[Reprint from The Yale Medical Journal, December, 1897.] 
A NEW METHOD OF NERVE RESECTION FOR 
AMPUTATION-NEUROMA. 
By N. Senn, M.D., Ph. D., LL.D., Professor of Surgery in Rush 
Medical College, and in the Chicago Polyclinic. Attending Surgeon 
Presbyterian Hospital. Surgeon-in-Chief St. Joseph’s Hospital. 
Neuroma, as a remote complication of amputation, appears 
in the form of a bulbous enlargement of the end of the principal 
nerve or nerves in the stump. Such a tumor usually makes its 
appearance a few weeks or months after the operation, and is 
the most frequent cause of painful stumps. The usually 
accepted theory attributes the enlargement of a nerve-end in 
amputation-neuroma to an abundant formation of small myelinic 
fibers produced from the neuroblasts which have been exposed 
for a long time to irritation caused by cicatricial tissue. It is 
well-known that an amputation-neuroma will only develop in 
connection with scar tissue and the irritation incident to the 
condition producing it. Every amputation-neuroma will be 
found imbedded in more or less of scar tissue. Witzel has 
recently shown that in many cases the neuroma is found 
attached to the end of the bud in the stump. It is more than 
probable that the cut ends of the nerve fibers become attached 
to the scar tissue which acts the part of a foreign substance and 
excites the active and abnormal tissue proliferation upon which 
depends the formation of the neuroma. The tumor presents 
itself in the form of a bulbous enlargement of the end of the 
nerve, which closely resembles a spring onion in outline. 
Cross-sections of such tumors show the numerical increase of 
myelinic nerve fibers. Nicoladoni’s assistant has made some 
very interesting investigations regarding the structure of ampu- 
tation-neuroma and has come to the conclusion that the numeri- 
cal increase of nerve fibers is apparent and not real. According 
to his observations the increase is due to the formation of loops 
growing out of the elongation of the pre-existing fibers. 
Virchow called attention to such a possibility years ago and 
emphasized particularly the difficulty in following out and trac- 
ing the nerve fibers. It is very desirable that future research should settle this question definitely. With the proliferation or 
growth of the nerve fibers the interstitial connective tissue is 
increased under the same influence, the resulting tumor consti- 
tuting histologically a true neurofibroma. 
Within a short time the tumor as a rule reaches its maximum 
size, seldom exceeding twice the circumference of the nerve 
trunk, when it becomes stationary and manifests little or no 
tendency to degenerative processes. In the majority of cases the 
tumor is limited and forms the bulbous extremity of the nerve; 
in some instances, as in the case reported by Hayem and Gil- 
bert, the nerve is at the same time enlarged for a considerable 
distance above the tumor, the enlargement being due to an 
abundant formation of interstitial connective tissue. Every 
surgeon of large experience knows that an amputation-neuroma 
in some cases is exceedingly prone to return after excision, and 
these are undoubtedly the cases in which the nerve is enlarged 
far beyond the bulbous extremity. The writer has known in- 
stances in which such neuromata were excised four and five 
times, and an early return of the pain, with recurrence of the 
tumor followed each operation. In one case a cure was finally 
effected by excising four inches of the sciatic nerve, far beyond 
the apparent limits of the tumor and enlargement of the nerve. 
Neuroma is more apt to appear in persons the subjects of an 
inherited or acquired predisposition to the active proliferation of 
the elements of which a nerve is composed more especially the 
presence in the injured nerve of an abnormal abundance of 
potential neuroblasts. 
Virchow, in speaking of the etiology of neuromata, very 
properly alludes to such a general aptitude which he terms neu- 
roblasty, or neuromatosis. A surgeon performs two amputa- 
tions for the same conditions and under the same circumstances, 
following the same technique and dealing with the same 
structures, in one the nerve ends become implicated, in the other 
they escape. The one who subsequently suffers from neuroma 
must necessarily have furnished the essential conditions for the 
development of this remote complication which were inadequate 
or absent in the other. Amputation-neuroma has become less 
frequent since surgeons have become aware of the fact that the 
exciting cause is always scar tissue formed around the end of 
the cut nerve. Excising the principal nerves a considerable dis- 
tance above the level of the wound and primary wound healing 
under aseptic precautions have succeeded in diminishing the 
frequency but not in preventing with certainty the occurrence of neuroma after amputation. Amputation-neuroma will continue 
to appear in the practice of the most careful and painstaking 
surgeons. The frequency with which such tumors recur after 
ordinary excision as generally practiced is well-known. 
The writer has seen a number of such cases in which excision 
was performed from four to six times by different operators 
without permanent relief. For nearly three years he has 
adopted a method of excision which has proved eminently suc- 
cessful in preventing recurrence. In several instances this pro- 
cedure proved permanently satisfactory in which repeated ex- 
cision had been followed by speedy recurrences. Recognizing 
the fact that neuroma, after amputation, always developes in 
connection with scar tissue and is undoubtedly the result of irri- 
tation of the cut ends of the fibers incorporated in the scar tis- 
sue, the writer was induced to excise the nerve at a safe distance 
from the tumor in a manner that would prevent such an occur- 
rence by bringing the cut ends of the nerve fibers in contact and 
by interposing between them and the scar tissue the normal cov- 
ering of the nerve—the nerve-sheath. After dissecting up the 
scar tissue in connection with the neuroma the nerve is liberated 
to the requisite extent and excised at a safe distance from the 
tumor by making a V-shaped incision forming a wedge on the 
part of the nerve removed and two small flaps on the proximal 
end. These little flaps, according to the size of the nerve, are 
brought together by one to three fine cat-gut sutures which 
gives the nerve end a conical shape. In nerves of the size of the 
median, ulnar and musculo-spiral, one suture at the apex of the 
cone answers the purpose. In operations on the sciatic nerve 
one terminal and two lateral sutures are necessary. This method 
of nerve resection furnishes absolute protection to the nerve 
fibers against irritation on the part of scar tissue and interposes 
between the nerve fibers and the scar tissue resulting from the 
operation the normal protection of the nerve—the nerve sheath. 
In case it becomes necessary to operate on two nerves in close 
proximity the same object is obtained by suturing the nerve 
ends together after excision of the neuromata. As an addi- 
tional precaution the nerve end can be further protected by cov- 
ering it with adjacent muscle tissue by a few points of buried 
absorbable sutures before closing the external wound.