RT Book, Section
A1 Kasper, Dennis L.
A1 Fauci, Anthony S.
A1 Hauser, Stephen L.
A1 Longo, Dan L.
A1 Jameson, J. Larry
A1 Loscalzo, Joseph
SR Print(0)
ID 1128782876
T1 Dizziness and Vertigo
T2 Harrison's Manual of Medicine, 19e
YR 2016
FD 2016
PB McGraw-Hill Education
PP New York, NY
SN 9780071828529
LK accessmedicine.mhmedical.com/content.aspx?aid=1128782876
RD 2024/04/25
AB APPROACH  TO  THE  PATIENT:  Dizziness  or  VertigoThe  term  dizziness  is  used  by  pts  to  describe  a  variety  of  sensations  or  gait  unsteadiness.  With  a  careful  history,  distinguishing  between  faintness  (presyncope;  Chap.  50)  and  vertigo  (a  sense  of  movement  of  the  body  or  the  environment,  most  often  a  feeling  of  spinning)  is  usually  possible.When  the  meaning  of  dizziness  is  uncertain,  provocative  tests  to  reproduce  the  symptoms  may  be  helpful.  Valsalva  maneuver,  hyperventilation,  or  postural  changes  leading  to  orthostasis  may  reproduce  faintness.  Rapid  rotation  in  a  swivel  chair  is  a  simple  provocative  test  to  reproduce  vertigo.Benign  positional  vertigo  is  identified  by  the  Dix-Hallpike  maneuver  to  elicit  vertigo  and  the  characteristic  nystagmus;  the  pt  begins  in  a  sitting  position  with  head  turned  45°;  holding  the  back  of  the  head,  examiner  gently  lowers  pt  to  supine  position  with  head  extended  backward  20°  and  observes  for  nystagmus;  after  30  s  the  pt  is  raised  to  sitting  position  and  after  1  min  rest  the  maneuver  is  repeated  on  other  side.If  a  central  cause  for  the  vertigo  is  suspected  (e.g.,  no  signs  of  peripheral  vertigo,  no  hearing  loss,  no  ear  sensations,  or  the  presence  of  other  neurologic  abnormalities  indicating  central  nervous  system  [CNS]  disease),  then  prompt  evaluation  for  central  pathology  is  required.  The  initial  test  is  usually  an  MRI  scan  of  the  posterior  fossa.  Distinguishing  between  central  and  peripheral  etiologies  can  be  accomplished  with  vestibular  function  tests,  including  videonystagmography  and  simple  bedside  examinations  including  the  head  impulse  test  (rapid,  small  amplitude  head  rotations  while  pt  instructed  to  fixate  on  the  examiner’s  face;  if  peripheral,  a  catch-up  saccade  is  seen  at  the  end  of  the  rotation)  and  dynamic  visual  acuity  (measure  acuity  at  rest  and  with  head  rotated  back  and  forth  by  examiner;  a  drop  in  acuity  of  more  than  one  line  on  a  near  card  or  Snellen  chart  indicates  vestibular  dysfunction).