흰쥐의 납중독 말초신경병에서 신경복합활동 전위와 형태학적 변화의 비교 연구

Abstract

[한글]

말초신경병에서 수초의 병인지 축삭의 병인지를 감별하는 것은 임상적으로 매우 중요하다. 그러나 형태학적 검사를 위해서는 신경을 절단해야만 하는등 여러가지 어려움이 있기 때문에 임상에서는 흔히 전기생리학적 검사로 병리소견을 추정하고 있다.

만성 납중독 말초신경병에서 아직 축삭변성 여부에 대해서는 논란이 되고 있으나 일반적으로 탈수초성 질환으로 알려져 있는데 본 연구에서는 만성 납중독 말초신경병의 형태학적 변화를 구명하고 이를 전기생리학적 변화와 비교 검토함으로 신경전도속도검사의 일상적 의의를 평가하고자 하였다. 실험대상은 Sprague-Dawley계 흰쥐 28마리로서 lead acetate를 3개월간 투여한 14마리의 실험군과 같은 환경조건하에 lead acetate를 투여하지 않은 14마리의 대조군에서 전기생리학적 변화를 관찰하고 이중 대조군 5마리, 실험군 10마리에서 형태학적 변화를 관찰, 비교하여 다음과 같은 결론을 얻었다.

1) 개체신경섬유를 분리한 관찰에서 분절성 탈수초현상이 흔히 발견되었다.

2) 전자현미경 관찰에서 신경의 변성은 축삭보다 수초에서 더 현저하였다.

3) 조직계측학적 관찰에서는 대조군에 비해 납투여군에서 신경섬유가 가늘어지고 수초가 얇아졌는데 특히 굵은 신경섬유에서 수초두께의 감소가 현저하였다. 그러나 축삭직경은 두 군 사이에 뚜렷한 차이가 없었다.

4) 신경복합활동전위는 모든 굵기의 신경섬유에서 신경전도속도가 지연되었는데 특히 굵은 유수신경섬유(Aαβ)에서 더 심하였다.

5) 굵은 유수신경섬유(Aαβ)의 신경복합활동전위는 지속시간이 연장되고 전위폭은 감소되었으나 전위의 면적 은 대조군과 차이가 없었다.

6) 무수신경섬유의 신경복합활동전위는 지속시간이 연장되었으나 전위폭과 면적은 통계적으로 유의한 차이는 없었다.

7) 신경복합활동전위의 변화는 형태학적 변화를 예민하게 반영하였다.

이상의 결과로 흰쥐의 납중독 말초신경병에서는 축삭변성은 경미한데 비해, 탈수초현상이 특히 굵은 유수신경섬유에서 심하며 이런 형태적 변화는 신경복합활동전위검사에 잘 반영됨을 할 수 있었고, 결국 탈수초성 말초신경병에서 신경전도검사의 유용성을 입증할 수 있었다.

Comparison Between Electrophysiologic and Morphologic Changes in Lead Induced

Peripheral Neuropathy in Rats

Youn Mee Hwang, M.D.

Department of Medical Science, The Graduate School, Yonsei University

(Directed by Prof. In Hyuk Chung, M.D.)

Differential diagnosis between myelinopathy and axonopathy is very important.

Elctrophysiologic and morpholosic examinations can be used for this purpose. To

predict the pathologic finding in peripheral neuropathy with electrophysiologic

study, it is necessary to know the precise relationship between morphologic and

electrophyosilogic changes.

The author compared morphologic changes with electrophysiologic changes in lead

induced peripheral neuropathy in rata which is characterized by segmental

demyelination. However this point is controversial because there are some reports

suggesting that associated axonal degeneration has occured in other species and

thus, this study also evaluated that controversy.

Sprague-Dawley rata, weighing about 250g, were divided into two groups.

Experimental animals were fed lead acetate and control animals were fed a normal

diet without lead acetate for 3 months. Morphologic examination was performed in 5

control animals(5 nerves) and 10 experimental animals(12 nerves).

Electrophysiologic study was performed in 14 control animals(24 nerves) and 14

experimental animals(28 nerves).

Morphologic examinations including teased fiber study, light microscopic stuffy,

electron microscopic study and morphometric study were performed.

In the electlophsiolosic study, compound nerve action potential composed of

Aαβ, Aδ and C were recorded in the exposed sciatic nerve with supramaximal

stimulation for each potential at the tibial nerve under ketamin hydrochloride

general anesthesia. In each potential, nerve conduction velocity calculated by the

latency of the initial and peak points of the potential, amplitude, duration and

area were measured and compared with each other.

The results were as follows.

1. Segmental demyelination was commonly found in the teased fiber study.

2. Overt demyelination with mild axonal degeneration wart observed in the

electron microscopic study.

3. In the morphometric study, decreases in nerve fiber diameter and myelin

thickness were noted and these were most prominent in large myelinated fibers.

However, there wart no significant decrease in axon diameter.

4. In the electrophysiologic study, nerve conduction velocity in all diameters of

nerve fibers was decreased, but prominent in large myelinated fibers (Aaβ). In the

Aαβ potential, duration was increased and amplitude decreased, but the area was

not changed. In the C potential, duration was increased but amplitude and area were

not significantly changed.

5. Changes in compound nerve action potentials were closely related to

morphologic changes.

From the above results, it can be concluded that in peripheral neuropathy induced

by lead in rats, demyelination is prominent especially in large myelinated fibers

while axonal degeneration is mild and these morphologic changes are reflected well

in an electrophysiologic examination.

[영문]

Differential diagnosis between myelinopathy and axonopathy is very important. Elctrophysiologic and morpholosic examinations can be used for this purpose. To predict the pathologic finding in peripheral neuropathy with electrophysiologic study, it is necessary to know the precise relationship between morphologic and electrophyosilogic changes.

The author compared morphologic changes with electrophysiologic changes in lead induced peripheral neuropathy in rata which is characterized by segmental demyelination. However this point is controversial because there are some reports suggesting that associated axonal degeneration has occured in other species and

thus, this study also evaluated that controversy.

Sprague-Dawley rata, weighing about 250g, were divided into two groups.

Experimental animals were fed lead acetate and control animals were fed a normal diet without lead acetate for 3 months. Morphologic examination was performed in 5 control animals(5 nerves) and 10 experimental animals(12 nerves).

Electrophysiologic study was performed in 14 control animals(24 nerves) and 14 experimental animals(28 nerves).

Morphologic examinations including teased fiber study, light microscopic stuffy, electron microscopic study and morphometric study were performed.

In the electlophsiolosic study, compound nerve action potential composed of Aαβ, Aδ and C were recorded in the exposed sciatic nerve with supramaximal stimulation for each potential at the tibial nerve under ketamin hydrochloride general anesthesia. In each potential, nerve conduction velocity calculated by the

latency of the initial and peak points of the potential, amplitude, duration and area were measured and compared with each other.

The results were as follows.

1. Segmental demyelination was commonly found in the teased fiber study.

2. Overt demyelination with mild axonal degeneration wart observed in the electron microscopic study.

3. In the morphometric study, decreases in nerve fiber diameter and myelin thickness were noted and these were most prominent in large myelinated fibers.

However, there wart no significant decrease in axon diameter.

4. In the electrophysiologic study, nerve conduction velocity in all diameters of nerve fibers was decreased, but prominent in large myelinated fibers (Aaβ). In the Aαβ potential, duration was increased and amplitude decreased, but the area was not changed. In the C potential, duration was increased but amplitude and area were not significantly changed.

5. Changes in compound nerve action potentials were closely related to morphologic changes.

From the above results, it can be concluded that in peripheral neuropathy induced by lead in rats, demyelination is prominent especially in large myelinated fibers while axonal degeneration is mild and these morphologic changes are reflected well in an electrophysiologic examination.