Types of Facial Paralysis - Peripheral vs Central Lesions



Facial weakness or paralysis may result either from (I ) a peripheral lesion of CN VII, the facial nerve, anywhere from its origin in the pons to its periphery in the face, or (2 ) a central lesion involving the upper motor neuron system between the cortex and the pons. A 

peripheral lesion of CN VII, exemplified here by a Bell's palsy, is compared with a central lesion, exemplified by a left hemispheric 

cerebrovascular accident. These can be distinguished by their different effects on the upper part of the face. 



The lower part of the face normally is controlled by upper motor neurons located on only one side of the cortex—the opposite side. 

Left hemispheric damage to these pathways, as in a stroke, paralyzes the right lower fate. The upper face, however, is controlled by pathways 

from both sides of the cortex. Even though the upper motor neurons on the left are destroyed, others on the right remain, and the 

right upper face continues to function fairly well. 



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** GrepMed Recommended Text: Bates' Guide to Physical Examination and History Taking - https://amzn.to/2Z6LYmf