BOSTON – The number of cases of meningitis caused by tuberculosis has fallen dramatically in the United States in recent decades as TB itself has become less common, according to findings from a study presented at the annual meeting of the American Academy of Neurology.
However,from patient hospitalizations during 1993-2013 in the Nationwide Inpatient Sample database also indicate that neurologic complications from TB meningitis are on the rise.
The findings suggest that neurologists need to become involved whenever a patient with TB shows signs of neurologic problems, said study lead author, of Cornell University, New York, in an interview. “They’re at high risk, and some complications can be life threatening.”
According to Dr. Merkler, TB meningitis occurs when a patient’s case of TB invades the meninges surrounding the brain. “It can lead to seizures, stroke, hydrocephalus, and death,” he said at the meeting.
TB meningitis can affect anyone with TB, he said, but those who are immunocompromised and those with diabetes are especially vulnerable.
For their current study, Dr. Merkler and his associates used the Nationwide Inpatient Sample database to track patients hospitalized in the United States with TB meningitis from 1993 to 2013. They found 16,196 new cases over the 20-year period and uncovered a dramatic decrease in the rate of hospitalizations: The incidence fell from 6.2 to 1.9 hospitalizations per million people (rate difference, 4.3; 95% confidence interval, 2.1-6.5; P less than .001), and mortality during index hospitalization fell from 17.6% (95% CI, 12.0%-23.2%) to 7.6%, (95% CI, 2.2%-13.0%).
Dr. Merkler said that mortality appears to have declined as TB itself has become less common. According to the Centers for Disease Control and Prevention, the number of reported TB cases nationally was 9,557 in 2015, a rate of 3.0 cases per 100,000 persons. The total number of annual cases fell each year from 1993 to 2014,, although the rate leveled off at around 3.0/100,000 from 2013 to 2015.
“The fewer people have lung TB, the less they’ll have it going into meningitis and the brain,” Dr. Merkler said. “In terms of mortality, it is going down because we have better supportive care. We’re better at keeping these patients alive and giving them antibiotics sooner.”
However, the study found that the rates of the following complications in hospitalized TB meningitis patients rose over the 20-year period:
• Hydrocephalus, from 2.3% (95% confidence interval, 0.5%-4.2%) to 5.4% (95% CI, 2.3%-10.0%).
• Seizure, from 2.9% (95% CI, 0.3%-5.4%) to 14.1% (95% CI, 7.3%-21.0%).
• Stroke, from 2.9% (95% CI, 0.6%-5.3%) to 13.0% (95% CI, 6.3%-19.8%).
• Vision and hearing impairment, from 8.2% (95% CI, 4.8%-11.6%) to 10.9% (95% CI, 4.1%-17.6%), and from 1.1% (95% CI, 0.0%-2.3%) to 3.3% (95% CI, 0.0%-6.9%), respectively.
Dr. Merkler said it’s not clear why these rates are going up, but it may be because patients have more complications as a result of living longer. Another theory is that a form of drug-resistant TB is boosting the level of these complications, Dr. Merkler said, but he’s skeptical of that idea: “I don’t know why drug resistance would lead to more neurological complications.”
The study was funded by the National Institute of Neurological Disorders and Stroke and the Michael Goldberg Stroke Research Fund. Dr. Merkler reported no relevant financial disclosures.