UCL Institute of Neurology



Nerve Excitability and Pathophysiology

Professor Hugh Bostock FRS

Clinical application of nerve excitability testing

Recently developed protocols for measuring multiple excitability properties of large human motor and sensory axons provide information about human axons that is different from, and complementary to, conventional nerve conduction studies. For example, excitability measures are much more sensitive to changes in resting membrane potential than measurements of conduction velocity. These methods are being applied to a range of conditions affecting human peripheral nerves, in order to help determine the pathophysiology of the neuropathy, or to improve diagnosis. Neuropathies currently under investigation include those associated with diabetes, uraemia and other metabolic disorders, and those associated with the chemotherapy in HIV infections and cancers.

Membrane properties of C fibres

Knowledge of mammalian C fibres has lagged far behind that of the larger, myelinated axons, since their small size has prevented intracellular recording or patch-clamping. Most extracellular recordings do not distinguish the contributions of different functional classes of C fibre, which have recently been shown to differ markedly in their membrane properties. Knowledge of the biophysical basis of these differences could be important clinically, to allow pharmacological differentiation between sympathetic C fibres, and fibres responsive to changes in temperature, to normally painful stimuli, or those that require sensitisation by inflammation. We are developing new approaches to studying C fibre membrane properties, using microneurographic recordings from single human C fibres in vivo, and in vitro excitability testing.