Genetic
advantage of deafness or what...?
How can you explain an individual with hereditary
autosomal recessive deafness giving birth to
offspring not only all normal hearing, but all resistant
to Noise-induced trauma? Well that was exactly the
findings of Åsa Skjönsberg
et al in a recent animal study reported in
Audiology and Neurotology 2005;10:323-330.
Abstract: A new strain of waltzing guinea pigs
arose spontaneously in a guinea pig breeding facility in
Germany in 1996. In addition to obvious vestibular
dysfunction, the waltzing animals appear deaf already at
birth. Histological analysis revealed that the waltzers
lack an open scala media due to the collapse of
Reissner's membrane onto the surface of the hearing
organ. Subsequent breeding has shown that this strain
has a recessive mode of inheritance. The homozygotes are
deaf and display a waltzing behaviour throughout their
lives while the heterozygotes show no significant signs
of inner ear injury despite being carriers of this
specific mutated gene of hearing impairment. However,
the heterozygous animals offer the opportunity to study
how hereditary factors interact with auditory stress. In
the present study, the susceptibility of the carriers to
noise was investigated. Auditory brainstem responses
were obtained prior to and after noise exposure (4 kHz,
110 dB, 6 h). The carriers were significantly less
affected by the noise as compared to control animals.
This difference was still significant at 4 weeks
following noise exposure. It is suggested that the
heterozygous animals have an endogenous resistance to
auditory stress
New
Forum For Otolaryngologists in Africa...
A
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Otolaryngologists in Africa share opinions, discuss
cases, and keep abreast of other global events
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Here...
Still on Paediatric
Cricotracheal Resection.....
As a follow up to the news on CTR for subglottic
stenosis in neonates (Vol1,
No.1, 2005) you may also want to view the
study by White, Cotton, Bean & Rutler who reported the
largest series of paediatric cricotracheal resection and
concluded that CTR may be safely performed in patients
with multiple airway lesions. Patients with a history of
vocal cord paralysis who undergo CTR often require more
than 1 open airway procedure for decannulation and
should be counseled appropriately.
Abstract: OBJECTIVE: To identify risk factors
for operation-specific outcomes of
pediatric cricotracheal resection (CTR). DESIGN: We
identified the first
100 consecutive children undergoing CTR at our
institution from January 1, 1993, to December 31, 2004.
Retrospective review of medical records provided data on
demographics, operation dates, decannulation dates, and
proposed risk factors, including age, stenosis grade,
vocal cord function, Down syndrome, history of distal
tracheal surgery, history of open laryngotracheal
surgery, presence of tracheotomy at the time of
operation, use of suprahyoid release, extended CTR, and
use of chin-to-chest sutures. Complete data sets were
available for 93 patients. We performed multivariable
logistic regression analysis to identify significant
independent risk factors. SETTING: A tertiary care
children's hospital.
PATIENTS: All patients younger than 18 years who
underwent CTR at our
institution. MAIN OUTCOME MEASURES: Operation-specific
and overall
decannulation rates. RESULTS: Results of the
preoperative evaluation showed grade III or IV stenosis
in 89 patients (96%). The overall decannulation rate
included 87 patients (94%); the operation-specific
decannulation rate, 66 patients (71%). The only
significant risk factor for failure to decannulate after
1 operation was the presence of unilateral or bilateral
vocal cord paralysis (P = .007). CONCLUSIONS:
Cricotraceal resection may be safely performed in
patients with multiple airway lesions. Patients with a
history of vocal cord paralysis who
undergo CTR often require more than 1 open airway
procedure for decannulation and should be counseled
appropriately. This study represents the largest
reported series of pediatric CTR.
