Correlation between parameters of electrophysiological, histomorphometric and sciatic functional index evaluations after rat sciatic nerve repair

Abstract

-The rat sciatic nerve is a well-established model for the study of recovery from peripheral nerve injuries. Traditional methods of assessing nerve regeneration after nerve injury and repair, such as electrophysiology and histomorphometry, despite widely used in neural regeneration experiments, do not necessarily correlate with return of motor and sensory functions. The aim of this experimental study is to investigate the possible correlation between several parameters of peripheral nerve regeneration after repair of sectioned sciatic nerve in Wistar rat. A two-stage approach was used to obtain 17 parameters after electrophysiological, morphometric and sciatic functional index evaluations. Pearson's correlation analysis was performed between these results. Only two positives correlations between different classes of peripheral nerve assessments were noted, between sciatic functional index and proximal nerve fiber diameter (r=0.56, p<0.01) and between sciatic functional index and distal fiber diameter (r=0.50, p<0.01). The data presented in our study demonstrates that there is a poor correlation between the sciatic functional index and outcome measures of electrophysiological and morphometric evaluations.KEY WORDS: nerve repair, sciatic functional index, rat sciatic nerve, nerve regeneration, nerve morphometry.Correlações entre parâmetros obtidos das avaliações eletrofisiológica, histomorfométrica e do índice funcional ciático após o reparo do nervo ciático do rato RESUMO -O nervo ciático do rato é o modelo mais amplamente utilizado para o estudo da regeneração após uma lesão de nervo. Apesar do uso amplo para a avaliação da regeneração os métodos tradicionais, como a avaliação eletrofisiológica e histomorfométrica, nem sempre apresentam correlações com a recuperação motora e sensitiva. O objetivo deste estudo é investigar as possíveis correlações entre vários parâmetros da regeneração após a secção e reparo do nervo ciático do rato. Foi utilizado um experimento dividido em dois estágios para obter 17 parâmetros após a realização de avaliações eletrofisiológica, histomorfométrica e funcional. A análise das possíveis correlações foi obtida através da aplicação do méto-do de Pearson. Somente duas correlações positivas entre diferentes tipos de avaliações foram obtidas, entre o índice funcional ciático e o diâmetro proximal das fibras (r=0,56, p<0,01) e entre o índice funcional ciáti-co e o diâmetro distal das fibras (r=0,50, p<0,01). Concluímos que as correlações entre diferentes métodos de avaliação da regeneração no nervo ciático do rato são pouco freqüentes. PALAVRAS-CHAVE: reparo do nervo, índice funcional ciático, nervo ciático do rato, regeneração nervosa, morfometria do nervo.The rat sciatic nerve is the most used model for evaluation of experimental peripheral nerve regeneration 1,2 . This occurs because rat sciatic nerve regeneration is extremely efficient and fast and this model has a relative low cost . In addition, this model permits assessment of nerve regeneration after repair using several t...

Correlation of three sciatic functional indices with histomorphometric findings in a rat sciatic nerve allograft repair model

“…54 The strong correlations between functional parameters and the MBP density of nerve sections of the nonoperated and operated sides also underline the validity of staining healthy myelin sheaths with antibodies in our study; histomorphometric outcomes of nerve sections of experimental groups I and II were correlated significantly with all three SFIs. As a comparison, the correlations reported between SFI and proximal nerve fiber diameter (r 5 0.56) and distal fiber diameter (r 5 0.50) were weak 55 and did not reach the significance of correlations described here.…”

Effects of Pulsed Electromagnetic Fields on Peripheral Nerve Regeneration Using Allografts in Sciatic Nerve: An Animal Model Study

“…Although both morphological and functional data have been used to assess neural regeneration after induced crush injuries, the correlation between these two types of assessment is usually poor [18][19][20]. Classical and newly developed methods of assessing nerve recovery, including histomorphometry, retrograde transport of horseradish peroxidase and retrograde fluorescent labeling [20] do not necessarily predict the reestablishment of motor and sensory functions [19,[21][22][23]. Although such techniques are useful in studying the nerve regeneration process, they generally fail in assessing functional recovery [19].…”

“…Classical and newly developed methods of assessing nerve recovery, including histomorphometry, retrograde transport of horseradish peroxidase and retrograde fluorescent labeling [20] do not necessarily predict the reestablishment of motor and sensory functions [19,[21][22][23]. Although such techniques are useful in studying the nerve regeneration process, they generally fail in assessing functional recovery [19]. Therefore, research on peripheral nerve injury needs to focus on functional assessment.…”

The effect of collagen-binding NGF-β on the promotion of sciatic nerve regeneration in a rat sciatic nerve crush injury model

“…At days 0, 7,11,14,18,21,25,28,35,42,49, 56, 70 after nerve crush the animals were submitted to walking track analysis and measurement of the sciatic functional index (SFI) using a method described by Bain et al [11]. We can calculate the SFI based on the following formula: SFI ¼ À38:3½ðEPL À NPLÞ=NPL þ 109:5½ðETS À NTSÞ=NTS þ 13:3½ðEIT À NITÞ=NIT À 8:8:…”