Biomedical subjects

P D Phelps

Publications and source records attributed to P D Phelps.

At least 19 recordsLinked to original sources

PubMed2003

Maxillary sinus mucocele presenting as a late complication of a maxillary advancement procedure.

Paranasal sinus mucoceles are benign, locally expansile cyst-like masses that are filled with mucus and lined with epithelium. Less than one per cent of them involve the maxillary sinus. Most of these are late complications of a Caldwell Luc procedure. A case is presented of a 31-year-old woman with a maxillary sinus mucocele who had undergone a Le Fort I maxillary advancement procedure 15 years previously - a complication never previously reported.

Adult↗

PubMed2003

Neuro-otological findings in Pendred syndrome.

Pendred syndrome is an autosomal recessive inherited disorder characterized by profound hearing impairment and inappropriate iodine release by the thyroid on perchlorate challenge. Thirty-three cases comprising members of 13 families and eight isolated cases were studied, with detailed audiological and vestibular investigation and computerized tomography. A uniform, profound, symmetrical sensorineural hearing loss was identified in all cases. Approximately one-third of the group reported progressive hearing impairment, in childhood or adolescence, associated with head injury, infection, or delayed secondary hydrops. Ninety per cent of the cases scanned showed dilated vestibular aqueducts, and all cases with progression of the hearing impairment demonstrated this structural abnormality. Approximately one-third of the cases had normal vestibular function, but a further third demonstrated a unilateral peripheral deficit, while the remaining third showed bilateral vestibular hypofunction. There was no intra-familial concordance of vestibular findings, and no correlation between vestibular abnormality and presence or absence of a dilated vestibular aqueduct, with or without a Mondini malformation. In older children and adults, Pendred syndrome was associated with a profound, symmetrical, sensorineural auditory impairment, and a variety of vestibular abnormalities, which are not uniform within families, or correlated with structural labyrinthine deformities.

Adolescent↗

PubMed2002

Hyrtl's fissure.

Hyrtl's fissure is a transient anatomic landmark in the developing fetal petrous temporal bone and is usually closed by the normal progression of ossification in the 24th week of gestation. It occasionally persists into extrauterine life and has been reported as an unusual cause of a perilabyrinthine cerebrospinal fluid fistula. We present a case of a child presenting with bacterial meningitis because of a persistent Hyrtl's fissure. We have reviewed aspects of the fissure's developmental anatomy and previously published clinical cases. We have also explored the provenance of the eponym. We were unable to uncover evidence in support of the contention that Joseph Hyrtl was actually responsible for describing the structure commonly known as Hyrtl's fissure.

Anatomy↗

PubMed2002

Cochlear implants in children with craniofacial syndromes: assessment and outcomes.

The aim of this retrospective study was to review the outcomes for children with craniofacial syndromes who had received a cochlear implant. The group comprised four children (three girls, one boy) aged between 3.3 and 10.1 years (mean 6.3 years) at time of implantation with the Cochlear CI-22M device. Two children had the CHARGE association. one had Goldenhar's syndrome and one had brachio-oculo-facial syndrome. All had full electrode insertion at time of surgery. At follow-up, three of the children demonstrated benefit in detection, recognition and identification of environmental sounds, and they continued to gain receptive spoken language skills, although none had intelligible speech. The group required careful mapping and higher levels of electrical stimulation of the implant compared to normal child implantees. Stimulation of the facial nerve was a problem with one child. The pre-implantation assessment of these children requires extensive interdisciplinary discussion and careful radiological investigation. Cases should be carefully selected. Parents should receive realistic counselling about outcomes and the time commitment necessary, as habilitation of these children can take twice as long as that of children without additional special needs. Post-implantation, these children continue to require well-coordinated medical and interdisciplinary management.

Auditory Threshold↗

PubMed2000

Enlarged vestibular aqueduct: a radiological marker of pendred syndrome, and mutation of the PDS gene.

Although the textbook view of Pendred syndrome is that of an autosomal recessive condition characterized by deafness and goitre, it is increasingly clear that not all such patients present this classical clinical picture. Malformations of the inner ear, specifically enlargement of the vestibular aqueduct, are common in Pendred syndrome and mutations in the PDS (Pendred Syndrome) gene have been recorded in patients presenting with deafness and vestibular aqueduct dilatation only, without other features of Pendred syndrome. Since this is the most common radiological malformation of the cochlea in deaf patients, we investigated what proportion of such cases were due to mutation of the PDS gene. We assessed 57 patients referred with radiological evidence of vestibular aqueduct enlargement, by history, clinical examination, perchlorate discharge test and molecular analysis of the PDS locus. Forty-one patients (72%) had unequivocal evidence of Pendred syndrome. The finding of a single heterozygous mutation at the PDS gene in a further eight was strongly suggestive of a critical role for pendrin, the protein product of the PDS gene, in the generation of enlarged vestibular aqueducts in at least 86% (49/57 cases) of patients with this radiological malformation. Securing the diagnosis of Pendred syndrome may be difficult, especially in the single case. Goitre is an inconstant finding, and the perchlorate discharge test, although helpful, is of diagnostic value only if abnormal. Enlargement of the vestibular aqueduct should be considered as the most likely presentation of Pendred syndrome and should prompt specific investigation of that diagnostic possibility. Pendred syndrome might henceforth be recharacterized as deafness with enlargement of the vestibular aqueduct, which is sometimes associated with goitre.

Adolescent↗

PubMed2000

Congenital malformations of the ear and cochlear implantation in children: review and temporal bone report of common cavity.

The objective of this review is to analyze aspects of congenital malformation of the ear in relation to cochlear implantation in children. Having briefly described the in utero development of the ear and the classification of types of external, middle and inner ear malformation, five practical aspects of these malformations are discussed. It seems likely that the combination of bilateral profound sensorineural deafness with bilateral microtia severe enough to make a surgical approach to the cochlea difficult will be extremely uncommon. No such cases have been reported, although Klippel-Feil deformity seems the syndrome most likely to produce this set of circumstances. Abnormalities in the intratympanic course of the facial nerve have been associated with cochlear malformation, emphasizing the benefit of intra-operative facial nerve monitoring, and a technique suggested for safely avoiding an abnormally placed nerve. Fistulae of cerebrospinal fluid (CSF) and perilymph can complicate surgery and are relatively common in common cavity and Mondini malformations. Strategies for facilitating surgery in the presence of 'gushers', for measuring the pressure of a gusher and for placement of the cochlear implant electrode array are reviewed, with reports of fluctuating levels of electric current when implants lie in dysplastic cochleas. The relationship of implant performance to VIIIth nerve tissue in malformed cochleas is discussed, with a description of the histological findings in a common cavity cochlea. Techniques for identifying the absence of the cochlear nerve are reviewed. Stimulation of the facial nerve by cochlear implants has been described in cases of congenital malformation of the labyrinth but is relatively uncommon. Case reports of the benefit received by implanted children with congenital cochlear malformation have appeared since 1988. Most cases reported have not yet been followed for long enough to establish a clear picture of the outcome following cochlear implantation in such children; no centre has yet built up a large series of cases, but there have been two multicentre postal surveys. It seems likely that in cochlear malformation the range of potential outcomes in terms of hearing threshold and the development of speech perception and production will be similar to the range found in implanted children without cochlear dysplasia. However there is, as yet, no clear picture of the mean level of performance within this range.

Adolescent↗

PubMed2000

Minimising radiation dose to the lens in axial computed tomography of the temporal.

In this study, 25 randomly selected CT scans of temporal bones performed in a busy radiology department were retrospectively analysed with particular attention paid to the number of sections passing through the orbits. Thirteen examinations were found to include sections through the eyes, thereby resulting in unnecessary radiation to the lens. The importance of proper scanning technique is therefore emphasised. The mean radiation dose to the eyes in axial CT examination of the temporal bones was determined by the use of thermoluminescent dosimeters taped to the eyelids. The authors concluded that appropriate scanning techniques can reduce the radiation dose to the orbit whilst imaging the temporal bone. All the relevant information can usually be obtained without any of the sections passing through the lens. The radiation dose to the lens was increased when additional sections were performed to obtain information about the jugular fossa.

Humans↗

PubMed1999

Histopathological findings suggest the diagnosis in an atypical case of Pendred syndrome.

Radiological malformation of the labyrinth, specifically dilatation of the vestibular aqueduct, has been clearly established as a feature in the majority of patients with Pendred syndrome. Mutations of the Pendred syndrome (PDN) gene have been identified in this autosomal recessive form of deafness. There is no direct correlation between the nature of the underlying mutation and the clinical features of deafness, thyroid dysfunction and cochlear malformation. We report a family, the proband of which was thought to deafness secondary to congenital hypothyroidism. At autopsy, histopathological examination of this patient revealed a dilated vestibular aqueduct. Subsequent work on the family has confirmed the diagnosis of Pendred syndrome in the proband and her affected sister.

Adolescent↗

PubMed1999

The common cavity deformity of the ear. A precursor of meningitis but now being implanted.

The first succinct description of otogenic meningitis related to the common cavity deformity of the inner ear was made from a post mortem study of 150 years ago. Since then there has been much confusion with less severe malformations of the cochlea, but these patients can now be treated by cochlear implant. It is therefore necessary that an accurate appraisal of the state of the cochlea is made beforehand by computed tomography and by Magnetic Resonance Imaging.

Cerebrospinal Fluid Otorrhea↗

PubMed1999

Imaging for cochlear implants.

All patients in the Birmingham Cochlear Implant Programme underwent computerized tomography (CT) scanning and were assessed and images interpreted by the main author. Of the first 100 cases, 20 were considered to have abnormalities of the inner ears by CT imaging. It is concluded that the commonest abnormality was cochlear otospongiosis followed by labyrinthitis ossificans. Otospongiosis is well shown by CT which gives a good predicator of luminal patency. However, labyrinthus obliterans, although usually apparent on CT, is not reliably shown in all cases and T2 weighted magnetic resonance imaging (MRI) is better.

Cochlea↗

PubMed1998

Labyrinthine involvement in Langerhans' cell histiocytosis.

BACKGROUND: Langerhans' cell histiocytosis, a rare condition caused by the proliferation of abnormal Langerhans' cells ('LCH cells') and an accompanying granulomatous infiltrate, can affect several organs including the ear. External and middle ear involvement are common with a reported incidence as high as 61%. The bony labyrinth is resistant to erosion by the granulation tissue, thereby protecting the cochlea and vestibular structures. Probably for this reason, involvement of the inner ear is rare, with few case reports in the literature. PATIENTS: We report two girls, one with bilateral and the other with unilateral mastoid involvement, in whom there was invasion of the labyrinth. The first girl had 'single system' LCH affecting only bone and developed an acute hearing loss due to invasion of the cochlea, while the second had both bone and skin involvement and labyrinthine involvement was diagnosed on imaging prior to the onset of labyrinthine symptoms. CONCLUSION: Inner ear involvement can lead to permanent deafness, which may be prevented by early institution of treatment. Threatened inner ear involvement requires urgent systemic medical therapy with steroids, possibly combined with chemotherapy.

Child, Preschool↗

PubMed1998

Radiological malformations of the ear in Pendred syndrome.

Pendred syndrome comprises the association of severe congenital sensorineural deafness with thyroid pathology. Although it is the commonest form of syndromic hearing loss, the primary genetic defect remains unknown. The variable clinical presentation allied to the difficulty in securing the diagnosis have resulted in relatively poor documentation of the radiological features of this syndrome. We now present data on 40 patients, all complying with strict diagnostic criteria for the disorder, and describe our experience of the prevalence of specific malformations of the inner ear as well as comparing the relative merits of computed tomography (CT) and magnetic resonance imaging (MRI) in the investigation of this inherited condition. Deficiency of the interscalar septum in the distal coils of the cochlea (Mondini deformity) was found to be a common but probably not a constant feature of Pendred syndrome. However, enlargement of the endolymphatic sac and duct in association with a large vestibular aqueduct was present in all 20 patients examined by MRI. We conclude that thin section high resolution MRI on a T2 protocol in the axial and sagittal planes is the imaging investigation of choice.

Cochlea↗

PubMed1998

Cochlear implant failure due to unexpected absence of the eighth nerve--a cautionary tale.

We present a case of bilateral absence of the eighth cranial nerve in the internal auditory meatus (IAM). This caused total failure of responses after cochlear implantation in a six-year-old patient with congenital deafness. Pre-operative magnetic resonance (MR) imaging is important to show not only the anatomy of the middle and inner ears but also the structures in the IAM.

Child↗

PubMed1998

Molecular analysis of the PDS gene in Pendred syndrome.

Pendred syndrome is an autosomal recessive disorder characterized by the association between sensorineural hearing loss and thyroid swelling or goitre and is likely to be the most common form of syndromic deafness. Within the thyroid gland of affected individuals, iodide is incompletely organified with variable effects upon thyroid hormone biosynthesis, whilst the molecular basis of the hearing loss is unknown. The PDS gene has been identified by positional cloning of chromosome 7q31, within the Pendred syndrome critical linkage interval and encodes for a putative ion transporter called pendrin. We have investigated a cohort of 56 kindreds, all with features suggestive of a diagnosis of Pendred syndrome. Molecular analysis of the PDS gene identified 47 of the 60 (78%) mutant alleles in 31 families (includes three homozygous consanguineous kindreds and one extended family segregating three mutant alleles). Moreover, four recurrent mutations accounted for 35 (74%) of PDS disease chromosomes detected and haplotype analysis would favour common founders rather than mutational hotspots within the PDS gene. Whilst these findings demonstrate molecular heterogeneity for PDS mutations associated with Pendred syndrome, this study would support the use of molecular analysis of the PDS gene in the assessment of families with congenital hearing loss.

DNA Mutational Analysis↗

PubMed1997

CT screening for temporal bone abnormalities in idiopathic bilateral sensorineural hearing loss.

Bilateral sensorineural hearing loss can be caused by a variety of temporal bone abnormalities including primary cochlear otosclerosis, local and systemic bony diseases and some metabolic conditions. These may be identified using computerized tomography (CT), with attenuation recordings taken across the cochlear capsule (CT densitometry). Eighty patients with bilateral sensorineural hearing loss were screened over a period of six and a half years using this technique, and only three cases (3.8 per cent) of treatable disease were detected. Positive yields may be increased by screening selected cases with other clinical or biochemical stigmata of temporal bone disease.

Absorptiometry, Photon↗

PubMed1997

Large endolymphatic sac. A congenital deformity of the inner ear shown by magnetic resonance imaging.

Fluctuant and progressive hearing impairment in a patient with a wide vestibular aqueduct has been called the 'large vestibular aqueduct syndrome'. Recently reports of magnetic resonance imaging (MRI) studies describe enlargement of the endolymphatic sac and duct in patients shown to have large vestibular aqueducts by computed tomography (CT). A patient with progressive deafness was shown to have borderline or slightly enlarged vestibular aqueducts by re-formatted sagittal CT. However, MRI in axial and sagittal planes gave a more satisfactory demonstration of both aqueduct and endolymphatic sac enlargement.

Adult↗

PubMed1997

Pendred syndrome--100 years of underascertainment?

Pendred syndrome is an autosomal recessive condition classically characterized by deafness and goitre. Since both cochlear and thyroid pathology are required to secure the diagnosis, it is unclear whether the condition might present without the classical features. The perchlorate discharge test, the gold-standard investigation for Pendred syndrome, is non-specific, and in the absence of alternative means of confirming the diagnosis, its sensitivity is unknown. We used the recent mapping of the gene to chromosome 7q to identify pedigrees with a likely diagnosis of Pendred syndrome, and assessed the prevalence of clinical parameters of disease in affected patients. Thirty-six familial cases showed co-segregation between disease and the Pendred syndrome locus on chromosome 7q. Clinical and investigative findings were compared in index cases (n = 18) vs. affected siblings (n = 18). The overall prevalence of goitre was 73%, higher in index cases (94%) than in siblings (56%), many of whom had not previously been considered to have the condition. One perchlorate discharge test was false-negative (2.9%). Radiological malformations of the cochlea were identified in 86% of cases. Securing a diagnosis of Pendred syndrome may be difficult, especially in the single case. The perchlorate discharge test, although valuable, is difficult to undertake in the younger patient, and radiology may assist in diagnosing such patients.

Adolescent↗

PubMed1997

Pendred syndrome: evidence for genetic homogeneity and further refinement of linkage.

Pendred syndrome is the association between congenital sensorineural deafness and goitre. The disorder is characterised by the incomplete discharge of radioiodide from a primed thyroid following perchlorate challenge. However, the molecular basis of the association between hearing loss and a defect in organification of iodide remains unclear. Pendred syndrome is inherited as an autosomal recessive trait and has recently been mapped to 7q31 coincident with the non-syndromic deafness locus DFNB4. To define the critical linkage interval for Pendred syndrome we have studied five kindreds, each with members affected by Pendred syndrome. All families support linkage to the chromosome 7 region, defined by the microsatellite markers D7S501-D7S523. Detailed haplotype analysis refines the Pendred syndrome linkage interval to a region flanked by the marker loci D7S501 and D7S525, separated by a genetic distance estimated to be 2.5 cM. As potential candidate genes have as yet not been mapped to this interval, these data will contribute to a positional cloning approach for the identification of the Pendred syndrome gene.

Adolescent↗