Secondary-progressive multiple sclerosis (SPMS); TM; This literature case was received on 14-Mar-2023, reported by other healthcare professional and concerned an adult patient in late 40s of unreported gender.   This study objective was to evaluate the prevalence and clinical characteristics of iatrogenic central nervous system (CNS) inflammation in a tertiary neuroimmunology clinic since various vaccines, tumor-necrosis-factor-alpha inhibitors (TNFAIs), immune-checkpoint inhibitors (ICIs), and other immunomodulators had been linked to inflammatory CNS events. However, the prevalence of iatrogenic events in the neuroimmunology clinic is unknown.  The patient's past medical history included brainstem clinically isolated syndrome (CIS). The patient's concomitant medications were not reported.  As reported, the patient had no other autoimmune disease or cancer.   On an unspecified date, the patient was vaccinated with influenza vaccine (brand not specified; dose, route of administration, anatomical location and indication: not reported). The batch number was not reported.  On an unspecified date, one day after receiving influenza vaccine, the patient had spinal motor attack followed by recurrent spinal attacks then transition to secondary progressive course, possible flu vaccine unmasking of secondary-progressive multiple sclerosis (SPMS) and progressive relapsing. As reported, the patient had prior brainstem CIS and then post-vaccine transverse myelitis (TM) followed by multiple relapses and transitions to secondary-progressive multiple sclerosis (SPMS), assessed as seven per Naranjo scoring system. The patient was treated intravenously with methylprednisolone, reported as 'IVMP' and had full response to corticosteroids.   The outcome for the events was not reported.   The reporter assessed the event of 'secondary progressive multiple sclerosis' to be probably related to influenza vaccine. As reported, probable flu vaccine was unmasking iatrogenic diagnosis of SPMS. However, the reporter did not provide causality assessment for the event of myelitis transverse.  Both events were considered to be medically significant by a Physician within Seqirus's Pharmacovigilance and Risk Management Department.  In conclusion of this study in was stated that iatrogenic CNS inflammation was rare and typically involved steroid-responsive monophasic events. A subset of iatrogenic events could unmask or worsen relapsing disorders. The probability of iatrogenicity was higher in vaccine and immune-checkpoint inhibitors (ICI)-related events compared to TNFAIs- related events.    This case is linked with cases 202301977, 20230978 and 202301986 (the same literature article).  Company comment: This study objective was to evaluate the prevalence and clinical characteristics of iatrogenic central nervous system (CNS) inflammation in a tertiary neuroimmunology clinic since various vaccines, tumor-necrosis-factor-alpha inhibitors (TNFAIs), immune-checkpoint inhibitors (ICIs), and other immunomodulators had been linked to inflammatory CNS events. An adult patient of unreported gender developed spinal motor attack followed by recurrent spinal attacks then transition to secondary progressive course, possible flu vaccine unmasking of secondary-progressive multiple sclerosis (SPMS) and progressive relapsing one day after vaccination with influenza vaccine. Reportedly, the patient had prior brainstem CIS and then post-vaccine transverse myelitis (TM) followed by multiple relapses and transitions to secondary-progressive multiple sclerosis (SPMS), assessed as seven per Naranjo scoring system. The patient was treated with methylprednisolone. The patient's past medical history included brainstem clinically isolated syndrome (CIS). The patient's concomitant medications were not reported. Considering plausible temporal relationship, causality is assessed as possibly related for both events. Limited information precludes assessment of the agency criteria for myelitis.; Sender's Comments: This study objective was to evaluate the prevalence and clinical characteristics of iatrogenic central nervous system (CNS) inflammation in a tertiary neuroimmunology clinic since various vaccines, tumor-necrosis-factor-alpha inhibitors (TNFAIs), immune-checkpoint inhibitors (ICIs), and other immunomodulators had been linked to inflammatory CNS events. An adult patient of unreported gender developed spinal motor attack followed by recurrent spinal attacks then transition to secondary progressive course, possible flu vaccine unmasking of secondary-progressive multiple sclerosis (SPMS) and progressive relapsing one day after vaccination with influenza vaccine. Reportedly, the patient had prior brainstem CIS and then post-vaccine transverse myelitis (TM) followed by multiple relapses and transitions to secondary-progressive multiple sclerosis (SPMS), assessed as seven per Naranjo scoring system. The patient was treated with methylprednisolone. The patient's past medical history included brainstem clinically isolated syndrome (CIS). The patient's concomitant medications were not reported. Considering plausible temporal relationship, causality is assessed as possibly related for both events. Limited information precludes assessment of the agency criteria for myelitis.