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Early bilateral cochlear implantation may treat postmeningitic deafness
Young NM. Arch Otolaryngol Head Neck Surg. 2010;136:993-998.
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Early simultaneous bilateral cochlear implantation may increase the chances of successful implantation and improve the ability to achieve binaural hearing in children with postmeningitic deafness, according to recent study data.
Because the introduction of the 7-valent pneumococcal conjugate vaccine (Prevnar, Wyeth) led to a significant decline in invasive pneumococcal disease, including meningitis, physicians now have less experience treating children with postmeningitic deafness.
“However, pneumococcal meningitis continues to occur, even in healthy children who receive the recommended PCV7 vaccination series in early childhood,” wrote Nancy M. Young, MD, and Tina Q. Tan, MD, of Children’s Memorial Hospital and Feinberg School of Medicine at Northwestern University in Chicago. “For this reason, it is important for cochlear implant programs to remain prepared to proceed with expeditious implantation in children recently deafened by meningitis.”
The researchers examined five vaccinated children aged 15 months to 10 years who developed deafness after pneumococcal meningitis infection and underwent cochlear implantation between 2005 and 2007 at Children’s Memorial Hospital. Vaccination status and results of auditory brain stem response (ABR), application of auditory steady-state response (ASSR) testing and 3-D steady-state free precision (SSFP) magnetic resonance imaging were included in the analysis.
Four children received pneumococcal meningitis diagnoses between ages 15 and 32 months. All were healthy, had no history of hearing loss or risk factors for pneumococcal disease. All children had also received the primary PCV7 vaccination series. The remaining child, dubbed patient 3, was aged 10 years and had pneumococcal meningitis 6 years earlier. The disease resolved without complications, but reinfection occurred despite preventive measures.
ABR/ASSR results indicated profound deafness in the four younger children between 4 and 28 days after diagnosis. Standard behavioral audiologic testing performed on the fourth day of hospitalization confirmed the condition in the older patient.
3-D SSFP MRI denoted considerably diminished T2 signal intensity within turns of the cochlea in patients 1 and 3 bilaterally and in the left ear of patient 5, according to the researchers, with surgical findings in the scala tympani revealing significant soft tissue. Only patient 1, however, had complete obstruction.
3-D SSFP MRI results were consistent with patent cochlea, the researchers wrote, with surgery indicating soft-tissue obstruction and ossification of the round window membrane and circumferential ossification narrowing of the scala tympani in one ear.
The average time between imaging and implantation was 9.8 days. “The use of ASSR testing and 3-D SSFP MRI enabled these five children to undergo expedited evaluation for [cochlear implantation] candidacy,” the researchers wrote.
They also said simultaneous bilateral implantation, which was achieved in all patients, may serve to capture the better ear when no difference between the two ears is apparent preoperatively. Additionally, the procedure precludes further development of ossification that could prevent electrode insertion and thereby raise a child’s chances of achieving binaural hearing.
There are two important messages in this publication. The first is that, despite routine use of PCV7 vaccine in this country, there are still cases of pneumococcal meningitis and some result in severe nerve deafness. The second is the importance of rapid and aggressive workup of patients with penumococcal meningitis and nerve deafness so that bilateral cochlear implantation can be performed before cochlear calcification results in a less successful surgical result. It has been known that one of the most frequent adverse outcomes of bacterial meningitis, especially pneumococcal meningitis is hearing loss, that may be mild, moderate or severe and bilateral. Since the introduction of PCV7, pneumococcal meningitis and its sequelae have been dramatically reduced. As is demonstrated by the five patients discussed in this publication, cases may occur due to pneumococcal infection with non-vaccine serotypes or may be due to vaccine failure. Introduction of PCV13 should result in reduction of the number in the former group.
– Robert Baltimore, MD
Infectious Diseases in Children Editorial Board
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