P/Q- and N-type calcium-channel antibodies: Oncological, neurological, and serological accompaniments

Voltage-gated calcium-channel autoimmunity (VGCC-P/Q and VGCC-N types) occurs beyond Lambert-Eaton syndrome and lung cancer.

We reviewed records for 236 Mayo Clinic patients with VGCC antibodies found in evaluation for paraneoplastic neurological autoimmunity (generally without myasthenic syndromes).

VGCC autoantibodies were detected in 3.4% of neurological patients, 1.7% of healthy controls, and 4% of neurologically asymptomatic lung cancer controls. Fifty neurological patients (21%) had ≥ 1 neoplasm, historically (46) or detected prospectively [small-cell lung carcinoma (2), breast adenocarcinoma (2), lymphoma (1), and suspected tonsillar carcinoma (1)]. Autoimmune neurological diagnosis frequencies (encephalopathy, ataxia, myelopathy, neuropathy, neuromuscular junction disorder, and myopathy) among patients with medium values (24%; 0.10-0.99 nmol/L) or low values (19%; 0.03-0.10 nmol/L) were fewer than among patients with antibody values exceeding 1.00 nmol/L (71%; P = 0.02 and 0.004, respectively).

Among neuronal VGCC-autoantibody-seropositive patients, autoimmune neurological phenotypes and cancer types are diverse. Cautious interpretation of results (particularly medium and low values) is advised. Muscle Nerve, 2016 Muscle Nerve 54: 220-227, 2016.