RT Book, Section
A1 Hauser, Stephen L.
A2 Loscalzo, Joseph
A2 Fauci, Anthony
A2 Kasper, Dennis
A2 Hauser, Stephen
A2 Longo, Dan
A2 Jameson, J. Larry
SR Print(0)
ID 1190471964
T1 Neurologic Causes of Weakness and Paralysis
T2 Harrison's Principles of Internal Medicine, 21e
YR 2022
FD 2022
PB McGraw-Hill Education
PP New York, NY
SN 9781264268504
LK accessmedicine.mhmedical.com/content.aspx?aid=1190471964
RD 2024/04/24
AB Normal  motor  function  involves  integrated  muscle  activity  that  is  modulated  by  the  activity  of  the  cerebral  cortex,  basal  ganglia,  cerebellum,  red  nucleus,  brainstem  reticular  formation,  lateral  vestibular  nucleus,  and  spinal  cord.  Motor  system  dysfunction  leads  to  weakness  or  paralysis,  discussed  in  this  chapter,  or  to  ataxia  (Chap.  439)  or  abnormal  movements  (Chap.  436).  Weakness  is  a  reduction  in  the  power  that  can  be  exerted  by  one  or  more  muscles.  It  must  be  distinguished  from  increased  fatigability  (i.e.,  the  inability  to  sustain  the  performance  of  an  activity  that  should  be  normal  for  a  person  of  the  same  age,  sex,  and  size),  limitation  in  function  due  to  pain  or  articular  stiffness,  or  impaired  motor  activity  because  severe  proprioceptive  sensory  loss  prevents  adequate  feedback  information  about  the  direction  and  power  of  movements.  It  is  also  distinct  from  bradykinesia  (in  which  increased  time  is  required  for  full  power  to  be  exerted)  and  apraxia,  a  disorder  of  planning  and  initiating  a  skilled  or  learned  movement  unrelated  to  a  significant  motor  or  sensory  deficit  (Chap.  30).