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Branchiootorenal (BOR) Syndrome By: Mackenzie Harris
10
Branchiootorenal Syndrome
By: Mackenzie Harris
Symptoms
Symptoms
• Branchiootorenal (BOR) syndrome is a genetic condition that interrupts the development of the neck tissues and creates malformations of the ears and kidneys. [3]
• The signs and symptoms of this condition are extremely diverse even within the same family unit. BOR manifests itself in different ways for people. [3]
Breaking it Down
Breaking it Down
Breaking down the word “Branchiootorenal”:
o “Branchio” attributes to the second branchial arch, an integral structure that develops into both the anterior and lateral tissues of the neck. Abnormal development can form masses in the neck known as branchial cleft cysts or unusual holes called fistulae in the side of the neck superior to the collarbone. [3]
o “Oto” refers to the ear. The majority of people with BOR experience
hearing loss and other ear anomalies. BOR encompasses all types of hearing loss including conductive, sensorineural, or mixed. Some individuals have small holes or extra pieces of tissue in front of their ears known as preauricular tags. [3]
o “Renal” deals with the kidneys. The severity of damage ranges from mild to severe through both structural and functional means. [3]
Most Common
Most Common Symptoms
In a study conducted on by Achih Chen, the most common anomalies associated with BOR syndrome include [1]:
Hearing loss (93%)
Preauricular pits (82%)
Renal anomalies (67%)
Branchial fistulae (49%)
Pinnae deformities (36%)
External auditory canal stenosis (29%)
Other Symptoms
Other Symptoms
Characteristic temporal bone findings include [1]:
o Cochlear hypoplasia (4/5 of normal size with only 2 turns)
o Dilation of the vestibular aqueduct
o Bulbous internal auditory canals
o Deep posterior fossae
o Acutely angled promontories
Incidence
Incidence & Prevalence
The incidence is approximately 1 in 40,000 in the general population and 2% among profoundly deaf children. [2, 6]
Prevalence
Prevalence
Prevalence: In a comprehensive study of 133 people conducted by Fraser et. Al [1980]., results indicated that hearing impairment was the single most common trait in BOR syndrome exhibiting all types [1, 2]:
o Mixed (50%)
o Conductive (30%)
o Sensorineural (20%)
Etiology & Pathology
Etiology & Pathology/ Site of Lesion
• BOR is an autosomal dominant disorder. [1, 5]
- Dominant disorders are said to occur when one copy of a gene is abnormal resulting in manifestation of the disease. [1, 5]
- Transmission of the abnormal gene can be inherited from either parent or can be the product of a new mutation (gene change) in the affected individual. [1, 5]
- There is equal risk of inheritance for both sexes. [1, 5]
- The chances of passing the abnormal gene from parent to offspring is 50% for each pregnancy. [1, 5]
Gene Mutations
Gene Mutations
BOR syndrome derives from mutations of three genes that include [3, 4]:
o EYA1 (codes for transcription factor)
o SIX5
o SIX1
• Majority of the gene mutations involve the EYA1 gene. However, there are numerous people diagnosed with BOR that have none of these gene mutations. [3, 4]
Site of Lesion
Site of Lesion
Since BOR can yield all types of hearing loss the site of lesion is dependent on the patient but can be found in either the central or peripheral systems of the auditory pathway.
Audiological Evaluation
Audiological Evaluation
BOR can yield all types of hearing loss. Therefore, a comprehensive audiological evaluation should be conducted to diagnose the type of hearing loss. Test battery should include, but is not limited to:
o Otoscopy
o Tympanometry
o MEMRs
o Pure tone air conduction audiometry
o Bone conduction audiometry
o SRTs
o WRSs
o ABR, if warranted
Case Study
Case Study
• In a study conducted by Mee Hyun Song, seven families (10 patients) diagnosed with BOR, were clinically analyzed to determine type of hearing loss through:
o Serial pure tone audiometries [7]
PTA was defined as average of thresholds at 500, 1000, 2000, and 3000 Hz [7]
o Speech audiometry, if possible [7]
o Language evaluation, if possible [7]
• Results:
o All patients in the study presented with a mixed type of hearing loss ranging from moderate to profound degree; Consistent with statistics regarding that majority of people with BOR exhibit a mixed loss. [7]
Audiologic Management
Audiologic Management
Due to the fact that all types of hearing loss are possible with BOR, audiologic management is contingent on each specific patient.
Conductive
Conductive
• For conductive hearing loss:
o Refer to ENT for MRI/CT scan. [7]
Possible middle ear surgeries or necessary medical procedures may be conducted. [7]
Sensorineural
Sensorineural
• For sensorineural hearing loss:
o Select and fit the patient with appropriate hearing devices to accommodate their individual needs. [7]
If they are not a hearing aid candidate, then explore other possibilities such as cochlear implants. [7]
Mixed
Mixed
• For mixed hearing loss:
o Refer to ENT for MRI/CT scan. [7]
Possible medical treatments available. [7]
o Following medical care, additional gain may be necessary through technological devices. [7]
Medical Evaluation
Medical Evaluation
• Audiologist can refer the patient with BOR to an ENT or primary care physician to identify any middle or inner ear anomalies by conducting:
o CT scans [7]
o MRIs [7]
Case Study
Case Study
• In a study conducted by Mee Hyun Song, seven families (10 patients) diagnosed with BOR, were clinically analyzed for temporal bone abnormalities through:
o High resolution temporal bone CT [7]
o Temporal MRI [7]
• Results:
o All patients presented with:
Cochlear hypoplasia [7]
Enlarged vestibular aqueduct [7]
Facial nerve anomalies [7]
Renal Evaluation
Renal Evaluation
• Renal abnormality is evaluated through:
o Urinalysis [5]
o Renal function tests [5]
o Imaging studies (Renal ultrasonography, CT scan) [5]
Medical Management
Medical Management
- Medical management is implemented on a case-by-case basis depending on what types of symptoms the patient presents with.
- Specialized treatment plans should be created by a team of professionals who collaborate to ensure the best outcomes.
Branchio
Branchio
• “Branchio” Medical management:
o Refer to primary care physician.
o Branchial cleft deformities can become infected and could require surgical treatment such as excision of the branchial cyst or fistulae. [5]
o Antibiotics may be administered to resolve infection. [5]
Oto
Oto
• “Oto” Medical management is tailored to the patient's specific needs.
o Referral to ENT, if warranted.
o Research has shown limited improvement in hearing for BOR patients from middle ear surgeries. [7]
o Most patients who still required gain after surgery utilized bilateral hearing aids. [7]
o Successful outcomes can be expected with cochlear implantations in patients with BOR syndrome who cannot benefit from hearing aids. [7]
Renal
Renal
• “Renal” Medical management:
o Refer to a nephrologist (physician who specializes in kidney issues). [5]
o Surgical repair may be necessary for correctable defects. [5]
o If kidney problems become severe, dialysis or kidney transplantation may be warranted. [5]
References List
References List
[1] Chen, A., Francis, M., Ni, L., Cremers, C., Kimberling, W., Sato, Y., … Smith, R. (n.d.). Phenotypic manifestations of branchiootorenal syndrome. American Journal of Medical Genetics, 58(4), 365–370. Retrieved from https://search-ebscohost-com.spot.lib.auburn.edu/login.aspx?direct=true&db=edswsc&AN=A1995RV00100012&site=eds-live&scope=site
[2] Fraser, F. C., Sproule, J. R., & Halal, F. (1980). Frequency of the branchio-oto-renal (BOR) syndrome in children with profound hearing loss. American Journal of Medical Genetics, 7(3), 341–349. Retrieved from https://search-ebscohost-com.spot.lib.auburn.edu/login.aspx?direct=true&db=cmedm&AN=7468659&site=eds-live&scope=site
[3] Genetics Home Reference. (2020). Your guide to understanding genetic conditions. Retrieved January 25, 2020, from https://ghr.nlm.nih.gov
[4] Musiek, F. E., Baran, J. A., Shinn, J. B., & Jones, R. O. (2012) Disorders of the auditory system. San Diego, CA: Plural.
[5] National Organization for Rare Disorders. (2018). Branchiootorenal spectrum disorders. Retrieved January 25, 2020, from https://rarediseases.org/rare-diseases/branchio-oto-renal-syndrome/
[6] Senel, E., Kocak, H., Akbiyik, F., Saylam, G., Gulleroglu, B. N., & Senel, S. (n.d.). From a branchial fistula to a branchiootorenal syndrome: a case report and review of the literature. Journal of Pediatric Surgery, 44(3), 623–625. https://doi-org.spot.lib.auburn.edu/10.1016/j.jpedsurg.2008.10.034
[7] Song, M. H., Kwon, T. J., Kim, H. R., Jeon, J. H., Baek, J. I., Lee, W. S., … Choi, J. Y. (2013). Mutational Analysis of EYA1, SIX1 and SIX5 Genes and Strategies for Management of Hearing Loss in Patients with BOR/BO Syndrome. PLOS ONE, 8(6), 1–11. https://doi-org.spot.lib.auburn.edu/10.1371/journal.po
Question 1
Question 1
1. What do each of the components of the word “Branchiootorenal” mean and name a corresponding symptom with each part.
Answer 1
Answer 1
“Branchio” refers to 2nd branchial arch
o Symptoms associated could be branchial cleft cysts; fistulae
“Oto” refers to ear
o Symptoms associated could be conductive, sensorineural, or mixed HL; preauricular pits; pinnae deformity; external auditory canal stenosis; enlarged vestibular aqueduct; cochlear hypoplasia; bulbous internal auditory canals; deep posterior fossae; and acutely angled promontories
“Renal” refers to kidneys
o Symptoms associated could be abnormal structure or function of kidneys
Question 2
Question 2
2. True/False: BOR is an autosomal recessive disorder.
Answer 2
Answer 2
FALSE, BOR is an autosomal DOMINANT disorder
Question 3
Question 3
3. Which type of hearing loss is most commonly seen with BOR patients?
a. Conductive
b. Sensorineural
c. Mixed
d. All of the above
e. None of the above
Answer 3
Answer 3
C (MIXED)