47

47 CASE 47


A 53-year-old man is brought to the emergency department by ambulance because he is having difficulty speaking.


The patient tried to explain to his wife that something was wrong, but he was unable to speak clearly. He is, however, able to communicate in writing. He has been on beta blockers to control hypertension and has type 2 diabetes that is being managed with diet and exercise.



PHYSICAL EXAMINATION



VS: T 36.5°C, P 85/min, R 18/min, BP 134/88 mm Hg, BMI 31

PE: The patient is anxious but able to respond to spoken commands. Reflexes are intact.


LABORATORY STUDIES



CT: Occlusion in the left hemisphere of a branch of the anterior main division of the middle cerebral artery supplying the frontal cortex.


DIAGNOSIS


Expressive aphasia after a stroke



PATHOPHYSIOLOGY OF KEY SYMPTOMS


The patient’s primary symptom is difficulty in speaking (expressive aphasia). Speech is a complex activity requiring correct function of premotor areas (especially Broca’s area) and motor areas of the cortex, as well as upper and lower motor neurons innervating the vocal cords and diaphragm. The abrupt loss of speech suggests a neurologic cause, such as inadequate perfusion.


A cerebrovascular accident (CVA, stroke) results from impairment of a vascular supply to the brain. Ischemic stroke can be caused by a thrombus or embolus that lodges in a small branch of cerebral blood vessels. Hemorrhagic stroke is caused by the rupture of a blood vessel, usually at the site of an aneurysm. In both cases, blood supply to neurons distal to the injury is interrupted. Neurons have a very low tolerance for ischemia, and neuronal death occurs within minutes. Prompt restoration of blood flow limits the size of neurologic damage and enhances recovery. Consequently, treatment involves rapid identification of the site of blockage and restoration of blood flow by stenting or treatment with thrombolytics. Permanent neurologic damage cannot currently be reversed, but physical therapy and occupational therapy can help restore function.


Risk factors for stroke include advanced age, hypertension, diabetes, enhanced coagulation, and atrial fibrillation. Approximately one in four individuals who recover from their stroke will have another stroke within 5 years. The incidence of future strokes can be prevented by treatment with antiplatelet agents and anticoagulants.


Broca’s area is a region of the posterior lateral prefrontal cortex and the premotor area. This region of the brain controls the motor patterns for expressing individual words. It is located adjacent to the prefrontal cortex, auditory cortex, and motor cortex and receives extensive innervation from all three. Broca’s area also interacts with the language comprehension region of the temporal lobe, Wernicke’s area. In contrast to most motor and sensory cortical regions, Broca’s area and Wernicke’s area are not bilaterally represented and are usually only found in the left hemisphere (Fig. 47-1).


image

FIGURE 47–1 Map of specific functional areas in the cerebral cortex, showing especially Wernicke’s and Broca’s areas for language comprehension and speech production, which in 95% of all people are located in the left hemisphere.

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Jul 4, 2016 | Posted by in PHYSIOLOGY | Comments Off on 47

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