinomatosis and an expansive formation in the right pontocerebellar angle, suggesting involvement of the right VIII cranial nerve. Examination of the cerebrospinal fluid disclosed the presence of neoplastic cells. Subsequently the patient rapidly deteriorated and eventually died. Involvement of VIII cranial nerve as the presentation of leptomeningeal carcinomatosis in ovarian carcinoma is rare. In the literature at least two other cases presented with deafness, suggesting that leptomeningeal carcinomatosis should be considered in the differential diagnosis when deafness appears in a cancer patient.

Diagnosis and treatment of paraneoplastic neurological syndromes.

Paraneoplastic neurological syndromes (PNS) are remote effects of cancer that may involve any part of the nervous system. Rarity hinders their diagnosis and management and at least 60% of cases do not present a tumor at neurological symptoms onset. An important diagnostic element is detection, in patients' serum or cerebrospinal fluid, of onconeuronal antibodies which recognize antigens expressed by the nervous system and by neoplastic cells during de-differentiation. Their detection also implies that PNS have autoimmune origin and that immunomodulation could be an effective treatment. The lack of clinical trials due to the rarity of PNS makes it hard to test the efficacy of immunomodulatory therapy, but dividing the diseases into two groups permits preliminary analysis. A humoral immunoresponse prevails in group one and antibodies seem to have a pathogenetic role, indicating antibody removal strategies. Group two are mainly PNS of the central nervous system with autoantibodies directed against intracellular antigens, probably involving a cell-mediated mechanism. Immunotherapy with steroids or cytotoxic immunosuppressive agents may be useful here. Immunomodulatory treatment is always indicated when a tumor is not found but neurological symptoms are progressing, since first line treatment is tumor identification and, where possible, removal.

Vasomotion in multiple spontaneous cervical artery dissections.

BACKGROUND AND PURPOSE: The etiology of spontaneous cervical artery dissection (sCAD) is still unknown, even though an underlying arteriopathy impairing vasomotion has often been suspected. This study was undertaken to investigate: (1) spontaneous, (2) endothelial-dependent, and (3) endothelial-independent vasodilation in patients with multiple sCAD. METHODS: In 19 consecutive patients with multiple carotid or vertebral artery dissections high-resolution ultrasound was used to assess spontaneous and endothelial-independent dilations (isosorbide dinitrate-mediated) in the common carotid, vertebral and brachial arteries, and endothelial-dependent dilation (flow-mediated arterial dilation) in the brachial arteries alone. The same parameters were measured in 19 healthy subjects matched for age, sex, and height (controls). Ultrasound studies were performed by one investigator, and off-line analysis by another investigator who was blinded to the clinical data and study status (patient or control). RESULTS: Spontaneous and endothelial-independent dilations were significantly impaired in the carotid (P=0.0006 and P<0.0001, respectively) and vertebral arteries (P=0.0121 and P=0.0047, respectively) of patients as compared with controls, whereas no statistically significant differences were found in the brachial arteries; conversely, endothelial-dependent dilation of the brachial arteries was significantly lower in patients as compared with controls (P<0.0001). CONCLUSIONS: Patients with multiple sCADs have a significantly impaired vasomotion, which may predispose to dissection.

Clinical, immunological and therapeutic aspects of autoimmune encephalitis.

Autoimmune encephalitis is a heterogeneous group of disorders probably resulting from a reaction of the immune system against antigens of the central nervous system. Historically, the autoimmune hypothesis was based on the neuropathological discovery of an immune cellular infiltrate in the brain parenchyma and around the cerebral blood vessels, resembling a form of viral encephalitis without any detectable viral antigens. These syndromes can be divided into forms with prevalent grey matter involvement, forms with prevalent white matter damage and forms in which the target of the immune process is the vessels. In this paper, we review recent knowledge about the syndromes belonging to the first group. This group encompasses syndromes in which there is neuronal loss and antibodies directed against antigens expressed in the neurons (anti-neuronal antibodies) are frequently detected in the sera or cerebrospinal fluid. These antibodies are not necessarily the cause of neurological impairment but are important markers for these syndromes. It is essential to acquire knowledge on these disorders since they are an important cause of rapidly progressive cognitive decline and behavioural problems which may remain underrecognized, but often improve with immunomodulatory therapies.

Paraneoplastic diseases associated with thymoma.

BACKGROUND: Thymoma is frequently associated with paraneoplastic diseases (PDs), most commonly with myasthenia gravis (MG). This association is thought to depend on thymoma's capacity to produce and export T lymphocytes. OBJECTIVE: (1) To determine the frequency and characteristics of thymoma-associated PDs other than MG; (2) to evaluate T cell maturation in thymomas with and without PDs. METHODS: We studied 260 patients with thymoma (associated with MG in 228). The occurrence of PDs was monitored together with the tumor outcome. Phenotypic characterization of thymocyte subsets in 14 thymoma samples (7 with and 7 without MG) was performed by FACS. RESULTS: A total of 47 PDs was diagnosed in 41/260 patients (15.8 %). Neurological PDs included neuromyotonia, limbic encephalitis, polymyositis, subacute hearing loss, psychosis and sleep disorders. A broad spectrum of nonneurological PDs were observed, among these, hematological and cutaneous diseases prevailed. Like MG, these disorders occurred either in the presence of the thymoma or at different times after thymomectomy; their onset often heralded a tumor recurrence. In thymomas from MG subjects, we found an increased proportion of fully mature CD4 single positive (SP) thymocytes and a reduced frequency of CD4SPCD25(+) cells; the latter finding may reflect a deficient generation of T regulatory cells, a reduced intratumorous activation of T cells, or both. CONCLUSIONS: We confirm the strong association of thymoma with PDs. These disorders often occurred in MG patients and their course in relation to thymoma was similar to that of MG. In accordance with previous observations, we found some alterations in the intratumorous production of mature CD4(+) T cells that could be involved in the pathogenesis of paraneoplastic autoimmunity.

Paraneoplastic encephalitis, psychiatric symptoms, and hypoventilation in ovarian teratoma.

We report four young women who developed acute psychiatric symptoms, seizures, memory deficits, decreased level of consciousness, and central hypoventilation associated with ovarian teratoma (OT) and cerebrospinal fluid (CSF) inflammatory abnormalities. Three patients recovered with treatment of the tumor or immunosuppression and one died of the disorder. Five other OT patients with a similar syndrome and response to treatment have been reported. Our patients' serum or CSF showed immunolabeling of antigens that were expressed at the cytoplasmic membrane of hippocampal neurons and processes and readily accessed by antibodies in live neurons. Immunoprobing of a hippocampal-expression library resulted in the isolation of EFA6A, a protein that interacts with a member of the two-pore-domain potassium channel family and is involved in the regulation of the dendritic development of hippocampal neurons. EFA6A-purified antibodies reproduced the hippocampal immunolabeling of all patients' antibodies and colocalized with them at the plasma membrane. These findings indicate that in a young woman with acute psychiatric symptoms, seizures, and central hypoventilation, a paraneoplastic immune-mediated syndrome should be considered. Recognition of this disorder is important because despite the severity of the symptoms, patients usually recover. The location and function of the isolated antigen suggest that the disorder is directly mediated by antibodies.