Nearly one third of adults in a Swedish cohort who contracted bacterial meningitis as children have permanent neurologic disabilities as a result, a new JAMA Network Open study suggests.
Led by scientists from Merck and the Karolinska Institutet in Stockholm, the analysis of nationwide registry data included 3,623 adults who had bacterial meningitis before they were 18 years old from 1987 to 2021 and 32,607 matched uninfected controls. The median age at meningitis diagnosis was 1.5 years, 44.2% were women, and 55.8% were men; median follow-up was 23.7 years.
The study authors noted that bacterial meningitis, inflammation of the membranes covering the brain and spinal cord, is a rare but life-threatening infection most common among children and older adults.
Often caused by Streptococcus pneumoniae, bacterial meningitis can be cured with antibiotics. But because antibiotics may need a few days to cross the blood-brain barrier, by the time they reach the brain, neurons can already have been damaged. "Further, there is the constant threat of antibiotic-resistance to face in the clinics," they wrote.
26% higher risk of structural head injuries
Participants who had bacterial meningitis as children had a higher rate of all seven studied neurologic disabilities, and nearly one-third (29.0%) had at least one such disability, compared with one-tenth of controls. The highest absolute risk of disabilities was for behavioral and emotional disorders, hearing loss, and impaired vision.
The greatest adjusted hazard ratios [aHRs] were for structural head injuries (aHR, 26.0), hearing loss (aHR, 7.90), and motor function disorders (aHR, 4.65). The aHRs for cognitive disabilities, seizures, hearing loss, and motor function disorders were significantly higher for people infected with S pneumoniae (eg, aHR, 7.89 for seizures), compared with Haemophilus influenzae (aHR, 2.46) and Neisseria meningitidis (aHR, 1.38).
The aHRs for cognitive disabilities, seizures, behavioral and emotional disorders, and intracranial structural injuries were significantly higher for children who developed bacterial meningitis at a younger age. For example, the aHR for seizures was 5.43 for those diagnosed when they were younger than the median age, compared with 2.87 for those diagnosed when older.
"Our interpretation is that the damage to the brain and nervous system that can follow an episode of bacterial meningitis is more detrimental for young children who are at a sensitive stage in their physical and mental development," the researchers wrote.
Importance of pneumococcal vaccine, clinical vigilance
The relative risk of disabilities was highest in the first 3 years after diagnosis but remained elevated at 5 years postdiagnosis. "The young age at diagnosis in this study (median, 1.5 years) imposes clinical difficulties on detection of disabilities after an episode of bacterial meningitis, which could explain why there was no significantly elevated risk of behavioral and emotional disorders during the first 1 to 3 years of follow-up (these disabilities are difficult to detect at an early age)," the authors wrote.
These are lifelong disabilities that become a major burden for both the individual and society, as those affected need health care support for the rest of their lives.
The study results, they added, underscore the need to educate parents on the benefits of pneumococcal vaccination and to promote the importance of clinical vigilance in detecting disabilities—particularly behavioral and emotional disorders, hearing loss, and visual problems—among pediatric bacterial meningitis survivors.
In a Karolinska Institutet press release, coauthor Federico Iovino, PhD, of the institute's neuroscience department, said childhood illness affects the entire family. "If a three-year-old child has impaired cognition, a motor disability, impaired or lost vision or hearing, it has a major impact," he said. "These are lifelong disabilities that become a major burden for both the individual and society, as those affected need health care support for the rest of their lives."
Iovino added that he and his colleagues are researching how to protect neurons during the time it takes for antibiotics to cross the blood-brain barrier. "We now have very promising data from human neurons and are just entering a preclinical phase with animal models," he said. "Eventually, we hope to present this in the clinic within the next few years."
