Abstract Details

Title Anti-SRP Necrotizing Myopathy in Association with Neuromyelitis Optic Spectrum Disorder

Topic Autoimmune Neurology

Presentation(s) P11 - Poster Session 11 (8:00 AM-9:00 AM)

Poster/Presentation
Number 8-004

Objective

To report a case of anti-SRP immune-mediated necrotizing myopathy in an individual with aquaporin-4 IgG positive neuromyelitis optica spectrum disorder (AQP4+NMOSD).

Background Myopathy has been reported in NMOSD, in some cases presumably mediated by aquaporin-4 IgG, and rarely in the context of an additional immune-mediated process.

Design/Methods Case report

Results A 70-year-old female with a history of Sjogren’s syndrome and AQP4+NMOSD presented with a three-month history of progressive proximal upper and lower extremity weakness, dyspnea and dysphagia. She was diagnosed with AQP4+NMOSD two years prior after experiencing right optic neuritis. One year later, she had a few-week episode of severe intractable nausea leading to weight loss, but she did not have imaging to confirm area postrema syndrome. She was not on immunosuppressive treatment for AQP4+NMOSD attack prevention. Neurologic exam demonstrated appendicular and proximal greater than distal muscle weakness, hypoactive reflexes, and Trendelenburg gait pattern. Labs demonstrated CK 4550 U/L, and positive APQ-4 (1:10000), ANA (1:1280), SSA, SSB, and anti-smooth muscle antibodies. Testing for antibodies associated with autoimmune myopathy showed strongly positive anti-SRP (1:15360, normal <1:240), and negative anti-HMG-CoA reductase and Myomarker panel. EMG confirmed myopathy affecting proximal appendicular and axial musculature with features suggestive of necrosis, splitting or vacuolization of muscle fibers. Left triceps muscle biopsy demonstrated many regenerating and a few necrotic fibers, mild focal increase of endomysial fibrous connective tissue, and few mononuclear cells at perivascular sites, compatible with anti-SRP immune-mediated necrotizing myopathy. CT chest demonstrated interstitial lung disease. Pulmonary function test confirmed a restrictive pattern. Rituximab was selected to treat both anti-SRP necrotizing myopathy and AQP4+NMOSD.

Conclusions

We illustrate an unusual case of anti-SRP immune-mediated necrotizing myopathy in a patient with AQP4+NMOSD. Although autoimmune aquaporin-4 myopathy has been described, multiple comorbid autoimmune disorders are also common in AQP4+NMOSD and differential diagnosis with other myositis etiologies is necessary.

Authors/Disclosures
Shemonti Hasan, MD PRESENTER	Dr. Hasan has nothing to disclose.
Duygu Selcen, MD, FAAN (Mayo Clinic)	Dr. Selcen has nothing to disclose.
Cristina Valencia Sanchez, MD (Mayo Clinic Arizona)	Dr. Valencia Sanchez has received personal compensation in the range of $500-$4,999 for serving on a Scientific Advisory or Data Safety Monitoring board for TG therapeutics. Dr. Valencia Sanchez has received personal compensation in the range of $500-$4,999 for serving on a Scientific Advisory or Data Safety Monitoring board for Merck. Dr. Valencia Sanchez has a non-compensated relationship as a member of the medical advisory board with The MOG Project that is relevant to AAN interests or activities.

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