New-Onset Multiple Sclerosis in Pregnancy: Diagnostic Approaches and Treatment Dilemmas.

Multiple sclerosis (MS) is an autoimmune disease of the CNS affecting the brain, spinal cord, and optic nerves. Research consistently shows that relapse rates in MS decrease during pregnancy, particularly in the third trimester. However, these rates increase postpartum, especially within the first three months after delivery, returning to prepregnancy levels. Importantly, studies indicate that pregnancy does not alter the overall course or progression of MS. While there are detailed accounts of new-onset MS presentations, documentation of cases that first present during pregnancy remains scarce. This case highlights a unique presentation that challenges the current understanding, as it deviates from previously reported literature. We emphasize the distinctive MRI findings that were crucial for diagnosing MS and discuss the difficulties in differentiating it from other neurological conditions. The case also underscores the importance of individualized care and a multidisciplinary approach, including preconception counseling, to reduce relapse risk and long-term disability while minimizing potential harm to both the patient and the offspring. We report the case of a 29-year-old gravida 2, para 1 female with an uneventful antenatal course until 25 weeks of gestation, when she developed new-onset neurological symptoms, beginning with numbness and weakness in her limbs. Initially, she experienced pins and needles in her left hand, which rapidly progressed to reduced sensation, immobility, and urinary retention. By 29 weeks, her symptoms had worsened, resulting in near-paralysis of both legs and the need for a prolonged indwelling catheter. At 35 weeks, she was referred to a tertiary care center. MRI scans revealed multiple hyperintense lesions in both the brain and spinal cord, particularly in the centrum semiovale and the C3-C4 regions, indicative of demyelination. Neuromyelitis optica spectrum disorder and anti-MOG antibody testing were negative, while CSF analysis revealed oligoclonal bands. Based on these findings, she was diagnosed with MS rather than transverse myelitis or clinically isolated syndrome. The patient underwent immunotherapy, including intravenous methylprednisolone and plasmapheresis, which resulted in significant improvement in leg mobility and sensory deficits. By six weeks postpartum, she demonstrated functional recovery, although some symptoms, such as sensory deficits and an abnormal gait, persisted. This case illustrates the diagnostic challenges of distinguishing MS from other neurological conditions during pregnancy. Key findings included hemiplegia, sensory loss, multiple MRI lesions in both the brain and spinal cord, and the presence of oligoclonal bands in CSF. The progressive symptomatology during pregnancy, alongside these clinical features, can guide clinicians in recognizing and managing similar cases.