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R T Ramsden

Publications and source records attributed to R T Ramsden.

At least 37 records · Page 2Linked to original sources
PubMed2002

Gaze-evoked tinnitus following acoustic neuroma resection: a de-afferentation plasticity phenomenon?

A review of the prevalence of gaze-evoked tinnitus in patients who have undergone acoustic neuroma resection was undertaken. The relationship of gaze-evoked tinnitus to tumour size, pre-existing tinnitus, side of the lesion or direction of eye gaze was also analysed. The design was a retrospective review of patients who underwent total unilateral translabyrinthine vestibular schwannoma resection by the senior author. Patients 1 year and 5 years following surgery were assessed. Results were obtained by either direct questioning in a clinical setting or via questionnaire. Data was collected on 36 subjects at an average of 14.6 months postoperatively (range 8-20 months) and on 32 subjects at an average 62 months postoperatively (range 56-68 months). Of the first group, 13 had evidence of gaze-evoked tinnitus (36%) compared with six (19%) of the second. The presence of preoperative tinnitus was a significant variable in univariate and multivariate analyses of the presence of postoperative tinnitus and postoperative gaze-evoked tinnitus. In a reduced model multivariate logistic regression using the two groups combined, the significant independent risk factors for gaze-evoked postoperative tinnitus were female sex (P = 0.046, odds ratio = 4.3), right side surgery (P = 0.02, odds ratio = 5.5) and pre-existing tinnitus (P = 0.008, odds ratio = 24.2). Gaze-evoked tinnitus is more common than previously reported in patients undergoing vestibular schwannoma resection. The underlying pathophysiology remains unclear but neural plasticity following unilateral de-afferentation remains a viable theory. The reduced prevalence over time suggests that this phenomenon may represent an active reinnervation process within the brain, which stabilizes with time. The significance of pre-existing tinnitus suggests that mechanisms of neural reorganization modify an existing physiological pathway. Further research is required into the longevity of this phenomenon, preferably with longitudinal studies.

Adult↗
PubMed2002

Molecular genetic analysis of the NF2 gene in young patients with unilateral vestibular schwannomas.

Neurofibromatosis type 2 (NF2) must be suspected in patients presenting with a unilateral vestibular schwannoma at a young age who are therefore at theoretical risk of developing bilateral disease. We identified 45 patients aged 30 years or less at the onset of symptoms of a unilateral vestibular schwannoma. Molecular genetic analysis of the NF2 gene was completed on peripheral blood samples in all 45 and on 28 tumour samples. No pathogenic NF2 mutations were identified in any of the blood samples. NF2 point mutations were identified in 21/28 (75%) tumour samples and loss of heterozygosity (LOH) in 21/28 (75%) tumour samples. Both mutational hits were identified in 18/28 (65%) tumour samples. In one multilobular tumour, one (presumably first hit) mutation was confirmed which was common to different foci of the tumour, while the second mutational event differed between foci. The molecular findings in this patient were consistent with somatic mosaicism for NF2 and the clinical diagnosis was confirmed with the presence of two meningiomas on a follow up MRI scan. A further patient developed a contralateral vestibular schwannoma on a follow up MRI scan in whom neither of the truncating mutations in the vestibular schwannoma were present in blood. It is important when counselling patients with unilateral vestibular schwannomas to identify (1) those at risk of bilateral disease, (2) those at risk of developing other tumours, and (3) other family members at risk of developing NF2. Comparing tumour and blood DNA cannot exclude mosaicism in the index case and cannot, therefore, be used to predict those at risk of developing further tumours. However, identification of both mutations or one mutation plus LOH in the tumour and exclusion of those mutations in the blood samples of the sibs or offspring of the affected case may be sufficient to render further screening unnecessary in these relatives.

Adolescent↗
PubMed2002

Endolymphatic sac tumours.

Endolymphatic sac tumours (ELST) are rare tumours of the petrous temporal bone. They may arise sporadically or be associated with von Hippel-Lindau disease. Their differential diagnosis is discussed. We present the clinical and histopathological features of two new patients with ELST and outline the management of their condition. In addition, we review a third case previously reported as a choroid plexus papilloma in which the histology has been re-assessed and the diagnosis changed to ELST. The controversy regarding the cellular origins of adenomatous tumours of the temporal bone is highlighted.

Adenocarcinoma↗
PubMed2001

Magnetic resonance imaging in the investigation of sensorineural hearing loss: is contrast enhancement still necessary?

High resolution T2-weighted magnetic resonance (MR) imaging has been proposed as a rapid, inexpensive means of investigating patients with sensorineural deafness, particularly to exclude vestibular schwannomas. Whether the accepted 'gold standard' of contrast-enhanced T1-weighted images can be omitted, however, remains controversial. Over a 22-month period the use of axial turbo-spin echo T2-weighted images (T2W) were prospectively compared with contrast-enhanced T1-weighted spin echo scans in the evaluation of 513 patients presenting with audiovestibular symptoms. A 2-D T2W turbo spin echo (TSE) sequence with 3 mm slices was used in 340 patients while a 3-D sequence with overlapping 1 mm slices was used in 173 patients. The T2-weighted image findings were documented and subsequently compared with contrast-enhanced images. With the 2-D sequence 24 patients (25 lesions) had internal auditory meatus (IAM)/cerebello-pontine angle (CPA) masses identified by contrast-enhanced T1-weighted images, all of which were seen on the T2-weighted TSE sequence; there was one false positive 'mass' on the T2-weighted scans and one false negative case of IAM dural enhancement on T1-weighted imaging; six were considered normal initially on the T2-weighted images although three were subtly abnormal in retrospect. With the 3-D sequence three acoustic neuromas were all identified correctly with no false positive and only one false negative result (labyrinthitis). The 2-D and 3-D images were judged technically inadequate for clinical assessment in 15 and nine per cent respectively. We conclude that mass lesions of the IAM/CPA can be reliably identified on T2W TSE imaging but labyrinthine lesions may be missed without contrast enhancement. This is of particular importance in planning the management of neurofibromatosis type 2. Non-neoplastic disorders of the inner ear are also likely to be missed.

Adolescent↗
PubMed2001

"Bones of Contention". The donation of temporal bones for dissection after the organ-retention scandals.

It is essential for the Otologist in training to become familiar with the anatomy of the temporal bone. Generations of trainees have acquired this knowledge, together with basic surgical skills and techniques by dissection of cadaver temporal bones. In recent years, however, the supply of temporal bones for dissection has become a contentious issue in many British hospitals. Media and public attention has recently focused on issues surrounding the retention of human tissues following post-mortem examinations. In response, the Chief Medical Officer, the Royal College of Pathologists in the UK, the Faculty of Pathology of the Royal College of Physicians in Ireland, the British Medical Association, and other bodies have issued new guidelines that are of relevance to the Otolaryngologist. This paper gives details of some of the UK guidelines and where they can be accessed. A copy of the Royal College of Pathologists preferred post-mortem consent form is presented. The authors' experience in Manchester is discussed and details of an information leaflet on the subject of temporal bone donation are given. It is concluded that, with knowledge of the existing guidelines and good communication with other hospital colleagues, as well as families of the deceased, it is still possible legally to obtain temporal bones for dissection.

Education, Medical, Graduate↗
PubMed2001

Peripheral primitive neuroectodermal tumour (pPNET) of the cerebellopontine angle presenting in adult life.

We report a case of a peripheral neuroectodermal tumour (pPNET) of the cerebellopontine angle of a 67-year-old woman. The patient's age at presentation was highly unusual. This case highlights the difficulties encountered, both clinically and pathologically, in securing the correct diagnosis of such a rare condition presenting in this relatively inaccessible area. The development of the nomenclature and classification of neuroectodermal tumours is traced. Recent advances in immunohistochemistry and genetic typing have shown the close relationship between pPNET and the previously difficult to classify Ewing's sarcoma and Askin's tumour.

12E7 Antigen↗
PubMed2000

Assessment of real-time clinical facial function during vestibular schwannoma resection.

OBJECTIVES: To describe a technique for quantifying residual facial function after vestibular schwannoma surgery. The intraoperative electrophysiological results are correlated with immediate postoperative clinical facial function to assess technique validity. STUDY DESIGN: Prospective blinded study. METHODS: Thirty-two patients undergoing translabyrinthine resection of vestibular schwannoma were included. Compound muscle action potential (CMAP) amplitude was calculated to supramaximal stimulation of the facial nerve, proximal to vestibular schwannoma compression, at the brain stem. The procedure was repeated after tumor removal. Comparison of the two CMAP amplitudes enabled estimation of change in facial function during surgery. The data were correlated with intracranial tumor diameter and immediate postoperative clinical facial function. RESULTS: CMAP amplitude recorded after tumor resection correlated with immediate postoperative clinical facial function (0.879, P < .01). Correlation was improved when residual facial function was calculated (0.944, P < .01). In contrast, preoperative tumor size had relatively poor correlation with immediate postoperative facial function (0.688, P < .01). CONCLUSIONS: Comparison of electrophysiological data before and after tumor removal reduces intersubject variability resulting from intersubject variation in facial muscle morphology. Residual facial function closely correlates with immediate postoperative clinical facial function, assessed using the House-Brackmann grading system. From the data presented, the technique can inform the surgeon of current clinical facial function at any point during the dissection process.

Action Potentials↗
PubMed2000

Facial nerve action potentials: a study to assess waveform reliability.

OBJECTIVE: To assess the reliability of the orthodromic facial nerve action potential (FNAP), recorded from the intratemporal portion of the facial nerve on stimulation within the cerebellopontine angle. STUDY DESIGN: Prospective study. SETTING: Tertiary referral center. PATIENTS: Ten consecutive patients undergoing translabyrinthine resection of vestibular schwannoma. INTERVENTION: Diagnostic. MAIN OUTCOME MEASURES: Ten consecutive FNAPs were recorded on stimulation of the facial nerve within the cerebellopontine angle. The FNAP recording probe was placed directly on the nerve surface after the fallopian canal was opened at the second genu. Ten consecutive compound muscle action potentials (CMAPs) were recorded simultaneously from surface electrodes overlying the facial musculature, by use of a standardized electrode placement technique. The stimulating and recording equipment were removed (excluding CMAP surface electrodes) and reapplied, and FNAP and CMAP data were recorded for a second time (test/retest). Peak-to-peak amplitudes of all waveforms were calculated. RESULTS: The average FNAP peak-to-peak amplitude for all patients was larger than the CMAP peak-to-peak amplitude (2.60 mV and 1.07 mV, respectively). Random effects analysis of variance was performed to assess the individual components of variation. This showed that CMAP was less variable than FNAP for replicate error (10 consecutive FNAPs and CMAPs) and test/retest error. However, subject variance was less for FNAP, where subject variance was by far the largest contributor to overall variation. The reliability coefficient for FNAP was 0.995 and for the CMAP was 0.982, where absolute reliability is 1.0. CONCLUSION: These data confirm that the FNAP, recorded by the technique described here, is a reliable waveform when compared with the CMAP and is a valid method for assessing facial nerve function.

Action Potentials↗
PubMed1999

Auditory rehabilitation in neurofibromatosis type 2: a case for cochlear implantation.

Cochlear implantation has a limited but definite role in the rehabilitation of certain neurofibromatosis type 2 (NF2) patients. The presence of a dead ear either before, or after, tumour removal does not necessarily imply loss of function in the eighth nerve; in some instances the hearing loss will be cochlear. Promontory or round window electrical stimulation may help to identify those individuals with surviving eighth nerve function. In such patients multichannel cochlear implantation promises a better level of audition than the auditory brain stem implant. This paper highlights such a case and the management problems are discussed.

Adolescent↗
PubMed1999

Cochlear implantation following temporal bone fracture.

Seven cases of profound hearing impairment following either unilateral or bilateral temporal bone fracture are presented who were implanted with the Nucleus 22 channel or Ineraid devices. Six patients suffered bilateral temporal bone fractures. One patient had prior congenital unilateral profound hearing impairment. This patient suffered a unilateral temporal bone fracture. Six patients became regular users of their implants. One gained little benefit and became a non-user. Two of the regular users experienced facial nerve stimulation, which could not be programmed out. In these two cases the implant was removed and the contralateral ear successfully implanted. Implant-aided audiometry demonstrated a hearing threshold of 40-50 dB at nine months after switch-on. The reliability of computed tomography (CT) scanning in predicting cochlear patency in cases of temporal bone fracture will be discussed. The benefit of complimentary imaging with magnetic resonance (MR) is highlighted.

Adolescent↗
PubMed1999

The large vestibular aqueduct syndrome: the role of cochlear implantation in its management.

In recent years the large vestibular aqueduct syndrome has become an increasingly recognized cause of a progressive sensorineural hearing loss. Cochlear implantation, although not correcting the bony abnormality, does offer an avenue for rehabilitation for affected individuals and initial results are encouraging. Of 15 patients identified with the large vestibular aqueduct syndrome we have implanted seven (five adults and two children). All patients underwent an uneventful electrode insertion with uncomplicated postoperative periods. Three of our adult patients are showing very good initial results with BKB speech recognition scores of 100%, 74% and 66% with the implant alone. It is still early days with the children, but initial results are encouraging. A full review of the large vestibular aqueduct syndrome is given along with our results.

Adolescent↗
PubMed1999

Imaging of temporal bone brain hernias: atypical appearances on magnetic resonance imaging.

Brain tissue with or without its dural covering may protrude into the temporal bone through a defect in the tegmen tympani. Infection or granulation tissue, with or without cholesteatoma may make diagnosis difficult. While computed tomography (CT) may demonstrate a bony defect, it is difficult to distinguish between herniated brain, cholesteatoma or granulation tissue. Magnetic resonance imaging (MRI) clearly demonstrates healthy herniated brain tissue, but ischaemic or necrotic elements may mimic other lesions. We present a series of five patients with brain hernia, highlighting the spectrum of preoperative radiological appearances, and some of the difficulties encountered in interpreting these images. MRI demonstrated herniation of healthy brain in two patients but in three, showed irregular soft tissue with signal characteristics consistent with cholesteatoma. Surgery in these three patients demonstrated necrotic brain with coexisting cholesteatoma in two. Brain hernias are often necrotic and may have morphological and signal characteristics similar to cholesteatoma with which they may coexist.

Adolescent↗
PubMed1999

Intraoperative electromyography for predicting facial function in vestibular schwannoma surgery.

OBJECTIVE: To assess the validity of intraoperative minimal stimulation threshold (MST) for predicting long-term facial function after vestibular schwannoma surgery. STUDY DESIGN: Prospective blinded study. METHODS: MST after tumor dissection and postoperative clinical facial function, assessed using the House Brackmann grading system (HB), were used to predict long-term clinical facial function, recorded at least 6 months after surgery. RESULTS: Two hundred and nine consecutive patients fulfilled selection criteria and 184 had successful intraoperative electrophysiologic monitoring and were eligible for further study. MST of 0.05 mA had moderate accuracy for predicting good long-term facial function, with 94% sensitivity, 91% positive predictive value (PPV), 60% specificity, and 70% negative predictive value (NPV). A more relevant group of 77 patients with poor postoperative facial function (HB III-VI) were assessed for predicting good long-term function. Applying this criteria, test accuracy fell, with 83% sensitivity, 64% PPV, 60% specificity, and 75% NPV. Postoperative clinical facial function had a greater accuracy for predicting good long-term function, with 83% sensitivity, 79% PPV, 75% specificity, and 79% NPV. A model of predicted probabilities of good outcome (HB I and II) was derived from a logistic regression with two additive predictors (postoperative HB and MST). This demonstrated that for patients with postoperative HB grade V, MST aided prediction. CONCLUSIONS: Intraoperative stimulation thresholds, when assessed against a relevant group of patients with poor postoperative facial function, had poor predictive accuracy. The severity of immediate postoperative clinical facial function was the most accurate predictor of long-term outcome. MST aided long-term prediction in a small but relevant group of patients with postoperative HB grade V facial function.

Cerebellar Neoplasms↗
PubMed1999

Paediatric presentation of type 2 neurofibromatosis.

BACKGROUND: Neurofibromatosis type 2 (NF2) is a highly penetrant autosomal dominant condition predisposing affected individuals to schwannomas and meningiomas. The proportion of children presenting with meningioma or schwannoma who have NF2 is not well described, and neither is the mode of presentation in most children with the inherited disease. AIMS: To determine the frequency of childhood meningioma and schwannoma cases caused by NF2 and the mode of presentation. METHODS: The records of the Manchester Children's Tumour Registry from 1954 were searched for cases of meningioma and schwannoma. Paediatric presentation in a large UK series of NF2 was also studied. RESULTS: 18% (61/334) of patients with NF2 on the UK database presented in the paediatric age group (0-15 years), frequently with the symptoms of an isolated tumour. More than half had no family history to alert the clinician to their susceptibility. Three of 22 children presenting with a meningioma on the Manchester Children's Tumour Registry have gone on to develop classic features of NF2. CONCLUSIONS: Clinicians should suspect NF2 in children presenting with meningioma, schwannoma, and skin features, such as neurofibromas/schwannomas, but fewer than 6 café au lait patches, who thus fall short of a diagnosis of neurofibromatosis type 1.

Child↗