Blackburn, Isaac Wright

English

Hochschulschriftenserver - Universität Frankfurt am Main

ON  THE MEDIAN ANTERIOR CEREBRAL ARTERY AS FOUND  AMONG  THE  INSANE 1.  W.  BLACKBURN From the Government Hospital for the Insane, Washington, D. C. WITH SIX  FIGURES The subject of  anomalies  of  the cerebral  arteries among  the insane has received considerable attention in the past, especially noteworthy being the article by Bullen in the Journal of Mental Science, volume 36,  1890,1 but unfortunately comparative  statis~ tics are meagre.  In 1907  I  made a  study of  the conditions  of development of the encephalic arteries in 220 consecutive cases of mental diseases, making a comparison with the studies of Windle2 in 200  cases of those presumably sane.  The results of this com~ parison seemed to  show a decided  predominance, in general, of anomalous conditions among the mentally diseased.  8 In the study above mentioned, being chiefly  conce,rned  with the  anomalies  of the circle of Willis,  sufficiently careful studies of  other arteries were not made,  and as  a result, the anomalous vessel which forms the subj ect of this paper was not as frequently found as subsequent observations show is probably the fact.  This artery is found of  course among the sane as  well as the insane. My studies, however, are based upon the examination of 400 con-secutive cases of mental disease examined with special reference to this vessel.  In all of  the text books of anatomy at my com-I IBuLLEN.  Post mortem Examination of  the Brain,  etc.  Journal  of Mental Science, vol. 36, 1890. 2 WINDLE.  On the Circle of Willis.  Reports of the British Medical Association, for 1887.  New York Medical J01trnal, vol. 2,  1888,  and JOltrnal  of  Anatomy and Psysiology, 1887-1888. a BLACKBURN.  Anomalies of the Encephalic Arteries among the Insane.  J our-nalof Comparative Neurology and Psychology, vol. 17,  no. 6,  1907. 186  1.  W.  BLACKBURN mand I  have either found no reference to the artery at all,  or a mere mention of it, as by  Cunningham,  as  a third anterior cere-bral artery sometimes present, or by Quain, as found in 4.5 per cent of cases.'l In  an  article in  the Journal  of Nervous  and Mental Disease, volume 12,  no.  3,  July, 1885,  under the heading, Ii On a  seldom described  Artery  (Arteria  Termatica)  etc,"  Professor  Wilder describes the artery and gives it the name of Arteria Termaiica, from  the place  of  location  and chief  distribution  in his  cases. Professor Wilder thus describes  the vessel which he found in a large percentage of human brains examined: It usually soon  divides into  a  right and left portion which  supply respectively the cinerea forming the surface of the triangular area ven-trad of the rostrum on either side,  and then extend around the genu to the dorsal  aspect of  the callosum. In another place in the same paper, he  describes  its  OrIgm,  as most frequently from  the place  of  junction of  the precerebrals, the  pre-communicant  being  absent,  an  important  observation in connection with the present subject.  In some respects most of my cases  of  this  artery have  varied  somewhat  from  Wilder's descrlption,  being  as  a  rule  larger,  and following  more  closely the description  of  the  median  anterior  cerebral  artery  as  de-scribed by Windle, who says, It  passes along the longitudinal fissure for two-thirds of the length of the callosum,  and divides  into two  branches,  supplying the opposite surfaces of  the hemispheres. Windle found this artery present in 9 of the 200 cases examined, and as  his  description of it is unqualified,  it may be concluded that most of his  cases were  of  the larger-sized vessels,  perhaps more properly named the median anterior cerebral artery, though I  have  no  doubt that Wilder, Windle and I  are describing  the same vessel. •  QUAIN'S Anatomy, 1892.  Other text books of Anatomy. MEDIAN  ANTERIOR  CEREBRAL  ARTERY  187 In a  typical median  anterior cerebral artery,  the description is as follows: The  vessel  arises  from  the  anterior  communicating  artery, usually near the middle; curves  upward, and in close proximity to the lamina terminalis, around the genu of the callosum, lying close to this body;  and at  about the  middle or at the junction of  the anterior two-thirds with the posterior  third  of  the callo-sum  it  divides  into  two  nearly  equal branches  which are dis-tributed to the paracentral lobules  and the quadrate lobules of the opposite  hemispheres.  In  the  course  of  the  main  trunk and the principal branches of  the vessel, small and unimportant branches are  given off  to  the lamina  terminalis, the callosum, and to the adjoining gyri, but these ultimate branches have not been worked  out, and  are  perhaps  relatively  unimportant.  A large majority  of  these  aberrant  vessels  have  this  origin  and distribution,  though  occasionally  the origin  may  be nearer  to one anterior cerebral artery than the other.  It may even seem to originate from one of these vessels near to the  junction with the communicans, 01' what is still more important for  our study, it not  infrequently  arises  from the  end of  the  junction  of the two  anterior  cerebrals when  these are  fused  and  the  anterior communicating artery as such is  absent. Differences in the size  and distribution of  the main branches are occasionally met with; sometimes one branch may be want-ing, and the vessel is  then distributed to one side only.  In the small or undeveloped vessels as  those described  by Wilder, the branches are all small and irregular, and are sent mainly  to  the lamina terminalis, the rostrum callosi, and the gyri in theimmedi-ate vicinity.5 In an article by Grunbaum and Sherrington in  Brain, 1902, 6r  find that on carefully removing the basal arteries and floating them out in water,  often a  long,  slender, arteria termatica is  unexpectedly revealed.  This leads me to suspect that arteries of this type are quite frequently present but are undiscovered; probably the percentage of median anterior cerebral arteries might be nearly doubled if careful search were thus made.  Whether these arteries are vestigial or reversionary, it is certain that in the majority of instances no such vessel arises from the anterior communicating artery, and that no corresponding vessel is mentioned among the branches of the artery by most anatomists. 188  1.  W.  BLACKBURN "Note on the arterial supply of the Brain in Anthropoid Apes," these observers state: Among  features  of  human  character  pertaining to  the  anthropoid apes, we find one not hitherto recorded, namely the existence in the cere-bral arterial supply of  a Circulus Willisii resembling that of  man.  In these highest apes,  as  in man, an anterior communicating artery quite frequently completes the circulus in front; and, quoting Parsons, they add: In all  of  the lower mammals which I  have examined, including the Platyrrhine monkeys,  Cercopithecus,  etc.,  I  find no anterior communi-cating artery. In  all  of  the  lower  forms  of  mammals  instead  of  the pair of  anterior cerebral  arteries,  there is  but a  single  azygos vessel, which in its course forward gives off branches to  the right and  left  hemispheres  respectively.  These  observers examined six  brains  of  chimpanzees,  and  one  orang-outang.  Of  the six chimpanzees, in five  the circulus had the human type.  In one of these two anterior cerebral trunks were united or fused into a common trunk about four mm. in length.  In the orang-outang also  the circulus was  completed by an anterior communicating artery, and in one of the six chimpanzees there was a single azygos anterior cerebral artery as in the lower mammalian forms.  This work,  which  is  in  accord  with  the writer's limited  experience, shows that the existence of an azygos vessel in pLace of the anterior communicating artery and the two  anterior cerebrals is the rule in the lower mammals,  and that the form found  in the higher anthropoid apes and in man is  a phylogenous development while it also suggests that in view of the frequency of anomalous forms in the anterior cerebrals, that this phylogeny is  as yet unstable. In these  arteries,  anomalies  of  development  are by all  odds more frequent than in any other sets of  vessels.  Windle in 200 cases found 8 of fusion,  9 median anterior cerebral arteries, and a large number of anomalies of the anterior communicating artery; in my own 220 cases, fusion of the vessels was found in 7 cases, in a FIG.  1.  a-e. FIG.  2.  a-e. FIG.  3.  a-e. MEDIAN  ANTERIOR  CEREBRAL  ARTERY  189 1 2 3 Developmental types of the anterior system of cerebral arteries. Reversionary types of the anterior eel'ebral arteries. Types of anomalies of the anterior cerebral arteries. 190  I.  W.  BLACKBURN 10 the right artery was very small, and the opposite carotid artery sent the blood supply to the two hemispheres through an enlarged anterior communicating artery, and in 6 cases the left artery was the smaller, and the main blood supply came from the right caro-tid system; in a large percentage of cases, anomalies of the com-municans were found.  I t is possible that in many of the apparent anomalies  of  the  anterior  cerebral  arteries  with  disproporiion in size of the trunks beyond the anterior communicating artery, the larger vessel may be a partial reversion to the primitive type; that is, a median anterior cerebral unusual only in place of origin. In fact, it is not at all uncommon for the larger of the two trunks to  send  branches  to  the  mesial  surfaces  of  both hemispheres. It  may then be granted that the lower types are being developed in the phylogeny of the races, and such being the case, reversion to the primitive type may now  and then be  expected.  I t  has seemed to the writer that the development and reversions might be shown graphically in the accompanying drawings,  nearly all of which are drawn from  actual specimens.  In Fig.  1,  a repre-sents  the primitive  form  as  met with  in  the lower  mammals; b shows  the fusion  of  the anterior  cerebrals with the remnant of the azygos vessel  at the end  of  the junction;  c a  later stage of  the development,  with  the remnant of  the azygos  vessel;  d shows the shortening of the place of junction, and e shows a fully developed anterior communicating artery.  Fig. 2 shows the occa-sional reversions met with; a gives the type of arteria termatica of Wilder; b gives the type of  termatic artery which arises from the end of  the short fusion of the two vessels; c shows the most common form of median anterior cerebral artery; d, that in which the anomalous artery is the largest of the three, and e, the almost complete reversion to the lower mammalian type; e, however, has not actually been seen by the writer, while d is  common.  a It  is suggested by these forms that in the higher phylogenetic development of the brain, the greater size of the frontal lobes has Quain says: "The two arteries have also been sec"n united in a single trunk, which runs in the longitudinal fissure,  giving off branches to both hemispheres." The writer has recently found one of these vessels,hence the series may be regarded as complete. MEDIAN  ANTERIOR  CEREBRAL  AH.TERY  191 necessitated a  development of  two  anterior lateral branches of the aZiygos  vessel into the two lateral anterior cerebral arteries, and that with this has progressively gone on a shortening of  the fusion of the two vessels and an atrophy of the azygos terminal, until finally we find the human type of  this vessel, the anterior communicating artery, and the two lateral cerebrals.  The fact that we occasionally meet with a  median vessel,  with fusion  of Median  Ant. Cerebral A. Right Ant. Cer. A. Left Ant. Cer.  A. Bifurcation and left paracentral branch of~LA.  C. A. Branch to left Precuneus FIG.  4.  Photograph of a  dissection showing the two lateral anterior cerebral arteries and a large median anterior cerebral artery with a typical distribution. the two anterior cerebrals,  and other anomalies  of  this set of vessels, I  think may be accounted for on the principle of  rever-sions and anomalies so frequently found among the insane. The median anterior cerebral artery has been found in all forms of mental diseases, possibly a little more frequently in forms of dementia.  In 400 cases of mental disease, 42 instances of the ab-normal vessel were found; 11 were in senile dementia, 7 in chronic 192  I.  W.  BLACKBURN dementia, 5 in epileptic dementia, 5 in arteriosclerotic dementia, 4 in paresis,  3 in  chronic melancholia,  2 in dementia  praecox, and 1 case each in manic-depressive insanity, organic dementia, acute delirious  mania,acute mania,  and idiocy.  Twenty-five of these cases were in white males,  11  in colored males, 4 in colored females  and  2  in  white  females.  The  disproportion  between the cases examined of  each color and sex makes this of relatively little value. r do not see that there can be any special relationship between the  mental  disease  per  se  and  the presence  of  this  anomalous vessel, but on the supervention of arterial diseases some very inter-esting cerebral conditions might be caused.  In most instances, cerebral arterial anomalies are compensated for before the develop-FIG.  5.  Diagram of  the Circle of  Willis with It  typical median antcrior ccre-bral artery. ment of  the psychosis,  the anomaly being then only indicative of  ill development. In these days of  bold operations upon the vessels and even on structures at the base of the brain, it might be well for the surgeon to bear in mind the existence of these anomalies.  In fact the main object of  the paper of  Grilnbaum and Sherrington, quoted from above, was to call  attention to the surgical relations of the ine-qualities  of  cross  anastomosis  of  the circulation in anomalies of this anterior arterial system.  Illustrative of these dangers may  be mentioned one of my own cases in which thrombosis of the intra-cranial  portion  of  the  carotid  artery  resulted  in  death  of  the MEDIA~ ANTERIOR  CEREBIl,AL  ARTERY  Hl3 whole left hemisphere on account of small size and sclerotic obstruc-tion of the anterior communicating artery and the left posterior cerebral artery. FIG.  6.  Photograph of the baRe of the bl'uin showing the origin of a large med-ian anterior cerebral artery. The conclusions which I think we may reach with certainty are as follows: 1.  There is  a .gradual  development of  the lower mammalian form of azygos anterior cerebral artery into the perfect Circulus Willisii of the human type. 2.  The frequent  variations of  this system of  vessels  suggest instability of ontogeny,  and of  phylogeny. 3.  The anomalies of these arteries together with the presence 194  1.  W.  BLACKBURN of  the  median anterior cerebral  artery are  frequent  among t.he Insane. 4..  That in keeping with other anomalies of the brain among the insane it is probable that many of these variations are in the direc-tjon of reversion to the primitive type, and that it is reasonable thaI"  the frequently found arteria termatica is one of these rever-sions  or  survivals such  as  are  not uncommon  in  other organs. Accepted  by the Wlstar Institute of Anatomy and BIology, March 24,  1010.  PrInted  July 7,  1910. 

On the median anterior cerebral artery as found among the insane

Abstract

Similar works

Full text

Available Versions

Hochschulschriftenserver - Universität Frankfurt am Main