Descriptive Psychopathology: The Signs and Symptoms of ...

70 Section 1: Present, past, and futureA three-way view of the motor systemSince the mid-nineteenth century, neurologists have relied on the crossing overthe midline of brain motor pathways and the lateralization of cerebral hemispherefunctions to localize brain lesions. Left hemi paresis follows a right anterior brainlesion; right upper motor neuron signs predict left-sided CNS disease. Aphasiafollows dominant hemisphere disease; visual–spatial problems are associated withnon-dominant hemisphere disease. The examination for motor dysfunction isassessed from this left/right view with asymmetry indicating contralateral disease.This anatomic rule also applies to psychopathology, and asymmetrical psychopathologyindicates contralateral brain disease.The back/front view of the motor system recognizes the frontal circuitry as thefront unit and the cerebellum as the back unit. Disorders of activity and motorregulation, catatonia, and basal ganglia signs are signature features of frontalcircuitry dysfunction. Behavioral syndromes associated with these features indicateeither intrinsic frontal circuitry disease (e.g. traumatic brain injury, Parkinson’sdisease, frontal–temporal dementia) or disruption of frontal circuitry functionsecondary to disease in related brain systems (e.g. temporolimbic disease).Bradykinesia (slowing of movement), bradyphrenia (slowing of cognition), anddeficits in executive cognitive functions are also hallmarks of frontal circuitry disease.The presence of basal ganglia motor signs (front) or cerebellar motor signs (back)delineate dysfunctional brain systems associated with many behavior syndromes.Patient 1.1 with an apathetic syndrome and loss of skilled motor ability due to basalganglia disease (front) is an example. His behavioral change was interpreted as signs ofdepression, but his motor symptoms revealed the true different nature of his condition.The top/bottom view of the motor system recognizes the frontal and prefrontalcortex and the parietal lobe sensory and associational cortices as the top unit andthe basal ganglia and cerebellum as the bottom unit. Patient 1.1 illustrates bottom(basal ganglia) and front (also basal ganglia) disease.Motor dysregulation signs are associated with prefrontal cortex disease andpraxis is associated with parietal cortex functioning. These cortical areas representthe top. The presence of problems with motor regulation or dyspraxia but nobasal ganglia or cerebellar signs indicates cortical disease.Brain structures that subserve movement are so widespread that most diseasesof the brain will impinge on part of that structure. The three views of the motorsystem permit the identification of many circumscribed brain conditions. Patient3.1 illustrates.Patient 3.1 (front/bottom)A 78-year-old man had a two-year “depression” unresponsive to antidepressanttreatment. He had no prior history of psychiatric disorder. The characterization