リハビリテーション医学に役立つ臨床神経生理学

Clinical Neurophysiology in Rehabilitation Medicine

はじめに

　リハビリテーション（以下，リハ）医学は，dysmobilityを診断，評価，治療する医学である．脳卒中をはじめとして，脊髄疾患，神経筋疾患，骨関節疾患，小児疾患，心疾患や呼吸器疾患などさまざまな疾患により，“ヒトは動きにくくなる”．リハをスムーズに進めていくために，疾患の原因を診断し，その程度を客観的に評価したい，リハ医療による治療およびその効果を明確に示したい，また生体信号をリハ治療の手段として用いたいなど，臨床神経生理学はこれらの場面で，とても助けとなり，とても“役に立つ”ものとなる．

　臨床神経生理学は，ヒトの中枢神経系，末梢神経系の機能をさまざまな方法で診断，評価し，治療に役立てる学問であり，この分野の発展は目覚ましい．脳波・筋電図ばかりではなく，誘発電位，機能画像等も近年それに含められており，中枢神経系・末梢神経系の区分を超えた学問へと発展している．それによって，運動機能，感覚機能，自律神経機能，高次脳機能などについて診断，評価が可能である．つまり脳波，筋電図，神経伝導検査，運動誘発電位（運動野興奮性の評価），感覚誘発電位，R-R間隔変動や交感神経性皮膚反応（Sympathetic Skin Response：SSR）などの自律神経機能，さらに脳磁図，fMRI（functional Magnetic Resonance Image），NIRS（Near Infra-Red Spectroscopy）などと同時に記録され，さまざまな側面からの評価ができる．

　本稿では，臨床神経生理学のリハ医学での有用性について解説を加える．

Abstract : Rehabilitation medicine focuses on the diagnosis, treatment and management of people with disabling medical conditions and dysmobility. Physiatrists work with people with disabilities to reduce the impact of their disease or disability on their daily life activities. On the other hand, clinical neurophysiology is a medical specialty that studies the central and peripheral nervous systems through the recording of bioelectrical activity, whether spontaneous or stimulated. Tests conducted are concerned with measuring the electrical functions of the brain, spinal cord, and nerves in the limbs and muscles. It can give the precise definition of site, the type and degree of the lesion, along with revealing the abnormalities that are in question. Due to these abilities, clinical neurophysiology is used to mainly help diagnose diseases. However, because it records bioelectrical activity, clinical neurophysiology is also useful as a treatment method i.e. electro- encephalogram (EEG) biofeedback and electromyography (EMG). Recently, EEG-based brain- machine interfaces (BMI) have been used for people with disabilities. As a BMI signal source, event-related desynchronization of alpha-band EEG during motor imagery (mu ERD), which is interpreted as desynchronized activity of the activated neurons, is commonly used. The ERD represents motor cortex excitability in normal people. ERD is also recorded over the affected side in M1 and represents motor cortex excitability in stroke patients. BCI EEG feedback is thought to induce some improvement in motor function and brain plasticity. BCI technology therefore will be useful for restoring brain function in patients with stroke. So, owing to these treatment capabilities, clinical neurophysiology is also a medical subspecialty in Rehabilitation Medicine.