Objective:

To describe the clinical features, diagnostic approach and treatments in patients diagnosed with paraneoplastic neurological syndromes (PNS).

Background:

PNS are due to an abnormal response of the immune system against the nervous system. In many cases, their identification allows early diagnosis of hidden tumors. Argentina ranks fifth in cancer frequency in Latin America, however data about PNS is lacking.

Design/Methods:

We performed a retrospective study including 42 adult patients with PNS treated between 2010 and 2021 in a referral center of Argentina.

Results:

Mean age at symptom onset was 59.6 years (range 20 to 82). The onset of symptoms was acute in 11 cases (26%), subacute in 25 (59.5%) and chronic in 6 (14.3%). The median time between the onset of symptoms and suspicion of PNS was 16.25 months (SD 16.7). The most frequent symptoms were paresthesias (23.8%) and limb weakness (19%).

Classic PNS was found in 6 patients (14.3%) and non-classic PNS were identified in 26 cases (61.9%). An onconeural antibody was identified in 36 patients (85.7%).

Primary tumors were found in 14 patients (33.3%). Lung cancer was the most frequent tumor (28.57%). The latency between suspected PNS and tumor diagnosis was 1.89 years (range 0.31 to 4.79).

Twenty eight patients (66.7%) received immunological therapy. Nine patients received onco-specific treatment (chemotherapy or radiotherapy) and two patients were treated with tumor resections.

Symptoms improved in 21.4% of patients, 57.1% remained stable and 21.4% worsened. Four patients died (9.5%).

Conclusions:

The clinical manifestations were under a non-classical syndrome, had a subacute course and were associated with lung cancer in the majority of cases. The latency between PNS onset and tumor identification was also variable despite the use of appropriate imaging techniques. The absence of antibodies does not rule out an occult tumor, which should not delay immunomodulatory treatment in the suspected cases.