Subacute Progressive Autoimmune Cerebellar Ataxia with ITPR1 and GRAF1 Antibodies: A Case Report
Hannah Enyart1, Chan Gu1, Stephen Aradi1, Mark Armanious1
1Neurology, University of South Florida
Objective:
To describe an unusual case of a patient presenting with subacute progressive cerebellar ataxia with cerebrospinal fluid testing revealing inositol 1, 4, 5-triphosphate receptor type 1 (ITPR1) and GTPase regulator associated with focal adhesion kinase pp125 (GRAF1) antibodies.
Background:
The GRAF1 and ITPR1 antibodies, first described in 2010 and 2014 respectively, often present with autoimmune cerebellar ataxia (ACA) but both have broader clinical presentations including psychiatric, cognitive symptoms, neuropathy, myelopathy, radiculopathy, and encephalopathy with seizures. Both are associated with malignancies.
Results:
We describe a case of a 23-year-old male who developed viral upper respiratory illness symptoms, progressing to include diplopia, dizziness, imbalance, and dysarthria. Examination following transfer to our facility revealed nystagmus, ataxic speech, and ataxic gait. MRI of the brain and cervical and lumbar spine were unremarkable. Lumbar puncture showed lymphocytic pleocytosis and elevated protein. The patient was treated with high-dose intravenous steroids escalating to IVIG due to minimal response. Serum autoimmune and paraneoplastic encephalopathy panel resulted negative. ITPR1 and GRAF1 antibodies would later result positive in CSF. Malignancy work-up was negative.
A PET Scan revealed a metabolic pattern consistent with autoimmune encephalitis and globally diminished metabolism in the cerebellum, which persisted on follow up PET approximately five months later. Currently, he is undergoing a trial of rituximab and scheduled IVIG. Trials of dalfampridine and clonazepam for his nystagmus have not provided lasting improvement of his oscillopsia and vertigo. Approximately six months after his initial imaging, repeat MRI brain demonstrated mild caudal, vermian, and medial cerebellar hemispheric volume loss.
Conclusions:
This is a unique case of subacute cerebellar ataxia with simultaneous ITPR1 and GRAF1 antibodies. The patient described has had negative workup for malignancy but continues with surveillance given high association with malignant processes reported in prior literature. Similarly to past cases, he has not responded well to therapy.
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