<s>[INST] context: This patient has tabes dorsalis, which is a form of neurosyphilis where the spirochete attacks the posterior columns and the dorsal roots of the spinal cord. This attack produces: 1. Impaired joint position sense (proprioception), leading to a broad-based ataxia and a positive Roan berg test 2. Loss of pain and vibration sensation 3. Joint damage (Charcot joints) caused by loss of pain sensation 4. Sensory disturbances manifesting as 'lightening pains' 5. Absent deep tendon reflexes 6. An Argyll Robeson pupil Demyelinization first begins in the middle poion of the dorsal root zone close to the posterior horns and then extends into the dorsal columns. Laboratory findings in the spinal fluid include a positive VDRL (2550%), a positive FTA-ABS (80-95%), a mild pleocytosis consisting of lymphocytes and mononuclear cells (not neutrophils), an increased protein with oligoclonal bands on high-resolution electrophoresis, and a normal glucose. An elevated protein and cell count is an indicator of disease activity. The treatment is aqueous penicillin G, 12 million to 24 million units daily given intravenously for 10-14 days. The history is not compatible with cryptococcosis (encapsulated yeast cells), Toxoplasmosis, or leptomeningeal spread of malignant cells. [/INST] question: A 65-yrs-old man has broad-based ataxia, loss of pain, and temperature sensation in the lower extremities with lightening pains. His pupils accommodate but do not constrict with direct light stimulation. The spinal fluid would be expected to exhibit. | options: A: Encapsulated yeast cells B: A neutrophil-dominant cell count C: A positive VDRL D: Toxoplasma cysts | answer: C </s>