Journal of

J. Neurol. 214, 281--287 (1977)

Neurology © by Springer-Verlag 1977

Retrograde Changes in Motor and Sensory Conduction Velocity after Nerve Injury M. St6hr l, F. Schumm ~, and P. Reill 2 I Neurologische Universit~itsklinik (Direktor: Prof. Dr. Hirschmann) und Abteilung Neurologische Poliklinik und Neuropsychologie (Direktor: Prof. Dr. Dr. K. Mayer), Liebermeisterstral3e 18--20, D-7400 Ttibingen, Federal Republic of Germany 2 Handchirurgische Abteilung (Leiter: Dr. P. Reill) der Berufsgenossenschaftlichen Unfallklinik (Direktor: Prof. Dr. Weller), Rosenauerweg 95, D-7400 Ttibingen, Federal Republic of Germany

Summary. Nerve section is followed by a reduction of motor and sensory conduction velocity in the proximal segment of the injured nerve. This reduction of velocity is associated with retrograde changes in fiber size. If reinnervation does not occur within the next 11/2--2 years, retrograde degeneration of nerve fibers results, and the amplitude of the evoked nerve potential in the proximal segment of the injured nerve decreases. This retrograde degeneration is probably significant in view of the poor results frequently obtained after nerve transplantation which is carried out too late.

Key words: Nerve lesions, traumatic - Nerve conduction velocity - Retrograde changes in nerve lesions - Nerve transplantation. Zusammenfassung. Traumatische Nervenl~tsionen sind regelm~iBig von einer Herabsetzung der maximalen motorischen und sensiblen Nervenleitgeschwindigkeit im supralasioneUen Abschnitt gefolgt. Dieser korrespondieren retrograde Faserver~inderungen mit Reduktion des Axondurchmessers, wobei wahrscheinlich die dicken, rasch leitenden Fasern bevorzugt betroffen sind. Das Ausbleiben einer Reinnervation innerhalb von 1~/2--2 Jahren ftihrt vermutlich zur retrograden Faser-Degeneration, da nach dieser Zeit eine starke Erniedrigung des evozierten Nervenpotentials im proximalen Nervenabschnitt resultiert. Diese retrograde Degeneration dtirfte ftir die oft schlechten Ergebnisse nach sp~it erfolgender Nerventransplantation von Bedeutung sein.

Electroneurographical examinations made after experimental nerve lesions have shown retrograde slowing of nerve conduction velocity correlated with a reduction of the fiber diameter [ 1,4, 6, 8, 9]. Delayed impulse conduction was found clinically by Ebeling et al. [5] in the case of a distal lesion of the ulnar nerve and by Thomas [18] in the carpal tunnel syndrome, not only distal but also proximal to the lesion. We made similar observations during reinnervation after distal nerve section. In order to establish frequency, extent, pathogenesis and significance of this

282

M. St6hr et al.

r e t r o g r a d e r e d u c t i o n in t h e c o n d u c t i o n v e l o c i t y , w e e x a m i n e d 63 p a t i e n t s d u r i n g reinnervation after traumatic paresis of the median and/or ulnar nerve.

Material and Methods The observations were made during reinnervation on 63 patients who had undergone nerve suture (n = 15) or autologous nerve transplantation (n = 48) following section of the distal median (n = 33) or ulnar nerve (n = 30). Depending on the degree of reinnervation, 3 groups were formed with poor (group 1), moderate (group 2) and good reinnervation. Our results are based on the clinical function test, the EMG, the stimulation E M G and the Moberg test (Table 1). The electroneurographical examinations were made using the Disa 2 channel electromyograph type 14A21 and the following measurements were taken: 1. M o t o r latency between distal nerve segment (3 cm proximal to the lesion) and thenar and hypothenar emminences respectively. 2. Maximal motor nerve conduction velocity in the nerve segment of the lower arm proximal to the lesion (in some cases the maximal motor nerve conduction velocity was also measured in the upper arm). 3. Maximal sensory nerve conduction velocity in the nerve segment distal and proximal to the lesion. Orthodromic measurements were made, stimulation being given at the index and little finger respectively, using ring electrodes. The maximal action potential was traced from the median or ulnar nerve 3 cm proximal to the lesion and at the level of the elbow. 32--512 measurements were taken and averaged using the Disa Digital Averager 14G01. For comparative purposes we calculated the same measurements for the contralateral side. In this case we measured the sensory nerve conduction velocity using the antidromic method [16]. In order to estimate the nerve conduction velocity, even when no reinnervation occurred, nerve stimulation was given 3 cm proximal to the lesion in 8 cases and the evoked nerve potential traced using teflon coated steel electrodes at the level of the elbow. In order to improve the relationship between the signal and the noise of the amplifier 256--512 measurements were averaged using a digital averager (Disa Type 14G01).

Table 1. Classification of reinnervation groups Reinnervation groups

Motor function Power of muscle

E M G (Maximal Innervation)

0

1

2

3

No active movements

Active movements against small resistance •

Active movements against moderate resistance

Active movements against strong resistance

No voluntary activity

Single oscillations

Mixed pattern

Normal interference

< 33%

33--66%

> 66%

Voltage of evoked No muscle action potential response (% of control side) Sensibility Sensory function in the autonomous zone

Analgesia anaesthesia

Algesia + stereoanaesthesia

Stereoaesthesia (+) 2 point discrimination _--

Retrograde changes in motor and sensory conduction velocity after nerve injury.

Journal of J. Neurol. 214, 281--287 (1977) Neurology © by Springer-Verlag 1977 Retrograde Changes in Motor and Sensory Conduction Velocity after Ne...
362KB Sizes 0 Downloads 0 Views