Objective: To report the efficacy and safety of long-term intrathecal interferon therapy in a patient with SSPE.

Background: Subacute Sclerosing Panencephalitis (SSPE), a fatal progressive neurodegenerative disorder caused by persistent defective measles virus infection, leads to death within 1–3 years without treatment. Vaccination provides 98% protection. While several therapeutic approaches have been explored, Interferon therapy has demonstrated potential survival benefits. We present a case of remarkable neurological recovery with long-term intrathecal interferon therapy, highlighting its underestimated role in SSPE management.

Method: A single-patient case report detailing clinical presentation, diagnosis, treatment, and longitudinal follow-up.

Results: A 17-year-old partially immunized girl developed progressive cognitive decline, initially presenting with inattention and executive dysfunction, followed by emotional blunting, impaired daily activities, and subsequent tonic-clonic seizures. Over one year, she progressed to cortical blindness, worsening cognition, aggression, hyperorality, myoclonic jerks, and an akinetic mute state. MRI revealed parieto-occipital hyperintensities, EEG showed periodic complexes, and cerebrospinal fluid (CSF) analysis confirmed SSPE via a strongly positive Measles Index, fulfilling Dyken’s criteria. She received intrathecal interferon-alpha alongside Isoprinosine, though the latter was discontinued due to financial constraints. Remarkable neurological improvement was observed over one year, with restored mobility, significantly improved speech, and partial vision recovery. At three-year follow-up, she remained clinically stable with sustained functional gains, demonstrating the potential of long-term intrathecal interferon therapy in SSPE.

Conclusion: Interferon therapy, introduced in the 1980s, exhibits antiviral and immunomodulatory effects in SSPE, generally leading to stabilization or mild neurological improvement. This case, however, demonstrates an exceptional recovery from Jabbour Stage 4 to Stage 1 within one year of intrathecal interferon therapy, far exceeding typical outcomes. While rare cases of spontaneous remission (up to 5%) exist, long-term sustained recovery is uncommon. The continued monthly interferon therapy in this patient underscores the need for larger studies to further elucidate SSPE pathogenesis and determine the true therapeutic potential of intrathecal interferon.

References: 1. Risk WS et al; Substantial spontaneous long-term improvement in subacute sclerosing panencephalitis. Six cases from the Middle East and a review of the literature. Arch Neurol. 1978 Aug;35(8):494-502.
2. Garg D et al; Disease-Modifying Therapy in Subacute Sclerosing Panencephalitis: An Area of Darkness. Ann Indian Acad Neurol. 2023 Jan-Feb;26(1):3-9.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/interferon-therapy-in-subacute-sclerosing-panencephalitis-an-underestimated-option/