Vertigo  occurs,  in  slight  and  vague  form — a  mere  sense  of  unsteadiness —
as  a  symptom  of  many  morbid  conditions,  in  which,  however,  it  is  subordi-
nate to  other  more  characteristic  symptoms.  Thus  it  is  met  with  in  anaemia,
in  hysteria,  and  in  various  conditions  of  nervous  weakness.  It  is  met  with,
although  rarely,  as  part  of  an  attack  of  migraine.  It  occurs,  also,  in  the  old
whose  brains  are  ill  nourished,  in  consequence,  perhaps,  of  arterial  degenera-
tion, and  also  at  the  onset  of  various  vascular  lesions  of  the  brain,  of  which

*  I  do  not  think  it  is  quite  certain  that  there  is  such  a  thing  as  definite  vertigo  of  purely
gastric  origin.  Thirty  years  ago  80  per  cent,  of  cases  of  giddiness  were  supposed  to  be  due
solely  to  the  stomach.  But  we  now  know  that  in  90  per  cent,  of  the  cases  of  definite  giddi-
ness a  morbid  state  of  the  labyrinth  is  the  real  cause  of  the  vertigo.  It  is  possible  that  in  the
small  remainder,  of  apparently  stomach  giddiness,  there  is  some  other  influence  that  is  the
real  cause,  e.  g.  a  morbid  state  of  the  semicircular  canals  causing  no  auditory  symptoms,  and
so  not  to  be  detected  save  by  its  effects.
1132  NEURALGIA.
it  may  be  a  premonitory  symptom.  It  is  conspicuous  in  some  cases  of  intra-
cranial tumor,  especially  tumors  of  the  cerebellum  or  of  the  pons  Varolii
(see  pp.  530  and  718).
