Table 3: Presentations of frontal network syndromes; clinical and radiological syndromes (Figure 10).

(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].