Carcinoma associated paraneoplastic peripheral neuropathies in patients with and without anti-onconeural antibodies

Objective-When to suspect a paraneoplastic disorder is a puzzling problem t hat has not recently been studied in a large series of patients referred fo r peripheral neuropathy. Methods-From 422 consecutive patients with peripheral neuropathy, 26 were a nalysed who concomitantly had carcinoma but no tumorous infiltration, drug toxicity, or cachexia. Their clinical, pathological, and electrophysiologic al data were analysed according to the presence of anti-onconeural antibodi es, the latency between presentation and cancer diagnosis, and the incidenc e of carcinoma in the corresponding types of neuropathy of the population o f 422 patients. Results-Seven patients (group I) had anti-onconeural antibodies (six anti-H u, one anti-CV2) and 19 did not (groups IIA amd B). In group I, subacute se nsory neuropathy (SSN) was the most frequent but other neuropathies includi ng demyelinating neuropathies were present. Patients in group II A had a sh ort latency (mean 7.88 months), and a rapidly and usually severe neuropathy which corresponded in 11/14 to an established inflammatory disorder includ ing neuropathy with encephalomyelitis, mononeuritis multiplex, and acute or chronic inflammatory demyelinating polyneuropathy (CIDP). Patients in grou p IIB had a long latency (mean 8.4 years) and a very chronic disorder corre sponding in four of five to an axonal noninfaammatory polyneuropathy. In th is population, the incidence of carcinoma occurring with a short latency wa s 47% in sensory neuronopathy, 1.7% in Guillain-Barre syndrome, 10% in mono neuritis multiplex and CIDP, and 4.5% in axonal polyneuropathy. Conclusions-Paraneoplastic neuropathies associated with carcinoma are heter ogeneous disorders. Neuropathies occurring with a long latency with tumours probably resulted from a coincidental association. Neuropathies which occu rred within a few years of the tumour evolved rapidly and corresponded most ly to inflammatory disorders. As dysimmune neuropathies are probably parane oplastic in a limited number of cases, patients with these disorders should probably not be investigated systematically for carcinoma in the absence o f anti-onconeural antibodies, except when the neuropathy is associated with encephalomyelitis and probably with vasculitis. Questions remain concernin g CIDP.