Anti-dppx-encephalitis in A Patient With Cerebral Vasculitis and Connective Tissue Disease - Anti-dppx-encephalitis in A Patient With Cerebral Vasculitis and Connective Tissue Disease - Open Access Pub

Since the first description in 2013, 39 cases of anti-DPPX-encephalitis have been described. Main features of this autoimmune encephalitis characterized by antibodies against the potassium-channel-associated regulatory protein DPPX are gastrointestinal symptoms, cognitive dysfunction and signs of CNS hyperexcitability. While the majority of patients responds to immunotherapy relapses are frequent and often successfully treated with rituximab. Here we report another case of anti-DPPX-encephalitis presenting with the above mentioned triad. However, this is the first case of anti-DPPX-encephalitis in the context of a connective tissue disease combined with cerebral arteriopathy along with brain parenchymal lesions that we interpreted as a secondary, CTD-associated cerebral vasculitis. While the latter resolved under immunosuppressive treatment, comprising glucocorticosteroids, cyclophosphamide, rituximab and plasmapheresis, deterioration of the CTD and multiple infectious complications finally led to the patient's death. As histological evidence for cerebral vasculitis is lacking, other differential diagnoses for the observed cerebral arteriopathy, especially reversible cerebral vasoconstriction syndrome, have to be considered. DOI 10.14302/issn.2470-5020.jnrt-17-1926 In 2013 Boronat et al. described an autoimmune encephalitis with gastrointestinal symptoms, cognitive dysfunction and signs of CNS hyperexcitability like myoclonus, hyperekplexia, tremor or epileptic seizures characterized by antibodies against "dipeptidyl peptidase-like protein 6" (DPPX) 1. DPPX is a regulatory protein associated with the Kv4.2-potassium-channel on the surface of central and peripheral neurons. DPPX-antibodies reversibly decrease DPPX and Kv4.2 protein on hippocampal neurons thereby causing hyperexcitability of enteric and central nervous system neurons 2, 3. So far, the disease has been described in 39 patients 2. In three patients the disease was associated with systemic lymphoma 2, 4. Like anti-DPPX-encephalitis, CNS vasculitis is a rare disease presenting with variable neurological symptoms. According to the etiology CNS vasculitis can be classified as a primary angiitis of the CNS (PACNS) or a secondary form associated with systemic disorders like infections, malignant or connective tissue diseases as well as systemic vasculitides 5. Diagnosis of CNS vasculitis is challenging as mimics like reversible cerebral vasoconstriction syndrome (RCVS) have to be considered and as there is no single test permitting definitive diagnosis 6. At age 27 this woman of Turkish origin