Papers by Terrence D Lagerlund
IEEE Transactions on Nuclear Science, 1982
Oxford University Press eBooks, Jun 1, 2021
Brain Communications, 2021
EEG source imaging is becoming widely used for the evaluation of medically refractory focal epile... more EEG source imaging is becoming widely used for the evaluation of medically refractory focal epilepsy. The validity of EEG source imaging has been established in several studies comparing source imaging to the surgical resection cavity and subsequent seizure freedom. We present a cohort of 87 patients and compare EEG source imaging of both ictal and interictal scalp EEG to the seizure onset zone on intracranial EEG. Concordance of EEG source imaging with intracranial EEG was determined on a sublobar level and was quantified by measuring the distance between the source imaging result and the centroid of the active seizure onset zone electrodes. The EEG source imaging results of a subgroup of 26 patients with high density 76-channel EEG were compared with the localization of three experienced epileptologists. Of 87 patients, 95% had at least one analysis concordant with intracranial EEG and 74% had complete concordance. There was a higher rate of complete concordance in temporal lobe e...
2006 International Conference of the IEEE Engineering in Medicine and Biology Society, 2006
We have proposed a new ictal source analysis approach by combining a spatio-temporal source local... more We have proposed a new ictal source analysis approach by combining a spatio-temporal source localization approach, and causal interaction estimation technique. The FINE approach is used to identify neural electrical sources from spatio-temporal scalp-EEGs. The Granger causality estimation uses source waveforms estimated by FINE to characterize the causal interaction between the neural electrical sources in order to distinguish primary sources, which initiate ictal events, from secondary sources, which are caused by propagation. In the present study, we applied the proposed analysis approach to an epilepsy patient with symptomatic MRI lesions. It is found that the primary ictal source is within the visible lesion, which gave the consistent presurgical evaluation as MRI for this patient.
American Journal of Physiology-Endocrinology and Metabolism, 1994
Insulin administration can cause or worsen experimental and human diabetic neuropathy ("insu... more Insulin administration can cause or worsen experimental and human diabetic neuropathy ("insulin neuritis"). In this study, we tested the hypothesis that insulin administration impairs tissue oxygenation. We infused insulin under nonhypoglycemic conditions and evaluated its effect on endoneurial oxygen tension, nerve blood flow, and the oxyhemoglobin dissociation curve of peripheral nerve in normal and diabetic rats. Intravenous insulin infusion resulted in a dose-dependent reduction in endoneurial oxygen tension in normal nerves (from 26% at 0.04 U/kg insulin to 55% at 32 U/kg). The nerves of rats with streptozotocin-induced diabetes were resistant, but with control of hyperglycemia this susceptibility to the endoneurial hypoxic effect of insulin returned. The reduction in endoneurial oxygen tension regressed with glycosylated hemoglobin (Y = 53.8-2.7X, where Y = %reduction in endoneurial oxygen tension and X = HbA1; r = 0.87; P = < 0.001). Diabetes or insulin administr...
Electroencephalography and Clinical Neurophysiology, 1998
To present clinical electrophysiologic studies performed on the pallido-ponto-nigral degeneration... more To present clinical electrophysiologic studies performed on the pallido-ponto-nigral degeneration (PPND) family linked to chromosome 17q21-22. Nine patients from this kindred were studied with 11 electroencephalograms (EEGs), 4 electroencephalographic background frequency analysis (BFA) studies, 4 electromyographic recordings (EMGs) including nerve conduction studies (NCSs), 4 electromyographic multichannel surface recordings (MSRs), one pattern visual evoked potential (VEP) study and one median nerve somatosensory evoked potential (SEP) study. EEGs revealed normal findings early in the disease and diffuse slowing which became more prominent with disease progression. BFA studies demonstrated rapid decrease in mean parietal frequencies with disease progression. EMGs and NCSs showed no abnormalities. MSRs revealed action myoclonus and a dystonic process. Long loop reflexes were absent in resting hand muscles. VEPs and SEPs were normal. Clinical neurophysiologic studies were consistent with a cortical and subcortical degenerative process. With clinical deterioration, there is a progressive decline in the mean parietal frequency and background rhythms. Tremor studies were consistent with action myoclonus and a dystonic process and did not show parkinsonian features of resting tremor or agonist-antagonist cocontraction. There was no evidence of peripheral nerve involvement or slowing in central sensory pathways. Electrophysiologic findings are characteristic for this illness.
Clinical Neurophysiology, 2016
The variety of clinical neurophysiological studies corresponds to a variety of structural generat... more The variety of clinical neurophysiological studies corresponds to a variety of structural generators in the body, including muscles, sweat glands, peripheral nerves, and various components of the central nervous system. Each structural generator may have associated with it several different types of physiological potential. This chapter reviews the generators of electrophysiological potentials in terms of basic cellular electrophysiology and the anatomical structures that generate electrophysiological potentials of clinical interest. Knowledge of the generators of the potentials recorded in clinical neurophysiological studies is helpful in understanding the characteristics and distribution of the recorded potentials and is the first step in correlating the alterations seen in disease states with the pathological changes demonstrated in the underlying generators.
Clinical Neurophysiology, 2009
This chapter reviews the generators of electrophysiologic potentials in terms of basic cellular e... more This chapter reviews the generators of electrophysiologic potentials in terms of basic cellular electrophysiology and the anatomical structures that generate electrophysiologic potentials of clinical interest. Knowledge of the generators of the potentials recorded in clinical neurophysiologic studies is helpful in understanding the characteristics and distribution of the recorded potentials and is the first step in correlating the alterations seen in disease states with the pathologic changes demonstrated in the underlying generators.
Clinical Neurophysiology, 2009
This chapter reviews the basic principles of electric and electronic circuits that are important ... more This chapter reviews the basic principles of electric and electronic circuits that are important to clinical neurophysiology. Knowledge of these basic principles and how to solve simple circuit problems is necessary for a complete understanding of the proper operation of equipment used in clinical neurophysiology and of the terminology and specifications given in equipment manuals.
International Review of Neurobiology, 1989
NERVE BLOOD FLOW AND OXYGEN DELIVERY IN NORMAL, DIABETIC, AND ISCHEMIC NEUROPATHY By Phillip A. L... more NERVE BLOOD FLOW AND OXYGEN DELIVERY IN NORMAL, DIABETIC, AND ISCHEMIC NEUROPATHY By Phillip A. Low, Terrence D. Lagerlund, and Philip G. McManis Deportment of Neurology Mayo Clinic and Mayo Foundation Rochester, Minnesota 55905 I. Special ...
Electroencephalography and Clinical Neurophysiology, 1993
Clinical Neurophysiology, 2009
This chapter reviews several quantitative analysis techniques that may be applied to digitized EE... more This chapter reviews several quantitative analysis techniques that may be applied to digitized EEG data. The technique of MEG is also discussed. Many of these techniques were primarily used as research tools; but as they have become more widely available, they are having an increasing effect on EEG interpretation and diagnosis.
Journal of Clinical Neurophysiology, 1997
Journal of Clinical Neurophysiology, 1999
Journal of Clinical Neurophysiology, 1996
Epilepsia, 2000
While undergoing video-EEG monitoring, a 20-year-old woman had a 56-second convulsive seizure, af... more While undergoing video-EEG monitoring, a 20-year-old woman had a 56-second convulsive seizure, after which she developed persistent apnea. The rhythm of the electrocardiogram complexes was unimpaired for approximately 10 seconds, after which it gradually and progressively slowed until it stopped 57 seconds later. Evaluation after successful cardio-respiratory resuscitation showed no evidence of airway obstruction or pulmonary edema. The patient had a previous cardio-respiratory arrest after a complex partial seizure without secondary generalization. Although epileptic seizures are known to be potentially arrhythmogenic to the heart, our observations strongly suggest that one probable mechanism of sudden unexplained death in epilepsy is the marked central suppression of respiratory activity after seizures.
Archives of Neurology, 1988
In the case described, electroencephalography (EEG) proved valuable for determining the nature of... more In the case described, electroencephalography (EEG) proved valuable for determining the nature of spells of loss of consciousness with brief clonic jerks associated with ear and throat pain. A 70-year-old woman had a history of episodic brief attacks of pain below the right ear and deep in the neck that had started three years previously. The spells became more severe and progressed to loss of awareness associated with clonic jerks of the extremities. Because of a concern that the spells represented seizures, an EEG was performed, with electrocardiographic monitoring. Multiple spells were recorded; they began with profound bradycardia followed by generalized slow-wave activity and then by suppression of all EEG activity correlating with loss of consciousness and clonic jerking. The spells were thought to represent syncopal attacks associated with glossopharyngeal neuralgia.
Archives of Neurology, 2012
Objective-To describe clinical characteristics and immunotherapy responses in patients with autoi... more Objective-To describe clinical characteristics and immunotherapy responses in patients with autoimmune epilepsy. Design-Observational, retrospective case series.
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Papers by Terrence D Lagerlund