11. A 35-year-old HIV-positive man consults because of incre…

11. A 35-year-old HIV-positive man consults because of increasing difficulty walking over the last 6 months.  He reports slowly increasing stiffness in his lower extremities that slowly became worse.  He also noticed increasing urinary frequency and urgency over the last 6 months.  On neurological examination, the patient displays mild paraparesis of lower extremities with spasticity and risk reflexes in the left knee and ankle, and bilateral Babinski sign.  Sensory examination showed moderate loss of proprioception and vibration and normal sensation to pain.  No sensory level.  Cerebrospinal fluid analysis shows a protein level of 63 mg/dl, 5 WBC/mm3, 100% lymphocytes, and glucose 50 mg/dl.  CSF viral and bacteriologic studies are normal.  Vitamin B12 level is normal.  MRI of the cervical, thoracic, and lumbar spine with gadolinium enhancement is normal.  Somatosensory-evoked potentials show a prolongation of the central conduction time.  The most likely diagnosis is

13. A 69-year-old woman complains of new-onset headaches.  S…

13. A 69-year-old woman complains of new-onset headaches.  She also describes pain in her jaw when chewing food. Three days before coming for medical help, she lost vision in her left eye.  She comes for evaluation on a Friday afternoon.  The neuro-ophthalmologic examination documents visual acuity of 20/30 in both eyes, with normal color vision and ocular motility in both eyes.  Visual field testing shows an inferior altitudinal defect in the left eye.  Funduscopic examination of the left eye discloses a pallid chalky-white optic disc on the superior margin of the optic nerve, and the optic nerve of the right eye appears normal, with a normal cup-to-disc ratio.  The rest of the neuro-ophthalmologic examination is normal.  Which of the following is the most appropriate management for this patient?

9. A 25-year-old woman is brought to the ER by ambulance aft…

9. A 25-year-old woman is brought to the ER by ambulance after a generalized tonic-clonic seizure at home. She has had headache, neck stiffness and fever for the past several days and has been somewhat confused and not acting like herself. The patient stops seizing with institution of anticonvulsant therapy. A lumbar puncture is performed. The cerebrospinal fluid (CSF) reveals 10 WBCs (normal 0-4) with a lymphocytic predominance, 76 red blood cells (normal 0), a protein level of 63 mg/dL (normal 15-45), and a normal glucose level. The opening pressure was slightly elevated. An electroencephalogram (EEG) shows sharp wave discharges in the temporal lobes. These findings are most likely to result from infection by what organism?