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Biomedical subjects

K M Grundfast

Publications and source records attributed to K M Grundfast.

At least 19 recordsLinked to original sources
PubMed1996

Laryngomalacia. The search for the second lesion.

OBJECTIVES: To determine the necessity of rigid endoscopy in the diagnosis and management of laryngomalacia and its associated synchronous airway lesions (SALs), to analyze the incidence of SALs associated with laryngomalacia and their significance, and to determine the need for epiglottoplasty in management of laryngomalacia. DESIGN: Retrospective medical chart review. SETTING: Tertiary care children's hospital. PATIENTS: Two hundred thirty-three patients with a primary diagnosis of laryngomalacia on flexible fiberoptic laryngoscopy treated at the Children's National Medical Center, Washington, DC, from January 1, 1984, to June 30, 1994. INTERVENTION: Evaluation and treatment of laryngomalacia and associated SAL by flexible fiberoptic laryngoscopy, radiographic studies, rigid endoscopy, and other surgical procedures. MAIN OUTCOME MEASURES: Resolution of airway symptoms from laryngomalacia and associated SAL. RESULTS: Ninety patients (38.6%) underwent rigid endoscopy, and 12 patients (5.2%) required epiglottoplasty. Synchronous airway lesions were discovered in 44 patients (18.9%). Eleven patients (4.7%) had SALs that wre considered clinically significant; nine (3.9%) of these required surgical intervention. CONCLUSIONS: Rigid endoscopy in evaluation of an infant with laryngomalacia is rarely necessary. Clinically significant SALs requiring surgical intervention are uncommon. Surgical intervention for laryngomalacia also is rarely necessary.

Airway Obstruction↗
PubMed1996

Balancing pediatric otolaryngology training for fellows and residents at a children's hospital.

OBJECTIVE: To determine the feasibility of providing surgical, endoscopic, and patient contact experience of high educational value at a children's hospital sufficient for adequately training contemporaneously both residents in otolaryngology-head and neck surgery and fellows in pediatric otolaryngology. DESIGN: Retrospective review of operating room case logs and assignment of cases based on arbitrary perception of inherent case complexity and skill and experience that are required to manage the case. SETTING: Tertiary care children's hospital located in a major metropolitan area. MAIN OUTCOME MEASURES: (1) Volume of surgical and endoscopic cases assigned retrospectively to junior resident, senior resident, or fellow. (2) Score on newly developed self-assessment skill list in pediatric otolaryngology. RESULTS: During 1 year, there were 3224 surgical and endoscopic procedures performed in the operating room. Of the total number of procedures, only 44 (1.4%) were designated as being exclusively assigned for hands-on experience to a fellow, but 380 (11.8%) were appropriate for both a senior resident and a fellow and therefore were apportioned in an alternating fashion. A self-assessment instrument has been developed to assess competency and comfort in the management of otolaryngic disorders, both surgical and nonsurgical, in children. CONCLUSIONS: The volume and assortment of surgical and endoscopy cases at a tertiary care children's hospital can provide the basis for a rich, practical hands-on experience for residents and fellows. Since few surgical or endoscopic cases require pediatric fellowship training for mastery, becoming a pediatric otolaryngologist depends on acquiring skills and competence that exceed the technical skills acquired in the operating room.

Clinical Competence↗
PubMed1996

Benign lesions of the external auditory canal.

Benign mass lesions of the external auditory canal, such as exostoses and osteomas, are common findings on physical examination but most often do not require treatment. The differential diagnosis of lesions in the external auditory canal, however, should not be limited to those benign processes discussed here, but should also include infectious, dermatologic, congenital, and malignant processes.

Cholesteatoma↗
PubMed1995

Enlarged vestibular aqueduct and sensorineural hearing loss in childhood.

OBJECTIVE: To determine if all children with enlarged vestibular aqueducts (EVAs) have development of uniform progressive sensorineural hearing loss (SNHL). To determine whether the size of the EVA correlates with severity, frequencies involved, and stability of SNHL. To determine if the audiologic pattern of SNHL correlates with likelihood of progression of SNHL. DESIGN: Retrospective study. SETTING: Children's National Medical Center, Washington, DC, a tertiary care center with a large otologic practice. PATIENTS: Fifteen children (26 ears) with EVA on computed tomographic scan. METHODS: History, physical examination, computed tomographic scans, and serial audiograms were reviewed. Factors analyzed included age at diagnosis, audiometric configuration (high tone, midtone, low tone, flat), degree of hearing loss at presentation, length of follow-up, and presence of associated inner ear anomalies. RESULTS: Nine ears had progressive SNHL, 16 ears had stable SNHL, and 1 ear had profound SNHL. The predominant audiologic configuration was flat. The audiogram configuration does not correlate with progression of SNHL. The size of the vestibular aqueduct does not correlate with the level, type, or progression of SNHL. CONCLUSION: Our study failed to uncover factors that might be predictive of progression of hearing loss. We conclude that until a better understanding of the natural history and pathophysiologic condition of EVAs is achieved, there is no surgical or other intervention that can be demonstrated as being efficacious.

Audiometry↗
PubMed1995

Delayed diagnosis and fate of congenital cholesteatoma (keratoma).

OBJECTIVE: To analyze clinical presentation, modes of detection, growth pattern, operative findings, and results of surgery in children 3 years old or older who had extensive congenital cholesteatoma (keratoma). DESIGN: Survey, case series. SETTING: Two academically affiliated medical centers: a children's hospital and an eye, ear, and throat hospital, both located in major metropolitan cities. PATIENTS: Twenty-five children selected according to specified criteria. INTERVENTION: Tympanomastoid surgery, ie, canal wall up and canal wall down, some with ossicular reconstructive surgery. MAIN OUTCOME MEASURE: Audiologic assessment (speech reception threshold) and recurrence (recidivism) of cholesteatoma. RESULTS: Incidence of recidivism, 52%. Hearing maintained within the range of normal to mild hearing impairment postoperatively in 91% of the patients for whom complete data are available. CONCLUSIONS: Congenital cholesteatoma may grow for years without causing signs or symptoms and, having grown without early detection, can extend to involve the epitympanum and mastoid antrum, cause ossicular erosion, and even extend to the middle cranial fossa. To adequately remove a congenital cholesteatoma that has gone undetected for many years, exposure of the anterior epitympanum is often necessary and removal of both the body of the incus and the head of the malleus often is required. Since congenital cholesteatoma usually develops in a child with a well-pneumatized mastoid that would create a large mastoid bowl if exteriorized, the otologic surgeon is likely to hesitate in using the canal wall down mastoidectomy technique. Alternatives to the canal wall down mastoidectomy technique, which can achieve reasonably good hearing results and avoid creation of a large mastoid bowl, include planned two-stage canal wall up surgery or canal preservation with primary reconstruction and close follow-up with otomicroscopy and serial computed tomographic scans.

Adolescent↗
PubMed1995

Further elucidation of the genomic structure of PAX3, and identification of two different point mutations within the PAX3 homeobox that cause Waardenburg syndrome type 1 in two families.

Waardenburg syndrome is an autosomal dominant disorder characterized by sensorineural deafness and pigmentary disturbances. Previous work has linked the disease to PAX3 on chromosome 2, and several mutations within the highly conserved paired-box and octapeptide motifs, but not the homeobox, have been reported. In this report, we have used the published cDNA sequence to further define the genomic structure of PAX3, using inverse PCR. We have identified exon/intron boundaries between exons 5 and 6 and between exons 6 and 7. Further, we have identified the first two mutations within the homeobox in two different families with type 1 Waardenburg syndrome. The first is a point mutation (G-->T) at the first base of exon 6, which substitutes phenylalanine for valine. In another family, we have identified a point mutation (C-->G) within the homebox, in exon 6, which substitutes a glycine for arginine at a highly conserved site. The homeodomain is important in binding of DNA and in effecting transcriptional control. These mutations likely result in structural change within the homeodomain that either change the DNA-binding specificity of the homedomain or reduce the affinity of the PAX3 protein for DNA. These homeodomain mutations should aid in elucidating the role of the homeodomain in the function of the PAX3 protein.

Amino Acid Sequence↗
PubMed1994

Management of otitis media and the New Agency for Health Care Policy and Research Guideline.

In these times of increasing dominance of managed care and diminishing autonomy for practitioners of medicine, any government pronouncement can be viewed as yet another of many annoyances. For otolaryngologists who yearn for the days when there were not so many intermediaries involved in patient care, the newly issued Clinical Practice Guideline, Otitis Media with Effusion in Young Children (see reference 2 for highlights) may seem more of an ominous threat than anything remotely beneficial. However, given the inexorable changes that are occurring, the Agency for Health Care Policy and Research (AHCPR) otitis media guideline is probably going to be more helpful than harmful.

Child↗
PubMed1994

A new nonsyndromic X-linked sensorineural hearing impairment linked to Xp21.2.

X-linked deafness is a rare cause of hereditary hearing impairment. We have identified a family with X-linked dominant sensorineural hearing impairment, characterized by incomplete penetrance and variable expressivity in carrier females, that is linked to the Xp21.2, which contains the Duchenne muscular dystrophy (DMD) locus. The auditory impairment in affected males was congenital, bilateral, profound, sensorineural, affecting all frequencies, and without evidence of radiographic abnormality of the temporal bone. Adult carrier females manifested bilateral, mild-to-moderate high-frequency sensorineural hearing impairment of delayed onset during adulthood. Eighteen commercially available, polymorphic markers from the X chromosome, generating a 10-15-cM map, were initially used for identification of a candidate region. DXS997, located within the DMD gene, generated a two-point LOD score of 2.91 at theta = 0, with every carrier mother heterozygous at this locus. Recombination events at DXS992 (located within the DMD locus, 3' to exon 50 of the dystrophin gene) and at DXS1068 (5' to the brain promoter of the dystrophin gene) were observed. No recombination events were noted with the following markers within the DMD locus: 5'DYS II, intron 44, DXS997, and intron 50. There was no clinical evidence of Duchenne or Becker muscular dystrophy in any family member. It is likely that this family represents a new locus on the X chromosome, which when mutated results in nonsyndromic sensorineural hearing loss and is distinct from the heterogeneous group of X-linked hearing losses that have been previously described.

Audiometry↗
PubMed1994

Locus heterogeneity for Waardenburg syndrome is predictive of clinical subtypes.

Waardenburg syndrome (WS) is a dominantly inherited and clinically variable syndrome of deafness, pigmentary changes, and distinctive facial features. Clinically, WS type I (WS1) is differentiated from WS type II (WS2) by the high frequency of dystopia canthorum in the family. In some families, WS is caused by mutations in the PAX3 gene on chromosome 2q. We have typed microsatellite markers within and flanking PAX3 in 41 WS1 kindreds and 26 WS2 kindreds in order to estimate the proportion of families with probable mutations in PAX3 and to study the relationship between phenotypic and genotypic heterogeneity. Evaluation of heterogeneity in location scores obtained by multilocus analysis indicated that WS is linked to PAX3 in 60% of all WS families and in 100% of WS1 families. None of the WS2 families were linked. In those families in which equivocal lod scores (between -2 and +1) were found, PAX3 mutations have been identified in 5 of the 15 WS1 families but in none of the 4 WS2 families. Although preliminary studies do not suggest any association between the phenotype and the molecular pathology in 20 families with known PAX3 mutations and in four patients with chromosomal abnormalities in the vicinity of PAX3, the presence of dystopia in multiple family members is a reliable indicator for identifying families likely to have a defect in PAX3.

Chromosome Mapping↗
PubMed1992

Waardenburg syndrome (WS) type I is caused by defects at multiple loci, one of which is near ALPP on chromosome 2: first report of the WS consortium.

Previous studies have localized the gene for Waardenburg syndrome (WS) type I to the distal portion of chromosome 2q, near the ALPP locus. We pooled linkage data obtained from 41 WS type I and 3 WS type II families which were typed for six polymorphic loci on chromosome 2q in order to refine the location of the WS locus (WS1) and evaluate the extent of genetic heterogeneity. In the course of this work, we developed diagnostic criteria for genetic and phenotypic studies. Our findings, based on two-locus and multilocus analysis using a linkage map established from reference pedigrees, suggest that there are two or more mutations causing WS, one of which (i.e., WS1) is located on chromosome 2q, between the ALPP and FN1 loci, at distances of 7.8 cM and 11.2 cM for each marker, respectively. The results also indicate that WS1 is responsible for the illness in approximately 45% of all families in this sample. However, the odds favoring this position over a location between ALPP and SAG are only 2:1 when alternate assumptions about the proportion of linked families are considered. We conclude that a more saturated map of this region of chromosome 2q, including highly polymorphic markers, will be needed to accurately distinguish linked families and, ultimately, isolate the mutant gene.

Alkaline Phosphatase↗
PubMed1992

Finding the gene(s) for Waardenburg syndrome(s).

Waardenburg syndrome is a recognizable disorder characterized by autosomal dominant inheritance of pigmentary abnormalities of the eyes, hair, and skin sometimes associated with congenital hearing impairment. At least two different types of Waardenburg syndrome have been described. The different types of Waardenburg syndrome are differentiated as follows: type I, with dystopia canthorum; type II, without dystopia canthorum; and type III, without dystopia, with unilateral eyelid ptosis and skeletal abnormalities. Results of pooled linkage analysis done by a consortium of investigators suggests that Waardenburg syndrome type I is genetically heterogeneous, meaning that there is probably more than one genotype that can be associated with the findings typical of the syndrome. A mutated gene that can cause Waardenburg syndrome type I has been discovered. Either a single base pair substitution or an 18 base pair deletion in exon 2 has been found in affected individuals but is not found in unaffected members. Most likely, the mutated gene causes a perturbation in DNA binding of a paired domain, in turn having an effect on the regulation of other genes so the development and spatial orientation of cells and structures derived from the neural crest are affected. Forty years after Waardenburg syndrome was first described, a mutant gene has been found that is known to cause the syndrome. The process of discovery that has transpired in the time from syndrome description to gene identification has been one of steady progress and interdisciplinary cooperation.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1991

Complete evaluation of the child identified as a poor listener.

With increasing awareness among educators of the importance of early identification of hearing impairment, growing numbers of children are being referred for evaluation when a teacher or day care supervisor perceives that a child is having difficulty listening. Some children who manifest difficulty listening in a pre-school play group or the classroom may have conductive or sensorineural hearing loss, while others have normal hearing with an underlying and yet-to-be-detected behavioral or psychoeducational disorder. This report presents suggestions for evaluation of the child referred for difficulty listening. The otologist should consider that a child may have an attention deficit disorder when results of initial audiologic assessment indicate there is no hearing loss or when the degree of hearing loss appears to be small in relation to the degree of inattentiveness that has been observed. The features of Attention-deficit Hyperactivity Disorder (ADHD) and Specific Developmental Disorder (SDD) are described, and illustrative case studies are presented. Clues to diagnosis are provided and a distinction between overlapping disorders is made.

Attention↗