PubMed Health⌕ Search

Biomedical subjects

T Sirimanna

Publications and source records attributed to T Sirimanna.

16 recordsLinked to original sources
PubMed2005

Chondrodysplasia punctata: case report and review of audiological and ENT features.

Chondrodysplasia punctata is a term referring to a clinically heterogeneous group of bone and cartilage dysplasias which cause characteristic epiphyseal stippling. The condition can involve the ear, nose and throat in diverse ways at many levels. We present a case of X-linked brachytelephalangic chondrodysplasia punctata, which illustrates the features of this condition particularly relevant to the audiological physician, otolaryngologist and neonatologist.

Bronchoscopy↗
PubMed2005

Audiological profile in Apert syndrome.

Apert syndrome is one of the craniosynostosis syndromes and is commonly associated with conductive hearing loss, but there are contradicting reports regarding the cause. Retrospective analysis of case notes of Apert syndrome patients seen between 1970 and 2003 was therefore undertaken. Seventy case notes were obtained; 59% were males. The incidence of congenital hearing impairment was 3-6%. Almost all had otitis media with effusion, which tends to persist into adulthood. More than 56% developed permanent low frequency conductive hearing loss by 10-20 years of age.

Acrocephalosyndactylia↗
PubMed2005

Management of hearing loss in Apert syndrome.

BACKGROUND: Apert syndrome is one of the craniosynostosis syndromes, with a birth prevalence estimated to be between 9.9 and 15.5/million, and accounts for 4.5 per cent of craniosynostoses. Although conductive hearing loss is common in Apert syndrome there are contradicting reports regarding the cause of this hearing loss. There is also no detailed information available on the management of hearing loss in Apert syndrome. MATERIALS AND METHODS: A retrospective analysis of case notes of Apert syndrome patients seen between 1970 and 2003 at Great Ormond Street Children's Hospital, London, was undertaken. RESULTS: Seventy case notes were obtained. The incidence of congenital hearing impairment was between 3 and 6 per cent. Almost all patients had otitis media with effusion (glue ear), which tended to persist into adult life. More than 56 per cent of cases developed permanent conductive hearing loss by 10-20 years. Repeated grommet insertion was common; even though 35 per cent had trouble with ear discharge and persistent conductive hearing loss. Statistically, grommets made no difference to the risk of developing permanent hearing loss. CONCLUSION: This study, of the largest number of Apert syndrome cases assembled to date, showed that early optimization of hearing with possible hearing aids needs to be considered. Repeated grommet insertion does not help in optimizing hearing, especially if ear discharge complicates the picture.

Acrocephalosyndactylia↗
PubMed2004

Evaluation of hearing thresholds in 3-month-old children with a cleft palate: the basis for a selective policy for ventilation tube insertion at time of palate repair.

Hearing thresholds in children with a cleft palate prior to cleft palate repair are not widely documented, and audiological criteria for short-term ventilation tube insertion do not exist. The aims of this prospective study are to estimate hearing thresholds in 40 children with a cleft palate by 3-month developmental age with auditory brainstem responses (ABRs) under natural sleep and to estimate a hearing threshold guideline for short-term ventilation tube insertion. Our results show a wide range of air conduction hearing thresholds using click ABRs (2-4 Hz), which ranged from 25 to 102 dBnHL in the left ear and from 25 to 80 dBnHL in the right ear with means of 53 and 49 and standard deviations of 17 and 13 respectively. The bone conduction thresholds ranged from 0 to 55 dBnHL with a mean of 26 and a standard deviation of 13. Eighty-three per cent of children had flat, type B, on high-frequency tympanograms, indicative of middle ear effusion. Thirty per cent of the infants had a cleft palate associated with a known syndrome. Currently, it is the authors' practice to use short-term ventilation tubes on a selective basis at the time of cleft palate repair when there is a conductive hearing loss of more than 55 dBnHL in the better ear as determined by ABR with type B high-frequency tympanograms. This threshold level takes into account electrophysiological and auditory pathway maturation discrepancies. With this as the guideline, between 28% and 35% of the children in this study would be eligible for surgery. This criterion still requires further validation.

Acoustic Impedance Tests↗
PubMed2004

Bone conduction auditory brainstem responses in infants.

The contribution of air conduction auditory brainstem response (AC-ABR) testing in the paediatric population is widely accepted in clinical audiology. However, this does not allow for differentiation between conductive and sensorineural hearing loss. The purpose of this paper is to review the role of bone conduction auditory brainstem responses (BC-ABR). It is argued that despite such technical difficulties as a narrow dynamic range, masking dilemmas, stimulus artifact and low frequency underestimation of hearing loss, considerable evidence exists to suggest that BC-ABR testing provides an important contribution in the accurate assessment of hearing loss in infants. Modification of the BC-ABR protocol is discussed and the technical difficulties that may arise are addressed, permitting BC-ABR to be used as a tool in the differential diagnosis between conductive and sensorineural hearing. Two relevant case studies are presented to highlight the growing importance of appropriate management in early identification of hearing loss. It can be concluded that BC-ABR should be adopted as a routine clinical diagnostic tool.

Bone Conduction↗
PubMed2003

A model of neuronopathic Gaucher disease.

Gaucher disease (GD) is a lysosomal disorder involving the accumulation of glucocerebroside in the liver, spleen, bones and brain. Some patients exhibit only systemic disease (type I), but others have additional neurological signs which may lead to rapid neurodegeneration in infancy (type II) or take a more intermediate course (type III). Types II and III are collectively known as neuronopathic Gaucher disease (NGD). Systemic disease can now be treated by enzyme replacement therapy (ERT), but its efficacy in NGD is limited. Two infants who presented with bulbar palsy and failure to thrive were enzymatically diagnosed at 8 months with NGD. They were started on high-dose ERT (120 IU/kg every 2 weeks). Both underwent serial oculomotor assessment and an audiological battery, including visual reinforcement audiometry, otoacoustic emissions, and the auditory brain stem response (ABR). Biochemical markers showed an incomplete systemic response to ERT, but neurological deterioration was relentless, leading to death at 16 and 25 months. Oculomotor testing revealed a complete absence of saccadic eye movements and progressive bilateral sixth nerve palsy in one. Audiological assessment revealed progressive deterioration of ABRs, but with normal peripheral hearing and otoacoustic emissions. Both infants showed neurological deterioration in spite of high-dose ERT. The audiological findings suggested a loss of inner hair cell pathway function with preserved outer hair function, similar to what is seen in auditory neuropathy. The unusual pattern of audiological and oculomotor abnormalities is consistent with an excitotoxic mechanism predisposing nerve cells to glucocerebroside toxicity. Such excitotoxic damage may be amenable to direct therapeutic intervention.

Airway Obstruction↗
PubMed2003

Auditory event-related potentials in the assessment of auditory processing disorders: a pilot study.

The aim of this pilot study was to investigate whether children with a suspected auditory processing disorder (sAPD) in the presence of normal hearing, differ significantly from normal age-matched controls on particular parameters of auditory event-related potentials. We assessed nine children (mean age 9.5 years) in whom the clinical profile and the results in a screening test for auditory processing disorder (SCAN/SCAN-A) suggested the presence of an auditory processing disorder, and nine age-matched normal control subjects, using auditory event-related potentials (ERP) to phonemes/ba/(standard) and/da/(deviant). Analysis of the auditory ERP recordings revealed an enlarged P85 - 120 and attenuated N1 and P2 in all sAPD children compared to controls. We also found significantly increased N1 peak latency, and a larger peak to peak amplitude of the P85 - 120-N1 and P2-N2 and smaller peak to peak amplitude of the N1-P2 in the sAPD children. Subtraction of the standard auditory ERP from the deviant revealed a mismatch negativity with no significant differences in duration, peak or onset latency between the control subjects and sAPD. Our results indicate that neurophysiological measures may identify a group of children with specific problems suggestive of an auditory processing disorder in the absence of an obvious structural or functional lesion who warrant further study in order to assess whether these findings reflect delayed CNS myelination.

Acoustic Stimulation↗
PubMed2001

Audiometric abnormalities in children with Gaucher disease type 3.

Exogenous enzyme replacement therapy achieves satisfactory biomedical correction in Gaucher type 1 disease and may halt or reverse neurological progression in type 3, while it does not appear to influence the outcome in type 2. In view of the therapeutic possibilities, early detection and monitoring of type 3 Gaucher disease, as well as evaluation of the effectiveness of enzyme therapy on neuronopathic involvement is necessary. The objective of this study was to evaluate the extent of brainstem disease in children with proven Gaucher type 3, by means of an audiological test battery. We studied 9 patients with Gaucher type 3 disease. The tests included baseline audiometric tests, as well as auditory brainstem evoked responses (ABR), acoustic reflexes and medial olivo-cochlear suppression by contralateral noise tests, that involve overlapping but not identical efferent and afferent pathways and brainstem structures. We found a constellation of abnormalities including bilaterally raised acoustic reflexes, poor medial olivo-cochlear suppression, and very poor brainstem evoked potentials. These abnormalities could be due to a single lesion in the dorsomedial brainstem, or to multiple lesions, and further study is needed to clarify this issue. Combined audiological tests may provide information on the severity of the neurological involvement and should therefore be part of a standard assessment for the diagnosis as well as for long term neurological monitoring of Gaucher type 3 patients.

Acoustic Impedance Tests↗
PubMed2001

Eighth nerve aplasia and hypoplasia in cochlear implant candidates: the clinical perspective.

OBJECTIVE: To identify the clinical and radiologic characteristics of aplasia and hypoplasia of the eighth nerve. STUDY DESIGN: Retrospective case-note review. SETTING: Cochlear implant program. PATIENTS: All children at the authors' institution in whom the cochlear implant assessment failed because of absence or hypoplasia of the eighth nerve. INTERVENTION: Computed tomography of petrous bones and magnetic resonance imaging of the brain. MAIN OUTCOME MEASURES: Presence or absence of eighth nerve and other radiologic factors contraindicating implantation. RESULTS: Of 143 cochlear implant candidates, 237 were judged ineligible for cochlear implantation. The preimplant assessment failed in 10 candidates of 143 because of bilateral aplasia or hypoplasia of the eighth nerve (7 cases) or unilateral aplasia or hypoplasia of the eighth nerve and a contraindication to operation on the other side (3 cases). The aplasia or hypoplasia of the eighth nerve was confirmed by magnetic resonance imaging in seven cases (5%): six were syndromic (3 CHARGE, 1 VATER-RAPADILLINO, 1 Möbius, 1 Okihiro), and one was nonsyndromic autosomal-recessive. All seven children had delayed motor milestones and absence of auditory brainstem responses. CONCLUSION: Aplasia and hypoplasia of the eighth nerve are not uncommon in pediatric cochlear implant candidates, particularly in the presence of a syndrome such as CHARGE. Magnetic resonance imaging of the brain is mandatory before implantation because it can identify the presence or absence of the eighth nerve. Parents of children with profound hearing loss, delayed motor milestones, absence of auditory brainstem responses, and a syndromic diagnosis, should be made aware of this possible abnormality.

Brain↗
PubMed2000

Temporal bone computed tomography findings in bilateral sensorineural hearing loss.

AIM: To examine the yield of computed tomography (CT) of the temporal bones when investigating sensorineural hearing loss (SNHL) and to identify factors associated with CT findings. METHODS: Retrospective analysis of 116 consecutively investigated children with bilateral SNHL at the audiology department of Great Ormond Street Hospital, London. Main outcome measures were CT results, hearing loss parameters, history, and clinical examination. RESULTS: A total of 33 (28.4%) CT scans were identified as abnormal. Children with profound and/or progressive hearing loss and/or craniofacial abnormalities were more likely to have an abnormal CT scan and together accounted for 25 abnormal CT scans. Sex, consanguineous parents, or family history of SNHL were not associated with CT findings. Dilated vestibular aqueduct was significantly correlated with the presence of progressive SNHL. CONCLUSIONS: All children with SNHL should undergo radiological investigation of the petrous bones/inner ear; abnormalities are more likely to be found in cases with craniofacial abnormalities, or profound or progressive hearing loss. The decision whether to perform a CT or magnetic resonance imaging will depend on scanner availability, expertise, and management considerations, but cochlear implant candidates will require both.

Child↗
PubMed1999

Unilateral sensorineural hearing loss and its aetiology in childhood: the contribution of computerised tomography in aetiological diagnosis and management.

OBJECTIVES: The objective of this study was to identify factors correlated with the CT outcome and to examine the contribution of the CT scan in the aetiological diagnosis and management of unilateral sensorineural hearing loss in childhood. METHODS: The records of 35 consecutively investigated patients by the Audiology Department of Great Ormond Street Hospital between January 1996 and June 1998 were reviewed. The CT results, population sample characteristics, initiation of further investigations after the CT results and management decisions based on the CT results were tabulated and analysed. RESULTS: In a series of 35 consecutively investigated children with unilateral sensorineural hearing loss, 11 CT scans were identified as abnormal. The CT findings were: labyrinthitis ossificans (3), unilaterally dilated vestibular aqueduct (2), bilaterally dilated vestibular aqueduct (2), unilateral deformity of the cochlea ('Mondini') (1), unilateral severe labyrinthine dysplasia (1), unilateral markedly narrow internal acoustic meatus (1), bilaterally dilated lateral semicircular canals (1). The presence of progressive hearing loss was a significant predictor of abnormal CT outcome, while the severity of hearing loss was not. The CT scans offered valuable information regarding the aetiological diagnosis in all cases and, in addition, prompted the appropriate vestibular rehabilitation in three cases, further investigations in four (with dilated vestibular aqueduct) and hearing preservation counselling in two (bilateral DVA) (seven out of 35 = 20%). CONCLUSION: All children with unilateral sensorineural hearing loss should have a CT scan of the petrous pyramids/IAMs performed at some stage, as not only aetiology but also prognosis and management of these cases may be significantly influenced by the CT outcome.

Adolescent↗
PubMed1999

Useful residual hearing despite radiological findings suggestive of anacusis.

A severe malformation of the inner ear, often referred to as severe labyrinthine dysplasia or common cavity deformity, consists of an absent or dilated cochlear basal coil, wide communication with the vestibule and a tapered internal acoustic meatus and can be associated with absent hearing. We discuss two children with severe labyrinthine dysplasia as shown by computed tomography (CT) scans and, in the first case, an absent VIIIth nerve bilaterally shown by magnetic resonance imaging (MRI). In 1995, both cases were precluded from cochlear implantation, on the basis of the absent VIIIth nerve (first case) and increased risk of CSF leak during operation (second case). However, audiometric results and vocalization patterns of both children suggested the presence of some residual hearing function, while recently reported specific surgical techniques have been found to be safe and effective in the cochlear implantation of the common cavity deformity. The management of such cases should be decided on the grounds of a full audiological assessment in conjunction with the radiological features, in the light of current surgical trends shown to be safe and effective.

Audiometry, Evoked Response↗
PubMedDate not supplied

Application of the Audioscan in the detection of carriers of genetic hearing loss.

The authors describe the establishment of normative stimulus parameters for the Audioscan, an automated sweep frequency audiometer, for its application in the detection of audiometric notches in carriers of recessive genetic hearing loss. A sweep rate of 30 s/octave over the frequency range 300 to 4000 Hz pulsing at 2.5 pulses/s at -5 dB with a step size of 5 dB were ultimately adopted. The criterion for notches was 15 dB or greater within the frequency range 500-3000 Hz. Adopting this criterion, 14.2% of control subjects had notches. Among parents of children with non-syndromal recessive hearing loss 55% were found to have notches. Notches were found more frequently among mothers and sisters than among fathers and brothers of the patients.

Adult↗