Barton L. Guthrie

Pituitary carcinoma : A clinicopathologic study of 15 cases

Pituitary carcinomas are rare adenohypophysial neoplasms, the definition, diagnosis, therapy, and prognosis of which are controversial.

Hitting a moving target: evolution of a treatment paradigm for atypical meningiomas amid changing diagnostic criteria

OBJECTnThe World Health Organization (WHO) reclassified atypical meningiomas in 2000, creating a more clear and broadly accepted definition. In this paper, the authors evaluated the pathological and clinical transition period for atypical meningiomas according to the implementation of the new WHO grading system at their institution.nnnMETHODSnA total of 471 meningiomas occurring in 440 patients between 1994 and 2006 were retrospectively reviewed to determine changes in diagnostic rates, postoperative treatment trends, and early outcomes.nnnRESULTSnBetween 1994 and 2000, the incidence of the atypical meningiomas ranged from 0 to 3/year, or 4.4% of the meningiomas detected during the entire period. After 2002, the annual percentage of atypical meningiomas rose over a 2-year period, leveling off at between 32.7 and 35.5% between 2004 and 2006. The authors also found a recent trend toward increased use of adjuvant radiation therapy for incompletely resected atypical meningiomas. Prior to 2003, 18.7% were treated with this therapy; after 2003, 34.4% of lesions received this treatment. Incompletely resected tumors were treated with some form of radiation 76% of the time. In cases of complete resection, most patients were not given adjuvant therapy but were expectantly managed by close monitoring using serial imaging and by receiving immediate treatment for tumor recurrence. The overall recurrence rate for expectantly managed tumors was 9% over 28.2 months, and 75% of recurrences responded to delayed radiation therapy.nnnCONCLUSIONSnThe authors documented a significant change in the proportion of meningiomas designated as atypical during a transition period from 2002 to 2004, and propose a conservative strategy for the use of radiation therapy in atypical meningiomas.

Activation of subthalamic neurons by contralateral subthalamic deep brain stimulation in Parkinson disease

Multiple studies have shown bilateral improvement in motor symptoms in Parkinson disease (PD) following unilateral deep brain stimulation (DBS) of the subthalamic nucleus (STN) and internal segment of the globus pallidus, yet the mechanism(s) underlying this phenomenon are poorly understood. We hypothesized that STN neuronal activity is altered by contralateral STN DBS. This hypothesis was tested intraoperatively in humans with advanced PD using microelectrode recordings of the STN during contralateral STN DBS. We demonstrate alterations in the discharge pattern of STN neurons in response to contralateral STN DBS including short latency, temporally precise, stimulation frequency-independent responses consistent with antidromic activation. Furthermore, the total discharge frequency during contralateral high frequency stimulation (160 Hz) was greater than during low frequency stimulation (30 Hz) and the resting state. These findings demonstrate complex responses to DBS and imply that output activation throughout the basal ganglia-thalamic-cortical network rather than local inhibition is a therapeutic mechanism of DBS.

A three dimensional guidance system for frameless stereotactic neurosurgery

A computer-based tool is being developed to assist neurosurgeons in both preoperative planning and surgery. This tool is called the Stereotaxic Planning and Surgery System (SPSS). SPSS utilizes a localization device coupled with two-dimensional and three-dimensional visualization techniques, and it provides useful information to the surgeon when locating and removing diseased tissue. With SPSS, a new surgical technique referred to as guided frameless stereotaxic surgery is also being developed.<<ETX>>

The relationship between clinical phenotype and early staged bilateral deep brain stimulation in Parkinson disease

OBJECTnWhile many centers place bilateral deep brain stimulation (DBS) systems simultaneously, unilateral subthalamic nucleus (STN) DBS followed by a staged contralateral procedure has emerged as a treatment option for many patients. However, little is known about whether the preoperative phenotype predicts when staged placement of a DBS electrode in the opposite STN will be required. The authors aimed to determine whether preoperative clinical phenotype predicts early staged placement of a second STN DBS electrode in patients who undergo unilateral STN DBS for Parkinson disease (PD).nnnMETHODSnEighty-two consecutive patients with advanced PD underwent unilateral STN DBS contralateral to the most affected hemibody and had at least 2 years of follow-up. Multivariate logistic regression analysis determined preoperative characteristics that predicted staged placement of a second electrode in the opposite STN. Preoperative measurements included aspects of the Unified Parkinsons Disease Rating Scale (UPDRS), motor asymmetry index, and body weight.nnnRESULTSnAt 2-year follow-up, 28 (34%) of the 82 patients had undergone staged placement of a contralateral electrode while the remainder chose to continue with unilateral stimulation. Statistically significant improvements in UPDRS total and Part 3 scores were retained at the end of the 2-year follow-up period in both subsets of patients. Multivariate logistic regression analysis showed that the most important predictors for early staged placement of a second subthalamic stimulator were low asymmetry index (OR 13.4, 95% CI 2.8-64.9), high tremor subscore (OR 7.2, CI 1.5-35.0), and low body weight (OR 5.5, 95% CI 1.4-22.3).nnnCONCLUSIONSnThis single-center study provides evidence that elements of the preoperative PD phenotype predict whether patients will require early staged bilateral STN DBS. These data may aid in the management of patients with advanced PD who undergo STN DBS.

Virtual interactive presence for real-time, long-distance surgical collaboration during complex microsurgical procedures

OBJECTnThe shortage of surgeons compels the development of novel technologies that geographically extend the capabilities of individual surgeons and enhance surgical skills. The authors have developed Virtual Interactive Presence (VIP), a platform that allows remote participants to simultaneously view each others visual field, creating a shared field of view for real-time surgical telecollaboration.nnnMETHODSnThe authors demonstrate the capability of VIP to facilitate long-distance telecollaboration during cadaveric dissection. Virtual Interactive Presence consists of local and remote workstations with integrated video capture devices and video displays. Each workstation mutually connects via commercial teleconferencing devices, allowing worldwide point-to-point communication. Software composites the local and remote video feeds, displaying a hybrid perspective to each participant. For demonstration, local and remote VIP stations were situated in Indianapolis, Indiana, and Birmingham, Alabama, respectively. A suboccipital craniotomy and microsurgical dissection of the pineal region was performed in a cadaveric specimen using VIP. Task and system performance were subjectively evaluated, while additional video analysis was used for objective assessment of delay and resolution.nnnRESULTSnParticipants at both stations were able to visually and verbally interact while identifying anatomical structures, guiding surgical maneuvers, and discussing overall surgical strategy. Video analysis of 3 separate video clips yielded a mean compositing delay of 760 ± 606 msec (when compared with the audio signal). Image resolution was adequate to visualize complex intracranial anatomy and provide interactive guidance.nnnCONCLUSIONSnVirtual Interactive Presence is a feasible paradigm for real-time, long-distance surgical telecollaboration. Delay, resolution, scaling, and registration are parameters that require further optimization, but are within the realm of current technology. The paradigm potentially enables remotely located experts to mentor less experienced personnel located at the surgical site with applications in surgical training programs, remote proctoring for proficiency, and expert support for rural settings and across different counties.

Spatial topographies of unilateral subthalamic nucleus deep brain stimulation efficacy for ipsilateral, contralateral, midline, and total Parkinson disease motor symptoms.

BACKGROUND: Subthalamic nucleus (STN) deep brain stimulation is a successful intervention for medically refractory Parkinson disease, although its efficacy depends on optimal electrode placement. Even though the predominant effect is observed contralaterally, modest improvements in ipsilateral and midline symptoms are also observed. OBJECTIVE: To elucidate the role of contact location of unilateral deep brain stimulation on contralateral, ipsilateral, and axial subscores of Parkinson disease motor symptoms. METHODS: Eighty-six patients receiving first deep brain stimulation STN electrode placements were identified, yielding 73 patients with 3-month follow-up. Total preoperative and postoperative Unified Parkinson Disease Rating Scale Part III scores were obtained and divided into contralateral, ipsilateral, and midline subscores. Contact location was determined on immediate postoperative magnetic resonance imaging. A 3-dimensional ordinary “kriging” algorithm generated spatial interpolations for total, ipsilateral, contralateral, and midline symptom categories. Interpolative reconstructions were performed in the axial planes (z = −0.5, −1.0, −1.5, −3.5, −4.5, −6.0) and a sagittal plane (x = 12.0). Interpolation error and significance were quantified by use of a cross-validation technique and quantile-quantile analysis. RESULTS: There was an overall reduction in Unified Parkinson Disease Rating Scale Part III symptoms: total = 37.0 ± 24.11% (P < .05), ipsilateral = 15.9 ± 51.8%, contralateral = 56.2 ± 26.8% (P < .05), and midline = 26.5 ± 34.7%. Kriging interpolation was performed and cross-validated with quantile-quantile analysis with high correlation (R2 > 0.92) and demonstrated regions of efficacy for each symptom category. Contralateral symptoms demonstrated broad regions of efficacy across the peri-STN area. The ipsilateral and midline regions of efficacy were constrained and located along the dorsal STN and caudal zona incerta. CONCLUSION: We provide evidence for a unique functional topographic window in which contralateral, ipsilateral, and midline structures may achieve the best efficacy. Although there are overlapping regions, laterality demonstrates distinct topographies. Surgical optimization should target the intersection of optimal regions for these symptom categories. ABBREVIATIONS: AC, anterior commissure DBS, deep brain stimulation PC, posterior commissure ROE, region of efficacy STN, subthalamic nucleus SW, Schaltenbrand-Wahren UPDRS, Unified Parkinson Disease Rating Scale

Construction of Relational Topographies from the Quantitative Measurements of Functional Deep Brain Stimulation Using a ‘Roving Window’ Interpolation Algorithm

The delivery of stimulus by a deep brain stimulation (DBS) contact electrode at a particular location may lead to a quantifiable physiologic effect, both intraoperatively and postoperatively. Consequently, measured data values can be attributed to discrete scattered points in neuroanatomic space, allowing for interpolative techniques to generate a topographic map of spatial patterns. Ultimately, by relating the topographies of various intraoperative measurements to the postoperative counterparts and neuroanatomic atlases, outcome-guided adjustments to electrode position can be pursued intraoperatively. In this study, 52 Parkinson’s disease patients were tested with a postoperative trial of stimulation and thresholds were recorded for motor adverse effects. A ‘roving window’ interpolation algorithm was adapted to generate a topographic map of voltage threshold along selected axial, coronal and sagittal planes. By developing these relational topographies for a variety of intraoperative and postoperative effects, a multivariable approach towards DBS optimization emerges.

The Relationship of Electrophysiologic Subthalamic Nucleus Length as a Predictor of Outcomes in Deep Brain Stimulation for Parkinson Disease

Background: Intraoperative measurement of subthalamic nucleus (STN) width through microelectrode recording (MER) is a common proxy for optimal electrode location during deep brain stimulation (DBS) surgery for Parkinson disease. We assessed whether the MER-determined STN width is a predictor of postoperative Unified Parkinson Disease Rating Scale (UPDRS) improvement. Methods: Records were reviewed for patients who underwent single-sided STN DBS placement for Parkinson disease between 2005 and 2010 at the UAB Medical Center. Reviews of preoperative and 3-month postoperative UPDRS part III, intraoperative MER records, and postoperative MRI scans were conducted. Results: The final cohort consisted of 73 patients (mean age 59 ± 9.7 years, length of disease 13 ± 9.7 years). STN widths were defined as depths associated with increased background activity and motor-driven, spiking action potentials on MER. The mean contralateral UPDRS improvement was 58% (± 24). The mean STN width was 5.1 mm (± 1.6, min = 0.0, max = 8.7). No significant relationship between STN width and UPDRS improvement was found, with and without AC-PC normalization (R2 < 0.05). Conclusion: This analysis raises questions about seeking the maximal electrophysiological width of STN as a proxy for optimal outcome in DBS for PD. We suggest this strategy for DBS placement in Parkinson disease be subject to more robust prospective investigation.

The Digital Imaging and Communications in Medicine (DICOM) archive is a dynamic component of a clinician image-related workflow solution.

The authors investigated clinician transactions against the Digital Imaging and Communications in Medicine (DICOM) archive within a clinical image management system (CIMS) in support of patient care. A Neurosurgical Oncology practice was audited for image utilization. There were 400 requests for 233 image studies during 297 sessions. Fifty percent were for current studies, and 50% were for historical studies. Current studies alone were requested in 37% of the sessions, current plus historical in 31%, and hisorical alone in 32% of the sessions. Seventy percent of studies were within 8 weeks old and were rapidly available from the CIMS disk cache without an archive image transaction. Conversely, 30% were older than 8 weeks, requiring a clinician transaction against the archive for image retrieval. Approximately 25% of studies were older than 3 months and 10% older than 6 months. Clinician image needs are complex and any CIMS solution must include a DICOM archive that can support clinician-based transactions.