title: Quantifying changes in material properties of stroke-impaired muscle.
abstract: BACKGROUND
  Material properties of muscles are clinically important parameters for evaluating altered muscle function. Stroke survivors display motor impairments almost immediately after the vascular event, and then gradually develop altered muscle properties. Little is known about the magnitude of these changes in muscle material properties, specifically stiffness. Previous measures of stiffness are limited to estimates of joint stiffness or groups of muscles. Thus, our aim was to determine changes in passive muscle stiffness and composition by measuring: (1) shear wave speed using shear wave ultrasound elastography and (2) echo intensity of the B-mode ultrasound images of the biceps brachii muscle in individuals who have had a stroke.
  
  
  METHODS
  Shear wave ultrasound elastography and B-mode ultrasound images of the biceps brachii muscle of the paretic and non-paretic limbs of sixteen stroke survivors were captured at rest.
  
  
  RESULTS
  Our main results show that shear wave speed and echo intensity of the paretic side were on average 69.5% and 15.5% significantly greater than those of the non-paretic side, respectively. Differences in shear wave speed between the non-paretic and the paretic muscles were strongly correlated with differences in echo intensity, time since stroke, and with Fugl-Meyer scores.
  
  
  CONCLUSIONS
  Muscle stiffness and muscle composition, as indicated by SW speed and echo intensity, may be altered in stroke-impaired muscle at rest. These findings highlight the potential for SW elastography as a tool for both investigating the fundamental mechanisms behind changes in stroke-impaired muscle, and for evaluation of muscle mechanical properties as part of clinical examination.
authors: Rehabilitation Institute of Chicago, Chicago, IL, USA; Department of Physical Therapy and Human Movement Sciences, Northwestern University, Chicago, IL, USA. Electronic address: s-lee@northwestern.edu.
authors: Sabrina S M
authors: SS
authors: Lee
authors: Rehabilitation Institute of Chicago, Chicago, IL, USA.
authors: Sam
authors: S
authors: Spear
authors: Rehabilitation Institute of Chicago, Chicago, IL, USA; Department of Physiology, Northwestern University, Chicago, IL, USA; Department of Biomedical Engineering, Northwestern University, Chicago, IL, USA.
authors: William Z
authors: WZ
authors: Rymer
mesh_terms: D001132:Arm / Q000503:physiopathology; D054459:Elasticity Imaging Techniques; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D018482:Muscle, Skeletal / Q000000981:diagnostic imaging / Q000503:physiopathology*; D012146:Rest; D020521:Stroke / Q000000981:diagnostic imaging / Q000503:physiopathology*; D017741:Survivors
keywords: Echo intensity; Muscle; Stiffness; Stroke; Ultrasound
references: Ultrasound Med Biol. 2009 Mar;35(3):443-6
references: 19081667
references: Neurology. 2013 Jan 15;80(3 Suppl 2):S20-6
references: 23319482
references: IEEE Trans Ultrason Ferroelectr Freq Control. 2004 Apr;51(4):396-409
references: 15139541
references: J Ultrasound Med. 1988 Sep;7(9):505-9
references: 3054144
references: FEBS Lett. 1996 Jul 29;390(3):304-6
references: 8706882
references: Arch Phys Med Rehabil. 1989 Feb;70(2):144-55
references: 2644919
references: Stroke. 2009 Feb;40(2):439-47
references: 19074480
references: Neurorehabil Neural Repair. 2002 Sep;16(3):232-40
references: 12234086
references: Muscle Nerve. 2015 Feb;51(2):284-6
references: 25187068
references: J Appl Physiol (1985). 2010 May;108(5):1389-94
references: 20167669
references: Muscle Nerve. 1980 Sep-Oct;3(5):413-6
references: 6448348
references: J Appl Physiol Respir Environ Exerc Physiol. 1982 May;52(5):1113-8
references: 7047468
references: Neurosci Lett. 1983 Feb 21;35(2):127-33
references: 6856191
references: J Pediatr. 1982 Nov;101(5):656-60
references: 7131136
references: Age Ageing. 1990 May;19(3):179-84
references: 2363378
references: Ultrason Imaging. 1991 Apr;13(2):111-34
references: 1858217
references: Circulation. 2010 Feb 23;121(7):e46-e215
references: 20019324
references: J Muscle Res Cell Motil. 2002;23(3):245-54
references: 12500904
references: Brain. 1994 Apr;117 ( Pt 2):355-63
references: 8186961
references: Am J Physiol Cell Physiol. 2013 Aug 1;305(3):C241-52
references: 23761627
references: Muscle Nerve. 2014 Jul;50(1):103-13
references: 24155045
references: J Anat. 1984 Mar;138 ( Pt 2):343-50
references: 6715254
references: Dev Med Child Neurol. 2001 May;43(5):314-20
references: 11368484
references: Biochem Soc Trans. 1991 Apr;19(2):368-73
references: 1716229
references: Clin Neurophysiol. 2010 Nov;121(11):1939-51
references: 20457538
references: Scand J Rehabil Med Suppl. 1983;9:108-17
references: 6585932
references: Muscle Nerve. 2005 May;31(5):535-51
references: 15714510
references: Neuromuscul Disord. 2007 Jul;17(7):509-16
references: 17537635
references: J Physiol. 2001 Jun 1;533(Pt 2):605-16
references: 11389216
references: Arch Phys Med Rehabil. 2012 Nov;93(11):2085-9
references: 22776155
references: Ann Indian Acad Neurol. 2011 Jan;14(1):23-6
references: 21633610
references: Muscle Nerve. 2004 May;29(5):615-27
references: 15116365
references: J Physiol. 2011 May 15;589(Pt 10):2625-39
references: 21486759
references: Arch Phys Med Rehabil. 2014 Nov;95(11):2207-19
references: 25064780
references: J Neurophysiol. 2011 May;105(5):2132-49
references: 21346215
references: Eur J Appl Physiol. 2012 Apr;112(4):1519-25
references: 21847576
references: Stroke. 1994 Apr;25(4):808-13
references: 8160225
references: Science. 1995 Sep 29;269(5232):1854-7
references: 7569924
references: Radiology. 2012 Jun;263(3):794-801
references: 22495685
references: Physiol Meas. 2013 Jun;34(6):713-21
references: 23719230
references: Clin Orthop Relat Res. 1979 Jul-Aug;(142):223-32
references: 159152
references: Muscle Nerve. 2003 Oct;28(4):464-71
references: 14506719
references: Stroke. 2010 Dec;41(12):2979-81
references: 20966418
references: J Neurol Neurosurg Psychiatry. 2000 Jul;69(1):34-9
references: 10864601
references: Ann Neurol. 1991 Dec;30(6):767-79
references: 1789693
references: J Biomech. 2012 Apr 5;45(6):978-84
references: 22326058
references: Physiol Meas. 2012 Mar;33(3):N19-28
references: 22370174
references: Hypertension. 2012 Aug;60(2):563-73
references: 22733458
references: J Physiol. 1972 Jul;224(1):231-44
references: 5039983
references: Age (Dordr). 2013 Dec;35(6):2377-88
references: 23456136
references: J Biomech. 2012 May 11;45(8):1424-9
references: 22406469
references: Muscle Nerve. 2010 Jan;41(1):32-41
references: 19722256
references: Science. 1985 Dec 13;230(4731):1280-2
references: 4071053
references: Clin Rehabil. 1999 Oct;13(5):373-83
references: 10498344
references: Conf Proc IEEE Eng Med Biol Soc. 2010;2010:2993-6
references: 21095718
references: Muscle Nerve. 2009 Jun;39(6):781-6
references: 19301363
references: J Neuroeng Rehabil. 2010 Jul 27;7:35
references: 20663189