Cognitive-motor dysfunction after severe traumatic brain injury: A cerebral interhemispheric disconnection syndrome.
OBJECTIVE
In most right-handed people, the left hemisphere is dominant for programming the temporal and spatial "how" (praxis) aspects of purposeful skilled movements, and the right hemisphere is dominant for control of the intentional "when" aspects of actions that mediate initiation, persistence, termination, and inhibition. Since the interhemispheric axons of the corpus callosum are especially susceptible to shearing from torsional forces during traumatic brain injury (TBI), the goal of this study was to learn whether participants with a history of severe traumatic brain injury demonstrate three types of cognitive-motor impairments that may result from callosal injury: ideomotor apraxia of the left hand, limb kinetic apraxia of the left hand, and hypokinesia of the right hand in response to left hemispatial stimuli.


METHODS
Nine participants with severe TBI and nine healthy control participants were studied for the presence of ideomotor apraxia, limb kinetic apraxia, and hypokinesia.


RESULTS
When compared to the control participants, the participants with TBI revealed ideomotor apraxia and limb kinetic apraxia of the left hand and hypokinesia in response to left-sided visual stimuli when tested with the right hand.


CONCLUSIONS
TBI appears to cause unilateral disorders of cognitive-motor functions. Future research is needed to understand how these cognitive-motor disorders are related to interhemispheric disconnection most likely induced by injury to the corpus callosum.
a Brain Rehabilitation Research Center of the Malcom Randall VAMC , Gainesville , FL , USA.|b University of Florida Department of Neurology and Center for Neuropsychological Studies, McKnight Brain Institute , Gainesville , FL , USA.|c Institute on Aging, University of Florida , Gainesville , FL , USA.
Adam D
AD
Falchook
a Brain Rehabilitation Research Center of the Malcom Randall VAMC , Gainesville , FL , USA.|c Institute on Aging, University of Florida , Gainesville , FL , USA.
Eric C
EC
Porges
a Brain Rehabilitation Research Center of the Malcom Randall VAMC , Gainesville , FL , USA.|b University of Florida Department of Neurology and Center for Neuropsychological Studies, McKnight Brain Institute , Gainesville , FL , USA.|c Institute on Aging, University of Florida , Gainesville , FL , USA.
Stephen E
SE
Nadeau
a Brain Rehabilitation Research Center of the Malcom Randall VAMC , Gainesville , FL , USA.|b University of Florida Department of Neurology and Center for Neuropsychological Studies, McKnight Brain Institute , Gainesville , FL , USA.
Susan A
SA
Leon
a Brain Rehabilitation Research Center of the Malcom Randall VAMC , Gainesville , FL , USA.|b University of Florida Department of Neurology and Center for Neuropsychological Studies, McKnight Brain Institute , Gainesville , FL , USA.|c Institute on Aging, University of Florida , Gainesville , FL , USA.
John B
JB
Williamson
a Brain Rehabilitation Research Center of the Malcom Randall VAMC , Gainesville , FL , USA.|b University of Florida Department of Neurology and Center for Neuropsychological Studies, McKnight Brain Institute , Gainesville , FL , USA.|c Institute on Aging, University of Florida , Gainesville , FL , USA.|d Geriatric Research Education and Clinical Center of the Malcom Randall VAMC , Gainesville , FL , USA.
Kenneth M
KM
Heilman
D000328:Adult; D000704:Analysis of Variance; D001072:Apraxias / Q000209:etiology; D001930:Brain Injuries / Q000150:complications*; D002540:Cerebral Cortex / Q000473:pathology; D003072:Cognition Disorders / Q000175:diagnosis / Q000209:etiology*; D003337:Corpus Callosum / Q000473:pathology*; D005260:Female; D007839:Functional Laterality / Q000502:physiology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D009069:Movement Disorders / Q000175:diagnosis / Q000209:etiology*; D009483:Neuropsychological Tests; D011930:Reaction Time / Q000502:physiology; D055815:Young Adult
Action-intention; Corpus callosum; Ideomotor apraxia; Limb kinetic apraxia; Traumatic brain injury