Seronegative and seropositive autoimmune autonomic ganglionopathy (AAG): Same clinical picture, same response to immunotherapy

[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.

Seronegative autoimmune autonomic ganglionopathy from dual immune checkpoint inhibition in a patient with metastatic melanoma

BACKGROUND

Immune checkpoint inhibitors have improved clinical outcomes including survival in several malignancies but have also been associated with a range of immune-related adverse events (irAEs). Neurological irAEs are rare compared to the more typical skin, gastrointestinal, and endocrine toxicities, and are often underrecognized and challenging to diagnose. Here, we report a case of seronegative autoimmune autonomic ganglionopathy (AAG) induced by dual immune checkpoint inhibitor therapy (ICI) in a patient with metastatic melanoma.

CASE PRESENTATION

A patient with metastatic melanoma was treated with ipilimumab and nivolumab. He developed a constellation of new symptoms including nausea, fatigue, and severe orthostatic hypotension refractory to fluid resuscitation. An infectious, cardiac, neurologic, and endocrine workup were unrevealing. Cardiovascular autonomic testing revealed poor sympathetic nervous system responses. He was diagnosed with seronegative AAG and significantly improved with immunomodulatory therapies including IVIG and steroids as well as varying doses of midodrine and fludrocortisone. He was able to restart nivolumab without recurrence of his symptoms. However, the AAG reoccurred when he was re-challenged with ipilimumab and nivolumab due to disease progression. While the AAG was manageable with steroids at that time, unfortunately his melanoma became resistant to ICI.

CONCLUSIONS

Immune checkpoint inhibitors can have a wide range of unusual, rare irAEs, including neurotoxicity such as AAG. Clinicians should maintain suspicion for this toxicity so that treatment can be rapidly provided to avoid disability.

Rituximab treatment in seronegative autoimmune autonomic neuropathy and autoimmune autonomic ganglionopathy: Case-report and literature review

BACKGROUND AND PURPOSE

Autoimmune autonomic ganglionopathy (AAG) is a rare disease with no well-established treatment. Until recently, AAG could be seropositive (50 to 60% of patients) or seronegative for ganglionic (α3-type) nicotinic acetylcholine receptor (Gα3NAChR) antibodies. In early 2018, the two forms of the disease were distinguished, separating seropositive from seronegative ones, designating this latter form "seronegative autoimmune autonomic neuropathy" (SAAN). Most described treatments are plasma exchange (PE) and intravenous immunoglobulin (IVIG). However in some cases with no or small benefit, other immunomodulatory therapies, such as rituximab have been reported. We report the case of a 24-year-old female patient successfully treated for SAAN with rituximab and steroids after IVIG and PE failure. We also provide a review of case-reports reporting rituximab treatment for both SAAN and AAG.

METHODS

To identify articles reporting SAAN and AAG treatment with rituximab, we searched the PubMed database using the terms "autoimmune autonomic ganglionopathy", "autoimmune autonomic neuropathy" or "seronegative autoimmune autonomic neuropathy" and "rituximab".

RESULTS

Including our patient, nine cases have been described in the literature (4 SAAN and 5 AAG). Rituximab had a significant positive effect in 2 out of 4 SAAN and all 5 AAG cases, used alone or in association with other etiologic treatments.

CONCLUSION

Our study suggests rituximab (alone or in association with other treatments) could provide efficacy in both SAAN and AAG when PE and/or IVIG are not effective enough.