Screening for autoantibodies against calcium channel (PQ) channels (VGCC-P / Q), is used in the investigation of patients with suspected paraneoplastic neuropathy, with Lambert-Eaton syndrome and cerebral dysfunction.
There are several types of calcium channels that resemble each other but are not completely identical, the most common being the N type found in cells throughout the brain and peripheral nervous system and the P / Q type found in Purkinje neurons in the cerebellum and in the granule cells of the cerebellum.
Antibodies against the calcium channels appear in paraneoplastic neuropathy e.g. in small cell lung cancer but may also be present without the presence of tumors. Antibodies against the calcium channels are observed in patients with Lambert-Eaton syndrome and cerebrovascular dysfunction. These are mainly VGCC-P / Q antibodies that are of clinical significance, whereas the importance of VGCC-N antibodies is less well known. Its classic clinical triad is the weakness of the proximal muscles, the absence of reflexes and the dysfunction of the autonomic nervous system.