Phenoconsonance: A New Form of Neurological Analysis That Complements Anatomical Localization and Disease Pattern Recognition

The semiology of clinical phenomena is central to neurological reasoning. When clinical manifestations occur in combination (e.g., weakness plus sensory loss), they are traditionally analyzed by considering anatomical localization (e.g., right-sided weakness and aphasia implicate the left cerebral cortex) and disease pattern recognition (e.g., tremor, bradykinesia, and rigidity indicate parkinsonism). The authors introduce a third, complementary approach-phenoconsonance-that relates neurological phenomena to each other not by their anatomical localization or disease pattern recognition but by their shared phenomenology. The authors identify the main components of the description of neurological phenomena in relation to where, what, and how neurological function is affected: examples for "where" include left-arm deficits in left brachial plexopathy or left hemispace neglect in right parietal lesions; examples for "what" include motor strength, visuospatial reasoning, or abstract planning; and examples for "how" include slowness, incoordination, or difficulty with initiation, because either the same function can be disrupted in qualitatively different ways-movement can be slowed or uncoordinated-or the same qualitative abnormality can apply to different functions-slowing may characterize movement, and it may also characterize thinking. The where, what, and how of neurological phenomenology correspond in the authors' synthesis to spatial phenoconsonance, domain phenoconsonance, and qualitative phenoconsonance, respectively. The historical context and conceptual underpinning of the notion of phenoconsonance are reviewed, as is its usefulness for the study of brain-behavior relationships in the evaluation and treatment of individuals with neurological and neuropsychiatric disorders.