Narcolepsy Type 1 as a Rare Manifestation of Autoimmune Glial Fibrillary Acidic Protein Astrocytopathy: A Case Report and Literature Review

ABSTRACT Autoimmune glial fibrillary acidic protein astrocytopathy (GFAP‐A) is an autoimmune meningoencephalitis/meningoencephalomyelitis characterized by anti‐GFAP‐α antibodies in the cerebrospinal fluid (CSF). In this case, a 47‐year‐old man was referred to our hospital with impaired consciousness, respiratory failure, and quadriplegia. Anti‐GFAP‐α antibodies were detected in CSF samples, without other evidence of autoimmune encephalitis‐associated antibodies or viral infections. Therefore, the patient was diagnosed with GFAP‐A. Upon improvement in consciousness levels after immunotherapy, excessive sleepiness and hypersomnia were noted. Considering these findings, along with CSF orexin levels of < 40 pg/mL, the patient was diagnosed with narcolepsy type 1 (NT1). With immunotherapy, the CSF orexin levels recovered to 93.4 pg/mL, and hypersomnia also gradually improved. This case suggests that GFAP‐A can be complicated with reversible NT1, which is probably attributable to transient dysfunction of orexin neurons following astrocyte injury rather than irreversible cell loss.