Table 3.

Definite and possible PNS according to diagnostic criteria as published by Graus et al. (2004)

Definite PNS	Possible PNS
Definite and possible diagnosis of PNS
1. A classical syndrome and cancer that develop within 5 years of the diagnosis of the neurological disorder	1. A classical syndrome, no onconeural antibodies, no cancer is diagnosed, but at high risk for having an underlying tumor
2. A non-classical syndrome that resolves or significantly improves after cancer treatment without concomitant immunotherapy provided that the syndrome is not susceptible to spontaneous remission	2. A neurological syndrome (classical or not) with partially characterized onconeural antibodies and no cancer
3. A non-classical syndrome with onconeural antibodies (well characterized or not) and cancer that develops within 5 years of the diagnosis of the neurological disorder	3. A non-classical syndrome, no onconeural antibodies and cancer present within 2 years of diagnosis
4. A neurological syndrome (classical or not) with well-characterized onconeural antibodies (anti-Hu, Yo, CV2, Ri, Ma2 or amphiphysin) and no cancer

Neurological syndrome with well-characterized antibodies (in bold) is a clinical setting that requires intense search for underlying malignancy and often enables its detection at an early stage. Reproduced from ‘Recommended diagnostic criteria for paraneoplastic neurological syndromes’ (Graus et al. 2004) with permission from BMJ Publishing Group Ltd.