Magnetic source imaging of cortical dysfunction in amyotrophic lateral sclerosis.

OBJECTIVE: The goal was to determine whether magnetic source imaging could identify a signature for cortical involvement in patients with amyotrophic lateral sclerosis (ALS), and to determine whether the method might provide insight into functional abnormalities associated with the disease process. DESIGN: Spontaneous brain activity recordings from whole-head 148-channel magnetoencephalography (MEG) were employed to look for localized dipolar sources of focal delta-theta (1-7 Hz) discharges in patients with ALS without dementia. Localized slow wave dipoles were mapped and counted by anatomic brain region, defined by MRI, and correlated against the revised ALS functional rating scale (a functional measure of ALS disability). In a substudy, defects in cortical activations mediating purposeful movement were investigated in an ALS patient with probable motor apraxia of an upper limb. RESULTS: MEG revealed localized slow wave dipole sources in 7/7 ALS patients, including two recently diagnosed patients (0/8 age-similar controls). Systematic brain mapping of dipole source generators was possible in all seven ALS patients. The slow wave bursts were being generated from frontal, temporal, and parietal cortices, but not from occipital areas. The density of slow wave dipoles in cingulate gyrus correlated with the severity of upper-extremity disability as judged by the functional ALS measure. Further magnetic source imaging in the substudy patient with unilateral limb apraxia revealed abnormal central processing of purposeful movement with absent M2 in the contralateral secondary motor areas generating slow waves. CONCLUSIONS: This exploratory study documents widespread cortical dysfunction in patients with ALS, including those with recent onset of their disease. MEG is likely to be a powerful new tool for researching the contribution of cortical dysfunction to the motor disability that characterizes the disease process.

High-resolution magnetoencephalographic functional mapping of the cortical network mediating intentional movement.

Magnetoencephalography (MEG) is a sensitive technique that can detect and map cortical electrophysiologic activations with high spatial (mm) and temporal (msecs) resolutions. We used 148-channel whole-head MEG to record the activation sequence for the somatosensory and motor cortical network during cued hand movements in a healthy 39-yr-old subject. The complex sequence and topography of cortical activations were superimposed onto the subject's brain magnetic resonance images. Frontal premotor and supplementary motor and cingulate areas activated well before the primary motor area and again repetitively from 200 msecs onward with activations alternating repeatedly between frontal and parietal areas. The network's very close functional integration of supplementary motor areas suggests how brain injury that is localized to these regions, but not to the primary motor area itself, can disrupt integrity of movement, and why preservation of functional integrity of some areas traditionally viewed as extramotor may be necessary for recovery from neurologic disability.

Relationship of lumen diameter to type and degree of arterial remodeling at sites of expanding wall or plaque thickness in human carotid artery.

BACKGROUND: Arterial remodeling exhibits a bidirectional capacity. Whether lumen size affects remodeling response to lesion change is unknown. METHODS: Prospective study by duplex ultrasonography over 2 years in 61 subjects with coronary artery disease. Direction and magnitude of vessel remodeling are calculated for internal carotid, bifurcation, and common carotid artery segments. RESULTS: A linear trend is discernible between lumen diameter and direction and magnitude of remodeling at sites of expanding intima-media thickness (IMT) or plaque. Rate of lesion change varied inversely with lesion thickness with an inflection between rates for low-dimension IMT and plaque. CONCLUSIONS: Dilatation versus shrinkage in the remodeling response to expanding lesions appears related to lumen size. IMT and plaque exhibit independent biologies.

Integration and added value of the modern noninvasive vascular laboratory in vascular diseases management.

BACKGROUND AND PURPOSE: Today's vascular laboratory technology offers broad applications throughout vascular medicine. We explore the diagnostic work-up and management of selected peripheral vascular diseases by benchmarking the institutional mix of invasive and noninvasive technology utilization and associated cost burdens. METHODS: Specialized diagnostic studies for prevention of stroke and pulmonary embolism, and diagnosis and management of femoral pseudoaneurysm were reviewed for our 355-physician clinic and hospital practice. The proportions and costs for invasive and noninvasive diagnostic procedures were tabulated for carotid stenosis, deep venous thrombosis (DVT), and iatrogenic femoral pseudoaneurysm. Current technology utilization mix cost burdens were compared to projected cost burdens for hypothetical equivalent medical value (i.e., the same total test volume) in the theoretical absence of noninvasive laboratory services. RESULTS: The technology utilization mix was dominated by noninvasive duplex ultrasonography for all 3 vascular disease workups. The technology utilization mix benchmarks were 92% noninvasive for carotid stenosis, 98% noninvasive for DVT, and 100% noninvasive for pseudoaneurysm. Under hypothetical constant test volume normalized to utilization level for the 2-year period, the maximal range in cost burdens between current reliance on noninvasive diagnoses versus projected 100% reliance on invasive procedures for the 3 vascular applications is approximately $6 million. CONCLUSION: Benchmark indices reveal near total adoption of noninvasive technology for vascular diagnostic workups at our center. The benefits to institutions of benchmarking their technology utilization mix and costs are discussed in relation to identifying potential for cost-containment from modifying technology utilization practices.