What Is Microtia?

Introduction

Facial features can supposedly reveal a lot about a person's character in astrology. For example, in astrology, the size of one's ears, whether big or small, is thought to hold significant insights into an individual's behaviour and nature. An Indian astrologer once emphasised that people with small ears tend to be fickle-minded, yet they often possess considerable wealth. On the other hand, another astrologer suggested that very small ears indicate a person's ability to persevere through challenges and get the job done, no matter how difficult it may be. 

Now, if we consider these astrological beliefs, it raises an interesting question: What does medical science have to say about the significance of small ears? Could having small ears be considered a blessing, especially if they are linked to wealth, but perhaps also associated with lower self-esteem affecting a person's psyche?

Microtia is a deformity of the outer ear or ear present at birth. The outer ear could be small, partially formed (underdeveloped) or totally absent. The word microtia comes from two Latin words, micro meaning small and otia, ears. Microtia loosely means small or little ear. It is a medical condition where the outer ear or pinna fails to fully develop during the first trimester of pregnancy, resulting in peanut-sized ears. 

Microtia can also present with narrowing of the ear canal or the absence of external acoustic meatus. The appearance of microtia ears varies in size but are usually smaller than normal ears. In over 87% of microtia cases, only one ear is deformed (unilateral), with the right ear being more affected than the left and those assigned female at birth (AFAB) being less affected. In cases involving the narrowing of the ear canal, hearing loss can result.

Types of microtia

Microtia presents with different grades and severity, ranging from mild with fewer complications to severe with serious complications.

1. Grade I: the external ear appears to be small but normal, with a narrow or missing ear canal. There may be alterations in the size and shape of the ear.
2. Grade II: some parts of the ear are missing. The upper two-thirds of the ear may be absent or malformed, while the lower third remains intact or normal. The ear canal could be narrow or absent in grade II type.
3. Grade III: the ear canal is usually blocked, and the external ear is largely reduced to a pea-sized earlobe remnant. It is the most common type of microtia.
4. Grade IV: this is the rarest form where the external ear is completely absent. It is also referred to as anotia.¹

Causes of Microtia

The exact cause of microtia is unknown, but microtia has been linked to genetic and environmental factors. In some cases, microtia has been associated with syndromes which result from genetic mutations. On the other hand, in the absence of syndromes, microtia could result from the exposure of the mother to alcohol and teratogens (drugs that cause malformation of a child’s body structures during pregnancy) like thalidomide, methamphetamine, and retinoids during the first trimester of pregnancy.¹

Symptoms of microtia

Symptoms of microtia include:

1. Abnormally formed ear(s): the most apparent symptom of microtia is the malformed appearance of the external ear.
2. Absence of external ear: in some cases, the external ear is absent.
3. Asymmetry: there may be a significant difference between the two ears, resulting in facial asymmetry.
4. Functional Challenges: owing to the severity of the condition and associated hearing loss, individuals with microtia might experience challenges with the localization of sound, understanding speech in noisy environments, and participating in social interactions.
5. Hearing loss: the presence of a malformation or the absence of the external ear can independently lead to conductive hearing loss. 

Additionally, microtia is associated with aural atresia, a condition characterised by the incomplete development of the middle ear and external auditory canal. Microtia is predominantly associated with conductive hearing loss – the inability of the outer ear to effectively transmit sounds to the inner ear as malformed ears can’t conduct sound adequately. 

Microtia significantly impacts patients’ appearance and self-esteem; therefore, it must be looked out for and rightly managed.

Diagnosis of microtia

Microtia is sometimes associated with hemifacial microsomia (a condition where half of the face does not grow in proportion with the other half), Treacher-Collins syndrome, and Melnick-Fraser syndrome. Since microtia is a congenital deformity, it is visible at birth as the physician carries out a physical examination of the newborn. Further tests are carried out to examine the severity of the deformity.¹

Clinical examination

Clinical examination of microtia involves a comprehensive assessment of the affected ear and surrounding structures. Clinical examination may be performed in the following steps:

• Observation: the physician, often an otorhinolaryngologist (doctor of the ear, nose and throat, also known as an ENT specialist) begins by observing the patient's ears and surrounding structures for any noticeable differences. They pay attention to the shape, size, appearance, position, and symmetry of the ears.
• Auricle Examination: they examine the details of the affected auricle (external ear), including the helix, antihelix, tragus, antitragus, and earlobe. They mentally or physically document any deformities, asymmetry, or absence of these structures as observed.
• Canal Examination: they assess the ear canal for any narrowing or absence that may be associated with microtia, as this could impact hearing function and effectual transmission of sound.
• Facial Nerve: they evaluate the facial nerve to ensure that its function is not compromised because facial nerve aberration is associated with the malformation of the middle ear, which is characteristic of microtia.
• Associated Anomalies: microtia can sometimes be associated with other congenital anomalies, such as craniofacial abnormalities or renal problems. Therefore, the physician conducts a thorough examination to identify any associated conditions.
• Hearing Assessment: physicians often recommend various hearing assessment tests like ABRE (Auditory Brainstem Response Evaluation) after birth to examine inner ear function.

An Auditory Brainstem Response (ABR) test is a diagnostic procedure used to assess the efficiency of sound transmission through the auditory nerve pathways from the ear to the brainstem. This test measures the brain's electrical responses to auditory stimuli, providing valuable information about a person's hearing function and potential issues in the neural pathways.

• Imaging: imaging techniques like computerised tomography (CT) scans or magnetic resonance imaging (MRI) may be performed to assess the internal structures of the ear, including the middle and inner ear, to identify any potential anomalies that might impact hearing and treatment planning.
• Treatment Planning: Based on the examination findings, the physician discusses treatment options with the patient and their family. Treatment options for microtia may include surgical reconstruction, prosthetic solutions, or a combination of both.
• Counselling: The physician provides information and counselling to the patient and their family about the condition, treatment options, potential outcomes, and realistic expectations.³

Clinical examination may vary depending on the physician’s experience and the resources available in the medical setting. A multidisciplinary approach involving otolaryngologists (ear, nose, and throat specialists), plastic surgeons, audiologists, and other specialists may be required for a comprehensive assessment and management of microtia.

Treatment options

Treatment options for microtia include reconstruction surgery and the use of hearing aids or implants (prosthetics).

There are two major reconstruction options depending on the patient’s age:

1. The rib cartilage or rib graft technique uses cartilage from the patient's chest region to reconstruct the external ear. This is usually done on patients above 8 years of age to avoid the risk of chest deformity.
2. Medpor graft surgical reconstruction is the second technique, which can be done on patients as young as 3 years of age. This technique employs the use of a synthetic porous polyethene framework covered by tissues harvested from the patient’s temporalis muscle (a muscle of the head that can be felt on the temple when the jaws are clenched).^1,2

The use of prosthetics is also an option when other techniques fail or are not suitable for the patient.  

Summary

In conclusion, microtia is a congenital deformity of the outer ear present at birth, varying in severity from mild to severe. Classified into different grades, the condition results in underdeveloped or absent external ears, often leading to functional and aesthetic challenges. Its causes are linked to genetic and environmental factors, with the first trimester of pregnancy being crucial. Clinical examination, conducted by specialists, involves observation, auricle and canal assessment, facial nerve evaluation, associated anomaly identification, hearing assessment, and imaging. Treatment options include reconstructive surgery and prosthetics. Challenges encompass long-term care, potential complications, and psychological impacts. Living with microtia can involve choosing surgery or not, with support groups aiding acceptance and confidence-building.

FAQs

Can microtia be completely corrected with surgery?

While reconstructive surgery can significantly improve the appearance of the ear and may enhance hearing in some cases, complete restoration of the ear to a fully normal appearance and function may not always be possible.

Can microtia be detected during pregnancy through prenatal screening?

Microtia is not detected through routine prenatal screening tests like ultrasound. It is only diagnosed after birth as the physician physically examines the baby’s ears.

Is microtia hereditary?

While there can be a genetic component to microtia, it is not always hereditary. Some cases may be linked to genetic mutations, but environmental factors during pregnancy can cause it.