Neurophysiologische befunde bei der diabetischen neuropathie: Neurographie, elektromyographie, vibratometrie, thermotestung

Diabetic neuropathy is a mixed, but predominantly axonal neuropathy of all fiber types. Axonal damage accounts for fibrillations in needle electromyography (EMG). Nerve conduction studies show amplitude reduction of compound muscle action potentials and sensory nerve action potentials due to axonal damage. Peripheral nerve demyelination induces slight or moderate nerve conduction slowing. In early stages, distal foot muscles show fibrillations, sural nerve conduction is abnormal, peroneal nerve F-wave and H-reflex-latencies are prolonged. In advanced stages, EMG of proximal leg muscles or even arm muscles and upper extremity nerve conduction are abnormal. Diabetic radiculopathies and mononeuropathies are diagnosed by EMG. Mechanical ethiologies have to be ruled out by neuroimaging. Quantitative sensory testing (QST) is of high diagnostic value in diabetic neuropathy. Vibratory and thermal threshold evaluation unveil early neuropathy. Thermotesting is particularly valuable in the assessment of diabetic small fiber neuropathy and allows monitoring of the disease.