we report on a chronic hemiparetic patient whose gait recovery was delayed until healing of an injured corticoreticulospinal tract ( crt ) , which was demonstrated on diffusion tensor tractography ( dtt ) .
a 71-year - old female presented with complete paralysis of the right extremities resulting from a spontaneous intracerebral hemorrhage . at 5 months after onset , when she was admitted for rehabilitation after undergoing rehabilitation at the previous university hospital , she presented with severe weakness of the right leg ( manual muscle test : 0  2- score ) and could not even stand .
motor weakness of her right leg improved to the point that she was able to extend her knee on gravity - eliminated position at 11 months and against some resistance at 30 months after onset .
this discontinuation elongated to the cerebral cortex on 32-month dtt , whereas on 32-month dtt , the right crt had become thicker compared with that on 5-month dtt .
an injured crt healed in a patient who was able to walk independently after approximately 2 years of rehabilitation starting 5 months after the onset of intracerebral hemorrhage .
gait dysfunction , a common sequela of brain injury , is usually caused by problems such as motor weakness , somatosensory problem , and movement in coordination .
approximately 20% to 30% of stroke patients do not regain gait ability ; therefore , gait disability is a serious disabling sequelae of stroke .
most gait recovery , and also motor recovery after stroke , occurs within 3 months after onset .
stroke patients can walk when the motor function recovers in the hip and knee joint of the leg at least to the degree of being able to lift against gravity .
several studies have reported gait recovery by the recovery of injured corticospinal tract ( cst ) or corticoreticulospinal tract ( crt ) .
jang et al found thickening of crt in the unaffected side showed association with gait function in 54 chronic stroke patients . in 2016 , jang and kwon reported that thickening of injured cst ( perilesional recovery ) at the early - stage rehabilitation contributed to gait function in a patient with a pontine infarct .
this suggests that detailed knowledge about gait recovery could aid more stroke patients in regaining their gait ability even for stroke patients who could not walk after 3 months from onset .
it contributes to gait function by controlling the proximal muscles of the extremities and axial muscles .
recent diffusion tensor tractography ( dtt ) , which is derived from diffusion tensor imaging ( dti ) , has a unique advantage in evaluation of microstructural integrity of white matter by detection of water diffusion properties .
a technique for identifying the crt using selection of fibers passing through regions of interest ( rois ) was reported in 2012 .
after introduction of identification of the crt by dtt , a few studies have reported on the recovery of an injured crt with gait function in stroke patients .
, we report on a chronic hemiparetic patient whose gait recovery was delayed until healing of an injured crt , which was demonstrated on dtt .
a 71-year - old right - handed female presented with complete paralysis of the right extremities [ medical research council ( mrc ) : 0/5 ] at the onset of a spontaneous intracerebral hemorrhage ( ich ) ( table 1 ) .
the volume of hemorrhage ( 22950.7  mm ) , was measured by insight toolkit - snake automatic partitioning program ( university of pennsylvania , philadelphia , pa ) .
no previous medical history of neurological , physical , or psychiatric illness was observed except for hypertension and diabetes .
five months after onset , she was admitted to the rehabilitation department of a university hospital after undergoing rehabilitation at a different university hospital .
brain magnetic resonance ( mr ) images taken upon admission showed a leukomalactic lesion in the left corona radiata and basal ganglia ( fig .
1a ) . for measurement of gait function , functional ambulation category ( fac , full mark : 5 points ) was measured .
she presented with mild conduction aphasia , severe weakness of the right leg ( mrc : hip flexor ; 2 , knee extensor : 0 , and ankle dorsiflexor : 0 ) and could not even stand ( fac : 0 point ) ( table 1 ) .
she began comprehensive rehabilitative therapy , which included neurotropic drugs ( methylphenidate , pramipexole , amantadine , levodopa , and venlafaxine ) , movement therapy , and neuromuscular electrical stimulation of the right knee extensor and ankle dorsiflexor .
movement therapy was conducted 30  min / d and 5 times per week in our physical and occupational therapy department .
her rehabilitation was continued until 32 months after onset at the inpatient clinic of our hospital and 2 other local rehabilitation hospitals , and the outpatient clinic of the rehabilitation department of our hospital .
motor weakness of her right leg improved to the point that she was able to extend her knee on gravity - eliminated position at 11 months and against some resistance at 30 months after onset .
she was able to walk independently at 30 months after her stroke ( fac : 3.5 points ) .
seven age and sex - matched normal control subjects ( mean age : 67.9    5.0 years , range : 6277 years ) with no history of neurological disease were recruited for this study .
the patient and all normal control subjects provided informed consent , and the study protocol was approved by yeungnam university hospital institutional review board .
a , brain computed tomography ( ct ) images show hematomas in the left corona radiata and basal ganglia at onset and t2-weighted magnetic resonance ( mr ) images show a leukomalactic lesion in the left corona radiata and basal ganglia at 5 months after onset .
the left corticospinal tract ( cst ) shows narrowing compared with the right cst on 5-month dtt .
the left corticoreticulospinal tract ( crt ) shows discontinuation at the basal ganglia level on 5-month dtt ( blue arrow ) and this discontinuation is elongated to the cerebral cortex on 32-month dtt ( red arrows ) , whereas on 32-month dtt , the right crt has become thicker than it was on the 5-month dtt ( green arrow ) .
diffusion tensor imaging scanning was performed at 5 and 32 months after onset , using a 6-channel head coil on a 1.5-t philips gyroscan intera ( philips , best , the netherlands ) with 32 gradients .
seventy contiguous slices and imaging parameters were acquired as follows : acquisition matrix  =  96    96 , reconstructed to matrix  =  192    192 , field of view  =  240    240  mm , tr  =  10,398  milliseconds , te  =  72  milliseconds , epi factor  =  59 and b  =  1000  s / mm , nex  =  1 , and a slice thickness of 2.5  mm .
fiber tracking was performed using the fiber assignment continuous tracking algorithm implemented within the dti task card software ( philips extended mr work space 2.6.3 ) ( threshold fractional anisotropy  =  0.15 , angle  =  27 ) .
images for correction of residual eddy - current image distortions and head motion effect , using a diffusion registration package ( philips medical systems ) . for reconstruction of the cst ,
2 rois were placed on the upper ( roi 1 ) and lower pons ( roi 2 ) on the axial image ( portion of the anterior blue color ) . for reconstruction of the crt , reticular formation of the medulla ( roi 1 ) , and tegmentum of the midbrain ( roi 2 ) on the axial image were used .
fractional anisotropy ( fa ) and tract volume of the cst and crt were measured .
dtt parameter values varying more than 2 sds from normal control values were defined as significant differences .
in contrast , the left cst was narrowed compared with the right cst , and similar findings were observed for both csts on 32-month dtt compared with 5-month dtt . regarding the crt , the left crt was discontinuous at the basal ganglia level on 5-month dtt , and this discontinuation elongated to the cerebral cortex on 32-month dtt .
in addition , the right crt presented integrity between the cortex and brainstem on 5-month dtt , and on 32-month dtt , the right dtt had become thicker compared with the 5-month dtt . regarding dtt parameters ,
the fa values of the cst and crt were similar in both hemispheres on both 5 and 32-month dtts .
however , the tract volumes were increased in the cst and crt in both hemispheres and the order of the increment of tract volume was as follows : the left crt : 2171254 ; the right crt : 9971588 ; the left cst : 368519 ; and the right cst : 15561712 . compared with normal controls , significant differences in fa , and tract volume of the left cst on both 5 and 32-month dtt were observed .
regarding the crt , significant differences in fa and tract volume of both crts on 5-month dtt were observed .
in addition , on 32-month dtt , both crts in fa were lower than that of normal controls , but the tract volume of both crts did not differ significantly from the normal controls .
diffusion tensor imaging scanning was performed at 5 and 32 months after onset , using a 6-channel head coil on a 1.5-t philips gyroscan intera ( philips , best , the netherlands ) with 32 gradients .
seventy contiguous slices and imaging parameters were acquired as follows : acquisition matrix  =  96    96 , reconstructed to matrix  =  192    192 , field of view  =  240    240  mm , tr  =  10,398  milliseconds , te  =  72  milliseconds , epi factor  =  59 and b  =  1000  s / mm , nex  =  1 , and a slice thickness of 2.5  mm .
fiber tracking was performed using the fiber assignment continuous tracking algorithm implemented within the dti task card software ( philips extended mr work space 2.6.3 ) ( threshold fractional anisotropy  =  0.15 , angle  =  27 ) .
images for correction of residual eddy - current image distortions and head motion effect , using a diffusion registration package ( philips medical systems ) . for reconstruction of the cst ,
2 rois were placed on the upper ( roi 1 ) and lower pons ( roi 2 ) on the axial image ( portion of the anterior blue color ) . for reconstruction of the crt , reticular formation of the medulla ( roi 1 ) , and tegmentum of the midbrain ( roi 2 ) on the axial image were used .
fractional anisotropy ( fa ) and tract volume of the cst and crt were measured .
dtt parameter values varying more than 2 sds from normal control values were defined as significant differences . on 5-month dtt , the entire right cst pathway was intact .
in contrast , the left cst was narrowed compared with the right cst , and similar findings were observed for both csts on 32-month dtt compared with 5-month dtt . regarding the crt , the left crt was discontinuous at the basal ganglia level on 5-month dtt , and this discontinuation elongated to the cerebral cortex on 32-month dtt .
in addition , the right crt presented integrity between the cortex and brainstem on 5-month dtt , and on 32-month dtt , the right dtt had become thicker compared with the 5-month dtt .
the fa values of the cst and crt were similar in both hemispheres on both 5 and 32-month dtts .
however , the tract volumes were increased in the cst and crt in both hemispheres and the order of the increment of tract volume was as follows : the left crt : 2171254 ; the right crt : 9971588 ; the left cst : 368519 ; and the right cst : 15561712 .
compared with normal controls , significant differences in fa , and tract volume of the left cst on both 5 and 32-month dtt were observed . regarding the crt , significant differences in fa and tract volume of both crts on 5-month dtt
in addition , on 32-month dtt , both crts in fa were lower than that of normal controls , but the tract volume of both crts did not differ significantly from the normal controls .
in this study , we investigated the changes of the cst and crt in a patient who was able to walk independently after approximately 2 years of rehabilitation starting 5 months after a cerebral hemorrhage .
the results of dtt parameters appeared to be consistent with the changes of dtt configurations : the discontinuous left crt elongated to the cerebral cortex and the right crt became thicker on 32-month dtt . because neither cst improved , we believe that the recovery of the injured left crt was most attributed to regaining gait ability in this patient .
the right crt also appeared to contribute to regaining gait ability , apparently consistent with a previous study showing that activation of the unaffected crt could contribute to gait recovery in stroke patients with severe injuries of the affected cst and crt . to the best of our knowledge ,
this is the first study to suggest recovery of the injured crt contributes to regaining gait ability in chronic hemiparetic patients .
since the introduction of dtt for the crt , a few studies have reported on the recovery of an injured crt . in 2013 ,
yeo and jang reported on a patient who showed recovery of a discontinued crt in the affected hemisphere during 3 weeks from 3 weeks after the onset of ich .
subsequently , in 2014 , a patient whose injured crt had recovered by transcallosal fibers during 10 weeks from 6 weeks after the onset of ich was reported . in 2015 , jang et al reported on a patient who developed reorganization of an injured crt to the medial area over a 4-week period starting 6 weeks after a cerebral infarct .
by contrast , we demonstrated the recovery of an injured crt in a chronic patient who was able to walk independently after approximately 2 years of rehabilitation beginning 5 months after the ich .
first , because this is a single - case study , we could not study differences in predictors of gait recovery such as age , type of stroke , or type of therapy .
second , results of dtt might present false - positive and negative results due to the hemorrhage or a malatic cavity .
third , although gait is involved in many neural tracts including extrapyramidal motor tracts , such as the rubrospinal tract and the vestibulospinal tract , we investigated only the cst and crt . therefore , further studies including larger case numbers and for overcoming the limitations should be warranted . in conclusion ,
recovery of an injured crt was found in a patient who was able to walk independently after approximately 2 years of rehabilitation starting 5 months after the ich .
 abstractobjectives : we report on a chronic hemiparetic patient whose gait recovery was delayed until healing of an injured corticoreticulospinal tract ( crt ) , which was demonstrated on diffusion tensor tractography ( dtt).case presentation : a 71-year - old female presented with complete paralysis of the right extremities resulting from a spontaneous intracerebral hemorrhage . at 5 months after onset , when she was admitted for rehabilitation after undergoing rehabilitation at the previous university hospital , she presented with severe weakness of the right leg ( manual muscle test : 0  2- score ) and could not even stand . 
 she received comprehensive rehabilitative therapy for 32 months after the onset . 
 motor weakness of her right leg improved to the point that she was able to extend her knee on gravity - eliminated position at 11 months and against some resistance at 30 months after onset . 
 she was able to walk independently at 30 months after onset.results:the left crt was discontinuous at the basal ganglia level on 5-month dtt . 
 this discontinuation elongated to the cerebral cortex on 32-month dtt , whereas on 32-month dtt , the right crt had become thicker compared with that on 5-month dtt.conclusions:an injured crt healed in a patient who was able to walk independently after approximately 2 years of rehabilitation starting 5 months after the onset of intracerebral hemorrhage . 
Objectives:
Case presentation:
Results:
Conclusions:
Introduction
Case report
Diffusion tensor tractography
Discussion