Hypersomnia as presenting symptom of anti-Ma2-associated encephalitis: case study

Neurological Immune-Related Adverse Events Induced by Immune Checkpoint Inhibitors

The use of immune checkpoint inhibitors (ICIs) for the treatment of various advanced and aggressive types of malignancy has significantly increased both survival and long-term remission rates. ICIs block crucial inhibitory pathways of the immune system, in order to trigger an aggravated immune response against the tumor. However, this enhanced immune activation leads to the development of numerous immune-related adverse events (irAEs), which may affect any system. Although severe neurological irAEs are relatively rare, they carry a high disability burden, and they can be potentially life-threatening. Therefore, clinicians must be alert and act promptly when individuals receiving ICIs present with new-onset neurological symptoms. In this narrative review, we have collected all the currently available data regarding the epidemiology, pathogenesis, clinical manifestations, diagnosis, and treatment of post-ICI neurological irAEs. This review aims to raise physicians' awareness, enrich their knowledge regarding disease pathogenesis, and guide them through the diagnosis and management of post-ICI neurological irAEs.

Management of Paraneoplastic Syndromes in the Era of Immune Checkpoint Inhibitors

OPINION STATEMENT

Our understanding of paraneoplastic neurologic syndromes (PNS) has blossomed over the past few decades. Clinicians have access to more robust diagnostic criteria and have a heightened index of suspicion for these disorders. Nonetheless, treatment, which typically includes immunosuppression, and response to treatment, varies. Due to persistent difficulty in making a definitive diagnosis, we favor empiric treatment when a possible diagnosis of PNS is suspected, and other alternative causes have substantially been excluded (e.g., infections, toxic-metabolic derangements, metastasis, or leptomeningeal disease). Treatment of the underlying cancer, if identified, is the first therapeutic step and can prevent disease worsening and in rare cases, can reverse neurologic symptoms. In addition to anti-cancer treatment, first line immunotherapies, which include corticosteroids, intravenous immunoglobulins (IVIG), or plasma exchange (PLEX) are typically used. If partial or no benefit is seen, second line immunotherapeutic agents such as rituximab are considered. Additionally, the severity of the initial presentation and possible risk for relapse influences the use of the latter agents. Symptomatic management is also an important component in our practice and will depend on the syndrome being treated. One of the more novel entities we are facing currently is the management of immune checkpoint (ICI)-induced PNS. In those cases, current American Society of Clinical Oncology (ASCO) guidelines are followed.

Anti-Ma2 Encephalitis: An Atypical Case Associated With Klüver-Bucy Syndrome and Hypothalamic Dysfunction

Anti-Ma2 encephalitis is a rare form of autoimmune encephalitis that has classically been described as a paraneoplastic neurobehavioral disorder due to its association with underlying malignancies. We discuss the case of a 30-year-old female with an exceptionally aggressive presentation of anti-Ma2 encephalitis accompanied by Klüver-Bucy syndrome and hypothalamic dysfunction. Her course was complicated by repeated aspiration events secondary to severe hyperphagia and delays in immunosuppressive treatment due to concerns of infection. The patient's encephalitis was refractory to multiple immunosuppressive therapies and she ultimately expired before a primary malignancy could be detected and treated.

Paraneoplastic Neurological Syndromes of the Central Nervous System: Pathophysiology, Diagnosis, and Treatment

Paraneoplastic neurological syndromes (PNS) include any symptomatic and non-metastatic neurological manifestations associated with a neoplasm. PNS associated with antibodies against intracellular antigens, known as "high-risk" antibodies, show frequent association with underlying cancer. PNS associated with antibodies against neural surface antigens, known as "intermediate- or low-risk" antibodies, are less frequently associated with cancer. In this narrative review, we will focus on PNS of the central nervous system (CNS). Clinicians should have a high index of suspicion with acute/subacute encephalopathies to achieve a prompt diagnosis and treatment. PNS of the CNS exhibit a range of overlapping "high-risk" clinical syndromes, including but not limited to latent and overt rapidly progressive cerebellar syndrome, opsoclonus-myoclonus-ataxia syndrome, paraneoplastic (and limbic) encephalitis/encephalomyelitis, and stiff-person spectrum disorders. Some of these phenotypes may also arise from recent anti-cancer treatments, namely immune-checkpoint inhibitors and CAR T-cell therapies, as a consequence of boosting of the immune system against cancer cells. Here, we highlight the clinical features of PNS of the CNS, their associated tumors and antibodies, and the diagnostic and therapeutic strategies. The potential and the advance of this review consists on a broad description on how the field of PNS of the CNS is constantly expanding with newly discovered antibodies and syndromes. Standardized diagnostic criteria and disease biomarkers are fundamental to quickly recognize PNS to allow prompt treatment initiation, thus improving the long-term outcome of these conditions.

Anti-kelchlike protein 11 antibody-associated encephalitis: Two case reports and review of the literature

BACKGROUND AND PURPOSE

Kelchlike protein 11 antibodies (KLHL11-IgGs) were first described in 2019 as a marker of paraneoplastic neurological syndromes (PNSs). They have mostly been associated with testicular germ cell tumors (tGCTs).

METHODS

Two patients with KLHL11-IgG encephalitis are reported, and the literature is comprehensively reviewed.

RESULTS

Patient 1 had been in remission from a tGCT 10 years prior. He developed episodic vertigo and diplopia progressing over a few days. Treatment with corticosteroids (CSs) was started a few days after symptom onset. Patient 2 had transient diplopia, which resolved spontaneously. Visual problems persisted for 7 months, when he additionally developed a progressive cerebellar syndrome. One year after onset, CS treatment was started. Initial magnetic resonance imaging was unremarkable in both patients, but analysis of cerebrospinal fluid (CSF) revealed chronic inflammation. KLHL11-IgG was positive in both patients (Patient 1 only in CSF, Patient 2 in serum). Neoplastic screening has so far not revealed any signs of active underlying malignancy. We found 15 publications of 112 patients in total with KLHL11-IgG encephalitis. Most patients (n = 82) had a cerebellar syndrome with or without signs of rhombencephalitis. The most common symptoms were ataxia (n = 82) and vertigo (n = 47), followed by oculomotor disturbances (n = 35) and hearing disorders (n = 31). Eighty of 84 patients had a GCT as an underlying tumor.

CONCLUSIONS

Our cases demonstrate classical symptoms of KLHL11-IgG encephalitis. Early diagnosis and therapy are imperative. As with other PNSs, clinical awareness is needed and further studies are required especially in regard to therapeutic management.

Sleep Disturbances Associated with Neurological Autoimmunity

Associations between sleep disorders and neurological autoimmunity have been notably expanding recently. Potential immune-mediated etiopathogenesis has been proposed for various sleep disorders including narcolepsy, Kleine-Levin syndrome, and Morvan syndrome. Sleep manifestations are also common in various autoimmune neurological syndromes, but may be underestimated as overriding presenting (and potentially dangerous) neurological symptoms often require more urgent attention. Even so, sleep dysfunction has been described with various neural-specific antibody biomarkers, including IgLON5; leucine-rich, glioma-inactivated protein 1 (LGI1); contactin-associated protein 2 (CASPR2); N-methyl-D-aspartate (NMDA)-receptor; Ma2; dipeptidyl-peptidase-like protein-6 (DPPX); alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor (AMPA-R); anti-neuronal nuclear antibody type-1 (ANNA-1, i.e., Hu); anti-neuronal nuclear antibody type-2 (ANNA-2, i.e., Ri); gamma-aminobutyric acid (GABA)-B-receptor (GABA-B-R); metabotropic glutamate receptor 5 (mGluR5); and aquaporin-4 (AQP-4). Given potentially distinctive findings, it is possible that sleep testing could potentially provide objective biomarkers (polysomnography, quantitative muscle activity during REM sleep, cerebrospinal fluid hypocretin-1) to support an autoimmune diagnosis, monitor therapeutic response, or disease progression/relapse. However, more comprehensive characterization of sleep manifestations is needed to better understand the underlying sleep disruption with neurological autoimmunity.

Sleep disorders in autoimmune encephalitis

Sleep disorders in people with autoimmune encephalitis have received little attention, probably overshadowed by the presence of other neurological and psychiatric symptoms in this group of conditions. However, sleep disorders are frequent, often severe, and usually persist beyond the acute disease stage, interfering with patients' recovery and quality of life. Because autoimmune encephalitis can affect any brain network involved in sleep initiation and regulation, all types of sleep disorders can occur, with varying distinct associations, frequency, and intensity. Anti-IgLON5 and anti-NMDA receptor encephalitis exemplify two diseases in which sleep disorders are prominent. In anti-IgLON5 disease, sleep disorders were the core symptoms that led to the description of this disease, whereas in anti-NMDA receptor encephalitis, sleep disorders vary according to the disease stage along with other neuropsychiatric symptoms. Comprehensive, systematic, multicentre studies are needed to characterise sleep disorders and their mechanisms in autoimmune encephalitis.

Sleep and neurological autoimmune diseases

Neurological autoimmune diseases are characterized by an inappropriate immune response that by mistake targets the nervous system. As a result, patients experiment a number of neurological manifestations that may include insomnia, excessive daytime sleepiness, cataplexy, central hypoventilation, and REM sleep behavior disorder. Polysomnographic evaluation may reveal disorganized sleep architecture involving both NREM and REM sleep, and REM sleep intrusions into wakefulness. The study of sleep disorders in the setting of autoimmune diseases (e.g., narcolepsy, anti-IgLON5 disease, paraneoplastic neurological syndromes) shows that an abnormal immune-mediated (humoral or cellular) response target the neuronal structures (e.g., brainstem, hypothalamus) and neurotransmitters systems (e.g., hypocretin) that regulate sleep resulting in sleep impairment. It is a window to examine the link between the autoimmune system and the sleep regulation at the molecular, cellular, and anatomic level.

Paraneoplastic movement disorders: phenomenology, diagnosis, and treatment

Paraneoplastic syndromes include, by definition, any symptomatic and non-metastatic condition associated with a neoplasm. Paraneoplastic movement disorders are a heterogeneous group of syndromes encompassing both hyperkinetic and hypokinetic conditions, characterized by acute/sub-acute onset, rapidly progressive evolution, and multifocal localizations with several overlapping features. These movement disorders are immune-mediated, as shown by the rapid onset and by the presence of antineuronal antibodies in biological samples of patients, fundamental for the diagnosis. Antineuronal antibodies could be targeted against intracellular or neuronal surface antigens. Paraneoplastic movement disorders associated with anti-neuronal surface antigens antibodies respond more frequently to immunotherapy. The underlying tumors may be different, according to the clinical presentation, age, and gender of patients. Our search considered articles involving human subjects indexed in PubMed. Abstracts were independently reviewed for eligibility criteria by one author and validated by at least one additional author. In this review, we sought to critically reappraise the clinical features and the pathophysiological mechanisms of paraneoplastic movement disorders, focusing on diagnostic and therapeutic strategies. Our main aim is to make clinicians aware of paraneoplastic movement disorders, and to provide assistance in the early diagnosis and management of these rare but life-threatening conditions.

Management of Autoimmune Encephalitis: An Observational Monocentric Study of 38 Patients

Over the last years the clinical picture of autoimmune encephalitis has gained importance in neurology. The broad field of symptoms and syndromes poses a great challenge in diagnosis for clinicians. Early diagnosis and the initiation of the appropriate treatment is the most relevant step in the management of the patients. Over the last years advances in neuroimmunology have elucidated pathophysiological basis and improved treatment concepts. In this monocentric study we compare demographics, diagnostics, treatment options and outcomes with knowledge from literature. We present 38 patients suffering from autoimmune encephalitis. Antibodies were detected against NMDAR and LGI1 in seven patients, against GAD in 6 patients) one patient had coexisting antibodies against GABA_A and GABA_B), against CASPR2, IGLON5, YO, Glycine in 3 patients, against Ma-2 in 2 patients, against CV2 and AMPAR in 1 patient; two patients were diagnosed with hashimoto encephalitis with antibodies against TPO/TG. First, we compare baseline data of patients who were consecutively diagnosed with autoimmune encephalitis from a retrospective view. Further, we discuss when to stop immunosuppressive therapy since how long treatment should be performed after clinical stabilization or an acute relapse is still a matter of debate. Our experiences are comparable with data from literature. However, in contrary to other experts in the field we stop treatment and monitor patients very closely after tumor removal and after rehabilitation from first attack.

Anti-Ma2-associated limbic encephalitis with coexisting chronic inflammatory demyelinating polyneuropathy in a patient with non-Hodgkin lymphoma: A case report

RATIONALE

We report the rare case of a 74-year-old man with anti-Ma2-associated paraneoplastic neurologic syndrome (PNS), and review and analyze the clinical manifestations, diagnosis, and treatment of the disease.

PATIENT CONCERNS

The patient presented with a 5-month history of muscle weakness, progressive body aches, and weakness and numbness in both lower extremities. Before his hospitalization, he had experienced cognitive function decline; ptosis, inward gaze, and vertical gaze palsy in the right eye; and occasional visual hallucinations. Brain and spinal cord magnetic resonance imaging (MRI) yielded normal results. Anti-Ma2 antibodies were detected in both serum and cerebrospinal fluid. A 4-hour electroencephalogram showed irregular sharp slow waves and δ waves in the temporal region. Electromyography showed peripheral nerve demyelination. Positron-emission tomography/computed tomography (PET-CT) examination revealed hypermetabolism in the lymph nodes of the whole body. Biopsy of the lymph nodes showed non-Hodgkin lymphoma.

DIAGNOSIS

A clinical diagnosis of lymphoma and PNS was made.

INTERVENTIONS

The patient was treated with intravenous dexamethasone (15 mg/day) for 3 days.

LESSONS

We have presented a rare case of a PNS involving both the central and peripheral nervous systems. The clinical features of this case indicated anti-Ma2-associated encephalitis and chronic inflammatory demyelinating polyneuropathy. PET-CT played a critical role in enabling early diagnosis and prompt treatment in this case.

Autoimmune paraneoplastic syndromes associated to lung cancer: A systematic review of the literature: Part 3: Neurological paraneoplastic syndromes, involving the central nervous system

The development of new immune treatment in oncology and particularly for lung cancer may induce new complications, particularly activation or reactivation of auto-immune diseases. In this context, a systematic review on the auto-immune paraneoplastic syndromes that can complicate lung cancer appears useful. This article is the third of a series of five and deals mainly with neurological paraneoplastic syndromes involving the central nervous system.

Autoimmune sleep disorders

A number of autoantibodies, some paraneoplastic, are associated with sleep disorders. Morvan syndrome and limbic encephalitis, associated with voltage-gated potassium channel-complex antibodies, principally against CASPR2 and LGI1, can result in profound insomnia and rapid eye movement sleep behavior disorder (RBD). Patients with aquaporin-4 antibodies and neuromyelitis optica may develop narcolepsy in association with other evidence of hypothalamic dysfunction, sometimes as the initial presentation. Central sleep apnea and central neurogenic hypoventilation are found in patients with anti-N-methyl-d-aspartate receptor antibody encephalitis, and obstructive sleep apnea, stridor, and hypoventilation are prominent features of a novel tauopathy associated with IgLON5 antibodies. In addition, paraneoplastic diseases may involve the hypothalamus and cause sleep disorders, particularly narcolepsy and RBD in those with Ma1 and Ma2 antibodies. Patients with antineuronal nuclear autoantibodies type 2 may develop stridor. Several lines of evidence suggest that narcolepsy is an autoimmune disorder. There is a strong relationship with the human leukocyte antigen (HLA) DQB1*06:02 haplotype and polymorphisms in the T-cell receptor alpha locus and purinergic receptor P2Y11 genes. Patients with recent-onset narcolepsy may have high titers of antistreptococcal or other antibodies, although none has yet been shown to be disease-specific but, supporting an immune basis, recent evidence indicates that narcolepsy in children can be precipitated by one type of vaccination against the 2009-2010 H1N1 influenza pandemic.

Anti-Ma2-encephalitis in a 2 year-old child: A newly diagnosed case and literature review

BACKGROUND

Anti-Ma2-associated encephalitis is a rare paraneoplastic neurological syndrome characterized by isolated or combined limbic, diencephalic, or brainstem dysfunction. It is rarely reported in children.

CASE STUDY

We describe the clinical data of a 2-year-old girl referred to our department for refractory focal seizures associated with fever, followed by behavioural changes, speech disturbances and confusional episodes. Brain magnetic resonance imaging (MRI) showed left temporoparietal brain involvement. Haematological, biochemical and infectious evaluations were unremarkable. Autoimmune encephalitis was suspected. Paraneoplastic antibodies tests showed positive results for anti-Ma2 antibodies. Screening for underlying tumour was negative. Immunomodulatory treatment was administrated. The patient showed improvement of vigilance and behaviour. However, she kept refractory epilepsy.

CONCLUSION

Although poor response to immunotherapy, early diagnosis and appropriate treatment of this disorder may prevent irreversible sequelae.

Paraneoplastic syndromes: an approach to diagnosis and treatment

Recent medical advances have improved the understanding, diagnosis, and treatment of paraneoplastic syndromes. These disorders arise from tumor secretion of hormones, peptides, or cytokines or from immune cross-reactivity between malignant and normal tissues. Paraneoplastic syndromes may affect diverse organ systems, most notably the endocrine, neurologic, dermatologic, rheumatologic, and hematologic systems. The most commonly associated malignancies include small cell lung cancer, breast cancer, gynecologic tumors, and hematologic malignancies. In some instances, the timely diagnosis of these conditions may lead to detection of an otherwise clinically occult tumor at an early and highly treatable stage. Because paraneoplastic syndromes often cause considerable morbidity, effective treatment can improve patient quality of life, enhance the delivery of cancer therapy, and prolong survival. Treatments include addressing the underlying malignancy, immunosuppression (for neurologic, dermatologic, and rheumatologic paraneoplastic syndromes), and correction of electrolyte and hormonal derangements (for endocrine paraneoplastic syndromes). This review focuses on the diagnosis and treatment of paraneoplastic syndromes, with emphasis on those most frequently encountered clinically. Initial literature searches for this review were conducted using PubMed and the keyword paraneoplastic in conjunction with keywords such as malignancy, SIADH, and limbic encephalitis, depending on the particular topic. Date limitations typically were not used, but preference was given to recent articles when possible.

Paraneoplastic syndromes of the CNS

Major advances in the management of paraneoplastic neurologic disorders (PND) include the detection of new antineuronal antibodies, the improved characterisation of known syndromes, the discovery of new syndromes, and the use of CT and PET to reveal the associated tumours at an early stage. In addition, the definition of useful clinical criteria has facilitated the early recognition and treatment of these disorders. In this article, we review some classic concepts about PND and recent clinical and immunological developments, focusing on paraneoplastic cerebellar degeneration, opsoclonus-myoclonus, and encephalitides affecting the limbic system.

Paraneoplastic neurological syndromes: diagnosis and treatment

PURPOSE OF REVIEW

The most relevant advances in the field of paraneoplastic neurological syndromes are described, with special emphasis on particular clinical-immunological associations and practical issues for the diagnosis and treatment of these disorders.

RECENT FINDINGS

Paraneoplastic neurological syndromes may present with classical neurological symptoms or less frequently with symptoms that do not initially raise suspicion of these disorders. Recent examples include patients who present with epilepsia partialis continua or frontal disequilibrium associated with Hu antibodies, hypersommnia and anti-Ma2 antibodies, Devic's syndrome and CV2/CRMP5 antibodies and a syndrome characterized by psychiatric features and central hypoventilation in young women with anti-N-methyl-D-aspartate receptor antibodies. The cause of the neuronal damage is still open to debate. The recent description of antibodies against membrane proteins in opsoclonus or encephalitis associated with teratoma strongly suggests that antibodies may be responsible for the clinical features in some cases. Early diagnosis and effective treatment of the tumor remain the best options to improve or stabilize the syndrome. Immunotherapy, including rituximab, seems effective in those cases associated with functional damage.

SUMMARY

Neurologists must be aware of neurological syndromes that may have a paraneoplastic origin. Detection of onconeural antibodies is crucial to make the correct diagnosis. Immunotherapy should be used, although the impact of the treatment is unclear in cases with irreversible neuronal damage.

Limbic encephalitis and variants: classification, diagnosis and treatment

BACKGROUND AND OBJECTIVE

Recent studies suggest that a substantial number of patients with autoimmune limbic encephalitis may improve if properly diagnosed and treated. This is due, in part, to the increasing recognition of disorders that associate with antibodies to neuronal cell membrane antigens. This review focuses in these disorders, framed in a clinically useful immunologic classification of limbic encephalitis.

REVIEW SUMMARY

Patients with limbic encephalitis usually present with rapidly progressive short-term memory deficits, psychiatric symptoms, and seizures. After excluding viral and systemic autoimmune disorders, many patients with limbic encephalitis (paraneoplastic or not) have cerebrospinal fluid inflammatory findings, EEG or MRI abnormalities in the temporal lobes, and antineuronal antibodies. These antibodies are directed against 2 broad categories of antigens: (1) intracellular or classic paraneoplastic antigens, including Hu, Ma2, CV2/CRMP5, and amphiphysin among others, and (2) cell membrane antigens, including voltage-gated potassium channels, N-methyl-D-aspartate receptor, and others expressed in the neuropil of hippocampus and cerebellum (pending characterization). Whereas the disorders related to the first category of antibodies associate with cancer (lung, testis and other), prominent brain infiltrates of cytotoxic T-cells, and limited response to treatment, the disorders related to the second category of antibodies associate less frequently with cancer (thymoma, teratoma), seem to be antibody-mediated, and respond significantly better to immunotherapy.

CONCLUSIONS

Once considered an extremely rare disorder, almost always related to cancer, and refractory to treatment, limbic encephalitis is now regarded as a relatively frequent disorder, often unrelated to cancer, and with clinical-immunologic variants that respond to treatment.

REM sleep behavior disorder and narcoleptic features in anti-Ma2-associated encephalitis

A 69-year-old man with anti-Ma2 paraneoplastic encephalitis presented with subacute onset of severe hypersomnia, memory loss, parkinsonism, and gaze palsy. A brain magnetic resonance imaging study showed bilateral damage in the dorsolateral midbrain, amygdala, and paramedian thalami. Videopolysomnography disclosed rapid eye movement (REM) sleep behavior disorder, and a Multiple Sleep Latency Test showed a mean sleep latency of 7 minutes and 4 sleep-onset REM periods. The level of hypocretin-1 in the cerebrospinal fluid was low (49 pg/mL). This observation illustrates that REM sleep behavior disorder and narcoleptic features are 2 REM-sleep abnormalities that (1) may share the same autoimmune-mediated origin affecting the brainstem, limbic, and diencephalic structures and (2) may occur in the setting of the paraneoplastic anti-Ma2-associated encephalitis.