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{{Infobox medical condition (new)
{{Infobox medical condition (new)
| name           = Michel aplasia
| name = Michel aplasia
| synonyms       =  
| synonyms = Complete labyrinthine aplasia, CLA
| image           = Cochlear aplasia with dysplastic vestibule.jpg
| image = Cochlear aplasia with dysplastic vestibule.jpg
| alt             =  
| alt = CT scan showing Michel's Aplasia
| caption         = This is a CT Scan showing Michel's Aplasia
| caption = CT scan showing Michel's Aplasia
| pronounce       =  
| pronounce =
| field           =  
| field = [[Otorhinolaryngology]], [[Medical genetics]]
| symptoms       =  
| symptoms = Profound congenital sensorineural deafness, balance impairment, microtia, microdontia
| complications   =  
| complications = Delayed development, risk of trauma and accidents
| onset           =  
| onset = At birth, or detectable within early childhood
| duration       =  
| duration = Lifelong
| types           =  
| types =
| causes         =  
| causes = Mutations in the [[FGF3]] gene, developmental failure of otic placode
| risks           =  
| risks = Autosomal recessive inheritance in families with [[LAMM syndrome]]
| diagnosis       =  
| diagnosis = Clinical findings, [[CT scan]] or [[MRI]], [[genetic testing]] for FGF3 mutation
| differential   =  
| differential = Other forms of congenital deafness, labyrinthitis ossificans
| prevention     =  
| prevention = Early intervention and precautions to prevent accidents
| treatment       =  
| treatment = Early intervention for deafness, vibrotactile hearing devices, cochlear implantation (if applicable)
| medication     =  
| medication =
| prognosis       =  
| prognosis = Dependent on early intervention, limited hearing ability
| frequency       =  
| frequency = Rare
| deaths         =  
| deaths = No direct cause of death, but risk due to associated developmental delays
}}
}}
'''Michel aplasia''', also known as '''complete labyrinthine aplasia''' (CLA), is a [[Congenital disorder|congenital abnormality]] of the [[inner ear]]. It is characterized by the bilateral absence of differentiated inner ear structures and results in complete [[Hearing loss|deafness]] ([[anacusis]]).
Michel aplasia should not be confused with michel dysplasia.<ref>Marsot-Dupuch K, Dominguez-Brito A, Ghasli K et-al. CT and MRI findings of Michel anomaly:inner ear aplasia. AJNR Am J Neuroradial. 1999;20(2):281 -4.</ref>  It may affect one or both ears.<ref name=":0">{{Cite journal|title = Complete labyrinthine aplasia: clinical and radiologic findings with review of the literature|pmid = 19147720|journal = AJNR. American journal of neuroradiology|date = 2009-04-01|issn = 1936-959X|pages = 774–780|volume = 30|issue = 4|doi = 10.3174/ajnr.A1426|first = B.|last = Ozgen|first2 = K. K.|last2 = Oguz|first3 = A.|last3 = Atas|first4 = L.|last4 = Sennaroglu}}</ref>


''[[Aplasia]]'' is the medical term for body parts that are absent or do not develop properly. In Michel aplasia, the undeveloped (anaplastic) body part is the [[bony labyrinth]] of the inner ear. Other nearby structures may be underdeveloped as well.<ref name=":0" />
== Alternate names ==
* Complete labyrinthine aplasia (CLA)
 
== Definition ==
'''Michel aplasia''' is a rare congenital abnormality of the inner ear that results in the complete absence of inner ear structures, leading to profound [[sensorineural deafness]] (congenital [[anacusis]]). It is also referred to as complete labyrinthine aplasia (CLA) and is associated with other abnormalities, including [[microtia]] (underdeveloped outer ear) and [[microdontia]] (small teeth).


== Pathology ==
== Pathology ==
Michel aplasia is thought to result from failure of development of the otic placode, due to developmental arrest at the third week of gestation. The common cavity deformity, a confluence of illdefined cochlea and vestibular organ results from a disruption during the fourth and fifth week. An arrest in fifth or sixth week of gestation result in cochlear aplasia or cochlear hypoplasia respectively.
Michel aplasia occurs due to failure in the development of the [[otic placode]], a structure involved in the formation of the inner ear. This developmental failure typically happens during the first few weeks of gestation. In the third week, there is a developmental arrest that leads to a common cavity deformity, which is characterized by a confluence of poorly defined cochlea and vestibular organs. If this arrest happens later in gestation, particularly during the fourth to sixth week, it can result in either cochlear aplasia or cochlear hypoplasia.
 
== Associations ==
Michel aplasia is associated with [[LAMM syndrome]], a condition caused by a mutation in the [[FGF3 gene]] (fibroblast growth factor 3), located on chromosome 11q13. LAMM syndrome is characterized by:
* [[Labyrinthine aplasia]] (absence of the inner ear structures)
* [[Microtia]] (underdeveloped external ear)
* [[Microdontia]] (small-sized teeth)


=== Associations ===
The inheritance of Michel aplasia is autosomal recessive, which means that affected individuals inherit two copies of the mutated gene, one from each parent.
'''Abnormal development of the skeletal portions of the second arch'''
# Nondifferentiation of the stapes, with resultant absence of round and oval window.
# Abnormal course of the facial nerve.
'''Skull base abnormalities'''
# Hypoplasia of the petrous temporal bone.
# Hypoplastic and sclerotic petrous apex may mimic labyrinthitis ossificans.
# Platybasia.
# Aberrant course of jugular veins.


== Molecular pathology ==
== Diagnosis ==
Michel aplasia is associated with '''LAMM''' syndrome(labyrinthine aplasia, microtia and microdontia), which is caused by mutation FGF3 gene on chromosome 11q13 which encodes fibroblast growth factor 3.
Diagnosis of Michel aplasia is based on a combination of clinical findings, imaging studies, and genetic testing:


'''Mode of inheritance'''
* '''Clinical findings''': Profound congenital sensorineural deafness is the hallmark of the disorder.
congenital deafness with michel's aplasia, microtia and aicrodontia is inherited in an autosomal recessive manner.
* '''Imaging''': [[CT scans]] or [[MRI]] of the inner ear reveal the absence of recognizable structures, such as the cochlea and vestibule.
* '''Molecular genetic testing''': Genetic testing to detect mutations in the [[FGF3]] gene can confirm the diagnosis. Testing for mutations in the FGF3 gene is especially helpful in families with a history of LAMM syndrome.


== Diagnosis ==
== Treatment ==
Diagnosis is based on clinical findings.
Treatment of Michel aplasia primarily focuses on managing the profound deafness and promoting early development. Treatment options include:
''''Clinical findings''''
* Profound congenital sensorineural deafness is present
* CT scan or MRI of the inner ear shows no recognizable structure in the inner ear.
* As michel's aplasia is associated with LAMM syndrome there will be Microtia and microdontia present(small sized teeth).


'''Molecular genetic Testing'''
* '''Early intervention programs''': Enrollment in programs for the deaf and hard of hearing is crucial for language development and communication skills.
# ''FGF3'' is the only gene, whose mutation can cause congenital deafness with Michel's aplasia, microdontia and microtia
* '''Vibrotactile hearing devices''': These devices use vibrations to convey sound to the user and can be helpful for those who cannot benefit from traditional hearing aids.
* '''Cochlear implants''': For individuals with a cochleovestibular nerve and a cochlear remnant, cochlear implants may be considered. This option is typically available for children over 12 months old, although the approach is contested by the [[Deaf community]] and may come with complications.
* '''Multidisciplinary surveillance''': Annual evaluations by a team of specialists, including an otolaryngologist, clinical geneticist, pediatrician, and neurologist, help monitor the individual's progress and development.


'''Carrier testing for at-risk relatives''' requires identification of mutations which are responsible for occurrence of disease in the family.
== Prevention (of secondary complications) ==
== Prevention (of secondary complications) ==
Presence of inner ear abnormalities lead to Delayed gross development of child because of balance impairment and profound deafness which increases the risk of trauma and accidents.
Preventing secondary complications focuses on minimizing the risks associated with hearing loss and developmental delays:
* Incidence of accidents can be decreased by using visual or vibrotactile alarm systems in homes as well as in schools.
* Anticipatory education of parents, health providers and educational programs about hazards can help.


== Treatment ==
* '''Safety measures''': Given the balance impairment and profound deafness, individuals with Michel aplasia are at increased risk for trauma and accidents. Installing visual or vibrotactile alarm systems in homes and schools, as well as providing anticipatory education for parents and caregivers, can help reduce these risks.
* '''Developmental support''': Early intervention programs to support cognitive, speech, and physical development are important to mitigate developmental delays.


# enrollment in appropriate early intervention programs for the deaf and hard of hearing.
== Prognosis ==
# consideration of vibrotactile hearing devices or brain stem implants for individuals with '''Congenital labyrinthine aplasia'''
The prognosis of individuals with Michel aplasia largely depends on the availability of early intervention and the severity of associated symptoms. Although the hearing loss is profound, individuals with appropriate interventions can lead productive lives. However, developmental delays, especially those related to balance and communication, can persist.
# Evaluation for cochlear implantation in patients who have cochleovestibular nerve and a cochlear remnant. This is done in children above the age of 12 months having severe or profound hearing loss. Cochlear implants in infant and children is notably contested by the Deaf community, and frequently results in failure and lifelong complications.
=== Surveillance ===
This can be done by annual evaluations by multidiciplinary team involving otolaryngologist, clinical geneticist, a pediatrician, the expertise of an educator of the deaf, a neurologist is appropriate.


== Epidemiology ==
== Epidemiology ==
Michel aplasia is a [[rare disease]]. It was first described by P. Michel in the year 1863. He found it in the autopsy report of an 11-year-old child who was deaf and dumb and died in Children's Hospital of Strasbourg.<ref name=":0" />
Michel aplasia is an extremely rare disease, with limited documented cases. It was first described by P. Michel in 1863, following the autopsy of an 11-year-old child who exhibited deafness and an absence of inner ear structures.


== See Also ==
* [[Labyrinthine aplasia]]
* [[Microtia]]
* [[Microdontia]]
* [[Congenital hearing loss]]
* [[Autosomal recessive inheritance]]
* [[Sensorineural deafness]]


==References==
<references />
== External links ==
== External links ==
{{Medical resources
{{Medical resources
| ICD10           = Q16.5
| DiseasesDB = 9349
| ICD9            = <!--{{ICD9|xxx}}-->
| ICD10 = Q16.5
|  ICDO            =
| OMIM = 607867
|  OMIM           =
| Orphanet = 2499
|  DiseasesDB      =
|  MedlinePlus    =
|  eMedicineSubj  =
|  eMedicineTopic  =
|  MeSH            =
|  GeneReviewsNBK  =
|  GeneReviewsName =  
| Orphanet       =  
}}
}}
[[Category:Ear]]
[[Category:Ear]]
[[Category:Cutaneous congenital anomalies]]
[[Category:Congenital disorders]]
[[Category:Genetic disorders]]
[[Category:Rare diseases]]
[[Category:Rare diseases]]
{{dictionary-stub1}}
{{Genetic-disorder-stub}}

Latest revision as of 20:44, 2 April 2025

Michel aplasia
CT scan showing Michel's Aplasia
Synonyms Complete labyrinthine aplasia, CLA
Pronounce
Field Otorhinolaryngology, Medical genetics
Symptoms Profound congenital sensorineural deafness, balance impairment, microtia, microdontia
Complications Delayed development, risk of trauma and accidents
Onset At birth, or detectable within early childhood
Duration Lifelong
Types
Causes Mutations in the FGF3 gene, developmental failure of otic placode
Risks Autosomal recessive inheritance in families with LAMM syndrome
Diagnosis Clinical findings, CT scan or MRI, genetic testing for FGF3 mutation
Differential diagnosis Other forms of congenital deafness, labyrinthitis ossificans
Prevention Early intervention and precautions to prevent accidents
Treatment Early intervention for deafness, vibrotactile hearing devices, cochlear implantation (if applicable)
Medication
Prognosis Dependent on early intervention, limited hearing ability
Frequency Rare
Deaths No direct cause of death, but risk due to associated developmental delays


Alternate names[edit]

  • Complete labyrinthine aplasia (CLA)

Definition[edit]

Michel aplasia is a rare congenital abnormality of the inner ear that results in the complete absence of inner ear structures, leading to profound sensorineural deafness (congenital anacusis). It is also referred to as complete labyrinthine aplasia (CLA) and is associated with other abnormalities, including microtia (underdeveloped outer ear) and microdontia (small teeth).

Pathology[edit]

Michel aplasia occurs due to failure in the development of the otic placode, a structure involved in the formation of the inner ear. This developmental failure typically happens during the first few weeks of gestation. In the third week, there is a developmental arrest that leads to a common cavity deformity, which is characterized by a confluence of poorly defined cochlea and vestibular organs. If this arrest happens later in gestation, particularly during the fourth to sixth week, it can result in either cochlear aplasia or cochlear hypoplasia.

Associations[edit]

Michel aplasia is associated with LAMM syndrome, a condition caused by a mutation in the FGF3 gene (fibroblast growth factor 3), located on chromosome 11q13. LAMM syndrome is characterized by:

The inheritance of Michel aplasia is autosomal recessive, which means that affected individuals inherit two copies of the mutated gene, one from each parent.

Diagnosis[edit]

Diagnosis of Michel aplasia is based on a combination of clinical findings, imaging studies, and genetic testing:

  • Clinical findings: Profound congenital sensorineural deafness is the hallmark of the disorder.
  • Imaging: CT scans or MRI of the inner ear reveal the absence of recognizable structures, such as the cochlea and vestibule.
  • Molecular genetic testing: Genetic testing to detect mutations in the FGF3 gene can confirm the diagnosis. Testing for mutations in the FGF3 gene is especially helpful in families with a history of LAMM syndrome.

Treatment[edit]

Treatment of Michel aplasia primarily focuses on managing the profound deafness and promoting early development. Treatment options include:

  • Early intervention programs: Enrollment in programs for the deaf and hard of hearing is crucial for language development and communication skills.
  • Vibrotactile hearing devices: These devices use vibrations to convey sound to the user and can be helpful for those who cannot benefit from traditional hearing aids.
  • Cochlear implants: For individuals with a cochleovestibular nerve and a cochlear remnant, cochlear implants may be considered. This option is typically available for children over 12 months old, although the approach is contested by the Deaf community and may come with complications.
  • Multidisciplinary surveillance: Annual evaluations by a team of specialists, including an otolaryngologist, clinical geneticist, pediatrician, and neurologist, help monitor the individual's progress and development.

Prevention (of secondary complications)[edit]

Preventing secondary complications focuses on minimizing the risks associated with hearing loss and developmental delays:

  • Safety measures: Given the balance impairment and profound deafness, individuals with Michel aplasia are at increased risk for trauma and accidents. Installing visual or vibrotactile alarm systems in homes and schools, as well as providing anticipatory education for parents and caregivers, can help reduce these risks.
  • Developmental support: Early intervention programs to support cognitive, speech, and physical development are important to mitigate developmental delays.

Prognosis[edit]

The prognosis of individuals with Michel aplasia largely depends on the availability of early intervention and the severity of associated symptoms. Although the hearing loss is profound, individuals with appropriate interventions can lead productive lives. However, developmental delays, especially those related to balance and communication, can persist.

Epidemiology[edit]

Michel aplasia is an extremely rare disease, with limited documented cases. It was first described by P. Michel in 1863, following the autopsy of an 11-year-old child who exhibited deafness and an absence of inner ear structures.

See Also[edit]

External links[edit]

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