Nerve conduction studies: essentials and pitfalls in practice

Abstract

neurologist has sent a patient for nerve conduction studies (NCS) and has received the report, but what does it mean? We hope to remove some of the mysteries that may surround NCS. The techniques and how they are affected by disease are described in general terms. These principles can be applied to specific conditions discussed elsewhere. We also discuss the numerous pitfalls that may be encountered with NCS. Understanding these basic concepts will allow you to get the most from your clinical neurophysiology department. NCS are only part of a complete peripheral neurophysiological examination (PNE) and are frequently accompanied by a needle electromyogram (EMG). The combination of both techniques and those detailed in other articles in this issue are often required for a complete diagnostic study. The process of choosing the appropriate tests is the responsibility of the clinical neurophysiologist (CN) and not the referring doctor and is planned as a dynamic series of steps designed to answer specific questions about nervous system function raised by the clinical picture. ABBREVIATIONS c Clinical neurophysiologists can employ a confusing number of terms and abbreviations. Box 1 lists the ones we use frequently.

Proposta De Um Sistema Para Estudos De Condução Nervosa

“…É importante notar que para obtenção de valores válidos em um ECN, é necessário que o estímulo seja supramáximo, o que garante que a amplitude da resposta tenha um valor máximo. Dessa forma, é esperado que os PACM registrados no mesmo nervo, com estímulos em pontos diferentes, possuam similaridade na forma e na amplitude com diferenças no tempo de latência da resposta [4]. Essa comparação pode ser feita nos registros do nervo ulnar (Figuras 4 e 5), onde pode ser vista uma diferença na amplitude das respostas.…”

“…Além disso, foi calculada a VC para o nervo ulnar, utilizando a equação VC = distância entre os locais de estimulação (distal e proximal) / Latência Proximal (LP) -Latência Distal (LD), em que a distância entre os locais de estímulo foi de 20,5 cm [4].…”

“…As variações destes indicadores estão relacionadas a doenças que causam desmielinização (danos na bainha de mielina) dos neurônios. Por outro lado, a amplitude do PA reflete a quantidade de fibras nervosas funcionais e as alterações na mesma podem indicar degeneração axonal [1,3,4].…”

Autophagy in Peripheral Neuropathy

“…NCS can be performed orthodromically or antidromically, depending on the direction of the nerve signal. In the orthodromic approach, the nerve action potential is transferred in the physiological direction, while in the antidromic the action potential is transferred against the physiological direction of the nerve signal [88]. When a nerve is electrically stimulated, an action potential propagates in both directions.…”

Functional MRI, Diffusion Tensor Imaging, Magnetic Source Imaging and Intraoperative Neuromonitoring Guided Brain Tumor Resection in Awake and Under General Anaesthesia

“…On the contrary, the transcranial magnetic stimulation (TMS) uses magnetic stimulation coil to generate electrical current in the brain tissue [54,55]. The stimulus intensity can be adjusted from 0 to 100% of the magnetic tesla (normally for single pulse motor mapping, 80-90 % stimulus intensity is needed [56,57]. Examples of recorded muscles are dorsal interrosseus, abductor pollicis brevis, brachioradialis, biceps, deltoid, thenar or hypothenar muscles or extensor digitorum longus for upper limb and first dorsal interrosseous, extensor hallucis longus, tibialis anterior, gastrocnemius, soleus, anterolateral thigh groups of muscles for the lower limb and for the face; frontalis and orbicularis oris in awake state and orbicularis oculi, oris or nasalis in unconscious state.…”