USMLE step 1 : 23-24 Answers

Question Number 23

Correct Answer: A

Explanation:
The clinical features are typical of facial nerve paralysis. Muscles of the lower half of the face are typically weakened. The normal folds and lines around the lips, nose, and forehead are ironed out, and the palpebral fissure is wider than normal. When the patient attempts to smile, the lower facial muscles are pulled to the opposite side. This distortion of the facial muscles may give the false appearance of deviation of the protruded tongue or the open jaw. Saliva and food are likely to collect on the paralyzed side

 

Question Number 24

 
Correct Answer: C

Explanation:
Pain typical of trigeminal neuralgia occasionally affects patients with lesions in the brain stem as a result of multiple sclerosis. They may also occur with vasculitis involving the descending root of the fifth cranial nerve. Trigeminal neuralgia usually occurs after other symptoms of MS. Of all patients with MS, however, about 10% have facial pain as a presentation, and other symptoms of MS may not appear for 6 years.

 

Question Number 25

Correct Answer: B

Explanation:
Glossopharyngeal neuralgia (known as tic douloureux of the ninth cranial nerve) is characterized by paroxysms of severe pain in the region of the tonsils but may also affect the posterior pharynx, back of the tongue and middle ear. Glossopharyngeal neuralgia is rare, occurring about 5% as often as trigeminal neuralgia. Pain is typically precipitated by swallowing, talking, or touching the tonsils or posterior pharynx. The attacks last only a few seconds but occasionally are prolonged for several minutes. The frequency of attacks varies from many times daily to once in several weeks. Long remissions are common. The diagnosis of glossopharyngeal neuralgia can be made from the description of the pain. The only differential diagnosis of any importance is neuralgia of the mandibular branch of the fifth nerve. This differentiation may be established by stimulation of the tonsils, posterior pharynx, or base of the tongue or when the pains are relieved by spraying the affected area with local anesthetic. When the membrane becomes anesthetized, the pains disappear and they cannot be pre cipitated by stimulation with an applicator. During this period, the patient can swallow food and talk without discomfort. The paroxysms occur at irregular intervals and there may be long remissions. During a remission the trigger zone disappears. The pains almost always recur unless they are prevented by medical therapy or the nerve is sectioned surgically. The disease does not shorten life, but affected patients may become emaciated because of the fear that each morsel of food will precipitate a pain paroxysm.