# Neurological side effects of checkpoint inhibitors: myasthenia gravis, Guillain-Barré syndrome, meningitis and encephalitis

Source: https://onco.cc/protocols/irae-neurological/  
OnCo record `irae-neurological` (Protocol). Data CC BY-NC 4.0, attribute "Data from OnCo (onco.cc)"; commercial use needs a licence.

## TL;DR

Immunotherapy rarely inflames the nerves, the brain or the junction between nerve and muscle. Drooping eyelids, double vision, trouble swallowing or speaking, weakness spreading up the legs, numbness, severe headache with a stiff neck, confusion or a seizure need urgent assessment. Treatment is quick high-dose steroids, often with immunoglobulin or plasma exchange, and a neurologist.

## Summary

Neurological irAEs occur in about 6% on PD-(L)1 inhibitors, 4% on CTLA-4 inhibitors and 12% on combinations, mostly grade 1 to 2; grade 3 or more is under 1% but can be fatal or permanent, usually within the first 3 months (SITC 2021). Myasthenia gravis carries about 20% mortality and clusters with myositis and myocarditis.

SITC 2021: refer every neurological irAE to a specialist whatever the grade. Myasthenia: antibody testing, a search for myositis, myocarditis and thyroid dysfunction, negative inspiratory force and vital capacity; stop the checkpoint inhibitor; steroids (prednisone 1 to 1.5 mg/kg for grade 2), pyridostigmine, and IVIG or plasma exchange (LE: 1); admission and possibly intensive care for grade 3 to 4. Guillain-Barré: spine MRI, lumbar puncture, EMG and nerve conduction; permanent discontinuation with IVIG or plasma exchange plus steroids (LE: 1). Encephalitis: MRI, lumbar puncture, EEG, autoimmune and paraneoplastic panels and infection PCR, empirical antivirals; pulse methylprednisolone 1000 mg for 3 to 5 days with IVIG or plasma exchange, then rituximab if refractory (LE: 1). Aseptic meningitis: MRI, lumbar puncture, cortisol and ACTH, antibiotics until bacterial meningitis is excluded, prednisone 0.5 to 1 mg/kg (LE: 4). The 2021 neurologic consensus definitions (seven core disorders, graded by certainty) standardise the diagnosis and advise brain imaging before lumbar puncture.

## Fields

- Kind: Protocol
- Last checked: 2026-11-11
- Also known as: neurologic irAEs; irAE-N; checkpoint inhibitor myasthenia gravis; immune-related Guillain-Barré syndrome; checkpoint inhibitor encephalitis; immune-related aseptic meningitis; immune-related neuropathy
- Tags: protocol; irae; acute-oncology; neurology

## Connected records

- protocols: [Checkpoint inhibitor hypophysitis and adrenal insufficiency: emergency treatment, replacement and steroid emergency card](https://onco.cc/protocols/irae-hypophysitis-adrenal/), [Eye side effects of checkpoint inhibitors: dry eye, uveitis and optic neuritis](https://onco.cc/protocols/irae-ocular/), [Immune-related myocarditis from checkpoint inhibitors](https://onco.cc/protocols/irae-myocarditis/), [Joint, muscle and other rheumatic side effects of checkpoint inhibitors](https://onco.cc/protocols/irae-rheumatological/), [Restarting a checkpoint inhibitor after an immune-related side effect](https://onco.cc/protocols/irae-rechallenge/)
- technologies: [Immune checkpoint inhibitors](https://onco.cc/technologies/checkpoint-inhibitor/)
- drugs: [Atezolizumab](https://onco.cc/drugs/atezolizumab/), [Avelumab](https://onco.cc/drugs/avelumab/), [Cemiplimab](https://onco.cc/drugs/cemiplimab/), [Dostarlimab](https://onco.cc/drugs/dostarlimab/), [Durvalumab](https://onco.cc/drugs/durvalumab/), [Human normal immunoglobulin (IVIg)](https://onco.cc/drugs/human-normal-immunoglobulin/), [Ipilimumab](https://onco.cc/drugs/ipilimumab/), [Methylprednisolone](https://onco.cc/drugs/methylprednisolone/), [Nivolumab](https://onco.cc/drugs/nivolumab/), [Pembrolizumab](https://onco.cc/drugs/pembrolizumab/), [Rituximab](https://onco.cc/drugs/rituximab/), [Tremelimumab](https://onco.cc/drugs/tremelimumab/)
- institutions: [American Society of Clinical Oncology (ASCO)](https://onco.cc/institutions/asco/), [European Society for Medical Oncology (ESMO)](https://onco.cc/institutions/esmo/), [Society for Immunotherapy of Cancer](https://onco.cc/institutions/sitc/)
- terms: [Immune-related adverse events (irAEs)](https://onco.cc/terms/irae/)
- key papers: [ASCO 2021 guideline: how to recognise and manage the immune-related side effects of checkpoint inhibitors](https://onco.cc/key-papers/paper-asco-irae-guideline-jco-2021/)

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