Rare Seronegative NMOSD Case Identified

A study reported a rare case of seronegative NMOSD with a middle-aged man in Nepal who did not improve in clinical status and performance after given treatment.

In a recent case report, a 35-year-old man from Nepal was diagnosed with seronegative neuromyelitis optica spectrum disorder (NMOSD) with longitudinally extending transverse myelitis (LETM) and Optic Neuritis based on 2015 diagnostic criteria. This was the first report of a diagnosis on seronegative NMOSD in Nepal although there have been few reported cases of LETM attributed to NMOSD with anti-aquaporin 4-immunoglobulin G (AQP4-IgG)-positive status.

The patient reported weakness below both knee joints and had difficulty walking, which was associated with bowel and bladder incontinence, with a progression of being unable to walk later. The weakness of bilateral lower limb along with bowel and bladder incontinence occurred for 2 days.

Lead investigator Bibek Khadka, Nepalese Army Institute of Health Sciences, Sanobharyang, Kathmandu, Nepal, and colleagues wrote, “Our patient has fulfilled core clinical characteristic of optic neuritis, left side and acute myelitis with LETM with characteristic MRI findings along with AQP4 antibody negative status.”1

The patient entered the emergency department with no comorbidities present and no significant findings were observed upon general examination. Motor examination showed power of 0/5 below the bilateral knee joints with upgoing plantars. Reflex and tone examination showed an exaggerated response at bilateral lower limb as both patellar and ankle clonus were present. Below the knee level, touch, pain, temperature, and joint proprioception were reduced in the sensory exam.

“So, our first impression by the history and clinical examination was found to be paraplegia with sensory abnormality involving at level of Lumbar spine 4–5 level. So, we had differential diagnosis of compressive myelopathy, Potts spine, posterior cord infraction and conus medullaris,” Khadka et al noted.1

The 2015 diagnostic criteria were proposed for seropositivity status of patients with more rigid clinical and imaging characteristics for a successful diagnosis of NMOSD in the absence of AQP4-Ab positive status.2

Azathioprine, was given to the patient as a therapy (75 mg twice a day) along with an oral steroid (1 mg/kg/day) and had planned to start rituximab (Rituxan; Genentech). After taking Azathioprine and an oral steroid (60 mg/day), the patient was discharged with recommendations for continuous physiotherapy.

Case Report Highlights Diagnosis of Antibody-Positive NMOSD After Second COVID-19 Vaccination

A rare case report illustrated an 80-year-old man with aquaporin-4 antibody-positive NMOSD following a second dose of the Pfizer-BioNTech COVID-19 mRNA BNT162b2 vaccine.

After two weeks, he was admitted again because of relapse and lack of improvement. Rituximab was then given on two doses of 1 gm as a start every two weeks, continuation to every six months. Although the patient adhered to the treatment, there was no significant improvement observed in clinical status and performance during the hospital stay.

“The mainstay of treatment for NMOSD includes immunosuppressive therapy for both acute attacks and prevention of recurrence and remissions. For the treatment of acute attacks high dose corticosteroids with typical starting dose 1000 mg of methylprednisolone intravenously for 5 days, followed by an oral steroid taper for 2–8 weeks is seen as first line therapy,” Khadka et al wrote.1

The limitation from the study was that there was no adequate follow-up after the second discharge with the patient. Hence, further research is needed on seronegative NMOSD with follow-up. Additionally, more studies on the development of diagnostic modalities in seronegative NMOSD are needed.

Khadka et al noted, “As such, increased scrutiny is the key in the detection of NMOSD with seronegative status per the newly revised criteria. It becomes increasingly crucial as NMOSD is associated with poor prognosis when compared to its differential diagnosis. The relapsing course of the disease, in particular, increases the disability and mortality among people affected by this condition. As such, prompt diagnosis and management to reduce relapse is necessary.”1

REFERENCES
1. Khadka B, Bhattarai AM, Dhakal B, Karki A, Acharya A, Poudel R. Seronegative neuromyelitis optica spectrum disorder with longitudinally extending transverse myelitis and optic neuritis: A case report. Ann Med Surg (Lond). 2022;78:103757. doi:10.1016/j.amsu.2022.103757
2. Wingerchuk DM, Banwell B, Bennett JL, et al. International consensus diagnostic criteria for neuromyelitis optica spectrum disorders. Neurology. 2015;85(2):177-89. doi: 10.1212/WNL.0000000000001729

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