Severe, Subacute, Progressive, Sensory Predominant Polyneuropathy in a Patient with Chronic Progressive Cerebellar Ataxia and Antibodies to ITPR-1
Jonathan Nutt1, Peter Morrison2, Phillip Mongiovi3, Christopher Tarolli4
1Neurology, University of Rochester Medical Center, 2University of Rochester, Neurology, 3Neurology, U of Rochester, Dept of Neurology, 4University of Rochester
Objective:
To advance understanding of clinical phenotypes of anti-ITPR1 related disease in patients with subacute progressive neuropathy and chronic cerebellar ataxia.
Background:
Antibodies against Inositol 1,4,5 trisphosphate receptor type 1 (ITPR1) are associated with subacute axonal and demyelinating polyneuropathies and chronic progressive cerebellar ataxia. Co-occurring malignancies have been identified in some cases. Despite evidence of autoimmunity, most cases have not shown benefit from immunosuppression.
Design/Methods:
Retrospective chart review of a case of a patient with chronic ataxia and subacute polyneuropathy with ITPR-1 antibodies.
Results:
67 year old male with nine year history of chronic, progressive cerebellar ataxia previously diagnosed with multiple system atrophy, cerebellar subtype, (MSA-c) presented with ten weeks of progressive ascending sensory loss and weakness. In addition to progression of appendicular ataxia, examination demonstrated absent sensation to pinprick and vibration in the lower extremities and in the upper extremities distal to the elbow, trace to absent reflexes, and distal predominant, upper and lower extremity weakness. Cerebrospinal fluid showed normal protein and glucose and was acellular. Given his severe ataxia, expanded work up found positive serum and CSF ITPR-1 antibodies, and CSF oligoclonal bands. Nerve conduction studies and electromyography showed a severe, sensory predominant polyneuropathy with motor conduction velocities in the indeterminate range. A PET scan showed no malignancy. He was treated with 2g/kg of IVIG, though no clinical improvement was seen.
Conclusions:
This case highlights the potential different clinical phenotypes seen in ITPR-1 mediated disease, though it is difficult to be certain whether the prior diagnosis of MSA-c was separate to the ITRP-1 mediated sensory polyneuropathy, or whether ITPR-1 was the unifying diagnosis for both clinical syndromes. As a result, consideration should be made to test for ITRP-1 in patients presenting with severe, subacute, progressive polyneuropathy or chronic progressive cerebellar ataxia.