GABAB receptor encephalitis in a patient diagnosed with amyotrophic lateral sclerosis

In 2010 the spectrum of known antigens in autoimmune encephalitis has been expanded by GABA(B) receptors. Until now over 80 patients with GABA(B) receptor encephalitis have been described. We report the occurrence of GABA(B) receptor antibodies in a patient with clinically diagnosed amyotrophic lateral sclerosis (ALS). GABA(B) receptor antibodies have not been described previously in an ALS patient. A 75-year-old female patient presented with cerebellar ataxia, bulbar palsy and cognitive impairment. In the later course of disease signs for affection of the second motor neuron evolved and she was diagnosed with ALS. A post-mortem analysis of cerebrospinal fluid revealed high titers of GABA(B) receptor antibodies. This case provides an idea of the natural course of GABA(B) receptor encephalitis and demonstrates that antibody-mediated autoimmunity could be one of several pathways leading to the ALS phenotype. Furthermore this unique case stimulates the question whether neuronal antibodies might be more common in ALS than previously suspected.