Michael Torrens

Postoperative Recovery of Third Nerve Palsy due to Posterior Communicating Aneurysms

Postoperative recovery of third nerve palsy due to a posterior communicating artery aneurysm was correlated with pre- and intraoperative factors. The only significant factor determining recovery was the degree of preoperative deficit. The presence of subarachnoid haemorrhage, timing of surgery and aspiration of the aneurysmal sac did not influence recovery.

Facial and acoustic nerve preservation during excision of extracanalicular acoustic neuromas using the suboccipital approach: Original Article

The results are presented from a consecutive operative series of 62 acoustic neuromas in 60 patients following the introduction of improved neurophysiological monitoring techniques. Twenty-two patients had usable preoperative hearing. Thirty tumours were less than 2.5 cm diameter and 32 greater in size. Operation was via a 3-4-cm diameter retromastoid craniectomy. The internal auditory meatus was opened by an ENT surgeon (RM) using a drill and the facial nerve identified by stimulation. The tumour was then centrally evacuated by a neurosurgeon (MT/HC) using an ultrasonic aspirator, and the thin exterior part of the tumour carefully dissected off the nerves in or around the capsule with constant stimulation and monitoring of facial EMG, BSAEP and electrocochleography. A new type of stimulation probe has been designed and coupled to a stimulator/integrator/tone burst generator (SB) so that continuous immediate direct feedback to the surgeon is possible. A variable amplitude discriminator rejects baseline EMG (> 50 microV) and a gating circuit prevents stimulus artefact (during monopolar stimulation) from causing interference. By these means the VII nerve could be identified even when translucent and undefinable as a nerve bundle. Anatomical preservation was possible in 98% of VII nerves. Full facial function was present in 20 cases immediately postoperatively. Full delayed recovery occurred in 23 cases giving an eventual total in House Grade I of 69%. Seven other cases recovered to House Grade II. There was therefore 81% satisfactory facial nerve function. This percentage is exactly the same for larger and for smaller tumours. Anatomical preservation of the VIII nerve was achieved in 24/62 (39%) of the whole series and 11/16 (69%) of those with a hearing loss of < 50 dB. Functional preservation of hearing described as usable by the patient (< 65 dB) was achieved in 7/22 cases (32%), 3/13 (23%) in tumours < 2.5 cm and 4/9 (44%) in those > 2.5 cm diameter. Hearing preservation of < 50 dB in patients with preoperative hearing threshold < 50 dB and tumours of < 2.5 cm was 3/11 (27%). Monitoring by BSAEP and ECochG was technically unsatisfactory because the responses were affected by drilling and stimulation. Acoustic nerve preservation should be attempted in all cases with measurable hearing, regardless of tumour size.

Urethral Sphincteric Responses to Stimulation of the Sacral Nerves in the Human Female

Stimulation of the human sacral nerves evokes, at higher voltages, a urethral relaxation which may be independent of bladder contraction. It persists after nerve section when the distal cut end is sti

Standardization of terminology in stereotactic radiosurgery: Report from the Standardization Committee of the International Leksell Gamma Knife Society: special topic.

OBJECT This report has been prepared to ensure more uniform reporting of Gamma Knife radiosurgery treatment parameters by identifying areas of controversy, confusion, or imprecision in terminology and recommending standards. METHODS Several working group discussions supplemented by clarification via email allowed the elaboration of a series of provisional recommendations. These were also discussed in open session at the 16th International Leksell Gamma Knife Society Meeting in Sydney, Australia, in March 2012 and approved subject to certain revisions and the performance of an Internet vote for approval from the whole Society. This ballot was undertaken in September 2012. RESULTS The recommendations in relation to volumes are that Gross Target Volume (GTV) should replace Target Volume (TV); Prescription Isodose Volume (PIV) should generally be used; the term Treated Target Volume (TTV) should replace TVPIV, GTV in PIV, and so forth; and the Volume of Accepted Tolerance Dose (VATD) should be used in place of irradiated volume. For dose prescription and measurement, the prescription dose should be supplemented by the Absorbed Dose, or DV% (for example, D95%), the maximum and minimum dose should be related to a specific tissue volume (for example, D2% or preferably D1 mm3), and the median dose (D50%) should be recorded routinely. The Integral Dose becomes the Total Absorbed Energy (TAE). In the assessment of planning quality, the use of the Target Coverage Ratio (TTV/ GTV), Paddick Conformity Index (PCI = TTV2/[GTV · PIV]), New Conformity Index (NCI = [GTV · PIV]/TTV2), Selectivity Index (TTV/PIV), Homogeneity Index (HI = [D2% –D98%]/D50%), and Gradient Index (GI = PIV0.5/PIV) are reemphasized. In relation to the dose to Organs at Risk (OARs), the emphasis is on dose volume recording of the VATD or the dose/volume limit (for example, V10) in most cases, with the additional use of a Maximum Dose to a small volume (such as 1 mm3) and/or a Point Dose and Mean Point Dose in certain circumstances, particularly when referring to serial organs. The recommendations were accepted by the International Leksell Gamma Knife Society by a vote of 92% to 8%. CONCLUSIONS An agreed-upon and uniform terminology and subsequent standardization of certain methods and procedures will advance the clinical science of stereotactic radiosurgery.

MRI in the diagnosis of spinal extradural angiolipoma

We report the case of a 68-year-old woman with a 1-year history of progressive spastic paraparesis, due to an extradural angiolipoma of the mid-thoracic spine. The MRI appearance of the angiolipoma is reported here for the first time. This appearance is characteristic, allows preoperative diagnosis and assists planning of the surgical approach.

The Clinical Contribution of Urodynamics

The purpose of this chapter is to show how urodynamic tests can help the clinician to improve diagnosis and treatment. There are four main ways in which this is possible. Firstly, the investigations may assist in the evaluation of an individual case, providing objective evidence on which to base decisions. Secondly, the analysis of groups of patients may, over a time, improve both the understanding of pathophysiology and the selection of patients for treatment. Thirdly, urodynamics may provide objective information before and after therapeutic intervention, allowing the clinician to monitor the results of treatment more accurately and, lastly, they assist the continuing education of clinicians themselves.

Urethral Closure Pressure Profiles in the Male

The shape of the urethral closure pressure profile of 281 male patients has been analysed. ‘Prostatic’ length, ‘prostatic’ peak, ‘prostatic’ plateau height and ‘prostatic’ plateau area have been measu

Assessment of organs-at-risk contouring practices in radiosurgery institutions around the world – The first initiative of the OAR Standardization Working Group

BACKGROUND AND PURPOSE This study was an initiative of the Organs-at-Risk Standardization Working Group for evaluating the current degree of variability in the clinical practice of contouring organs-at-risk (OAR) for radiosurgery planning. MATERIALS AND METHODS Imaging datasets for typical lesions (cavernous sinus meningioma, vestibular schwannoma, pituitary adenoma) treated with Leksell Gamma Knife Perfexion were circulated to 12 centers. Observers were asked to contour the target and OARs as per their standard clinical practice. The analyzed parameters were the intersection (AV100), union volumes (AV100/N) and the 50% agreement volume (AV50). The ratio of AV100 and AV100/N (the Agreement Volume Index, AVI) was used as a measure of agreement level together with a generalized conformity index (CIgen) and a pairwise averaged conformity index (CIpairs). The maximum doses were also determined. RESULTS Results showed a wide variability in terminology, choice of structures contoured and in the size and shape of the contoured structures. The highest variability was observed for the left and right optic tract for cavernous sinus meningioma where the AV100 was zero. The highest consistency was observed for the right optic nerve in the cavernous sinus case followed by the cochlea for the vestibular schwannoma case for which the AVI was still only 0.13 and 0.054, respectively. Corresponding results for the CIgen and CIpairs also showed the highest variability for the right optic tract and the highest consistency in contours for the right optic nerve, both in the cavernous sinus meningioma case. CONCLUSION The results quantify the large variability in OAR contouring in clinical practice across Gamma Knife radiosurgery centers with respect to the choice of OARs to be contoured, nomenclature and size and shape of OARs. This motivates future effort to standardize practices to enable more effective collaboration.

Cervical spondylosis Part 1: Pathogenesis, diagnosis and management options

Cervical spondylosis is a term in frequent use but its definition is not quite so clear. It is usually held to mean some chronic degenerative disorder of the joints of the cervical spine, though the Greek etymology is rather more general, meaning ‘a condition (-osis) involving the vertebra (spondylos)‘. For the purpose of this review the term will mean ‘the degenerative diseases of the cervical intervertebral discs and their associated intervertebral joints that produce symptoms ‘. The first of these two reviews is concerned with the understanding and diagnosis of the condition in order that logical and effective management decisions can be made. The second will describe the surgical treatment.

Radiosurgery nomenclature: A confusion of tongues

Since the time of its inception within neurosurgery, the practice of radiosurgery has grown and evolved with the introduction of new technologies and the involvement of other disciplines. Currently, radiosurgery practices involve neurosurgery, radiation oncology, medical physics and, in many centers, neuroradiology. Various commercially available radiosurgical devices are used, including the conventional linear accelerator, CyberKnife, Gamma Knife, and even particle therapy units. The historical roots of each radiosurgery practice affect the terminology and procedures applied for treatment planning and delivery, resulting in wide variability in image acquisition, planning, and verification practices across the community. This organic development has led to a “confusion of tongues,” challenging our ability to interpret the published scientific literature in a meaningful way and hindering the radiosurgery community’s ability to collaborate effectively to advance the science and practice of radiosurgery. The broader radiation therapy literature contains a growing body of evidence that the quality of radiation delivery has a significant impact on clinical outcomes. This was highlighted in a secondary report of a large multicenter phase 3 trial of head and neck cancer, which showed