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Clinical Neuro - CN
CN cases quiz
Question | Answer |
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A pt has noticed blurry vision. On examination her pupils are equal in size. As the flashlight is shined from eye to eye, you see the pupil dilate when you shine the flashlight in the right eye. What is the most likely explanation for her blurry vision? | The patient has a relative afferent pupillary defect of the right eye; means less light is perceived therefore the pupil will dilate when the flashlight swings over to the involved eye. Decreased visual acuity is seen with optic nerve lesions |
A 12-year-old boy complains of side by side or horizontal double vision when looking to the left. When he looks to the left and the left eye is covered, the most peripheral image disappears. The cause of his diplopia is paralysis of which cranial nerve? | L CN 6. The eye can't abduct so there is double vision when looking to the left. The false image is always the most peripheral image and is always from the abnormal eye. Covering the left eye eliminates the false or ghost image so it is the abnormal eye. |
A 55-yr-old diabetic male complains of double vision. On exam of his extraocular movements, you notice limited adduction, elevation, and depression of his right eye. The pupils are equal and reactive. Pt most likely has a lesion of which cranial nerve? | R CN3; Why isn't the R pupil dilated as well? If lesion was caused by compression of the n. then the parasympathetic fibers which travel on the outer side of the nerve are involved and there is always a dilated unreactive pupil associated with the palsy. |
The patient's eyes do not turn in the opposite direction of head movement. Which one of the supranuclear gaze systems is affected? | Frontal gaze center; Parietal-occipital gaze center; *Vestibulo-ocular system; Occipital mesencephalic pathways |
The patient has difficulty with large amplitude eye movements needed to fix on a new target. Which one of the supranuclear gaze systems is affected? | The frontal gaze center is for saccadic eye movements which are rapid eye movements used to bring new objects being viewed on to the fovea. |
The patient has difficulty seeing objects 6 inches in front of nose. Which one of the supranuclear gaze systems is affected? | The occipital mesencephalic pathways are important for vergence which is keeping an image on the fovea when the viewed object is moved near to the face. |
The patient has difficulty visually tracking a horse and rider moving from left to right. Which one of the supranuclear gaze systems is affected? | The parietal-occipital gaze center is important for smooth pursuit eye movements used to keep a moving image centered on the fovea. |
A 60-year-old man has decreased sensation to pin prick over the left cheek but the forehead and jaw area are normal. This finding is most consistent with a sensory loss of which one of the following? | Left maxillary division of the 5th cranial nerve. The sensory field for the maxillary division of the 5th cranial nerve is the cheek and the roof of the mouth. |
On exam. a patient has the following on the Rinne-Weber test: The tuning fork on the forehead lateralizes to the right ear and air conduction is greater than bone conduction in both ears. These findings are most consistent with what type of hearing loss? | Neurosensory hearing loss. With this hearing loss the vibration of the tuning fork placed on the forehead is perceived loudest in the normal ear. Air conduction is greater then bone conduction for both ears because there is no conductive hearing loss. |
A 38-year-old woman has noticed asymmetry of her smile and drooling from the left side of her mouth. On examination, she can wrinkle her forehead bilaterally. She most likely has which one of the following? | Left central 7th paresis. The patient has sparing of the frontalis muscle so this is an upper motor lesion affecting the left side of the face. The lesion is in the corticobulbar tract coming from the right cerebral cortex. |
When the patient sticks out her tongue, it deviates to the right. This finding is most likely secondary to which one of the following? | Right 12th cranial nerve palsy. The tongue deviates toward the side of the abnormal 12th cranial nerve. |
The patient has difficulty seeing objects on the left side of space. He closes one eye, then the other, and it doesn't make any difference. He cant see things superiorly or inferiorly on the left. Where is the lesion that has caused the patient's problem? | B/c R optic tr. is post. to optic chiasm, fibers contained in it "see" the same side of space although from different eyes. So a lesion of the R optic tract would result in a left hemianopsia that is present when testing each eye together or separately. |
A lesion of the right medial longitudinal fasciculus (MLF) would cause which one of the following? | Incomplete abduction of the L eye. Incomplete abduction of the R eye. *Incomplete adduction of the R eye. Incomplete adduction of both eyes Incomplete adduction of the L eye. |
A lesion of the left MLF would result in what ocular motion deficit? | Incomplete adduction of the left eye. |
A pt has excessive nasal air escape when saying "ka, ka, ka." Then when he says "ah" there is incomplete elevation of the palate. When you gag him, there is a strong gag reflex. The most likely cause of this patient's problem is what? | Bilateral UMN lesion affecting cranial nerves 9 and 10. Pts with a bilateral upper motor weakness will lack voluntary movement of the palate but reflex activity will be preserved and even be hyperactive ( just like hyperreflexia in the UMN syndrome). |
A 60-year-old male has a stroke which gives him a right 5th cranial nerve lesion. What would you expect to see on examination? | Jaw deviation to the R on opening to resistance. The jaw deviates toward the side of the lesion because of the unopposed action of the pterygoid muscle on the normal side. |