Trismus and Dysarthria in a Man With Paraneoplastic Kelch-like Protein-11 (KLHL11) Encephalitis

A 45-year-old man was diagnosed with paraneoplastic Kelch-like protein-11 (KLHL11) rhomboencephalitis based on a constellation of neurologic symptoms and signs (vertigo, bilateral ptosis, binocular diplopia, nystagmus, dysarthria, dysphagia, tinnitus, facial weakness, facial sensory deficits, trismus, and gait instability), progressive fluid-attenuated inversion recovery hyperintensity on magnetic resonance imaging (MRI) involving the dorsal medullopontine junction, and KLHL11-IgG in serum (titer, 1:3840) and cerebrospinal fluid (titer, 1:64). Scrotal ultrasonography identified a testicular mass consistent with a regressed germ cell tumor.

The patient’s diplopia, gait instability, and MRI findings improved with high-dose intravenous corticosteroids and cyclophosphamide, but he demonstrated residual trismus and dysarthria, as seen in this video.

Emerging case reports and series are defining the clinical spectrum of paraneoplastic autoimmune KLHL11 encephalitis associated with germ cell tumors, first described in 2019.

Click the Related Article link for full case details and discussion.