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(A) Lesion studies (multimodality MRI or CT imaging) | |
(1) Symptom related: most conditions present with the triad of inattention, executive dysfunction, and dysmemory. A working memory disorder (worried well) as opposed to early Alzheimer’s disease is also frequent. | |
(2) Syndrome related: basic clinical (abulia, disinhibition, dysexecutive). | |
(3) Syndrome pathophysiologically related. Examples include frontal stroke, herpes simplex encephalitis, leukoaraiosis, watershed infarction such as “Man-in-the-Barrel syndrome”, or tumor related such as the Foster Kennedy syndrome. | |
(4) Anatomically lobar: motor, premotor prefrontal dorsolateral, prefrontal mediobasal, and prefrontal orbitofrontal. | |
(5) Anatomically network: frontal subcortical circuits | |
(6) Anatomically long range network: brainstem, cerebellar, occipital lesions associated with FNS | |
(B) No radiological abnormality-neurotransmitter syndromes | |
Serotonin syndrome | |
Neuroleptic malignant syndrome | |
Malignant hyperpyrexia | |
Cholinergic and anticholinergic toxidromes | |
Paroxysmal autonomic instability and dystonia syndrome (PAIDS) | |
(C) Synaptopathies (for example Limbic encephalitis) | |
Disorders with antibodies against synaptic proteins such as NMDA, AMPA, and GABA-B receptors. Present with seizures and encephalopathies and yet are treatable [19]. | |
(D) Networktopathies and participatory networks (f-MRI) | |
The default mode network, salience network, and attentional network may be evaluated by f-MRI (e.g., abnormal in AD, FTD, TBI, MS, depression, e.g.,) [20] | |
Functional MRI-task-related activity seen, for example, with the Stroop, Word List Generation tests, and Wisconsin Card Sorting Test activating particular networks [21]. | |
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