Neuroimaging of multimodal sensory stimulation in amyotrophic lateral sclerosis.
OBJECTIVE
Structural and functional imaging techniques were combined to investigate sensory system function in amyotrophic lateral sclerosis (ALS).


METHODS
Functional MRI (fMRI) was used to investigate cortical activity during visual, auditory and somatosensory stimulation in 14 ALS patients and 18 control subjects. Changes in amplitude, latency and duration of the blood oxygen level dependent response were modelled. Furthermore, diffusion tensor imaging was used to investigate changes in white matter networks.


RESULTS
During visual stimulation, fMRI demonstrated a decreased response in secondary visual areas in ALS, possibly related to demyelination of sensory nerve fibres. Increasing brain activity in associative cortices was linked to a decrease in physical functioning and might represent a compensatory process. Additionally, reduced white matter functioning became evident for fibres projecting to the extrastriate visual cortex. For auditory stimulation, a delayed response in secondary auditory areas probably linked to prolonged nerve conductance time and an altered cortical pattern in areas involved in target processing/detection became evident in ALS patients. Structural white matter changes in the primary and secondary auditory cortices were observed. For somatosensory stimulation, a prolonged/reduced response in sensory integration areas of the parietal lobe was observed, perhaps linked to the reduced visceral inflow due to immobility.


CONCLUSIONS
Multiparametric MRI suggests a progressive functional deficit in secondary/higher order sensory processing areas in ALS, probably associated with reduction of re-afferent information flow due to progressive immobility. The changes described might also represent an expression of the disease process itself. Evidence for compensatory processes in multimodal associative cortices was found.
Lulé
Dorothée
D
Section of Neurophysiology, University of Ulm, Ulm, Germany. dorothee.lule@uni-ulm.de
Diekmann
Volker
V
Müller
Hans-Peter
HP
Kassubek
Jan
J
Ludolph
Albert C
AC
Birbaumer
Niels
N
D000161:Acoustic Stimulation; D000328:Adult; D000344:Afferent Pathways / Q000473:pathology / Q000503:physiopathology*; D000368:Aged; D000690:Amyotrophic Lateral Sclerosis / Q000473:pathology / Q000503:physiopathology*; D002540:Cerebral Cortex / Q000503:physiopathology; D003627:Data Interpretation, Statistical; D038524:Diffusion Magnetic Resonance Imaging; D018450:Disease Progression; D005260:Female; D006309:Hearing / Q000502:physiology; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D009415:Nerve Net / Q000503:physiopathology; D009483:Neuropsychological Tests; D010100:Oxygen / Q000097:blood; D010775:Photic Stimulation; D010812:Physical Stimulation; D012677:Sensation / Q000502:physiology*; D013003:Somatosensory Cortex / Q000503:physiopathology; D014110:Touch / Q000502:physiology; D014785:Vision, Ocular / Q000502:physiology
D010100:Oxygen