Anti-Sez6l2 encephalitis: exploratory imaging assessed in five patients

A rare disease, a very small cohort

Anti-Sez6l2 encephalitis is a rare autoimmune disease characterized notably by cerebellar ataxia, which affects coordination, and cognitive impairment. The researchers followed five patients with anti-Sez6l2 antibodies, aged 15 to 72 years. All had both manifestations.

The study combines this longitudinal cohort with a systematic review covering 18 cases in total. The authors report the first documented adolescent case. The follow-up duration and detailed patient selection methods are not specified in the available abstract.

Different signals depending on the scan

Structural MRI showed cerebellar atrophy in three of the five patients. Combined positron emission tomography and MRI, using the tracer 18F-DPA714, detected a signal interpreted as microglial activation in the cerebellum in four patients and in the bilateral mesial temporal regions in one patient.

According to the authors, the location of these signals corresponded to the clinical manifestations. In just one patient, clinical improvement was accompanied by a 7–8% decrease in cerebellar tracer uptake. This parallel change remains an individual observation: it does not demonstrate that the measurement can predict recovery or guide treatment.

The treatments cannot be ranked

The authors describe marked cognitive and psychiatric recovery in three patients who received first- and second-line immunotherapies, mentioning efgartigimod and ofatumumab. By contrast, a 66-year-old patient with established atrophy responded poorly to first-line treatment alone.

However, these patients do not form comparable groups. The abstract describes neither randomization nor a control group. Age, baseline condition and differences in care therefore prevent the observed changes from being attributed to a specific drug. Adverse effects are not detailed in the excerpt.

A research avenue, not a validated test

The review of 18 cases found ataxia in all patients and cognitive impairment in 72% of them, with substantial residual disability reported. These data describe published cases, not necessarily everyone with the disease.

The main contribution is a broader description of the disease and a potential monitoring tool. Establishing its clinical utility would require, among other things, showing that imaging provides reliable information that leads to beneficial changes in care.

What we can take away

This study suggests that 18F-DPA714 imaging may be useful for exploring anti-Sez6l2 encephalitis. It validates neither its routine use nor the superiority of a treatment combination.