Network


Latest external collaboration on country level. Dive into details by clicking on the dots.

Hotspot


Dive into the research topics where Geoffrey Parker is active.

Publication


Featured researches published by Geoffrey Parker.


American Journal of Neuroradiology | 2011

Transverse Sinus Stenting for Idiopathic Intracranial Hypertension: A Review of 52 Patients and of Model Predictions

Rebekah M. Ahmed; Mark Wilkinson; Geoffrey Parker; Matthew J. Thurtell; J. Macdonald; Peter McCluskey; R. Allan; V. Dunne; M. Hanlon; Brian Owler; G.M. Halmagyi

Current thinking is that transverse sinus stenosis with significant pressure gradient across the narrowing may play a role in pseudotumor cerebri and that treatment may improve symptoms. Here, the authors review their experience with 52 patients who were clinically followed for 2–8 months after stenting. During this time all pressure gradients improved and symptoms were abolished. Symptom relapse occurred in 6 patients and all showed sinus restenosis. At the end of the study period, 49 of 52 patients were cured of their headaches and the authors concluded that transverse sinus stenting is beneficial in this clinical setting. BACKGROUND AND PURPOSE: Transverse sinus stenosis is common in patients with IIH. While the role of transverse sinus stenosis in IIH pathogenesis remains controversial, modeling studies suggest that stent placement within a transverse sinus stenosis with a significant pressure gradient should decrease cerebral venous pressure, improve CSF resorption in the venous system, and thereby reduce intracranial (CSF) pressure, improving the symptoms of IIH and reducing papilledema. We aimed to determine if IIH could be reliably treated by stent placement in transverse sinus stenosis. MATERIALS AND METHODS: We reviewed the clinical, venographic, and intracranial pressure data before and after stent placement in transverse sinus stenosis in 52 of our own patients with IIH unresponsive to maximum acceptable medical treatment, treated since 2001 and followed between 2 months and 9 years. RESULTS: Before stent placement, the mean superior sagittal sinus pressure was 34 mm Hg (462 mm H20) with a mean transverse sinus stenosis gradient of 20 mm Hg. The mean lumbar CSF pressure before stent placement was 322 mm H2O. In all 52 patients, stent placement immediately eliminated the TSS pressure gradient, rapidly improved IIH symptoms, and abolished papilledema. In 6 patients, symptom relapse (headache) was associated with increased venous pressure and recurrent stenosis adjacent to the previous stent. In these cases, placement of another stent again removed the transverse sinus stenosis pressure gradient and improved symptoms. Of the 52 patients, 49 have been cured of all IIH symptoms. CONCLUSIONS: These findings indicate a role for transverse sinus stent placement in the management of selected patients with IIH.


Journal of Clinical Neuroscience | 2002

Cranial venous outflow obstruction in the pseudotumour syndrome: incidence, nature and relevance

I. Johnston; Christopher Kollar; S. Dunkley; N. Assaad; Geoffrey Parker

This study reports a retrospective analysis of the evidence of cranial venous outflow pathology in 188 patients with pseudotumour syndrome (PTS) investigated over the period 1968-1999. Standard methods of investigation appropriate to the period were used, i.e. cerebral angiography, CT and MR scanning. Recently, some patients had specific venous studies including intraluminal cranial venous sinus pressure measurements. A sub-group (25 patients) was investigated for haematological abnormalities. The overall incidence of cranial venous outflow abnormality was 19.7% (37 cases). In decades, related to the predominant investigative method, the figures were: to 1979, 4.2% (2 cases); to 1989, 15.0% (8 cases); to 1999, 31.0% (27 cases). A cause of the venous abnormality was identified in 20 cases, most commonly haematological and iatrogenic. In 17 patients (all females) no cause was identified. Fifteen of the 25 patients (60%) tested specifically were found to have a haematological abnormality, although no correlation was shown between this and a demonstrable venous outflow abnormality. The conclusion was drawn that there is a high incidence (close to one-third) of venous outflow abnormalities in PTS with detailed investigation. Issues of mechanism and therapy are discussed.


Annals of Otology, Rhinology, and Laryngology | 1997

Vestibular Abnormalities in Charge Association

Toshihisa Murofushi; Robert I. Graham; Robert A. Ouvrier; Merl Da Silva; Geoffrey Parker; G. Michael Halmagyi

We report the vestibular abnormalities in 5 patients with the CHARGE association (Coloboma, Heart disease, Atresia of choanae, Retarded growth and development and/or central nervous system anomalies, Genital hypoplasia, and Ear anomalies). All patients had absent vestibular function as indicated by absent vestibulo-ocular reflexes and severe imbalance on simultaneous deprivation of proprioception and vision, as well as delayed motor development. All 6 semicircular canals were aplastic in each of the patients. While cochlear function was severely reduced in 6 of the 10 ears, it was absent only in 3 ears and was actually intact below 3 kHz in 1 ear. All 10 bony cochleas were present on computed tomography, and although 7 appeared abnormal, 3 appeared normal. This study confirms that absence of the bony semicircular canals in the presence of a bony cochlea is a characteristic finding in CHARGE association. It also demonstrates that these disproportionate structural abnormalities are reflected in the functional abnormalities: absent vestibular function with preservation of some cochlear function.


British Journal of Neurosurgery | 2003

Pseudotumour cerebri, CSF rhinorrhoea and the role of venous sinus stenting in treatment.

Brian Owler; R. Allan; Geoffrey Parker; Michael Besser

We present a case of pseudotumour cerebri (PTC), which is important as it illustrates the effects of chronically raised CSF pressure, the relationship between PTC and venous sinus obstruction and the successful treatment of PTC using a venous sinus stent. A 38-year-old woman, previously diagnosed with PTC and unsuccessfully treated 10 years previously represented with spontaneous CSF rhinorrhoea. Imaging revealed dramatic changes of chronically raised CSF pressure and a defect in the anterior cranial fossa. The CSF leak was corrected surgically and a lumbo-peritoneal shunt inserted to correct a large postoperative subgaleal CSF collection. Direct retrograde cerebral venography (DRCV) demonstrated venous sinus obstruction due to a filling defect. This was associated with a pressure gradient and a high superior sagittal sinus pressure. The venous sinus obstruction was successfully treated with a venous sinus stent and the lumbo-peritoneal shunt was removed. Chronically raised CSF pressure in untreated cases of PTC may cause widespread changes in the skull, which in this case, culminated in a spontaneous CSF leak despite relatively mild headache and visual symptoms. Furthermore, cases of PTC secondary to venous sinus obstruction may be successfully treated using venous sinus stenting. The index of suspicion for venous sinus stenosis or obstruction should be raised in the investigation of patients with PTC.


American Journal of Neuroradiology | 2014

Transverse Sinus Stenting for Pseudotumor Cerebri: A Cost Comparison with CSF Shunting

Rebekah M. Ahmed; F. Zmudzki; Geoffrey Parker; Brian Owler; G.M. Halmagyi

BACKGROUND AND PURPOSE: Transverse sinus venous stent placement has been shown to lower intracranial pressure in patients with venogenic pseudotumor cerebri and to reverse, or at least stabilize, its symptoms and signs. There have been no studies comparing the cost of venous stenting with the time-honored treatment for pseudotumor cerebri–CSF shunting. The purpose of this study was to compare the cost of trasverse sinus stenting versus CSF shunting for the treatment of pseudotumor cerebri. MATERIALS AND METHODS: This work was a retrospective cost analysis of individual resource use in 86 adults who were stented for pseudotumor cerebri during a 12-year period compared with resource use in 110 children who were shunted for hydrocephalus during a 3-year period. RESULTS: There was no significant difference between the cost of inserting an initial venous stent (


Journal of Clinical Neuroscience | 2011

Interventional treatment of carotid cavernous fistula

Richard C. Barry; Mark Wilkinson; Rebekah M. Ahmed; Charmaine S.M. Lim; Geoffrey Parker; Peter McCluskey; G. Michael Halmagyi

13,863 ± 4890) versus inserting an initial CSF shunt (


International Journal of Cardiology | 2014

Impact of new task force criteria in the diagnosis of arrhythmogenic right ventricular cardiomyopathy

Giuseppe Femia; C. Hsu; S. Singarayar; Raymond W. Sy; Michael J. Kilborn; Geoffrey Parker; Mark A. McGuire; Christopher Semsarian; Rajesh Puranik

15,797 ± 5442) (P = .6337) or between inserting an additional venous stent (


European Journal of Radiology | 2012

Imaging of endolymphatic hydrops in Meniere's disease at 1.5 T using phase-sensitive inversion recovery: (1) Demonstration of feasibility and (2) overcoming the limitations of variable gadolinium absorption

Stuart M. Grieve; Rupert Obholzer; Nathan Malitz; W. P. R. Gibson; Geoffrey Parker

9421 ± 69) versus revising a CSF shunt (


The Annals of Thoracic Surgery | 2003

Late quadriplegia after adult coarctation repair

Paul Peters; Jeffrey W. Brennan; Clifford F. Hughes; Martin McGee-Collett; Geoffrey Parker

10,470 ± 1245) (P = .4996). There were far fewer additional venous stent insertions per patient than there were subsequent CSF shunt revisions; 87% of stents placed required just 1 stent procedure, whereas only 45% of shunts required 1 shunt procedure. The main cause of the cost difference was the need for repeated revisions of the shunts, especially when they became infected—24 instances of a total 143 shunt procedures (16.8%) at an average cost of


Journal of Neuro-ophthalmology | 2013

Venous hypertension as the cause of intracranial hypertension in patients with transverse sinus dural arteriovenous fistula.

Rebekah M. Ahmed; Khoury B; Mark Wilkinson; Geoffrey Parker; G.M. Halmagyi

84,729, approximately 5 times the cost of an initial shunt insertion. CONCLUSIONS: Venous stenting costs significantly less per 100 procedures than does CSF shunting, due largely to the high cost of treating shunt infections and the need for repeated shunt revisions.

Collaboration


Dive into the Geoffrey Parker's collaboration.

Top Co-Authors

Avatar

Brian Owler

Children's Hospital at Westmead

View shared research outputs
Top Co-Authors

Avatar
Top Co-Authors

Avatar

G. Michael Halmagyi

Royal Prince Alfred Hospital

View shared research outputs
Top Co-Authors

Avatar

Mark Wilkinson

Royal Prince Alfred Hospital

View shared research outputs
Top Co-Authors

Avatar
Top Co-Authors

Avatar

G.M. Halmagyi

Royal Prince Alfred Hospital

View shared research outputs
Top Co-Authors

Avatar

Rajesh Puranik

Royal Prince Alfred Hospital

View shared research outputs
Top Co-Authors

Avatar

C. Hsu

Royal Prince Alfred Hospital

View shared research outputs
Top Co-Authors

Avatar
Top Co-Authors

Avatar

Jason Macdonald

Royal Prince Alfred Hospital

View shared research outputs
Researchain Logo
Decentralizing Knowledge