A 65-year-old man is brought to the emergency department due to right-sided weakness. The patient was at dinner when he suddenly experienced right arm weakness and difficulty using his fork. He also had trouble standing due to right leg weakness. Medical history is significant for hypertension, hyperlipidemia, and type 2 diabetes mellitus. Blood pressure is 164/90 mm Hg and pulse is 80/min and regular. Neurologic examination shows 2/5 muscle strength and 3+ deep tendon reflexes in the right upper and lower extremities. There is flattening of the left nasolabial fold, and he is unable to completely close the left eye. Which of the following is the most likely location of this patient's lesion?

Question

A 65-year-old man is brought to the emergency department due to right-sided weakness.  The patient was at dinner when he suddenly experienced right arm weakness and difficulty using his fork.  He also had trouble standing due to right leg weakness.  Medical history is significant for hypertension, hyperlipidemia, and type 2 diabetes mellitus.  Blood pressure is 164/90 mm Hg and pulse is 80/min and regular.  Neurologic examination shows 2/5 muscle strength and 3+ deep tendon reflexes in the right upper and lower extremities.  There is flattening of the left nasolabial fold, and he is unable to completely close the left eye.  Which of the following is the most likely location of this patient's lesion?

Quizplus · Accepted Answer

Explanation: 11ec25c8_d5b1_83a7_bc81_9f4254f4d9af_MD0003_00 This patient with risk factors for stroke (eg, hypertension, diabetes mellitus) has crossed signs of: right arm and leg weakness with an upper motor neuron pattern (ie, hyperreflexia). left facial weakness that involves the upper (cannot close eye) and lower (flattening of nasolabial fold) face, corresponding to a lower motor neuron pattern of facial weakness. Because the brainstem is where most cranial nerves originate and many motor and sensory fibers cross the midline, acute cranial nerve deficits accompanied by contralateral hemiparesis or hemisensory loss (ie, crossed signs) are consistent with brainstem stroke. The facial nerve (CN VII) originates in the pons. Therefore, lesions above the pons (eg, midbrain, internal capsule, or cortical strokes) lead to an upper motor neuron pattern of facial weakness (spares the upper face, contralateral to the site of the lesion). Lesions at or below the level of the pons result in a lower motor neuron pattern of facial weakness (weakness of the upper face, ipsilateral to the site of the lesion). Therefore, this patient's lesion is likely in the left pons, resulting in contralateral (right) arm and leg weakness with ipsilateral (left) facial nerve palsy. (Choices A and D) Lesions affecting the posterior limb of the internal capsule (lacunar stroke) can lead to corticospinal tract injury, causing contralateral weakness impacting the leg, arm, and face. Facial weakness displays an upper motor neuron pattern (sparing of the upper face, contralateral to the site of weakness). Therefore, weakness of face, arm, and leg would impact the same (contralateral) side (left-sided weakness for right internal capsule, right-sided weakness for left internal capsule). lacunar stroke (Choices C and F) Lesions impacting the precentral gyrus (primary motor cortex) can lead to weakness of the contralateral body and lower face with sparing of the upper face (central facial weakness). A lesion of the left precentral gyrus would cause right-sided weakness; a lesion of the right precentral gyrus would result in left-sided weakness. central facial weakness (Choice E) A lesion in the right pons would lead to contralateral (left) weakness of the arm and leg with ipsilateral (right) facial weakness. Educational objective: Stroke in the pons can lead to contralateral weakness of the arm and leg with ipsilateral facial weakness. Facial weakness occurs in a lower motor neuron pattern (sparing of upper face, ipsilateral to lesion) because the damage occurs at the level of the facial nerve (CN VII) origination. References: The crossed paralyses. The original brain-stem syndromes of Millard-Gubler, Foville, Weber, and Raymond-Cestan. (http://www.ncbi.nlm.nih.gov/pubmed/7763214)

A 65-Year-Old Man Is Brought to the Emergency Department Due