Descriptive Psychopathology: The Signs and Symptoms of ...

157 Chapter 7: Disturbances of motor functionwind, is characteristic of Huntington’s disease. Small, rapidly increasing steps(festination) with loss of arm swing signals Parkinsonism. 19 A flexed postureof the trunk while walking and decreased arm swing without rigidity are seenin patients with frontal lobe dementias. A gait apraxia, the slipping clutchsyndrome, is recognized when a patient with adequate elementary neurologicfunction has difficulty starting to walk and then does so in bursts of small steps.Many musculoskeletal diseases elicit difficulties in walking. 20Disturbances of motor regulationDifficulty regulating one’s movement despite adequate muscle strength is ahallmark of many behavioral syndromes and includes “soft neurologic signs”,features of neurologic disturbance, but less localizing than classic aphasias andparalysis. 21 When these features dominate the clinical picture, the evaluationshould first focus on the identification of structural brain disease.Pathological inertiaWhen adequate limb function is present and the patient understands the task,movement should be started quickly and ended immediately when the task iscompleted. Failing to promptly start, hesitation and false starts as if to gainmomentum, and persisting of movement when no longer appropriate definepathological inertia. Pathological inertia is seen in patients with frontal lobedementia, Parkinsonism, depressive illness, and schizophrenia. Catalepsy withits prolonged immobility is an extreme form of pathological inertia.Perseveration and impersistenceMotor perseveration is the unnecessary repetition or continuation of movementor position beyond what is needed and despite injunctions that the movementshould stop. Impersistence is the inability to continue a movement or maintaina position until told to stop (15s). Assessment includes asking the patient tomake a fist, keep his eyes closed, and hold his arms out. Motor overflow is alsoconsidered with these tasks.Adventitious motor overflowUnneeded extra movements that occur during a task are signs of motor dysregulation.A young child sticking the tip of his tongue out while practicing hisletters is an example of overflow that usually resolves with maturation.Choreiform movements, involuntary sudden brief twisting jerks, may occur whena patient is asked to hold his arms out in front, palms down. When pronounced, asin Huntington’s disease, the patient may try to disguise the movement by continuing