Abstract
Anti-contactin-associated protein-like 2 (CASPR2) antibody-associated autoimmune encephalitis is commonly characterized by limbic encephalitis with clinical symptoms of mental and behavior disorders, cognitive impairment, deterioration of memory, and epilepsy. The classical lesions reported are located at the medial temporal lobe or hippocampus, whereas prominent brainstem lesions have not been addressed to date. Herein, we reported two patients mimicking progressive brainstem infarction with severe neurological manifestations. On brain magnetic resonance imaging (MRI), prominent brainstem lesions were noted, although multifocal lesions were also shown in the juxtacortical and subcortical white matters, basal ganglia, hippocampus, and cerebellar hemisphere. Unexpectedly and interestingly, both cases had detectable CASPR2 antibodies in sera, and an exclusive IgG1 subclass was documented in the further analysis. They were treated effectively with aggressive immunosuppressive therapies including corticosteroids, intravenous immunoglobulin G, and rituximab, with the first case achieving a rapid remission and the other undergoing a slow but gradual improvement. To the best of our knowledge, this is the first report on prominent brainstem involvement with definite MRI lesions in anti-CASPR2 antibody-associated autoimmune encephalitis, which helps to expand the clinical spectrum of this rare autoimmune disease and update the lesion patterns in the CNS.
Highlights
Contactin-associated protein-like 2 (CASPR2) belongs to a distinct subgroup of the neurexin superfamily expressed at the distal part of the axon initial segment and in the juxtaparanodal region of nodes of Ranvier on myelinated axons of the peripheral nervous system (PNS) and the central nervous system (CNS) [1]
The detection of anti-contactin-associated protein-like 2 (CASPR2) antibodies in serum or Cerebrospinal fluid (CSF) is crucial for the definite diagnosis of anti-CASPR2 antibody-associated disorders [3], whereas in recent years, the extensive expansion of clinical spectrum has made it more difficult to differentiate this disease from other mimics, in particular when anti-CASPR2 antibodies cannot be tested or the results have not been obtained [4, 15]
To the best of our knowledge, this is the first report that showed prominent brainstem involvement with definite magnetic resonance imaging (MRI) lesions in antiCASPR2 antibody-associated autoimmune encephalitis, which emphasized the necessity of thorough investigations including autoimmune parameters in patients with progressive brainstem involvement that cannot be explained by ischemic infarction
Summary
Contactin-associated protein-like 2 (CASPR2) belongs to a distinct subgroup of the neurexin superfamily expressed at the distal part of the axon initial segment and in the juxtaparanodal region of nodes of Ranvier on myelinated axons of the peripheral nervous system (PNS) and the central nervous system (CNS) [1]. Brain MRI showed multifocal T1 hypointensities and T2 and FLAIR hyperintensities in the left brainstem (medulla, brachium pontis, and midbrain) and juxtacortical and subcortical white matters of bilateral frontal lobes and the left occipital lobe (Figure 3) The majority of these lesions revealed hyperintensities on DWI and isointensities relative to normal white matter on ADC map (Supplemental Figure 2). The patient was diagnosed as anti-CASPR2 antibody-associated autoimmune encephalitis and treated with intravenous immunoglobulin therapy (IVIg; 0.4 g/kg body weight for 5 consecutive days) combined with intravenous methylprednisolone pulse therapy (1,000 mg/day for 3 days, 500 mg/day for 3 days, 240 mg/day for 3 days, 120 mg/day for 3 days) followed by oral prednisone at an initial dose of 50 mg daily with a slow tapering schedule of 5 mg every 3 weeks.
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