A previously healthy 68-year-old male presents with progressive muscle weakness in his right hand, swallowing difficulty and difficulty with walking. He believes these symptoms occurred 'out of the blue' and have worsened over the last 2-3 months. His temperature is 98.6 deg F (37 deg C), blood pressure 145/86 mmHg, pulse is 80/min, and respirations are 17/min. Neurologic examination is significant for mild dysarthria. He has atrophy of the thenar muscles of the right hand and forearm, and 2/5 strength on wrist extension and flexion, as well as 3/5 power in intrinsic hand muscles on right. He has some fasciculations in his right thigh, and mild (4+/5) weakness of hip flexors bilaterally. Tone is increased in both legs. Sensory examination is intact. 3+ patellar reflexes are noted on the left lower extremity. On gait testing, the patient has poor balance, and spastic gait. Which of the following is the most likely diagnosis?

A previously healthy 68-year-old male presents with progressive muscle weakness in his right hand, swallowing difficulty and difficulty with walking. He believes these symptoms occurred 'out of the blue' and have worsened over the last 2-3 months. His temperature is 98.6 deg F (37 deg C), blood pressure 145/86 mmHg, pulse is 80/min, and respirations are 17/min. Neurologic examination is significant for mild dysarthria. He has atrophy of the thenar muscles of the right hand and forearm, and 2/5 strength on wrist extension and flexion, as well as 3/5 power in intrinsic hand muscles on right. He has some fasciculations in his right thigh, and mild (4+/5) weakness of hip flexors bilaterally. Tone is increased in both legs. Sensory examination is intact. 3+ patellar reflexes are noted on the left lower extremity. On gait testing, the patient has poor balance, and spastic gait. Which of the following is the most likely diagnosis?

A 42-year-old man presents with generalized tonic-clonic convulsions on day 2 of his hospitalization for the management of acute pancreatitis. Prior to the convulsive event, the patient felt anxious, tremulous, and agitated. Medical history is significant for alcohol-use disorder, with multiple hospitalizations for alcohol intoxication and acute pancreatitis. On physical examination, the patient is diaphoretic and convulsing. There is no evidence of stigmata of liver disease. The patient does not appear malnourished. Appropriate laboratory tests are obtained. Which of the following is the best initial treatment?

An 8-year-old boy presents to the Emergency Department with altered mental status and weakness. The mother reports that her son had a fever and complained of a headache two days prior to presentation, along with upper extremity weakness. Earlier in the day, his headache worsened, he had vomiting, and appeared confused. The mother states that approximately one week ago, he had a viral illness but appeared to have fully recovered. Beyond this, he is neurologically normal at baseline. While performing the physical exam, he has a generalized tonic-clonic seizure, requiring benzodiazepine administration. Vital signs show that he is afebrile with a normal blood pressure. On physical exam, the patient has mild nuchal rigidity, a right relative afferent pupillary defect, right and left-sided weakness, and a bilateral Babinski reflex. Magnetic resonance imaging (MRI) showed diffuse white matter lesions. Which of the following is most likely the diagnosis?

The Central Nervous System is made up of the:

Which of the following statements about resting potential is true?