Clinical Spectrum, Therapeutic Outcomes and Prognostic predictors in Paraneoplastic Neurological Syndromes - Experiences from a Tertiary Care Center in India.

Background: Paraneoplastic Neurological Syndromes (PNSs) are a heterogeneous group of immune-mediated disorders that often precede tumor diagnosis. There are few systematic studies on the spectrum and follow-up of PNSs.

Objective: To analyze the clinical spectrum, associated tumors, antibody profile, outcomes, and prognostic predictors in a cohort of PNSs admitted in a tertiary care center.

Methods: This retrospective study included 97 patients (2008-2019). PNSs were further classified as "classical," "nonclassical," "definite," and "possible." Clinical profile, diagnostic strategies, therapeutic options, and predictors of outcomes were identified.

Results: The median age was 54 years (range 17-81). Thirty-nine (40.2%) had classical PNS, and 58 (59.8%) had nonclassical PNS, 74 (76.3%) had "Definite" PNS while 23 (23.7%) had "Possible" PNS. Cerebellar degeneration, peripheral neuropathy, and encephalopathy were the three most common neurological syndromes. Tumors were diagnosed in 66 (68%) patients; Lung cancer was the most common primary tumor. Antibodies were positive in 52 (53.6%). Anti-Yo antibody and anti-Ma2 antibody were the most common antibodies. The majority (57.7%) received immunotherapy in addition to definitive treatment for the tumor. A good outcome was seen in 53 (54.6%). Factors associated with good outcome were: early diagnosis, mRS <3 at presentation, absence of metastatic disease, and adjuvant immunotherapy.

Conclusion: A high index of clinical suspicion is essential for early diagnosis and prompt management of PNS, especially the nonclassical syndromes. Multimodality diagnostic imaging techniques and antibody profiling play a crucial role in the diagnosis. A favorable prognosis can be expected with the judicious use of immunotherapy and definitive treatment of malignancy.