Autoimmune autonomic ganglionopathy in a pediatric patient presenting with acute encephalitis

Autoimmune Autonomic Neuropathy: From Pathogenesis to Diagnosis

Autoimmune autonomic ganglionopathy (AAG) is a disease of autonomic failure caused by ganglionic acetylcholine receptor (gAChR) autoantibodies. Although the detection of autoantibodies is important for distinguishing the disease from other neuropathies that present with autonomic dysfunction, other factors are important for accurate diagnosis. Here, we provide a comprehensive review of the clinical features of AAG, highlighting differences in clinical course, clinical presentation, and laboratory findings from other neuropathies presenting with autonomic symptoms. The first step in diagnosing AAG is careful history taking, which should reveal whether the mode of onset is acute or chronic, followed by an examination of the time course of disease progression, including the presentation of autonomic and extra-autonomic symptoms. AAG is a neuropathy that should be differentiated from other neuropathies when the patient presents with autonomic dysfunction. Immune-mediated neuropathies, such as acute autonomic sensory neuropathy, are sometimes difficult to differentiate, and therefore, differences in clinical and laboratory findings should be well understood. Other non-neuropathic conditions, such as postural orthostatic tachycardia syndrome, chronic fatigue syndrome, and long COVID, also present with symptoms similar to those of AAG. Although often challenging, efforts should be made to differentiate among the disease candidates.

Dysautonomia associated with immune checkpoint inhibitors

OBJECTIVE

The purpose of this study is to report the clinical characteristics of dysautonomia associated with immune checkpoint inhibitors (ICIs).

METHODS

We reported two patients with autoimmune autonomic ganglionopathy (AAG) occurring as immune-related adverse events (irAEs). We also performed a review of previous case reports presenting dysautonomia during ICI therapy. Moreover, we conducted pharmacovigilance analyses using the US Food and Drug Administration Adverse Events Reporting System (FAERS) to investigate dysautonomia associated with ICI.

RESULTS

Two patients in our care developed both AAG and autoimmune encephalitis following ICI therapy for lung cancers. We comprehensively reviewed 13 published cases (M:F = 11:2, mean onset age of 53 years) with ICI-associated dysautonomia including AAG (n = 3) and autonomic neuropathy (n = 10). Of these, ICI monotherapy was performed in seven and combination ICI use in six. In 6 of 13 patients, dysautonomia appeared within one month after the start of ICIs. Orthostatic hypotension was observed in 7 and urinary incontinence or retention in five. All patients except three showed gastrointestinal symptoms. Anti-ganglionic acetylcholine receptor antibodies were undetectable. All but two patients received immune-modulating therapy. Immuno-modulating therapy was effective in three patients with AAG and two patients with autonomic neuropathy, but ineffective in the others. Five patients died, of either the neurological irAE (n = 3) or cancer (n = 2). The pharmacovigilance analyses using FAERS showed that ipilimumab monotherapy and the combination of nivolumab and ipilimumab constituted significant risks for developing dysautonomia, consistent with the review of literature.

CONCLUSION

ICIs can cause dysautonomia including AAG, and autonomic neuropathy is a neurological irAE.

[Acute-onset autoimmune autonomic ganglionopathy remarkably effective in intravenous high-dose immunoglobulin therapy]

A 77-year-old woman developed acute onset of orthostatic hypotension, urinary retention, and constipation. Neurological examination on admission showed severe orthostatic hypotension accompanied by syncope, mydriatic pupils, and attenuation of light reflexes with no abnormalities in other neurological systems. Autonomic testing revealed denervation hypersensitivity in norepinephrine (NE) intravenous infusion test and 0.125% pilocarpine instillation test, low NE in the serum, and decreased amount of sweating in quantitative sudomotor axon reflex test. These findings indicated dysfunction of postganglionic autonomic nerves. Autoimmune autonomic ganglionopathy (AAG) was diagnosed due to the presence of anti-ganglionic acetylcholine receptors. The patient was given intravenous high-dose immunoglobulin therapy (IVIg), improving orthostatic hypotension, urinary retention, and constipation. Previous reports indicated that the response to IVIg varied from case to case. Thus, this case suggests that IVIg is effective in acute-onset AAG cases.

Progressive Encephalomyelitis with Rigidity and Myoclonus (PERM)-like Symptoms Associated with Anti-ganglionic Acetylcholine Receptor Antibodies

This report describes a 59-year-old woman who presented with progressive encephalomyelitis with rigidity and myoclonus (PERM)-like symptoms and severe dysautonomia, including orthostatic hypotension, sinus bradycardia, dysuria, and prolonged constipation. Her neurological symptoms improved after immunotherapy, but the dysautonomia persisted. Anti-ganglionic acetylcholine receptor (gAChR) α3 subunit antibodies, which are frequently identified in patients with autoimmune autonomic ganglionopathy, were detected in the pre-treatment serum. The central distribution of the nicotinic acetylcholine receptors, a target of anti-gAChR antibodies, and immunotherapeutic efficacy observed in this case indicate that anti-gAChR α3 subunit antibodies are associated with the PERM-like features accompanied by autonomic manifestations.

gAChR antibodies in children and adolescents with acquired autoimmune dysautonomia in Japan

Objective

Patients with acquired autonomic dysfunction may have antibodies specific to the ganglionic nicotinic acetylcholine receptor (gAChR). However, the clinical features of children and adolescents with acquired autonomic dysfunction (AAD) remain unclear. This study aimed to determine the clinical features of pediatric patients with acquired autonomic dysfunction.

Methods

This study retrospectively examined a series of patients of AAD with serum gAChR antibodies who were referred to our laboratory for antibody testing between January 2012 and April 2019. The study included 200 patients (<20 years, 20 cases; ≥20 years, 175 cases) with clinical features of AAD.

Results

Upon comparing pediatric and adult patients, we found that antecedent infection and autonomic symptoms at onset with gastrointestinal symptoms occurred more frequently in children with AAD. We confirmed that four children (20.0%) met the diagnostic criteria for postural orthostatic tachycardia syndrome (POTS). A significantly higher number of children than adults had POTS (P = 0.002). In addition, upper GI dysfunction was more prevalent in children than in adults (P = 0.042). In particular, nausea and vomiting occurred in 60.0% of children with AAD and in 21.1% of adults (P < 0.001). The frequency of paralytic ileus was significantly higher in children with AAD (20.0%) relative to adults (6.3%) (P = 0.030). Regarding extra‐autonomic manifestations, encephalopathy was more frequent in children (15.0%) than in adults (1.1%) (P < 0.001).

Interpretation

Pediatric AAD patients have their own clinical characteristics, and these features may be unique to children and adolescents.

Antibodies to the α3 subunit of the ganglionic-type nicotinic acetylcholine receptors in patients with autoimmune encephalitis

Since autonomic dysfunction is closely associated with autoimmune encephalitis (AE), the objective of this study was to determine the autonomic symptoms and the prevalence of anti-α3 subunit of the ganglionic-type nicotinic acetylcholine receptor (gAChRα3) antibodies in the patients with AE. We reviewed the clinical features of 19 AE patients, and specifically analyzed sera for anti-gAChRα3 antibodies using the luciferase immunoprecipitation system (LIPS) assay. Cardiovascular autonomic symptoms were found to be common in patients with AE, and hypersalivation was seen only in patients with NMDAR encephalitis. LIPS detected anti-gAChRα3 antibodies in the sera from patients with AE (5/29, 26%). This study is the first to demonstrate that clinical characteristics including autonomic symptoms of AE patients with seropositivity for gAChR autoantibodies. It will be important to verify the role of gAChR antibodies in autonomic dysfunction and brain symptoms to clarify the pathogenesis of AE.

[Autoimmune autonomic ganglionopathy]

Autoimmune autonomic ganglionopathy (AAG) is an acquired immune-mediated disorder of widespread autonomic failure. Approximately half of the patients with AAG have the autoantibodies against the neuronal nicotinic acetylcholine receptor (AChR) in autonomic ganglia. These ganglionic AChR antibodies have the potential to mediate the synaptic transmission in sympathetic, parasympathetic, and enteric ganglia. Therefore, seropositive AAG patients exhibit various autonomic symptoms. Extra-autonomic manifestations (coexistence with brain involvement, sensory disturbance, endocrine disorders, autoimmune diseases and tumors) are present in many patients with AAG. The nicotinic AChRs comprise a family of abundantly expressed ligand-gated cation channels found throughout the central and peripheral nervous systems. Moreover, limited manifestations of autoimmune dysautonomia including autoimmune gastrointestinal dysmotility are newly recognized clinical entity. Although combined immunomodulatory therapy is beneficial for almost all patients with AAG, several case reports of some AAG patients with small benefit exist. This review focuses on the recent progress in the clinical approaches of AAG and its related disorders involving the role of autoantibodies and clinical practice.

[A case of encephalopathy showing various psychiatric and autonomic symptoms with positive anti-ganglionic acetylcholine receptor (gAChR) antibody]

An 84-year-old woman developed spontaneous recurring mutism. During the periods in which she was able to speak, she described that she had a peculiar delusion where her body was melting away. She did not obey orders although she was able to move her limbs spontaneously. Severe fluctuations in blood pressure measurements were observed; they were unaffected by postural changes. She also had urinary retention and constipation. Her psychiatric and autonomic symptoms showed marked daily and diurnal fluctuations. The brain MRI showed no abnormality in the limbic system or temporal lobes. The cerebrospinal fluid showed slightly elevated protein with normal cells counts. This case was initially thought to be an encephalopathy of unknown etiology. On subsequent testings she was shown to have positive anti-ganglionic acetylcholine receptor (gAChR) antibodies. Although the initial steroid pulse and intravenous immunoglobulin therapies markedly improved both psychiatric and autonomic symptoms, they turned ineffective in subsequent recurrences. We were not able to treat her with plasmapheresis or with other immunisuppressive drugs because of her poor general status, thus their effectiveness could not be determined. Judging from her clinical course, in which immunotherapy was effective although somewhat limited, a possible involvement of an autoimmune mechanism was suspected; however, the exact pathogenesis remains undetermined. It is possible that in this case there may have been an involvement of the immune system and that the patient might have had an encephalopathy with anti-gAChR antibodies.

Autoimmune autonomic ganglionopathy: an update on diagnosis and treatment

INTRODUCTION

Autoimmune autonomic ganglionopathy (AAG) is an acquired immune-mediated disorder that leads to autonomic failure. The disorder is associated with autoantibodies to the ganglionic nicotinic acetylcholine receptor (gAChR). We subsequently reported that AAG is associated with an overrepresentation of psychiatric symptoms, sensory disturbance, autoimmune diseases, and endocrine disorders. Area covered: The aim of this review was to describe AAG and highlight its pivotal pathophysiological aspects, clinical features, laboratory examinations, and therapeutic options. Expert commentary: AAG is a complex neuroimmunological disease, these days considered as an autonomic failure with extra-autonomic manifestations (and various limited forms). Further comprehension of the pathophysiology of this disease is required, especially the mechanisms of the extra-autonomic manifestations should be elucidated. There is the possibility that the co-presence of antibodies that were directed against the other subunits in both the central and peripheral nAChRs in the serum of the AAG patients. Some patients improve with immunotherapies such as IVIg and/or corticosteroid and/or plasma exchange. ¹²³I-MIBG myocardial scintigraphy may be a useful tool to monitor the therapeutic effects of immunotherapies.