To describe a case of anti-metabotropic glutamate receptor 1 (mGluR1) antibodies mediated cerebellar ataxia and to review all previously reported cases in the English literature.

Immune-mediated neurological disorders literature is evolving like no other field of neurological illnesses. Many new antibodies and disorders have been described in the last decade. The cerebellum is one of the brain structures susceptible to these immune mediated pathologies and anti-mGluR1 antibodies is one with predilection to cerebellar tissue. It triggers an acute or subacute cerebellar syndrome of varying degrees of severity. Cerebellar ataxia associated with anti-mGluR1 is a rare autoimmune-mediated cerebellar ataxia that have been reported 20 times. As one-third of the reported cases are paraneoplastic, investigating for an occult malignancies is important. This is the first ever reported mGluR1 mediated cerebellar ataxia in the Middle East.

We describe a case of non-paraneoplastic cerebellar ataxia associated with anti-mGluR1 antibodies in a 56-year-old female. She presented with cerebellar ataxia, dysarthria, tremors, and diplopia following a febrile illness. CSF analysis showed lymphocytic pleocytosis with positive oligoclonal bands. Brain MRI was initially unremarkable and six months later showed cerebellar atrophy. Serum anti-mGluR1 antibody titers were 1:1000 and the CSF anti-mGluR1 antibody titers were 1:32.  She was treated with pulse intravenous methylprednisolone, intravenous immunoglobulin (IVIg), plasma exchange (PLEX) as acute treatment. For maintenance, she received IVIg, PLEX, rituximab, and azathioprine over the course of 3 years. She improved and stayed in remission until now and extensive workup including PET scan showed no occult malignancy.

Anti-mGluR1 Cerebellar Ataxia is an immune mediated disorder that warrants early diagnosis to initiate therapy in a timely manner with the goal to achieve better outcome. Testing for mGluR1 antibodies should be considered in any acute or subacute cerebellar ataxia specially when it follows a prodrome of febrile illness.