Surgical management of symptomatic cavum septum pellucidum cysts: systematic review of the literature.

Cavum septum pellucidum (CSP) and cavum vergae (CV) cysts are commonly found incidentally. They are usually asymptomatic but may present with symptoms related to obstructive hydrocephalus. There is no consensus about the management of symptomatic CSP and CV cysts. We present, to the best of our knowledge, the first systematic review of the different treatment options for symptomatic CSP and CV cysts. We conducted a literature review using PubMed database, searching for cases of symptomatic CSP and CV cysts managed surgically, and published until April 2019. Preoperative characteristics, surgical procedure, and postoperative outcome were analyzed using SPSS® software (Statistical Package for Social Sciences, IBM®). We found 54 cases of symptomatic CSP and CV cysts managed surgically (34 males, 20 females, 1.7/1 male to female ratio). Mean age was 24.3 ± 20.1 years. The most common presentation was headaches (34 patients, 62%), followed by psychiatric symptoms (27 patients, 49.1%). Preoperative radiological hydrocephalus was present in 30 patients (54.5%). The most common surgical procedure was endoscopic fenestration (39 patients, 70.9%), followed by shunting (10 patients, 18.2%), open surgery (3 patients, 5.5%), and stereotactic fenestration (1 patient, 1.8%). Complete resolution of symptoms was achieved in 36 patients (65.5%) and partial resolution in 7 patients (12.7%), and symptoms were unchanged in 2 patients. The present review suggests that surgical treatment could provide resolution of the symptoms in most of the cases, regardless of the procedure performed. Although mean follow-up was short among the studies, recurrence rate was low.

A randomised controlled trial comparing autologous cranioplasty with custom-made titanium cranioplasty: long-term follow-up.

OBJECTIVE: To compare the long-term outcomes of patients who had been randomly allocated to receive primary titanium cranioplasty or autologous bone graft following decompressive craniectomy. METHODS: Sixty-four patients had been previously enrolled and randomised to receive either their own bone graft or a primary titanium cranioplasty. Functional and cosmetic outcomes had previously been assessed at 1-year following the cranioplasty procedure. Hospital records and the Picture Archiving communication system were reviewed to determine how many patients had cranioplasty failure or associated complications such as seizures beyond 1 year-with a minimum of 24-month follow-up. RESULTS: Amongst the 31 patients in the titanium group (one patient had died), no patients had a partial or complete cranioplasty failure at 12 months follow-up and there had been no failures beyond 12 months. Amongst the 31 patients who had an autologous cranioplasty (one patient had died), 7 patients had complete resorption of the autologous bone such that it was adjudged a complete failure at 12-month follow-up. Five of these patients had had titanium augmentation and two patients declined further surgery. Both of these patients requested cranial augmentation for functional and cosmetic reasons subsequent to the 12-month follow-up. Another patient who had previously been noted to have moderate resorption at 12 months presented 1 year later with progressive bone flap resorption and also required subsequent augmentation for functional and cosmetic reasons. When follow-up was extended to a minimum of 24 months, use of titanium instead of autologous bone for primary cranioplasty resulted in a significant reduction in the number of patients who required rescue cranioplasty (0 vs 25%, 95% confidence interval [CI] 9.1-42.1%; p = 0.001). In addition, there were significantly less total hospital healthcare costs in those patients randomised to the titanium arm of the trial (difference = A$9999, 95%CI 2231-17,768; p = 0.015). CONCLUSIONS: Bone resorption continued to occur beyond 12 months after autologous cranioplasty; use of primary titanium cranioplasty after decompressive craniectomy reduced the number of reoperations needed and the associated long-term total hospital costs.

Change in Low Back Movement Patterns After Neurosurgical Intervention for Lumbar Spondylosis.

OBJECTIVES: The purpose of this study was to assess the use of computer-aided combined movement examination (CME) to measure change in low back movement after neurosurgical intervention for lumbar spondylosis and to use a CME normal reference range (NRR) to compare and contrast movement patterns identified from lumbar disk disease, disk protrusion, and nerve root compression cases. METHODS: A test-retest, cohort observational study was conducted. Computer-aided CME was used to record lumbar range of motion in 18 patients, along with pain, stiffness, disability, and health self-report questionnaires. A minimal clinically important difference of 30% was used to interpret meaningful change in self-reports. z Scores were used to compare CME. Post hoc observation included subgrouping cases into 3 discrete pathologic conditions-disk disease, disk protrusion, and nerve root compression-to report intergroup differences in CME. RESULTS: Self-report data indicated that 11, 7, and 10 patients improved by ≥30% in pain, stiffness, and function, respectively. Three patients experienced clinically significant improvement in health survey. A CME pattern reduced in all directions suggested disk disease. Unilaterally restricted movement in side-flexed or extended directions suggested posterolateral disk protrusion with or without ipsilateral nerve root compression. Bilateral restrictions in extension suggested posterior disk protrusion with or without nerve root compression. In 11 of the 18 cases, CME converged toward the NRR after surgery. CONCLUSION: We described the use of CME to identify atypical lumbar movement relative to an NRR. Data from this short-term postoperative study provide preliminary evidence for CME movement patterns suggestive of disk disease, disk protrusion, and nerve root compression.

Structure-Specific Movement Patterns in Patients With Chronic Low Back Dysfunction Using Lumbar Combined Movement Examination.

OBJECTIVE: A test-retest cohort study was conducted to assess the use of a novel computer-aided, combined movement examination (CME) to measure change in low back movement after pain management intervention in 17 cases of lumbar spondylosis. Additionally we desired to use a CME normal reference range (NRR) to compare and contrast movement patterns identified from 3 specific structural pathologic conditions: intervertebral disc, facet joint, and nerve root compression. METHODS: Computer-aided CME was used before and after intervention, in a cohort study design, to record lumbar range of movement along with pain, disability, and health self-report questionnaires in 17 participants who received image-guided facet, epidural, and/or rhizotomy intervention. In the majority of cases, CME was reassessed after injection together with 2 serial self-reports after an average of 2 and 14 weeks. A minimal clinically important difference of 30% was used to interpret meaningful change in self-reports. A CME NRR (n = 159) was used for comparison with the 17 cases. Post hoc observation included subgrouping cases into 3 discrete pathologic conditions, intervertebral disc, facet dysfunction, and nerve root compression, in order to report intergroup differences in CME movement. RESULTS: Seven of the 17 participants stated that a "combined" movement was their most painful CME direction. Self-report outcome data indicated that 4 participants experienced significant improvement in health survey, 5 improved by ≥30% on low back function, and 8 reported that low back pain was more bothersome than stiffness, 6 of whom achieved the minimal clinically important difference for self-reported pain. Subgrouping of cases into structure-specific groups provided insight to different CME movement patterns. CONCLUSION: The use of CME assists in identifying atypical lumbar movement relative to an age and sex NRR. Data from this study, exemplified by representative case studies, provide preliminary evidence for distinct intervertebral disc, facet joint, and nerve root compression CME movement patterns in cases of chronic lumbar spondylosis.

The anatomy of the caudal zona incerta in rodents and primates.

The caudal zona incerta is the target of a recent modification of established procedures for deep brain stimulation (DBS) for Parkinson's disease and tremor. The caudal zona incerta contains a number of neuronal populations that are distinct in terms of their cytoarchitecture, connections, and pattern of immunomarkers and is located at a position where a number of major tracts converge before turning toward their final destination in the forebrain. However, it is not clear which of the anatomical features of the region are related to its value as a target for DBS. This paper has tried to identify features that distinguish the caudal zona incerta of rodents (mouse and rat) and primates (marmoset, rhesus monkey, and human) from the remainder of the zona incerta. We studied cytoarchitecture, anatomical relationships, the pattern of immunomarkers, and gene expression in both of these areas. We found that the caudal zona incerta has a number of histological and gene expression characteristics that distinguish it from the other subdivisions of the zona incerta. Of particular note are the sparse population of GABA neurons and the small but distinctive population of calbindin neurons. We hope that a clearer appreciation of the anatomy of the region will in the end assist the interpretation of cases in which DBS is used in human patients.

Decompressive craniectomy for diffuse cerebral swelling after trauma: long-term outcome and ethical considerations.

BACKGROUND: There is currently much interest in the use of decompressive for the management of diffuse cerebral swelling after trauma. Although the use of the procedure may improve survival, some of those survivors may be left severely disabled. The aim of this study was to see whether severe disability can be predicted and discuss the difficult ethical issue that this raises. METHODS: This was a retrospective cohort subgroup analysis of those patients with severe head injury in Western Australia between 2004 and 2008 who had had a decompressive craniectomy for intractably raised intracranial pressure despite maximal medical management. RESULTS: Among a total of 1,786 adult neurotrauma patients admitted between 2004 and 2008, 74 patients required a bifrontal decompressive craniectomy for intractably raised intracranial pressure. After the application of Corticosteroid Randomization After Significant Head Injury (CRASH) trial collaborators' prediction model, predicted and observed outcomes were compared. The mean timing and median timing of surgery were 42 hours and 30 hours after hospital admission, respectively. The timing of decompressive craniectomy was inversely correlated to the severity of the head injury (Spearman's correlation coefficient = -0.251, p = 0.031). At 18-month follow-up, 16 patients were deceased, 3 were in a persistent vegetative state, and 10 were severely disabled. In contrast to these unfavorable outcomes, 35 patients had a good outcome and 10 were moderately disabled at 18 months. The discrimination of the CRASH prediction model was excellent (area under receiver-operating characteristic curve, 0.905; 95% confidence interval, 0.829-0.982; p = 0.001). CONCLUSION: Our data provide some evidence that the CRASH prediction model may help clinicians and families to make informed decision about the benefits and risks of decompressive craniectomy for diffuse cerebral swelling.

Cost-effectiveness of decompressive craniectomy as a lifesaving rescue procedure for patients with severe traumatic brain injury.

BACKGROUND: Decompressive craniectomy has been traditionally used as a lifesaving rescue procedure for patients with refractory intracranial hypertension after severe traumatic brain injury (TBI), but its cost-effectiveness remains uncertain. METHODS: Using data on length of stay in hospital, rehabilitation facility, procedural costs, and Glasgow Outcome Scale (GOS) up to 18 months after surgery, the average total hospital costs per life-year and quality-adjusted life-year (QALY) were calculated for patients who had decompressive craniectomy for TBI between 2004 and 2010 in Western Australia. The Corticosteroid Randomisation After Significant Head Injury prediction model was used to quantify the severity of TBI. RESULTS: Of the 168 patients who had 18-month follow-up data available after the procedure, 70 (42%) achieved a good outcome (GOS-5), 27 (16%) had moderate disability (GOS-4), 34 (20%) had severe disability (GOS-3), 5 (3%) were in vegetative state (GOS-2), and 32 (19%) died (GOS-1). The hospital costs increased with the severity of TBI and peaked when the predicted risk of an unfavorable outcome was about 80%. The average cost per life-year gained (US$671,000 per life-year) and QALY (US$682,000 per QALY) increased substantially and became much more than the usual acceptable cost-effective limit (US$100,000 per QALY) when the predicted risk of an unfavorable outcome was >80%. Changing different underlying assumptions of the analysis did not change the results significantly. CONCLUSIONS: Severity of TBI had an important effect on cost-effectiveness of decompressive craniectomy. As a lifesaving procedure, decompressive craniectomy was not cost-effective for patients with extremely severe TBI.

Surgical intervention for severe head injury: ethical considerations when performing life-saving but non-restorative surgery.

BACKGROUND: The aim of this study was to compare the predicted outcome with observed outcome in those patients who have had a unilateral decompressive craniectomy following evacuation of an intracranial mass lesion and to consider some of the ethical issues that need to be addressed when performing life-saving but non-restorative surgery. METHODS: By using the web-based outcome prediction model developed by the CRASH trial collaborators predicted and observed outcomes were compared for those patients who had had a unilateral decompression after evacuation of a mass lesion in the two major neurotrauma hospitals in Western Australia between 2004 and 2008. Three cases were selected with differing outcome predictions. RESULTS: For the three selected cases the predicted risk of an unfavourable outcome at 6 months was 65.8%, 78.9% and 91.3%, respectively. For the 11 patients in this cohort with an outcome prediction between 61% and 70%, the observed outcome at 18 months (GOS) was: 5 had a good outcome, 4 were moderately disabled, and 3 were severely disabled. For the ten patients with an outcome prediction between 90-100%, observed outcome confirmed: one patient was moderately disabled, four patients were severely disabled, one patient was in a permanent vegetative state, and four patients had died. CONCLUSION: As the index of injury severity (as adjudged by the CRASH outcome prediction model) increases, clinical decision making and discussion with surrogates must reflect the evidence provided by observed outcome, prior to life-saving but potentially non-restorative decompressive surgery.

Delayed oculomotor nerve palsy associated with a ruptured anterior communicating aneurysm: Case report.

BACKGROUND AND IMPORTANCE: Oculomotor nerve palsy (ONP) is usually associated with posterior communicating (PCOM) aneurysms. ONP in patients with anterior circulation aneurysms are extremely rare, with only a handful of such published cases to date. There is currently no accepted mechanism to explain this clinical finding. CLINICAL PRESENTATION: We describe a case of a 60-year-old female that benefitted from endovascular coiling of a ruptured anterior communicating (ACOM) aneurysm. In the following days, she clinically deteriorated and benefitted from another digital subtraction angiography (DSA) with intravascular verapamil for suspected vasospasm, and subsequently developed a right ONP. CONCLUSION: Although classically related to PCOM aneurysm, ONP may be associated with ACOM aneurysms. The causative mechanism is unclear, but vasospasm may alter the microvascularisation of the oculomotor nerve, leading to ischemia.

The Magnetic Resonance Imaging (MRI)-Directed Implantable Guide Tube Technique: Accuracy and Applications in Deep Brain Stimulation.

OBJECTIVE: The magnetic resonance imaging (MRI)-directed implantable guide tube technique allows for direct targeting of deep brain structures without microelectrode recording or intraoperative clinical assessment. This study describes a 10-year institutional experience of this technique including nuances that enable performance of surgery using readily available equipment. METHODS: Eighty-seven patients underwent deep brain stimulation surgery using the guide tube technique for Parkinson disease (n = 59), essential tremor (n = 16), and dystonia (n = 12). Preoperative and intraoperative MRI was analyzed to measure lead accuracy, volume of pneumocephalus, and the ability to safely plan a trajectory for multiple electrode contacts. RESULTS: Mean target error was measured to be 0.7 mm (95% confidence interval [CI] 0.6-0.8 mm) in the anteroposterior plane, 0.6 mm (95% CI 0.5-0.7 mm) in the mediolateral plane, and 0.8 mm (95% CI 0.7-0.9 mm) in the superoinferior plane. Net deviation (Euclidean error) from the planned target was 1.3 mm (95% CI 1.2-1.4 mm). Mean intracranial air volume per lead was 0.2 mL (95% CI 0.1-0.4 mL). In total, 52 patients had no intracranial air on postoperative imaging. In all patients, a safe trajectory could be planned to target for multiple electrode contacts without violating critical neural structures, the lateral ventricle, sulci, or cerebral blood vessels. CONCLUSIONS: The MRI-directed implantable guide tube technique is a highly accurate, low-cost, reliable method for introducing deep brain electrodes. This technique reduces brain shift secondary to pneumocephalus and allows for whole trajectory planning of multiple electrode contacts.

Deep Brain Stimulation and Swimming Performance: A Randomized Within-Person Crossover Study.

OBJECTIVE: To determine whether deep brain stimulation (DBS) causes swimming impairment, we systematically compared swimming ability between DBS on vs off in 18 patients. METHODS: We conducted a randomized blinded crossover study, comparing swimming ability between DBS on vs off, within participants. Participants swam 3 laps of front crawl and 3 laps of breaststroke. Prespecifed primary outcomes were proportion of lap completed, lap time, and Aquatic Skills Proficiency Assessment (ASPA) score. Prespecified secondary outcomes were a qualitative description of marked changes observed. RESULTS: Eighteen participants with Parkinson disease (n = 13), essential tremor (n = 3), Tourette syndrome (n = 1), or posttraumatic brain injury proximal tremor (n = 1), treated with posterior subthalamic area (n = 15) or globus pallidus interna (n = 3) DBS were assessed. There was no significant effect of DBS on/off status on any outcome measure for front crawl or breaststroke. Three participants showed changes in both qualitative and quantitative assessments. Of these, 1 participant displayed reduction in swimming ability: impairment in all outcomes with DBS on, normalizing with DBS off (the same individual as previously reported). The participant displayed difficulty coordinating limb movement as well as postural control. Two participants showed improvements in lap time and ASPA scores with DBS on. CONCLUSION: Overall DBS did not impair swimming performance, although 1 patient demonstrated a stimulation-induced drowning hazard. There were no anatomic or clinical features unique to the individual with swimming impairment. Patients should be warned about the possibility of DBS-induced drowning hazard and should swim with capable supervision after DBS. CLASSIFICATION OF EVIDENCE: This study provides Class IV evidence that for patients with implanted DBS electrodes, the stimulation on condition, compared with stimulation off, did not significantly impair swimming performance. A formal assessment of unblinding would have been helpful.

Decompressive craniectomy for neurotrauma: the limitations of applying an outcome prediction model.

BACKGROUND: There is currently much interest in the use of decompressive craniectomy for patients with severe head injury. A number of studies have demonstrated that not only can the technique lower intracranial pressure but can also improve outcome. Whilst many patients who would otherwise have died or had a poor outcome now go on to make a good recovery, there is little doubt that complications can have a very significant impact on long term outcome. METHODS: By using the corticosteroid randomisation after significant head injury (CRASH) collaborators outcome prediction model, three patients were selected who had a similar outcome prediction. All three patients developed intracranial hypertension following trauma and had a decompressive craniectomy. RESULTS: Despite having a similar outcome prediction only one patient made an uneventful recovery. The remaining two patients suffered significant complications. CONCLUSIONS: This report illustrates the potential clinical applications and limitations of an outcome prediction model and demonstrates the impact that complications can have on eventual outcome.

Defining the Border of the Subthalamic Nucleus for Deep Brain Stimulation: A Proposed Model Using the Symmetrical Sigmoid Curve Function.

BACKGROUND: The subthalamic nucleus (STN) is an important target during deep brain stimulation (DBS). Accurate lead placement is integral to achieving satisfactory clinical outcomes; however, the STN remains a structure whose visualization is highly variable with borders often difficult to define. We aimed to develop an objective method of evaluating the visibility of the STN on preoperative magnetic resonance imaging (MRI) to standardize future comparative assessments between imaging protocols and patient-specific parameters. METHODS: An imaging study of 64 prospectively collected patients undergoing bilateral DBS of the STN for various movement disorders was performed with institutional approval. MRI scans were acquired using a uniform protocol involving general anesthesia, cranial fixation in a Leksell stereotactic frame, and long acquisition times using a 3T MRI scanner. The images were analyzed using the iPlan Stereotaxy, version 2.6, workstation. High-resolution T2-weighted axial sections were evaluated, and the voxel values in the region of the presumed posterior border of the STN (as defined by the operating neurosurgeon) were obtained. A 4-parameter logistic symmetrical sigmoid curve was used to map the voxel values as they progressed from within to outside the region of the STN border. The inflection point and Hill coefficient of this symmetrical curve was calculated to provide objective information on the location and clarity of the STN border, respectively. These findings were compared with the surgeon's judgment of the STN border. To demonstrate the use of the sigmoid curve, the patients' head volumes were also calculated and evaluated to assess whether larger head volumes adversely affected STN visibility. RESULTS: The symmetrical sigmoid curve model provided objective information on the visibility of the STN on T2-weighted MRI scans and could be generated in 86% of the patients. The other 14% of patients had MRI scans that generated linear graphs, indicating the poorest scoring for STN image quality. No correlation between head volume and STN visibility was identified. CONCLUSIONS: Our proposed statistical model allows for standardized examination of the visibility of the STN border for DBS and has potential for both clinical and academic applications.

Association of quantitative sensory testing parameters with clinical outcome in patients with lumbar radiculopathy undergoing microdiscectomy.

BACKGROUND/AIM: This study aimed to establish the somatosensory profile of patients with lumbar radiculopathy at pre-and post-microdiscectomy and to explore any association between pre-surgical quantitative sensory test (QST) parameters and post-surgical clinical outcomes. METHODS: A standardized QST protocol was performed in 53 patients (mean age 38 ± 11 years, 26 females) with unilateral L5/S1 radiculopathy in the main pain area (MPA), affected dermatome and contralateral mirror sites and in age- and gender-,and body site-matched healthy controls. Repeat measures at 3 months included QST, the Oswestry Disability Index (ODI) and numerous other clinical measures; at 12 months, only clinical measures were repeated. A change <30% on the ODI was defined as 'no clinically meaningful improvement'. RESULTS: Patients showed a significant loss of function in their symptomatic leg both in the dermatome (thermal, mechanical, vibration detection p < .002), and MPA (thermal, mechanical, vibration detection, mechanical pain threshold, mechanical pain sensitivity p < .041) and increased cold sensitivity in the MPA (p < .001). Pre-surgical altered QST parameters improved significantly post-surgery in the dermatome (p < .018) in the symptomatic leg and in the MPA (p < .010), except for thermal detection thresholds and cold sensitivity. Clinical outcomes improved at 3 and 12 months (p < .001). Seven patients demonstrated <30% change on the ODI at 12 months. Baseline loss of function in mechanical detection in the MPA was associated with <30% change on the ODI at 12 months (OR 2.63, 95% CI 1.09-6.37, p = .032). CONCLUSION: Microdiscectomy resulted in improvements in affected somatosensory parameters and clinical outcomes. Pre-surgical mechanical detection thresholds may be predictive of clinical outcome. SIGNIFICANCE: This study documented quantitative sensory testing (QST) profiles in patients with lumbar radiculopathy in their main pain area (MPA) and dermatome pre- and post-microdiscectomy and explored associations between QST parameters and clinical outcome. Lumbar radiculopathy was associated with loss of function in modalities mediated by large and small sensory fibres. Microdiscectomy resulted in significant improvements in loss of function and clinical outcomes in 85% of our cohort. Pre-surgical mechanical detection thresholds in the MPA may be predictive of clinical outcome.

Statins may not protect against vasospasm in subarachnoid haemorrhage.

Statins have been shown in two recent small phase I/II trials to be associated with a marked reduction in clinical and transcranial Doppler (TCD) evidence of vasospasm after aneurysmal subarachnoid haemorrhage (SAH). The purpose of this study was to assess the clinical impact of this treatment in a larger number of patients. Fifty-eight individuals were treated in the year before, and 72 patients treated in the year after, the introduction of a 2week course of 40mg/day pravastatin therapy for SAH. Statins did not result in reduced TCD velocities, clinical or angiographic vasospasm, or improvements in global outcome at the time of hospital discharge. A measurable reduction in the rates of vasospasm was expected, based on the size of the effect of statin therapy in the previous small studies. There remains significant uncertainty as to the role of statins in preventing vasospasm after SAH.

Ventricular catheter placement accuracy in non-stereotactic shunt surgery for hydrocephalus.

We aimed to compare the accuracy of different shunt catheter approaches to the lateral ventricle in adults with hydrocephalus. We conducted a retrospective review of 138 consecutive patients with hydrocephalus undergoing freehand initial shunt surgery. Of these, 79 had a post-operative brain scan and therefore the results were available for analysis. Scans were graded for successful catheter tip placement in the ventricular target zones: the frontal horn for frontal and occipital approaches, and the atrium for the parietal approach. Ventricular target zones were successfully catheterized in 85% of parietal and 64% of frontal shunts (this difference is not statistically significant). In contrast, only 42% of occipital shunts were correctly placed (p<0.01). Therefore, parietal and frontal catheters are more likely to be placed successfully in the target ventricle. This may be due to the smaller range of successful trajectories open to the occipital approach. Solutions to this problem may include using the theoretically favourable frontal approach for freehand surgery or using stereotactic guidance.

Modulation of saccades in humans by electrical stimulation of the posterior subthalamic area.

OBJECTIVE: Posterior subthalamic area (PSA) deep brain stimulation (DBS) targeting the zona incerta (ZI) is an emerging treatment for tremor syndromes, including Parkinson's disease (PD) and essential tremor (ET). Evidence from animal studies has indicated that the ZI may play a role in saccadic eye movements via pathways between the ZI and superior colliculus (incerto-collicular pathways). PSA DBS permitted testing this hypothesis in humans. METHODS: Sixteen patients (12 with PD and 4 with ET) underwent DBS using the MRI-directed implantable guide tube technique. Active electrode positions were confirmed at the caudal ZI. Eye movements were tested using direct current electrooculography (EOG) in the medicated state pre- and postoperatively on a horizontal predictive task subtending 30°. Postoperative assessments consisted of stimulation-off, constituting a microlesion (ML) condition, and high-frequency stimulation (HFS; frequency = 130 Hz) up to 3 V. RESULTS: With PSA HFS, the first saccade amplitude was significantly reduced by 10.4% (95% CI 8.68%-12.2%) and 12.6% (95% CI 10.0%-15.9%) in the PD and ET groups, respectively. With HFS, peak velocity was reduced by 14.7% (95% CI 11.7%-17.6%) in the PD group and 27.7% (95% CI 23.7%-31.7%) in the ET group. HFS led to PD patients performing 21% (95% CI 16%-26%) and ET patients 31% (95% CI 19%-38%) more saccadic steps to reach the target. CONCLUSIONS: PSA DBS in patients with PD and ET leads to hypometric, slowed saccades with an increase in the number of steps taken to reach the target. These effects contrast with the saccadometric findings observed with subthalamic nucleus DBS. Given the location of the active contacts, incerto-collicular pathways are likely responsible. Whether the acute finding of saccadic impairment persists with chronic PSA stimulation is unknown.

Ventricular catheter trajectories from traditional shunt approaches: a morphometric study in adults with hydrocephalus.

OBJECT: The purpose of this study was to compare the margins of error of different shunt catheter approaches to the lateral ventricle and assess surface anatomical aiming landmarks for free-hand ventricular catheter insertion in adult patients with hydrocephalus. METHODS: Four adults who had undergone stereotactic brain magnetic resonance (MR) imaging and had normal ventricles, and 7 prospectively recruited adult patients with acute hydrocephalus were selected for inclusion in this study. Reconstructed MR images obtained prior to surgical intervention were geometrically analyzed with regard to frontal, parietal, and parietooccipital (occipital) approaches in both hemispheres. RESULTS: The ventricular target zones were as follows: the frontal horn for frontal and occipital approaches, and the atrium/posterior horn for parietal approaches. The range of possible angles for successful catheter insertion was smallest for the occipital approach (8 degrees in the sagittal plane and 11 degrees in the coronal plane), greater for parietal catheters (23 and 36 degrees ), and greatest for the frontal approach in models of hydrocephalic brains (42 and 30 degrees; p < 0.001 for all comparisons except frontal vs parietal, which did not reach statistical significance). There was no single landmark for aiming occipital or parietal catheters that achieved ventricular target cannulation in every case. Success was achieved in only 86% of procedures using occipital trajectories and in 66% of those using parietal trajectories. CONCLUSIONS: The occipital approach to ventricular catheter insertion provides the narrowest margin of error with regard to trajectory but has less aiming point variability than the parietal approach. The use of patient-specific stereotaxy rather than generic guides is required for totally reliable, first-pass ventricular catheterization via a posterior approach to shunt placement surgery in adults.

A survey of surgical techniques for catheterising the cerebral lateral ventricles.

The objective of this paper is to characterise the frequency of different surgical techniques for targeting the lateral ventricle in shunt surgery and the attitudes of Australasian neurosurgeons and advanced neurosurgical trainees to stereotactic adjuncts. Secondarily, we aim to learn from and collate the practical experiences of neurosurgeons for those attempting to improve their operative success. A survey of all practising and training members of the Neurosurgical Society of Australasia (NSA) was conducted. One hundred and eleven surveys were completed generating an overall response rate of 57%. Of those 108 performing shunt surgery, 10 (9%) preferred a frontal approach and 70 (65%) a posterior approach to the frontal horn. Twenty-seven neurosurgeons (25%) preferred the posterior approach to the atrium or body of the lateral ventricle. A wide range of burr hole sites and targeting landmarks were described and are discussed. There was no consistent pattern for neurosurgeons changing their preferred approach during their careers. Seventy-five per cent of respondents make adjustments to measurements for children by a wide range of methods. Frameless or frame-based stereotaxy is used at times by about half of all neurosurgeons. Posterior approaches to the lateral ventricle using freehand techniques are preferred among NSA members and their trainees but there are a wide variety of landmarks used. Many of these techniques have been developed over years of operative experience and could be modelled with planning software to assess their theoretical merits. There is no evidence of the uptake of generic accuracy guides but there is evidence of significant exposure to frameless stereotactic techniques that may grow in popularity as the technology improves.