The pathophysiology of oxaliplatin-induced neurotoxicity

Nerve dysfunction is a common accompaniment of chemotherapy, typically occurring in a dose-dependent manner, so that the higher the dose and the longer the time of exposure, the more likely neuropathy is to occur. With the majority of chemotherapies, the mechanisms of neurotoxicity have not been clearly established. Cessation of therapy may prevent progression to a more severe syndrome and is often necessary even if there has been tumour response. Alternatively dose reduction may slow or halt progression. The clinical investigation of patients with suspected nerve dysfunction related to chemotherapy remains problematic. While routine nerve conduction studies can document the presence of a neuropathy, they do not provide further insight into pathophysiology. In contrast, measurements of nerve excitability by threshold tracking provide complementary information to conventional nerve conduction studies and may be used to infer the activity of a variety of ion channels, energy-dependent pumps and ion exchange processes activated during the process of impulse conduction. The present review will focus on recent developments in clinical rating scales and novel neurophysiological methods for the clinical investigation of chemotherapy-induced neurotoxicity, and will highlight how such methods may prove useful to study the neurological effects of chemotherapy. Specific emphasis will be placed on oxaliplatin, a platinum-based chemotherapy effective for colorectal cancer that exhibits dose-limiting neurotoxicity.