There  are  usually  no  premonitory  symptoms  that  indicate  the  ap-
proach of  the  attack.  The  patient  does  not  (as  a  rule,  at  least)  lose
consciousness;  although  there  may  be  a  slight  confusion  of  the  mental
faculties  for  a  time.  In  some  instances,  however,  coma  accompanies  the
attack  of  paralysis.  Although  so  eminent  an  authority  as  Nothnagel
states  that  embolic  attacks  are,  as  a  rule,  accompanied  by  profound  coma,
m3'  experience  does  not  confirm  that  view.  I  regard  such  cases  as  ex-
ceptions to  the  general  history  of  embolism ;  although  it  cannot  be  denied
that  they  are  frequent  exceptions.  Even  then  the  patient  recovers  con-
sciousness gradually  within  a  few  hours.  Ptosis,  a  squint  of  one  eye,
and  even  blindness  have  been  known  to  accompany  the  attack;  but  these
complications  are  rather  infrequent.  In  still  rarer  cases,  paralysis  may
not  be  developed  in  any  part  of  the  body.     The  paralysis  tends  to  exhibit


232  LECTURES   ON   NERVOUS   DISEASES.
a  marked  improvement  within  forty-eight  hours,  if  collateral  circulation
is  established.
The  difficulty  in  speech  which  commonly  results  from  cerebral  em-
bolism is  not,  as  a  rule,  due  to  paralysis  of  the  hypoglossal  nerve,  as  it
is  present  in  cases  where  the  movements  of  the  tongue  are  normal.  It  is
to  be  attributed  to  sudden  anaemia  of  the  "  speech  centre  "  of  Broca.  This
is  situated  chiefly  in  the  base  of  the  third  frontal  convolution  and  the
adjacent  "ishind  of  Reil."  There  are  cases  reported  where  both  the
hypoglossal  and  facial  nerves  have  been  simultaneouslj'  paralyzed  as  a
result  of  embolism,  but  they  are  exceptional.
