This study is a multicenter, prospective, randomized, double-blind, placebo-controlled exploratory investigation conducted in China.

To evaluate the efficacy and safety of Crisugabalin, a China-developed novel third-generation calcium channel modulator, for neuropathic pain in neuromyelitis optica spectrum disorder (NMOSD). Patients are randomized 1:1 to receive Crisugabalin or placebo for 2 weeks , followed by an 8-week open-label extension period .The main questions of this study aim to answer are:

Does Crisugabalin lower pain scores after 2 weeks and 10 weeks? What medical problems do participants have when taking crisugabalin? This trial is to compare Crisugabalin to a placebo for the first 2 weeks to see if it reduces pain.

Participants will:

Take Crisugabalin or a placebo twice daily for 2 weeks (double-blind) Then take Crisugabalin for 8 more weeks (open-label) Visit the clinic at weeks 1, 2, 4, and 8 Complete questionnaires about pain, sleep, spasms, anxiety, and depression Last updated on December 2, 2025

**Inclusion Criteria:**

Subjects who meet all of the following criteria will be enrolled in this study:

1. Able to understand and voluntarily sign the written informed consent form;
2. Male or female aged between 18 years (inclusive) and 75 years;
3. Diagnosed with aquaporin-4 (AQP4) antibody-positive neuromyelitis optica spectrum disorder (NMOSD) according to the International Panel for NMO Diagnosis (IPND, 2015) criteria;
4. Patients with comorbid neuropathic pain, DN4 ≥ 4; no change in medication dosage within the past month;
5. Numeric Rating Scale (NRS) for pain score ≥ 4 at screening;
6. First-time use of Crisugabalin Capsules.

**Exclusion Criteria:**

Subjects who meet any of the following criteria will not be enrolled in this study:

1. Presence of peripheral neuropathy or pain unrelated to NMOSD that, in the investigator's judgment, may confound the assessment;
2. Known history of allergy to the investigational drug components, or to other drugs with similar chemical structures, or to any excipients;
3. Prior use of pregabalin ≥ 300 mg/day, gabapentin ≥ 1200 mg/day, or mirogabalin ≥ 30 mg/day with lack of clinical efficacy as judged by the investigator;
4. Severe liver or kidney function abnormalities, meeting any of the following clinical laboratory findings:

1) Liver function: alanine aminotransferase (ALT) or aspartate aminotransferase (AST) > 3 × upper limit of normal (ULN); 2) Estimated glomerular filtration rate (eGFR) < 60 mL/min/1.73 m² (calculated using the simplified MDRD formula); 5. Women who are pregnant, planning to become pregnant during the study period, or currently breastfeeding; subjects who are unwilling to use reliable contraceptive measures (including condoms, spermicides, intrauterine devices, etc.) from the time of signing the ICF until 28 days after the last dose of the investigational drug; 6. Current use of IL-6 receptor blockers (e.g., tocilizumab, satralizumab); 7. History of suicidal behavior or suicidal ideation; 8. Participation in any other clinical study within 30 days prior to screening; 9. The investigator determines that there are other situations in which participation in the study is inappropriate.