A 14-year-old boy presents to your office because the side of his face is droopi

Question

A 14-year-old boy presents to your office because the side of his face is drooping. His mother states that he complained yesterday of decreased food taste. Today, while at school, he could not use the microscope in science class because he couldn't close his left eye, and his teacher noted that his smile was crooked. Physical examination reveals no abnormalities and no vesicles in his ears. Mental status on neurologic examination is normal, pupil responses are normal, extraocular movements are full, and there is no nystagmus or reported double vision. He is unable to close his left eye or raise his left eyebrow, has decreased left-side nasolabial folds, and cannot close his mouth to puff out his cheeks. His palate and tongue movements are normal. Motor examination reveals normal proximal and distal strength in both arms and normal regular and tandem gait.

1. Elaborate all individual symptoms and signs in BOLD with regard to structures affected.

2.Where is the localization of the lesion?  

Explanation / Answer

Acute focal or generalized weakness is a medical emergency requiring a systematic history and neurologic examination to localize the problem. For acute focal weakness, the problem can localize to the brain, brainstem, spinal cord, anterior horn cell, root, nerve, junction, or muscle. Often, the physical examination can localize the problem to one of these levels. In the case of acute unilateral facial weakness, as described for the boy in the vignette, the typical differential diagnosis is acute facial nerve palsy (ie, Bell palsy) or a more rostral disease process of the brainstem or brain (cerebrum, motor cortex) such as a stroke. The key diagnostic point for facial weakness is whether the weakness involves the entire side of the face or the face below the forehead. A 7th nerve palsy affects all the innervated muscles, weakening or paralyzing the entire hemi-face from forehead to chin. A lesion above the facial nerve nucleus typically weakens the face below the forehead. The boy described in the vignette has full left-sided facial weakness, including the muscles in his forehead. Such findings localize to the facial nerve, and in this clinical setting, neuroimaging is not revealing. Facial weakness due to an acute brain process, such as a left middle cerebral artery stroke, usually presents with involvement of both the contralateral right face and the right hand. The brainstem, specifically the pons, is the source of the facial nerve, and brainstem diseases can produce full hemi-facial weakness. However, due to the close proximity of other brainstem nuclei, a brainstem lesion affecting the left face also should affect other functions, including the left 6th nerve, which abducts the left eye. Often, sensory and motor findings on the opposite side of the body, the so-called "crossed signs," indicate brainstem disease.

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