Meningitis is one of the leading postnatal causes of hearing loss. Hearing loss is the first thing that is ruled out in children having speech and language disabilities. The earlier you diagnose a hearing loss the better it is. Therefore, if a child is afflicted with meningitis, it is very crucial to get a hearing test done, because hearing loss can put even the brightest children a few rungs behind in their academic growth.
Here, we will try to understand how meningitis affects the hearing ability of a child as well as about the diagnostic tools and remedies.
What is Meningitis?
Meningitis is a condition involving infection and inflammation of the meninges. Meninges are the protective membranes which cover the brain and spinal cord.
There are various types of meningitis, but the most common is bacterial meningitis. Meningitis is an emergency and requires early medical attention.
Long-Term Side Effects of Meningitis
Various studies have documented a wide range of side effects of meningitis; however, the most common side effect of meningitis is hearing loss. The other side effects seen are:
- Coma
- Brain edema
- Vasculitis
- Hydrocephalus
- Seizures
- Difficulty in learning
Hearing Loss and Meningitis
Bacterial meningitis leaves behind residual hearing loss that can affect the hearing approximately by 30%. This hearing loss can happen both due to the direct effect of the infection on the brain as well as from the body's response to the disease. Meningitis caused by Streptococcus pneumoniae, Neisseria meningitidis, and Haemophilus influenzae are usually responsible for the development of sensorineural hearing loss. The major symptoms signaling the sensorineural hearing loss are headache, nausea, disorientation, or cranial nerve deficits.
The cochlea (the inner ear structure) is the most affected part in an individual with hearing loss. The meningitis-causing bacteria get into the cochlea through the perilymphatic duct and causes a condition called suppurative labyrinthitis (inflammation of the inner ear along with the formation of pus). This in turn, destroys the blood-labyrinth barrier and leads to damage of the Organ of Corti (known as the body's microphone). Organ of Corti contains numerous hair cells (which are the actual vibration receptors) that get damaged. This leads to the death of neurons in the spiral ganglion, which increases over time. If this happens within the cochlea or the neural pathway that leads to the auditory cortex, sensorineural hearing loss occurs.
Importance of Proper Diagnosis
One of the major factors that influence development of hearing loss is age, putting newborn babies at the highest risk. The child's social development and language skills get affected severely if they develop hearing loss at a tender age. Therefore, the importance of diagnosing hearing impairment as early as possible cannot be sufficiently stressed. The child must undergo hearing tests, as soon as he recovers from meningeal infection.
Diagnostic Procedures
The procedures involved in the diagnosis, apart from a detailed case history and physical examination, are:
- Cerebrospinal fluid (CSF) evaluation: This is carried out by lumbar puncture. Elevated protein levels and decreased glucose level in cerebrospinal fluid (CSF) indicates sensorineural hearing loss.
- Oto-Acoustic Emission (OAE) test: This is available in many countries and forms an important part of Newborn Hearing Screening Program (NHSP).
- Brainstem Auditory Evoked Response (BAER): Another diagnostic tool to detect hearing loss.
Treatment for Hearing Loss
Treatment consists mainly of appropriate antibiotic therapy and corticosteroids. Due to progressive hair cell loss and nerve cell destruction, cochlear implants don't give desired results in many cases. It depends on the extent of damage and the survival of the cochlear nerve. However, a recent study has shown the success of neurotrophic agents in preventing neuronal loss.
Recent Advances
The latest news in this field, which could help children with hearing loss, is a new technique called hair cell regeneration, in which damaged hair cells can be successfully replaced by the growth of new cochlear cells. This can be initiated through stem cell therapy.
Early detection is the key to help your child with hearing loss. In these times, when parents sacrifice so much for achievement of their child's academic brilliance, this is just a small step in the right direction.
