TY  - CHAP
M1  - Book, Section
TI  - CEREBROVASCULAR DISEASES
A1  - Smith, Wade S.
A1  - Johnston, S. Claiborne
A1  - Hemphill, J. Claude
A2  - Hauser, Stephen L.
A2  - Josephson, S. Andrew
PY  - 2018
T2  - Harrison's Neurology in Clinical Medicine, 4e
AB  - Cerebrovascular  diseases  include  some  of  the  most  common  and  devastating  disorders:  ischemic  stroke  and  hemorrhagic  stroke.  Stroke  is  the  second  leading  cause  of  death  worldwide,  causing  6.2  million  deaths  in  2011,  and  is  double  the  rate  of  heart  disease  in  China.  Strokes  cause  ~200,000  deaths  each  year  in  the  United  States  and  are  a  major  cause  of  disability.  The  incidence  of  cerebrovascular  diseases  increases  with  age,  and  the  number  of  strokes  is  projected  to  increase  as  the  elderly  population  grows,  with  a  doubling  in  stroke  deaths  in  the  United  States  by  2030.  A  stroke,  or  cerebrovascular  accident,  is  defined  as  an  abrupt  onset  of  a  neurologic  deficit  that  is  attributable  to  a  focal  vascular  cause.  Thus,  the  definition  of  stroke  is  clinical,  and  laboratory  studies  including  brain  imaging  are  used  to  support  the  diagnosis.  The  clinical  manifestations  of  stroke  are  highly  variable  because  of  the  complex  anatomy  of  the  brain  and  its  vasculature.  Cerebral  ischemia  is  caused  by  a  reduction  in  blood  flow  that  lasts  longer  than  several  seconds.  Neurologic  symptoms  are  manifest  within  seconds  because  neurons  lack  glycogen,  so  energy  failure  is  rapid.  If  the  cessation  of  flow  lasts  for  more  than  a  few  minutes,  infarction  or  death  of  brain  tissue  results.  When  blood  flow  is  quickly  restored,  brain  tissue  can  recover  fully  and  the  patient’s  symptoms  are  only  transient:  this  is  called  a  transient  ischemic  attack  (TIA).  The  definition  of  TIA  requires  that  all  neurologic  signs  and  symptoms  resolve  within  24  h  without  evidence  of  brain  infarction  on  brain  imaging.  Stroke  has  occurred  if  the  neurologic  signs  and  symptoms  last  for  >24  h  or  brain  infarction  is  demonstrated.  A  generalized  reduction  in  cerebral  blood  flow  due  to  systemic  hypotension  (e.g.,  cardiac  arrhythmia,  myocardial  infarction,  or  hemorrhagic  shock)  usually  produces  syncope  (Chap.  11).  If  low  cerebral  blood  flow  persists  for  a  longer  duration,  then  infarction  in  the  border  zones  between  the  major  cerebral  artery  distributions  may  develop.  In  more  severe  instances,  global  hypoxia-ischemia  causes  widespread  brain  injury;  the  constellation  of  cognitive  sequelae  that  ensues  is  called  hypoxic-ischemic  encephalopathy(Chap.  33).  Focal  ischemia  or  infarction,  conversely,  is  usually  caused  by  thrombosis  of  the  cerebral  vessels  themselves  or  by  emboli  from  a  proximal  arterial  source  or  the  heart.  Intracranial  hemorrhage  is  caused  by  bleeding  directly  into  or  around  the  brain;  it  produces  neurologic  symptoms  by  producing  a  mass  effect  on  neural  structures,  from  the  toxic  effects  of  blood  itself,  or  by  increasing  intracranial  pressure.  
SN  - 
PB  - McGraw-Hill Education
CY  - New York, NY
Y2  - 2024/04/17
UR  - neurology.mhmedical.com/content.aspx?aid=1145769276
ER  -