Tuberculous Meningoencephalitis!

This week, we heard about a fascinating case of tuberculous meningoencephalitis from Dr. Bruce Kaufmann.

On presentation, his patient described a subacute, progressive headache, with nonfocal neurologic changes, and neck stiffness which was immediately concerning for a CNS infectious process. She underwent urgent workup including imaging and a lumbar puncture, and was started on empiric antibiotics.

We reviewed our classic lumbar puncture workup to differentiate between bacterial, viral, and fungal/TB etiologies:

This chart can be a little overwhelming sometimes, especially when comparing bacterial and fungal/TB etiologies. In general, the major differences are the presence of lymphocytes (vs. neutrophils) and the less dramatic elevation of protein and less dramatic drop in glucose. I like to think of the bacterial organisms as consuming glucose and generating protein waste product. Finally, extremely high protein levels are also consistent with meningeal carcinomatosis!

In the case of Bruce’s patient, nucleic acid testing sent from the initial lumbar puncture quickly returned consistent with tuberculosis! She was started on appropriate antibiotics, and follow up imaging demonstrated persisting multifocal tuberculomas, however, and a prolonged course of antibiotics has been initiated.

Meningeal Tuberculosis is a rare phenomenon in the United States, with recent data suggesting only 100 cases in the US yearly. It comprises 1% of total TB cases, and 5-15% of extrapulmonary TB. What was puzzling in this case was the apparent lack of risk factors (known immunosuppression, exposure history) in an otherwise healthy, young woman who had emigrated from Vietnam several decades prior to presentation. Bruce’s learning point focused on high-quality evidence supporting a short-term mortality benefit of adjunctive corticosteroids in addition to appropriate antibiotics.