Prognostic value of cortically induced motor evoked activity by TMS in chronic stroke: caveats from a revealing single clinical case.
BACKGROUND
We report the case of a chronic stroke patient (62 months after injury) showing total absence of motor activity evoked by transcranial magnetic stimulation (TMS) of spared regions of the left motor cortex, but near-to-complete recovery of motor abilities in the affected hand.


METHODS
Multimodal investigations included detailed TMS based motor mapping, motor evoked potentials (MEP), and Cortical Silent period (CSP) as well as functional magnetic resonance imaging (fMRI) of motor activity, MRI based lesion analysis and Diffusion Tensor Imaging (DTI) Tractography of corticospinal tract (CST). Anatomical analysis revealed a left hemisphere subinsular lesion interrupting the descending left CST at the level of the internal capsule. The absence of MEPs after intense TMS pulses to the ipsilesional M1, and the reversible suppression of ongoing electromyographic (EMG) activity (indexed by CSP) demonstrate a weak modulation of subcortical systems by the ipsilesional left frontal cortex, but an inability to induce efficient descending volleys from those cortical locations to right hand and forearm muscles. Functional MRI recordings under grasping and finger tapping patterns involving the affected hand showed slight signs of subcortical recruitment, as compared to the unaffected hand and hemisphere, as well as the expected cortical activations.


CONCLUSIONS
The potential sources of motor voluntary activity for the affected hand in absence of MEPs are discussed. We conclude that multimodal analysis may contribute to a more accurate prognosis of stroke patients.
Neurodynamic Laboratory, Departament of Psychiatry and Clinical Psychobiology Universitat de Barcelona, 08035, Barcelona, Spain. julian.amengual@gmail.com
Julià L
JL
Amengual
Antoni
A
Valero-Cabré
Misericordia Veciana
MV
de las Heras
Nurja
N
Rojo
Seán
S
Froudist-Walsh
Pablo
P
Ripollés
Nils
N
Bodammer
Bahram
B
Mohammadi
Jordi
J
Montero
Carles
C
Grau
Thomas F
TF
Münte
Antoni
A
Rodríguez-Fornells
D002908:Chronic Disease; D019054:Evoked Potentials, Motor; D006801:Humans; D008297:Male; D008875:Middle Aged; D009069:Movement Disorders / Q000150:complications* / Q000175:diagnosis*; D011379:Prognosis; D020521:Stroke / Q000150:complications* / Q000175:diagnosis*; D050781:Transcranial Magnetic Stimulation / Q000379:methods*