Dec 2019 The Hearing Journal
“A wife who loses a husband is called a widow.
A husband who loses a wife is called a widower.
A child who loses his parents is called an orphan.
There is no word for a parent who loses a child.
That's how awful the loss is.”
– Jay Neugeboren, An Orphan's Tale (1976)
For Kristen Spytek and her husband, John, losing their 21-month-old daughter Evelyn Grace from complications of congenital cytomegalovirus (CMV) was a call to action.
The bereaved but determined couple formed the National CMV Foundation in July 2014, with Kristen serving as the president and CEO, to raise awareness of the common virus that causes complications in pregnant women and others with compromised immune systems. In January 2016, their organisation joined forces with three other regional nonprofits, all founded by families of patients—-Maddie's Mission, Stop CMV, and Utah CMV Council—in an effort to combine strengths and increase their impact in eliminating congenital CMV in the United States for the next generation. “We have initiated new programs to fund research, mobilise volunteers, and conduct community outreach efforts,” said Spytek. “Our success to date has largely been driven by our motivated board of directors, esteemed scientific advisory committee, and extremely passionate parents. Storytelling is key.”
The harsh reality is that nine out of 10 pregnant women are not aware of CMV—the litany of complications includes hearing loss (5 to 20% according to the Official Journal of the American Academy of Paediatrics)—yet it is considered to be the most common neonatal cause of permanent disability (one in five) in the United States. And those sobering statistics are actually a significant improvement in what is a curious uphill battle. Shannon Ross, MD, MSPH, an associate professor of pediatrics and microbiology, said it goes beyond the general public since paediatricians, ENTs, family practitioners, OB/GYN doctors, etc., should all be more generally aware of CMV. “Public health and provider awareness are some of the biggest challenges to more widespread congenital CMV screening,” explained Ross, whose area of expertise is paediatric infectious diseases. “Even though the disease burden due to congenital CMV is significant and higher than many other well-known diseases in newborns, the awareness of congenital CMV is the lowest.”
Spytek acknowledged that CMV does not receive the same type of prenatal counseling as the likes of toxoplasmosis, listeria, alcohol use, and Zika. Their organisation recently launched a new public health campaign called “CMVIRUS: Spread the Word, Not the Virus” to combat what she confirmed is “alarmingly low” national awareness (federal funding, focus on a vaccine, and media coverage). “We felt it was our responsibility to initiate a campaign that may shock and awe the general public,” she said. “The images are visually compelling—the virus is vividly personified, and transmission is demonstrated through saliva, tears, and urine, in this case, from a toddler to a pregnant woman.”
Karen Fowler, PhD, a professor of infectious diseases at the University of Alabama-Birmingham School of Medicine, sees an uphill climb, and praises the work of the Spyteks and others in the quest for more positive outcomes. “Many health care providers are aware of CMV, but it is not an infection that they focus on with their patients,” she said, echoing the sentiment that lack of awareness remains the biggest obstacle. “There is a need for more CMV advocacy, and parents in the United States, such as the National CMV Foundation, and similar organisations in the world have taken up this advocacy. Parents are the best advocates, and they have driven much of the public health awareness and legislation that have happened in the country. It is time for the medical community to catch up and also advocate for education and prevention of congenital CMV infection.”
“The mechanisms of CMV-induced hearing loss remain unclear,” noted Fowler. “Recent animal models have suggested that potential mechanisms are virus-induced cochlear inflammation rather than direct virus-mediated damage. These animal studies have also demonstrated that even with altered auditory function, there is no significant loss of hair cells. These models fit with what is seen in children with CMV-related hearing loss who may have fluctuating losses. However, other children with CMV-related hearing loss may have complete losses of hearing function that would suggest that CMV can permanently affect the cochlear hair cells.”
Ross explained that the presence of viral antigens or inclusions in the cochlea and/or vestibular apparatus of human temporal bones suggest that CMV can readily infect both the epithelium and neural cells in the inner ear and that hearing loss can occur as a result of direct virus-mediated damage to the neural tissue. She pointed to studies on guinea pigs that may provide some information on the possible mechanisms of CMV-related hearing loss. “Foetal infection with guinea pig CMV occurs in offspring of dams infected in the first or second or trimester of pregnancy, and hearing abnormalities occur in some pups. CMV antigens were demonstrated in spiral ganglion cells and cochlear modiolar vein endothelial cells. In addition, inflammatory infiltrates were present in the perilymphatic scalae in a small number of animals. One guinea pig study suggested the importance of inflammation in pathogenesis and demonstrated that virus infection in immunocompromised animals was not associated with the typical pathologic findings of virus infection in normal animals,” Ross added. “Other studies using antiviral compounds to limit viral replication resulted in no inner ear pathology. Together, these studies suggest that both viral replication and the host immune response contribute to the pathogenesis of CMV-related SNHL.”
As for hearing loss, a lack of state-to-state testing makes it difficult to nail down the exact impact on newborns born with CMV. “There are no limits to the current newborn testing methods, but there are challenges,” said Fowler, who stressed the need for testing before three weeks of age.
Angela Shoup, PhD, also pointed to some inherent challenges in testing, the gold standard of which is identifying CMV through a urine or saliva sample within three weeks of birth. “If CMV is detected in a urine or saliva sample obtained after three weeks, it is not possible to determine whether the CMV was congenital or acquired,” said Shoup, the director of the Division of Communicative and Vestibular Disorders at UT Southwestern Medical Centre in Dallas, TX. “This distinction is important, as CMV acquired after birth is not associated with hearing loss or other deleterious sequelae found with congenital CMV.”
Dried blood spot (DBS) screening has been considered for widespread CMV screening, but Fowler noted that this methodology is not sensitive enough to detect most or all CMV infections in newborns. “If the DBS is positive for CMV, it confirms CMV infection, but if it is not positive, you cannot be sure that CMV is not present in the tested infant,” she said. “Ongoing studies are working on improving this methodology, but currently, CMV screening by DBS will miss many infants with CMV infection. Another challenge to DBS is that many CMV-infected infants may not have detectable virus in their blood at delivery, unlike the large quantity of virus that is found in the saliva and urine of CMV-positive infants.”
Fowler explained that the Joint Committee on Infant Hearing recommends CMV testing as part of the medical screening to evaluate the etiology of hearing loss. However, she stressed that waiting until hearing loss is confirmed in an infant (after three weeks) may be too late to determine whether CMV is the etiology of the infant's hearing loss. Because the age of an infant at hearing loss diagnosis may be too late for CMV confirmation, experts have been considering CMV testing for infants who fail the newborn hearing screening for either ear. “Individual hospitals and some states have adopted this targeted CMV screening approach in recent years,” said Fowler.
Shoup added that while some studies have indicated possible improvement in the hearing outcomes of symptomatic infants treated with antivirals, potential risks of treatment have limited their use in infants with just hearing loss and no other clinical signs or symptoms. “Further research is needed to evaluate the risk-benefit of antiviral treatment in infants with congenital CMV that exhibit hearing loss only,” said Shoup, who added that Albert Park, MD, the chief of paediatric otolaryngology at the University of Utah is leading a study focused on this issue.
An overarching issue is also one of treatment. “Infants should be screened for congenital CMV in infancy, and those infants with moderate to severe disease should receive antiviral treatment,” said Fowler. “These infants, along with infants with isolated sensorineural hearing loss and infants without any symptoms or hearing loss, should also receive early intervention services and have diagnostic audiologic evaluations to assess for possible hearing loss.”
Infants with moderate to severe symptoms receive antiviral treatment, but that's not routinely recommended for asymptomatic infants with isolated sensorineural hearing loss, according to Fowler. “A clinical trial is underway to assess treatment in these infants,” she said, adding that the study completion date is not until the summer of 2024, while another clinical trial for treatment of asymptomatic infants with normal hearing is due by the end of the same year.
While audiologists alone cannot win the war against CMV, they can—as a community—become a formidable platoon. “Infants with asymptomatic or mild symptomatic congenital CMV infection will not be identified in the newborn nursery unless they undergo screening,” stressed Ross. “The only way to identify all infants at risk for hearing loss due to congenital CMV infection is to test for CMV in the newborn period.”
Fowler pointed to the need for diagnostic audiology evaluations every six months until 3 years of age and annually after that to identify progressive or late-onset hearing loss. She noted that if the hearing status has changed, the child should be evaluated every three months until the hearing loss stabilises. Additionally, she advised that children with defined hearing loss be closely monitored through adolescence for potential progression, and children with identified hearing loss be referred to early intervention programs.
Shoup cautioned that while universal screening is still not common and remains under debate, she sees some positive signs. “Some states are increasingly implementing hearing-targeted CMV (HT-CMV) screening,” she said, pointing to the European Consensus Statement on Diagnosis and Management of Congenital Cytomegalovirus that supports testing for CMV “based on the presence of one or more of the most frequently observed clinical features,” including sensorineural hearing loss. Shoup was among those who implemented screening in 1999 at Parkland Hospital in Dallas, and has monitored it closely ever since, publishing the results in 2017. “This allows us to identify those infants with hearing loss due to congenital CMV and to inform treatment plans,” she said. “However, with HT-CMV, we are aware that asymptomatic infants with CMV at risk for developing delayed onset hearing loss may be missed. Research has indicated that although many infants with CMV and sensorineural hearing loss will be identified with HT-CMV screening, an estimated 43 percent who may have delayed onset of hearing loss in the early infant period will not be identified.”
According to the CDC, those born with CMV-related hearing loss are at risk for it to progress from mild to severe during the first two years of life, a critical time for language and learning. This considered, technology is encouraged to help mitigate the loss of vital communication of social skills. Ross, Fowler, and Shoup agree on the significant roles of hearing aids and cochlear implants in treating CMV-related hearing loss. “Like other forms of sensorineural hearing loss, hearing aids and cochlear implants are important treatment modalities for children with hearing loss due to CMV,” said Ross. Added Fowler: “Both hearing aids and cochlear implants are used to treat CMV-related hearing loss. Many children may start with hearing aids, but due to the progression of their hearing loss, later qualify for cochlear implants.”
Although CMV likely produces neural damage, the degree of the damage may not be sufficient to affect cochlear implant performance in the CMV patients. Shoup added that hearing aid and/or cochlear implants should be offered as soon as possible after confirmation of hearing status.
“In addition, early intervention services and family support should be available and accessible to the family,” said Shoup. “Once any infant or child is identified with hearing difficulties or receives amplification or cochlear implant services, ongoing monitoring of hearing status and development is necessary.”
This is another area where audiologists must remain vigilant, according to Shoup, who pointed to the increased probability of progression of hearing loss in infants and children with CMV. “If the infant or child is initially fit with hearing aids, close surveillance should be implemented to adjust the devices as needed if hearing status changes. Furthermore, the audiologist should be alert to make timely referral for cochlear implantation should progression of hearing difficulty render traditional amplification of limited or no benefit.”