In about 25% of cases of hearing loss there is a non-genetic cause that can be identified. Non-genetic hearing loss is most often caused by illness or trauma before birth or during the birth process but can also develop in older infants and children.
Risk Factors for Non-Genetic Hearing Loss
Non-genetic hearing loss can result from a wide variety of illnesses and problems. Medical professionals depend on a careful review of birth information to help them identify non-genetic hearing loss. Read more about each risk factor below.
- Maternal Infections
- Neonatal Intensive Care Unit (NICU) Stays
- Low APGAR Scores
- Prolonged Mechanical Ventilation
- Low Birth Weight
- Ototoxic Medications
- Bacterial or Viral Meningitis
- Hyperbilirubinemia (Jaundice)
- Head Trauma
Maternal Infections
Some viral infections are known to be associated with hearing loss. The highest risk of hearing loss is present if the mother has the illness during pregnancy or passes the infection to her baby during birth. The amount of hearing loss that can result varies widely and some babies show no hearing loss at all, even if they have one of these infections. These infections can affect other systems in the body as well and medical professionals will need extensive birth history and test information to identify these infections as a cause for hearing loss.
The primary infections are
- Cytomegalovirus (also known as CMV)
- Toxoplasmosis (Cat-scratch disease)
- Syphilis
- Rubella (German Measles)
- Herpes simplex virus
NICU (Neonatal Intensive Care Unit) Stays
Newborns who spend time in the NICU after birth are often at higher risk of developing hearing loss. Risk factors for hearing loss that are often associated with NICU stays include low APGAR scores, prolonged mechanical ventilation, low birth weight, and ototoxic medications.
Low APGAR Scores
All babies are evaluated at birth on a 10-point scale, called an APGAR score. Newborns are given APGAR scores at 1 minute and 5 minutes after birth. The higher the score, the healthier the baby is. When babies have scores of 0-4 at one minute or 0-6 at five minutes, their risk for having hearing loss increases.
- A: Activity (muscle tone)
- P: Pulse
- G: Grimace (reflex irritability)
- A: Appearance (skin color)
- R: Respiration
Prolonged Mechanical Ventilation
Prolonged (5 or more days) mechanical ventilation due to persistent pulmonary hypertension in a newborn has been associated with hearing loss. The presence of this condition at birth indicates the need to monitor hearing closely after discharge from the hospital.
Low Birth Weight
Newborn specialists identify 1500 grams (approx. 3.3 lbs.) as a cut-off point. Children who weigh less than 1500 grams at birth have an increased risk of hearing loss.
Ototoxic Medications
Medications that are known to be ototoxic (damaging to hearing) are sometimes prescribed to babies to treat serious infections or birth complications. The most common ototoxic medications are a family of antibiotics called aminoglycosides, with names such as gentamycin, tobramycin, kanamycin, and streptomycin.
Hearing loss resulting from the use of these antibiotics may also have a genetic component. Ototoxic medications present more of a risk to hearing when they are used multiple times or in combination with other medications, such as diuretics. Although cancer in infants and young children is rare, there are some chemotherapy drugs that are used which are also ototoxic, especially when used to treat tumors that are in the skull.
Bacterial or Viral Meningitis
One illness that carries a high risk of causing hearing loss and/or balance problems is bacterial or viral meningitis. Because of improvements in immunizations, cases of bacterial meningitis have declined sharply in recent years, but immunizations are not available for the viral type of this infection. Because meningitis is an infection of the lining of the brain and spinal cord, the sense organs of hearing and balance are especially sensitive to this infection.
Hyperbilirubinemia (Jaundice)
Jaundice that is severe enough to require a blood transfusion can also result in hearing loss. This is related to the potential damage that high levels of bilirubin can cause to the nerves of hearing.
Head Trauma
Hearing loss is sometimes reported after accidents resulting in trauma to a child’s head. This hearing loss might be permanent, but often is mild and many children recover.
