LAUSR

Neuromyelitis optica spectrum disorder (NMOSD) is an inflammatory, demyelinating disease of the central nervous system that is characterized by severe attacks of optic neuritis and myelitis [1]. Because 80–90% of patients with NMOSD experience relapsing episodes of optic neuritis and myelitis, early diagnosis and maintenance immunosuppressive therapy are important for preventing relapse. Although longitudinally extensive transverse myelitis (LETM), which is defined as myelitis extending over ≥ 3 vertebrae in magnetic resonance imaging (MRI) scans, is an NMOSD-specific radiologic finding, patients with NMOSD may also present with short transverse myelitis (STM). However, very short myelitis occupying less than half of a segment is extremely rare in NMOSD. A 41-year-old Korean woman presented with a 3-month history of a tingling sensation and allodynia in her lower torso. A neurologic examination revealed left-side hyperesthesia below the T7 dermatome. No abnormalities were found in laboratory evaluation. Spinal MRI scans revealed two spinal cord lesions at the centroposterior portion of the T2 vertebra and the left eccentric portion of the T9 vertebra (Fig. 1). Cerebrospinal fluid analysis revealed a slightly elevated protein level (67 mg/dL; normal range, < 45 mg/dL), an elevated immunoglobulin G index (0.80), and the absence of white blood cells and oligoclonal bands. Brain MRI scans revealed no abnormalities. No tests for anti–aquaporin-4 (anti-AQP4) antibodies were performed. She received steroid treatment for 2 months, and she experienced full symptom relief after 9 months. Fifteen months after the first attack, she presented with severe lower-limb weakness and urinary difficulties. A neurologic examination showed that she had grade 1 right-leg muscle strength and grade 4 left-leg muscle strength. A sensory examination revealed reduced sensitivity to pain and temperature extremes in her torso and in both legs below the T4 dermatome. The power of her lower-extremity deep tendon reflexes was elevated, and she exhibited extensor plantar responses. Spinal MRI scans revealed LETM along her C6–T9 vertebrae and gadolinium enhancement along her T2–T4 vertebrae (Fig. 2), and she tested positive for anti-AQP4 antibodies. She was therefore, diagnosed with NMOSD. Her paraparesis was aggravated during steroid pulse therapy (methylprednisolone at 1 g/day for 5 days) and improved after plasmapheresis (8 rounds performed on alternating days). With long-term immunosuppressive therapy (azathioprine at 100 mg/day), she has been relapsefree for 28 months. LETM is a characteristic sign of NMOSD, and lesions throughout the spinal cord with a predominant localization in the central gray matter are commonly observed in NMOSD [2]. In our patient’s case, T2-weighted spinal MRI scans taken at her first presentation showed two separate hyperintensity lesions that each extended along half of a thoracic vertebra. The upper lesion was located in the centroposterior cord, and the lower lesion was located in the lateral cord. We did not consider a diagnosis of NMOSD during the first presentation, and the diagnosis was delayed until the second presentation, which involved severe paraparesis. Recent studies have shown that 14.5–19.8% of patients with NMOSD present with STM as their first NMOSDrelated sign [3, 4]. The median diagnostic delay is greater for patients who initially present with STM than for patients who initially present with LETM [5]. Although STM is not uncommon in patients with NMOSD, STM occupying less than half of a segment is rare in patients with NMOSD. In * Min Su Park [email protected]