To describe the incidence, characteristic elements, and similarities/differences in autonomic dysfunction (AD) in immune-mediated encephalitis syndromes.

The presence of AD in autoimmune encephalitis has been shown to be associated with poorer outcomes, higher rates of ICU admission, and longer hospital stays. Impairment of the autonomic nervous system is a frequent component of autoimmune encephalitis, frequently manifesting as tachy/bradycardia, tachypnea, central hypoventilation, hypo/hyperthermia, orthostasis, blood pressure lability, impaired urinary or bowel function, mydriasis, altered pilomotor activity, hyper/hypohidrosis, sexual dysfunction, and paroxysmal sympathetic hyperactivity, among others. However, the pertinent literature is limited, particularly in less-common etiologies.

A comprehensive literature search was performed using multiple databases to identify all substantial reports of AD in cases of immune-mediated encephalitis, and the features attributable to a specific antibody/syndrome were reported. When possible, incidence rates were included. Articles were excluded if information was not attributable to a specific antibody.

Distinct clusters of symptoms were identified and characterized for many etiologies of autoimmune encephalitis. Reported incidence rates of AD vary widely, and likely relate to inconsistent diagnostic criteria and reporting. Phenotypes specifically regarding AD are described for a wide range of immune-mediated encephalitis syndromes, including those targeting Anti-NMDAR, LGI1, CASPR2, GAD65, GlyR, GABA_B, IgLON5, GFAP, Hu, CV2/CRMP5, AChR, VGCC, Zic4, GABA_A, and VGKC. There were no reported cases of AD in cases of anti-MGluR, anti-Neurexin-3α, anti-Ma, anti-DPPX, anti-MOG, anti-AMPA, or anti-Ri encephalitis. Cases in which targeted treatment for specific AD features was successful were also reported.

Specific immune-mediated encephalitis syndromes are often associated with distinct clusters of autonomic dysfunction features. This is the first comprehensive study of existing literature regarding AD within various etiologies of autoimmune encephalitis. Further categorization of these clusters may lead to improved syndrome-specific diagnosis and treatment guidelines for better neurological outcomes.