Publications by authors named "Benjamin Jonker"

There have been promising outcomes from the use of unilateral High-intensity focused ultrasound (HiFUS) thalamotomy in tremor-dominant Parkinson's disease. However, the reliability of this treatment has been questioned due to the high rate of tremor relapse. Authors have hypothesized that treatment failure is due to insufficient HiFUS lesion size, though detailed volumetric lesion analyses are lacking.

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Papillary craniopharyngioma (PCP) and adamantinomatous craniopharyngioma (ACP) are distinct, slow-growing tumors of the suprasellar region. Their location, composition, and biology have historically evaded successful surgical radiation and medical therapy. Meanwhile compromise of critical structures either by tumor or treatments increase morbidity, impacting patient and carer quality of life.

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Background: Magnetic resonance-guided focused ultrasound (MRgFUS) for treatment of essential tremor (ET) traditionally targets the ventral intermediate (Vim) nucleus. Recent strategies include a secondary lesion to the posterior subthalamic area (PSA).

Objective: The aim was to compare lesion characteristics, tremor improvement, and adverse events (AE) between patients in whom satisfactory tremor suppression was achieved with lesioning of the Vim alone and patients who required additional lesioning of the PSA.

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Background: The current literature comparing outcomes after a unilateral magnetic resonance image-guided focused ultrasound (MRgFUS) thalamotomy between tremor syndromes is limited and remains a possible preoperative factor that could help predict the long-term outcomes.

Objective: The aim was to report on the outcomes between different tremor syndromes after a unilateral MRgFUS thalamotomy.

Methods: A total of 66 patients underwent a unilateral MRgFUS thalamotomy for tremor between November 2018 and May 2020 at St Vincent's Hospital Sydney.

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Introduction: MRI-guided focused ultrasound (MRgFUS) thalamotomy provides an exciting development in the field of minimally invasive stereotactic neurosurgery. Current treatment options for focal hand dystonia are limited, with potentially more effective invasive stereotactic interventions, such as deep brain stimulation or lesional therapies, rarely used. The advent of minimally invasive brain lesioning provides a potentially safe and effective treatment approach with a recent pilot study establishing MRgFUS Vo-complex thalamotomy as an effective treatment option for focal hand dystonia.

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Objective: Skull density ratio (SDR) influences the permeability of the skull to the ultrasound waves used in magnetic resonance-guided focused ultrasound (MRgFUS) for the treatment of tremor. SDR values vary across the skull and the mean value is known to be predictive of sonication thermal increase. The aim of this investigation was to explore the effects of the SDR distribution on clinical outcomes following treatment with MRgFUS.

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Objectives: Magnetic resonance-guided focussed ultrasound (MRgFUS) is an incisionless ablative procedure, widely used for treatment of Parkinsonian and Essential Tremor (ET). Enhanced understanding of the patient- and treatment-specific factors that influence sustained long-term tremor suppression could help clinicians achieve superior outcomes improved patient screening and treatment strategy.

Methods: We retrospectively analysed data from 31 subjects with ET, treated with MRgFUS at a single centre.

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Background: Radiologically undifferentiated lesions of the cavernous sinus can pose a diagnostic challenge. Although radiotherapy is the mainstay for treatment of cavernous sinus lesions, histologic diagnosis allows access to a wide variety of alternative treatment modalities. The region is considered a high-risk area for open transcranial surgical access, and the endoscopic endonasal approach presents an alternative technique for biopsy.

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Background: Whilst MRI guided Focused Ultrasound (MRgFUS) thalamotomy is an effective treatment option for tremor disorders, there are reports of tremor recurrence in patients with tremor dominant Parkinson's disease (PD). The mechanisms for tremor recurrence are unknown but likely relate to the duality of tremor network pathways with ramifications for subsequent treatment options.

Cases: We report two cases of tremor dominant PD who experienced tremor recurrence following MRgFUS thalamotomy with subsequent successful subthalamic nucleus deep brain stimulation (DBS).

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 Sellar pathologies are frequently found on imaging performed to investigate headache. However, both headache and incidental sellar lesions are common. Hence, this study prospectively examined headache prevalence, phenotype, and severity in patients with sellar pathologies and the impact of transsphenoidal surgery on headache.

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Background: Cerebral palsy (CP) is a common cause of acquired dystonia, which can lead to significant interference with quality of life and societal participation. In the last two decades, the surgical treatment of dystonia has primarily focused on deep brain stimulation targeting the basal ganglia and thalamic circuits. However, stimulation of the basal ganglia has generally been less effective in acquired combined forms of dystonia, including dystonic CP.

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Objective: Transsphenoidal surgery (TSS) is the first-line treatment for Cushing's disease. The objectives of the study were to determine remission and recurrence rates after TSS for Cushing's disease, identify factors that predict these outcomes, and define the threshold for postoperative morning serum cortisol (MSeC) that most accurately predicts sustained remission.

Methods: Records were retrospectively reviewed for consecutive adults undergoing TSS for Cushing's disease at a tertiary centre (1990-2019).

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Recently, there has been increased interest worldwide in the use of conventional linear accelerator (linac)-based systems for delivery of stereotactic radiosurgery/radiotherapy (SRS/SRT) contrasting with historical delivery in specialised clinics with dedicated equipment. In order to gain an understanding and define the current status of SRS/SRT delivery in Australia and New Zealand (ANZ) we conducted surveys and provided a single-day workshop. Prior to the workshop ANZ medical physicists were invited to complete two surveys: a departmental survey regarding SRS/SRT practises and equipment; and an individual survey regarding opinions on current and future SRS/SRT practices.

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Magnetic resonance-guided focused ultrasound (MRgFUS) is being increasingly utilized in the treatment of movement disorders such as essential tremor (ET) and Parkinson's disease (PD). Whilst skull density ratio (SDR) has previously been correlated with achieving lesional temperature rises, other patient factors such as brain and cerebrospinal fluid (CSF) volume have not previously been investigated. We aimed to investigate the effect of brain and CSF volumes on lesional temperature rises, as well as the effect of brain and CSF volumes and SDR on post-treatment lesion sizes.

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Cavernous sinus invasion (CSI) by pituitary tumors is associated with subtotal resection and persistent endocrinopathy. The Knosp classification is a magnetic resonance imaging (MRI) tool used to define CSI in the 2017 World Health Organization Classification. However, alternative criteria may have superior diagnostic performance.

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Article Synopsis
  • A study examined the effectiveness of multidisciplinary care (MDT) in pituitary surgery by comparing patient outcomes before and after MDT implementation at a specialized medical center.
  • Primary outcomes included complications related to surgery and endocrine issues, as well as hospital stay duration and residual tumor presence.
  • Findings showed that after MDT introduction, complications decreased, hospital stays were shorter, and overall patient outcomes improved, suggesting that MDTs provide significant benefits in managing pituitary diseases.
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Optic nerve sheath meningiomas (ONSMs) are rare, benign neoplasms of the anterior visual pathway. The optimal modality of radiotherapy for treatment has not yet been established. This is the first study to show significant difference in visual outcomes between radiotherapy subtypes in the management of ONSM.

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Summary: Cushing's disease is a rare disorder characterised by excessive cortisol production as a consequence of a corticotroph pituitary tumour. While the primary treatment is surgical resection, post-operative radiation therapy may be used in cases of ongoing inadequate hormonal control or residual or progressive structural disease. Despite improved outcomes, radiotherapy for pituitary tumours is associated with hypopituitarism, visual deficits and, rarely, secondary malignancies.

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Purpose: Transsphenoidal surgery (TSS) is the first-line treatment for Cushing's disease (CD). This review aimed to synthesize the remission and recurrence rates following TSS for CD and identify predictors of these outcomes.

Methods: Medline (1946-) and Embase (1947-) were searched until 23rd January 2019 for original studies.

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 Olfactory groove meningiomas (OGMs) are often associated with loss of smell following resection. Loss of smell has a measurable impact on quality of life. Smell preservation has been previously described in open approaches for early stage or unilateral OGMs.

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The objective was to determine the impact of surgical resection and adjuvant therapies on survival in intramedullary ependymoma and astrocytoma. Secondary goals were to determine predictors of survival in surgical patients including histological grading, age and gender. Searching of Medline, Embase and Clinicaltrials.

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