Neurographic studies are an extension of clinical examination and are performed for the functional assessment of peripheral nerves. The study of motor and sensory conduction velocity and the presence, amplitude, morphology and symmetry of the response to electrical stimulation are crucial for the diagnosis and management of peripheral neuromuscular disorders. Neurography also plays an important role in the search for so-called late responses comprising the F wave, H reflex, axonal response and A wave. By analysing the parameters of each late wave, this paper addresses the pathophysiological features and the most common conditions impairing the physiology of late responses, with a special focus on A waves.
Keywords: A waves; Axon reflex; F waves; H reflex; Neurography; Neuropathy.