2024 American Academy of Neurology Abstract Website

Objective:

Describe the clinical course, diagnostic approach and outcomes following thymectomy in four non-myasthenic patients with synaptic antibody-mediated autoimmune neurologic disease.

Background:

There is limited data on the therapeutic implications of thymectomy in non-myasthenia autoimmune neurologic conditions, and prior case reports on autoimmune encephalitis have suggested that the presence of a thymoma can be linked with poor outcomes without surgical intervention.

Design/Methods:

We queried the University of Utah Autoimmune Neurology Clinic patient database for any patients who underwent thymectomy for a non-myasthenic indication.

Results:

We identified four patients between the ages of 22-42, out of which two were female. Three out of the four patients had elevated CASPR2 antibody levels in the serum at time of diagnosis while the remaining patient had positive NMDAR antibodies. One of the CASPR2 antibody positive patients had been diagnosed with AMPA receptor encephalitis two years prior, with continuing episodic disease fluctuations despite immunotherapy. All patients underwent thymectomy due to concern for thymoma based on imaging, with one of them testing positive for ovarian teratoma as well requiring surgical intervention. Two patients were treated with maintenance immunotherapy with IVIG and/or rituximab while the other two only received a short course of steroids followed by surgical intervention. CSF profile and MRI brain were largely normal in all patients. All patients had significant disease stability and clinical improvement following thymectomy, with only one patient needing to continue immunotherapy long term.

Conclusions:

Thymectomy allowed for improvement and stabilization of all patients in our cohort, and cessation of immunotherapy in three out of the four. There are no trials or high-quality data to guide appropriateness of thymectomy for CNS autoimmune disorders, but it is often considered in synaptic-antibody mediated neurologic syndromes—especially when multiple autoantibodies are present that are otherwise requiring prolonged immunotherapy or where long-term immunotherapy is contraindicated or not desired by patients.