THE NEUROMA-LIKE STRUCTURE OF THE LONG-TIME SEVERED
AND ISOLATED NERVE STUMPS
EROS ABRANTES ERHART * CECIL J. REZZE * *
Neuromas of the proximal stumps of transected nerves are know for a
long time. They are due chiefly to the tremendous regenerative capacity
of the injured peripheral neuron which axis-cylinders growing in a disorganized
way result in a complex nervous nodule capped by fibrous tissue.
It is not our scope to discuss in this paper the neuromas, but report the
presence of a neuroma-like structure we have mentioned in previous papers,
while studying the nerve fibres of the long-time severed and experimentally
isolated nerve stumps, Erhart and col.
1 , 2, 3, 4. Although we did not find any
reference in literature about these neuroma-like structures, they were
fre-quently found in our experimental material in the extremities of the repopulated
intermediate and distal nerve segments, close to the site of section, and in
some proximal extremities of distal stumps of human nerves which were
examined at the time these patients were submitted to nerve suture years
after the accidental nerve transection.
M A T E R I A L A N D M E T H O D S
A s said b e f o r e , t h e m a t e r i a l w h i c h w i l l be p r e s e n t e d a n d discussed in this p a p e r consists o f t h e e x c i s e d e x t r e m i t i e s o f d i s t a l a n d i n t e r m e d i a t e s t u m p s o f f i b u l a r , i n t e r c o s t a l , p h r e n i c a n d u l n a r n e r v e s o f d o g s w h i c h w e r e s u b m i t t e d t o d i f f e r e n t e x p e -r i m e n t a l c o n d i t i o n s o f n e -r v e t -r a n s e c t i o n as -r e f e -r -r e d by o -r p -r e v i o u s p a p e -r s on this s u b j e c t .
T h e s t u m p e x t r e m i t i e s o f t h e t r a n s e c t e d d o g n e r v s and t h e tissues b r i d g i n g t h e n e r v e s e g m e n t s w e r e D e C a s t r o s i l v e r i m p r e g n a t e d a n d s e r i a l s e c t i o n e d 8fi.
R E S U L T S
F r o m t h e 40 e x p e r i m e n t a l d i s t a l a n d f o r i n t e r m e d i a t e n e r v e s t u m p s — 8 f i b u l a r , 18 i n t e r c o s t a l , 4 p h r e n i c a n d 10 u l n a r — m a i n t a i n e d u n d i s t u r b e d i n t h e i r s u r r o u n d i n g c o n n e c t i v e bed f o r m o r e t h a n six m o n t h s a f t e r c o m p l e t e n e r v e t r a n s e c t i o n , in w h i c h t h e n e r v e f i b r e r e p o p u l a t i o n w a s e v i d e n t , 26 p r e s e n t e d i n t h e i r e x t r e m i t i e s , c l o s e t o t h e site of s e c t i o n , a n e u r o m a - l i k e s t r u c t u r e .
I n s e r i a l l o n g i t u d i n a l and c r o s s - s e c t i o n s o f such s t u m p e x t r e m i t i e s , m o v i n g f r o m t h e s t u m p t o t h e i r e x t r e m i t y or e x t r e m i t i e s t h e f o l l o w i n g c o u l d be seen ( f i g . 1 ) : T h e n e r v e f i b r e s w h i c h w e r e b r a n c h i n g and r e p o p u l a t i n g t h e p a t t e r n n e r v e f a s c i c l e s in t h e i s o l a t e d s t u m p s , a f t e r s p r e a d i n g o f f t h e n e r v e f a s c i c l e s in a d i s o r g a n i z e d w a y , f o r m e d n e u r o m a - l i k e s t r u c t u r e s ( f i g s . 1 a n d 2 ) , f r o m w h e r e s p r o u t e d f e w a n d d i f f u s e n e r v e f i b r e s w h i c h w e r e c a p p e d b y f i b r o u s tissue, c l o s e t o t h e site o f s e c t i o n .
S e v e r a l a x i s - c y l i n d e r s s h o w e d t h e f u s i f o r m s w e l l i n g s c o n s i d e r e d as c h a r a c t e r i s t i c of r e g e n e r a t i n g n e r v e f i b r e s .
D I S C U S S I O N
to be found in these stump extremities. But, our findings reported and
discussed in previous papers, lead us to different conclusions.
Numerous nerve fibres which origin in still a matter of research and
discussion, were seen branching and repopulating the long-time severed
inter-mediate and distal nerve segments maintained undisturbed in their connective
bed, although completely separated from each other and from the proximal
stump. Several of these axis-cylinders showed beaded appearance and fusiform
swellings in their extremities, characteristics of what has been considered as
nerve fibres in regeneration. Therefore, the neuroma-like structures are
probably the final result of a biological regenerative process equivalent to
the one which originates the common neuromas. These latter as it is known, are
formed by growing nerve fibres from the proximal stump; the former would
be the result of growing nerve fibres proper of the intermediate and distal
isolated nerve stumps.
S U M M A R Y
The long-time severed and isolated intermediate and distal nerve segments,
maintained undisturbed in their connective tissue bed, completely separated
from each other and from the proximal stump, are repopulated by
nerve-fibres which origin is still unknown. The extremities of such nerve segments
present complex nervous nodules capped by fibrous tissue, neuroma-like
structures.
R E S U M O
Segmentos intermédios e distais de nervos lesados há mais de seis meses,
completamente separados entre si e do côto proximal, mas mantidos em seus
respectivos leitos conetivos naturais, apresentam-se repopulados por fibras
nervosas cuja origem é ainda motivo de discussão e pesquisa. Nas
extremi-dades desses segmentos de nervos existem complexos nódulos, recobertos por
tecido cicatricial, portanto, verdadeiras formações neuromatosas.
R E F E R E N C E S
1. E R H A R T , E . A . — N o r m a l n e r v e f i b r e s in t h e d i s t a l s e g m e n t o f n e r v e s c o m p l e t e l y s e p a r a t e d f r o m t h e p r o x i m a l s t u m p f o r m o r e t h a n six m o n t h s . A r q . N e u r o -P s i q u i a t . ( S ã o -P a u l o ) 20:289-306, 1962. 2. E R H A R T , E . A . & E R H A R T , M . B . — N o r m a l a x i s - c y l i n d e r s in t h e d i s t a l s e g m e n t o f n e r v e s c o m p l e t e l y s e p a r a t e d f r o m t h e p r o x i m a l s t u m p f o r up t o 24 y e r s . P r e s e n t e d b e f o r e t h e V I I I n t e r n a t i o n a l C o n g r e s s o f A n a t o m i s t s , N e w Y o r k , A p r i l 1960. A n a t . R e c . , 136:189, 1960. 3. E R H A R T , M . B . & E R H A R T , E. A . — S ô b r e o c o m p o r t a m e n t o das f i b r a s n e r v o s a s d o c ô t o d i s t a l d e n e r v o f i b u l a r de Canis familiaris a p ó s t r a n s e c ç ã o t o t a l . P r e s e n t e d b e f o r e t h e I I I M e e t i n g o f t h e S o c . B r a s i l e i r a de A n a t o m i a , P o r t o A l e g r e , O c t . 1958. F o l i a C l i n i c a e t B i o l o g i c a ( S ã o P a u l o ) 28:98-100, 1958/59. 4. E R H A R T , E . A . & R E Z Z E , J. C. — N e r v e f i b r e s in i s o l a t e d s e g m e n t s o f d o g u l n a r n e r v e s a f t e r c o m p l e t e b r a c h i a l p l e x o -t o m y a n d p e r i a x i l a r a r -t e r y s y m p a -t h e c -t o m y . A r q . N e u r o - P s i q u i a -t . ( S ã o P a u l o ) 2 3 : 82-90, 1965.
