RT Book, Section
A1 Martin, John H.
SR Print(0)
ID 1189286975
T1 Vasculature of the Central Nervous System and the Cerebrospinal Fluid
T2 Neuroanatomy: Text and Atlas, 5e
YR 2021
FD 2021
PB McGraw Hill
PP New York, NY
SN 9781259642487
LK neurology.mhmedical.com/content.aspx?aid=1189286975
RD 2024/04/19
AB CLINICAL  CASE  |  Right  Side  Paralysis,  and  Global  AphasiaA  57-year-old  right-handed  man  was  brought  to  the  emergency  department  after  being  discovered  by  his  wife  to  be  unable  to  move  his  right  arm  or  leg.  On  testing,  his  right  upper  limb  strength  was  0/5  and  the  lower  limb,  1/5.  The  left  limbs  had  normal  strength  and  spontaneous  movements.  In  addition,  there  was  drooping  of  the  right  side  of  the  lower  face.  Pinch  of  the  nail  beds—a  mildly  noxious  stimulus  that  normally  elicits  a  withdrawal  response—revealed  withdrawal  of  the  left  arm  but  no  response  for  the  right  arm.  The  patient  was  able  to  look  to  the  left  but  not  the  right;  there  were  no  saccadic  (rapid,  conjugate)  eye  movements  to  the  right.  The  patient  was  unable  to  speak  and  only  followed  simple  commands.Figure  3–1A  shows  a  horizontal  T1-weighted  MRI.  The  large  white  territory  corresponds  to  the  infarcted  region  on  the  left  side  of  the  cerebral  hemisphere.  Figure  3–1B  is  a  magnetic  resonance  angiogram  (MRA),  showing  the  distribution  of  arteries  with  flowing  blood.  The  MRA  is  asymmetric,  with  an  absence  of  middle  cerebral  artery  perfusion  on  the  left  side.Answer  the  following  questions  based  on  your  readings  of  the  case  report  and  this  chapter.1.  Occlusion  of  which  cerebral  artery  produced  the  lesion,  and  what  were  the  differential  contributions  of  its  deep  and  superficial  branches  of  the  occluded  artery?2.  Damage  to  what  single  key  structure  could  produce  the  major  limb  and  facial  motor  signs?3.  Why  is  there  loss  of  lower,  but  not  upper,  facial  muscle  control?4.  Why  is  the  patient  neither  able  to  follow  verbal  commands  nor  to  speak?5.  Why  can  the  patient  look  to  the  left  but  not  to  the  right?  Does  this  mean  that  the  right  eye  is  paralyzed?Conclusion:  The  patient  had  an  occlusion  of  the  middle  cerebral  artery,  close  to  where  the  artery  branches  from  the  internal  carotid  artery.  As  a  consequence,  the  brain  regions  supplied  by  the  artery  are  deprived  of  their  blood  supply  and  the  tissues  became  infarcted.  Both  the  superficial  and  the  deep  branches  of  the  artery  are  affected.  This,  in  turn,  affects  both  cortical  areas  supplied  by  the  artery  and  parts  of  the  basal  ganglia.  However,  the  thalamus  is  not  affected  because  it  receives  blood  from  the  posterior  cerebral  artery.Key  neurological  signs  and  corresponding  damaged  brain  structuresParalyzed  right  arm  and  legThe  corticospinal  tract  is  key  to  moving  the  contralateral  arm  and  leg  voluntarily.  Axons  of  the  corticospinal  tract  descend  subcortically  and  then  travel  in  the  posterior  limb  of  the  internal  capsule  (see  Figure  2–16).  The  internal  capsule  and  the  more  dorsal  parts  of  the  posterior  limb  are  supplied  by  deep  branches  of  the  middle  cerebral  artery.  The  infarction  also  would  have  destroyed  part  of  the  lateral  precentral  gyrus,  where  the  corticospinal  tract  to  the  arm  segments  of  the  spinal  cord  originates.  This  cortical  area  is  supplied  by  superficial  branches  of  the  middle  cerebral  artery.  By  contrast,  the  infarction  spares  the  leg  area  of  motor  cortex  (see  Figure  10–8).  Whereas  the  descending  axons  are  destroyed  when  they  are  in  the  internal  ...