Learning curves of open and endoscopic fetal spina bifida closure: systematic review and meta-analysis.

OBJECTIVE: The Management of Myelomeningocele Study (MOMS) trial demonstrated the safety and efficacy of open fetal surgery for spina bifida aperta (SBA). Recently developed alternative techniques may reduce maternal risks without compromising the fetal neuroprotective effects. The aim of this systematic review was to assess the learning curve (LC) of different fetal SBA closure techniques. METHODS: MEDLINE, Web of Science, EMBASE, Scopus and Cochrane databases and the gray literature were searched to identify relevant articles on fetal surgery for SBA, without language restriction, published between January 1980 and October 2018. Identified studies were reviewed systematically and those reporting all consecutive procedures and with postnatal follow-up ≥ 12 months were selected. Studies were included only if they reported outcome variables necessary to measure the LC, as defined by fetal safety and efficacy. Two authors independently retrieved data, assessed the quality of the studies and categorized observations into blocks of 30 patients. For meta-analysis, data were pooled using a random-effects model when heterogeneous. To measure the LC, we used two complementary methods. In the group-splitting method, competency was defined when the procedure provided results comparable to those in the MOMS trial for 12 outcome variables representing the immediate surgical outcome, short-term neonatal neuroprotection and long-term neuroprotection at ≥ 12 months of age. Then, when raw patient data were available, we performed cumulative sum analysis based on a composite binary outcome defining successful surgery. The composite outcome combined four clinically relevant variables for safety (absence of extreme preterm delivery < 30 weeks, absence of fetal death ≤ 7 days after surgery) and efficacy (reversal of hindbrain herniation and absence of any neonatal treatment of dehiscence or cerebrospinal fluid leakage at the closure site). RESULTS: Of 6024 search results, 17 (0.3%) studies were included, all of which had low, moderate or unclear risk of bias. Fetal SBA closure was performed using standard hysterotomy (11 studies), mini-hysterotomy (one study) or fetoscopy by either exteriorized-uterus single-layer closure (one study), percutaneous single-layer closure (three studies) or percutaneous two-layer closure (one study). Only outcomes for standard hysterotomy could be meta-analyzed. Overall, outcomes improved significantly with experience. Competency was reached after 35 consecutive cases for standard hysterotomy and was predicted to be achieved after ≥ 57 cases for mini-hysterotomy and ≥ 56 for percutaneous two-layer fetoscopy. For percutaneous and exteriorized-uterus single-layer fetoscopy, competency was not reached in the 81 and 28 cases available for analysis, respectively, and LC prediction analysis could not be performed. CONCLUSIONS: The number of cases operated is correlated with the outcome of fetal SBA closure, and the number of operated cases required to reach competency ranges from 35 for standard hysterotomy to ≥ 56-57 for minimally invasive modifications. Our observations provide important information for institutions looking to establish a new fetal center, develop a new fetal surgery technique or train their team, and inform referring clinicians, potential patients and third parties. Copyright © 2019 ISUOG. Published by John Wiley & Sons Ltd.

Curvas de aprendizaje del cierre de la espina bífida fetal mediante cirugía abierta y endoscópica: revisión sistemática y metaanálisis OBJETIVO: El ensayo del Estudio sobre la Gestión del Mielomeningocele (MOMS, por sus siglas en inglés) demostró la seguridad y eficacia de la cirugía fetal abierta para la espina bífida aperta (EBA). Las técnicas alternativas recientemente desarrolladas pueden reducir los riesgos de la madre sin comprometer los efectos neuroprotectores del feto. El objetivo de esta revisión sistemática fue evaluar la curva de aprendizaje (CA) de diferentes técnicas de cierre de la EBA fetal. MÉTODOS: Se realizaron búsquedas en las bases de datos de MEDLINE, Web of Science, EMBASE, Scopus y Cochrane, así como en la literatura gris, para identificar artículos relevantes sobre cirugía fetal para la EBA, sin restricción de idioma, publicados entre enero de 1980 y octubre de 2018. Se examinaron sistemáticamente los estudios identificados y se seleccionaron los que informaban de todos los procedimientos consecutivos y con seguimiento postnatal ≥12 meses. Los estudios se incluyeron sólo si informaban sobre las variables de resultado necesarias para medir la CA, definidas por la seguridad y la eficacia para el feto. Dos autores recuperaron los datos de forma independiente, evaluaron la calidad de los estudios y clasificaron las observaciones en bloques de 30 pacientes. Para el metaanálisis, los datos se agruparon mediante un modelo de efectos aleatorios cuando fueron heterogéneos. Para medir la CA, se usaron dos métodos complementarios. En el método de división de grupos, la competencia se definió cuando el procedimiento proporcionó resultados comparables a los del ensayo MOMS para 12 variables de resultados que representaban el resultado quirúrgico inmediato, la neuroprotección neonatal a corto plazo y la neuroprotección a largo plazo a ≥12 meses de edad. Luego, cuando se dispuso de los datos brutos de los pacientes, se realizó un análisis de suma acumulada basado en un resultado binario compuesto que definió el éxito de la cirugía. El resultado compuesto combinó cuatro variables clínicamente relevantes en cuanto a la seguridad (ausencia de parto pretérmino extremo <30 semanas; ausencia de muerte fetal a ≤7 días después de la cirugía) y eficacia (reducción de la hernia del rombencéfalo y ausencia de cualquier tratamiento neonatal de dehiscencia o derrame de líquido cefalorraquídeo en el lugar del cierre). RESULTADOS: De los 6024 resultados de la búsqueda, se incluyeron 17 (0,3%) estudios, todos ellos con un riesgo de sesgo bajo, moderado o incierto. El cierre de la EBA fetal se realizó mediante histerotomía estándar (11 estudios), mini histerotomía (un estudio) o fetoscopia, ya fuera mediante el cierre exteriorizado del útero de una sola capa (un estudio), el cierre percutáneo de una sola capa (tres estudios) o el cierre percutáneo de dos capas (un estudio). Sólo se pudieron metaanalizar los resultados de la histerotomía estándar. En general, los resultados mejoraron significativamente con la experiencia. Se alcanzó la competencia después de 35 casos consecutivos para la histerotomía estándar y se predijo que se alcanzaría después de ≥57 casos para la mini histerotomía y ≥56 para la fetoscopia percutánea de dos capas. En el caso de las fetoscopias percutánea y exteriorizada del útero de una sola capa, no se alcanzó la competencia en los 81 y 28 casos disponibles para el análisis, respectivamente, y no se pudo realizar el análisis de predicción de la CA. CONCLUSIONES: El número de casos operados está correlacionado con el resultado del cierre de la EBA fetal, y el número de casos operados necesarios para alcanzar la competencia estuvo entre 35 para la histerotomía estándar y ≥56-57 para las operaciones con mínima agresividad. Las observaciones realizadas proporcionan información importante para las instituciones que buscan establecer un nuevo centro fetal, desarrollar una nueva técnica de cirugía fetal o entrenar a su equipo, e informar a los médicos que remiten a especialistas a los posibles pacientes y a terceros. Copyright © 2019 ISUOG. Published by John Wiley & Sons Ltd.

Absorption of wireless radiation in the child versus adult brain and eye from cell phone conversation or virtual reality.

Children's brains are more susceptible to hazardous exposures, and are thought to absorb higher doses of radiation from cell phones in some regions of the brain. Globally the numbers and applications of wireless devices are increasing rapidly, but since 1997 safety testing has relied on a large, homogenous, adult male head phantom to simulate exposures; the "Standard Anthropomorphic Mannequin" (SAM) is used to estimate only whether tissue temperature will be increased by more than 1 Celsius degree in the periphery. The present work employs anatomically based modeling currently used to set standards for surgical and medical devices, that incorporates heterogeneous characteristics of age and anatomy. Modeling of a cell phone held to the ear, or of virtual reality devices in front of the eyes, reveals that young eyes and brains absorb substantially higher local radiation doses than adults'. Age-specific simulations indicate the need to apply refined methods for regulatory compliance testing; and for public education regarding manufacturers' advice to keep phones off the body, and prudent use to limit exposures, particularly to protect the young.

Radiosurgery from the brain to the spine: 20 years experience.

INTRODUCTION: Radiosurgery evolved from brain to spine. Mechanical and computer advances in linear accelerator (LINAC) radiosurgery apply precise single/fractional stereotactic radiation to multiple pathologies. METHODS: During a 10-year span the senior author used proton-beam radiosurgery in over 300 lesions, followed by gamma-knife, adapted and dedicated LINACS, including cyber-knife, in another 700 patients. The last 10 years, experience was accumulated with the Novalis in over 3,000 patients. Novalis uses a beam-shaper in a high-speed delivery LINAC. It operates using conventional circular arc, conformal static beam, dynamic conformal or intensity modulated modes. Patients treated with Novalis at the UCLA since 1997 were evaluated regarding effectiveness, complications and failure. These results were compared with previous 1997 data. RESULTS: Over 4,000 patients with trigeminal neuralgia/intractable pain, arteriovenous malformations/angiomas, metastases, ependymomas, gliomas, meningiomas hemangiopericytomas, schwannomas, adenomas, hemangioblastomas, and chordoma were treated. Spinal lesions were treated with frameless stereotaxis and on-line precision checks. Treatment was expeditious, comfortable and with reduced complications. Success is similar or superior to published data. Reduced treatment time of complex lesions and highly homogeneous dose compares favorably to other radiosurgery. CONCLUSIONS: The senior author's experience validates the novel shaped-beam approach. Long-term follow-up supports safety and effectiveness and capability to treat brain and spine.

Deep brain stimulation in intraoperative MRI environment - comparison of imaging techniques and electrode fixation methods.

We performed 118 consecutive DBS cases from November 1999 to June 2002. Intraoperatively there were 10 cases studied with fluoroscopy, 73 with 0.2 Tesla (T) MRI and 35 with 1.5 T MRI. Ten electrodes were secured by Medtronic caps, 25 by methyl methacrylate with titanium miniplates, and 82 by Navigus caps. The 3-dimensional displacement between the planned target and actual electrode position (3DD) was determined by fusing the postoperative MRI with the preoperative imaging. The 3DD for using Medtronic caps, methyl methacrylate with miniplates, and Navigus caps were 4.80 +/- 3.16, 2.64 +/- 1.26 and 2.23 +/- 1.15 mm (mean +/- SD), respectively. Navigus caps had statistically significant accuracy (P = 0.03) in holding the electrode when compared with Medtronic caps, and it facilitated electrode revision. The fixation devices significantly affect the final vertical position of the electrode. The 3DD for fluoroscopy, 0.2 T and 1.5 T MRI cases were 4.80 +/- 3.16, 2.31 +/- 1.21 and 2.34 +/- 1.14 mm (mean +/- SD), respectively. No statistically significant difference (P = 0.91) in 3DD was demonstrated between 0.2 T and 1.5 T MRI cases. The presence of intraoperative 1.5 T MRI allowed near real-time electrode position confirmation and early detection of hemorrhagic complications. Satisfactory microelectrode recording was feasible in low-field 0.2 T and high-field 1.5 T MRI environments. Further studies on performing DBS in real-time intraoperative MRI are warranted.

Functional neurosurgery in the MRI environment.

OBJECTIVE: The purpose of this study was to evaluate the feasibility of microelectrode recording, electrical stimulation, and electrode position checking during functional neurosurgical procedures (DBS, lesion) in the interventional magnetic resonance imaging (iMRI) environment. METHODS: Seventy-six surgical procedures for DBS implant or radiofrequency lesion were performed in an open 0.2 T MRI operating room. DBS implants were performed in 54 patients (72 surgical procedures) and unilateral radiofrequency lesions in three for a total of 76 surgeries in 57 patients. Electrophysiological studies including macrostimulation and microelectrode recordings for localization were obtained in the 0.5 to 10 mT fringes of the magnetic field in 51 surgeries. MRI confirmation of the electrode position during the procedure was performed after electrophysiological localization. RESULTS: The magnetic field associated with the MRI scanner did not contribute significant noise to microelectrode recordings. Anatomical confirmation of electrode position was possible within the MRI artifact from the DBS hardware. Symptomatic hemorrhage was detected in two (2.6 %) patients during the operation. Image quality of the 0.2 T MRI scan was sub-optimal for anatomical localization. However, image fusion with pre-operative scans permitted excellent visualization of the DBS electrode tip in relation to the higher quality 1.5 T MRI anatomical scans. CONCLUSION: This study shows that conventional stereotactic localization, microelectrode recordings, electrical stimulation, implant of DBS hardware, and radiofrequency lesion placement are possible in the open 0.2 T iMRI environment. The convenience of having an imaging modality that can visualize the brain during the operation is ideal for stereotactic procedures.

Noninvasive linear accelerator radiosurgery as the primary treatment for trigeminal neuralgia.

The application of a dedicated linear accelerator (DLINAC) as a noninvasive surgical treatment for trigeminal neuralgia has not yet been demonstrated. This work evaluates the outcome and indications of 22 patients submitted to DLINAC radiosurgery as a primary treatment for essential trigeminal neuralgia. At last follow-up evaluation, 21 patients (95.5%) had sustained significant pain relief. DLINAC radiosurgery is safe and effective as a primary noninvasive surgical treatment for selected patients with essential trigeminal neuralgia.

Simulações da SAR na cabeça e antenas planares para telefones móveis / SAR simulations and planar antennas for mobile phones

A Taxa de Absorção Específica (SAR) na cabeça dos usuários de telefones móveis é simulada utilizando o método das Diferenças Finitas no Domínio do Tempo (FDTD) quando antenas tipo monopolo convencionais e quando antenas diretivas planares são utilizadas. São também resumidos o projeto de antenas tipo patch retangular em microstrip, suas características de desempenho esperadas e medidas são apresentadas. São calculados entre outros, a taxa de onda estacionária e a largura de banda simuladas no software Ensemble®, o diagrama de irradiação no plano horizontal e o campo na região próxima, claculado em simulação em três dimensões - 3D com algoritmo baseado em FDTD. Medidas da taxa de Onda Estacionária VSWR e dos diagramas de irradiação horizontal são mostradas. Verifica-se uma excelente correlação entre os resultados das medidas e os obtidos com o método FDTD em simulações com plano de terra finito e sem aterramento efetivo. Observa-se que este tipo de antena pode ser utilizado em uma nova geração de telefones móveis, constituindo-se em uma alternativa conveniente para melhorar o desempenho destes transcetores, diminuindo também os riscos à saúde dos usuários

Radiosurgery and stereotactic radiation therapy of skull base meningiomas: proposal of a grading system.

OBJECTIVE: The development of a grading system to guide treatment selection, and predict treatment difficulty and outcome of skull base meningiomas infiltrating the cavernous sinus which are managed by stereotactic radiosurgery (SRS) and stereotactic radiotherapy (SRT), based on an 8-year experience with stereotactic radiation of skull base meningiomas. METHODS: T1 gadoliniun-enhanced magnetic resonance imaging (MRI) of 40 patients with skull base meningiomas, with or without prior surgery, who underwent radiosurgery or stereotactic radiation therapy from 1991 to 1998 at the UCLA Medical Center were reviewed, and the result of treatment was related to the tumor grade. Grade was based on tumor infiltration of the cavernous sinus and extension into adjacent structures. Treatment was performed with a linac-based system. The dose prescribed to the periphery of the tumor for SRS patients (n = 34) ranged from 12 to 22 Gy, and the maximum dose delivered to the tumor ranged from 24 to 46 Gy. SRT (n = 6). Treatment was planned using a single isocenter, usually prescribed to the 90% isodose volume, bringing the fractionation scheme to the maximal tolerance of the optic apparatus. The periphery dose ranged from 24 to 46 Gy with a maximum dose of 45 to 51 Gy. Clinical and MRI follow-up was performed every six months for the first 3 years and every year thereafter. RESULTS: Grade I meningiomas were restricted to the cavernous sinus (n = 12). Grade II cavernous sinus meningiomas extended to the clivus and/or the petrous bone, without compression of the brainstem (n = 9). Grade III meningiomas had superior and/or anterior extension with compression of the optic nerve or tract (n = 9). Grade IV tumors compressed the brain stem (n = 8), and Grade V were bilateral lesions (n = 2). Tumor control rates were 90% for Grade I, 86% for Grade II, 86% for Grade III, 42% for Grade IV and no control for tumors Grade V. Complications were not related to tumor grade. CONCLUSION: This grading system correlated with outcome and difficulty in planning radiosurgery. Failure of treatment was more likely to occur in patients with higher Grade tumors.

Radiosurgery performed with the aid of a 3-mm collimator in the subthalamic nucleus and substantia nigra of the vervet monkey.

OBJECT: Radiosurgery for functional neurosurgery performed using a linear accelerator (LINAC) has not been extensively characterized in preclinical studies. In the present study, the properties of a newly designed 3-mm-diameter collimator were evaluated in a dedicated LINAC, which produced lesions in the basal ganglia of vervet monkeys. Lesion formation was determined in vivo in three animals by examining magnetic resonance (MR) images to show the dose-delivery precision of targeting and the geometry and extent of the lesions. Postmortem immunohistochemical studies were conducted to determine the extent of lesion-induced radiobiological effects. METHODS: In three male vervet monkeys, the subthalamic nucleus (STN; one animal) and the pars compacta of the lateral substantia nigra (SN; two animals) were targeted by a Novalis Shaped Beam Surgery System that included a 3-mm collimator and delivered a maximum dose of 150 Gy. Magnetic resonance images obtained 4, 5, and 9 months posttreatment were reviewed, and the animals were killed so that immunohistological characterizations could be made. CONCLUSIONS: The generation of precise radiosurgical lesions by a 3-mm collimator was validated in studies that targeted the basal ganglia of the vervet monkey. The extent of the lesions created in all animals remained restricted in diameter (< 3 mm) throughout the duration of the studies, as assessed by reviewing MR images. Histological studies showed that the lesions were contained within the STN and SN target areas and that there were persistent increases in glial fibrillary acidic protein immunoreactivity. Increases in immunoreactivity for tyrosine hydroxylase, the serotonin transporter, and the GluR1 subunit of the alpha-amino-3-hydroxy-5-methyl-4-isoxazole propionate glutamate receptor in penumbral regions of the lesion were suggestive of compensatory neuronal adaptations. This radiosurgical approach may be of particular interest for the induction of lesions of the STN and SN in studies of experimental parkinsonism, as well as for the development of potential radiosurgical treatments for Parkinson disease.

Experimental radiosurgery simulations using a theoretical model of cerebral arteriovenous malformations.

BACKGROUND AND PURPOSE: A novel biomathematical arteriovenous malformation (AVM) model based on electric network analysis was used to investigate theoretically the potential role of intranidal hemodynamic perturbations in elevating the risk of rupture after simulated brain AVM radiosurgery. METHODS: The effects of radiation on 28 interconnected plexiform and fistulous AVM nidus vessels were simulated by predefined random or stepwise occlusion. Electric circuit analysis revealed the changes in intranidal flow, pressure, and risk of rupture at intervals of 3 months during a 3-year latency period after simulated partial/complete irradiation of the nidus using doses <25 and >/=25 Gy. An expression for risk of rupture was derived on the basis of the functional distribution of the critical radii of component vessels. The theoretical effects of radiation were also tested on AVM nidus vessels with progressively increasing elastic modulus (E:) and wall thickness during the latency period, simulating their eventual fibrosis. RESULTS: In an AVM with E=5. 0x10(4) dyne/cm(2), 4 (14.3%) of a total 28 sets of AVM radiosurgery simulations revealed theoretical nidus rupture (risk of rupture >/=100%). Three of these were associated with partial nidus coverage and 1 with complete treatment. All ruptures occurred after random occlusion of nidus vessels in AVMs receiving low-dose radiosurgery. Intranidal hemodynamic perturbations were observed in all cases of AVM rupture; the occlusion of a fistulous component resulted in intranidal rerouting of flow and escalation of the intravascular pressure in adjacent plexiform components. Risk of rupture was found to correlate with nidus vessel wall strength: a low E: of 1.9x10(4) dyne/cm(2) resulted in a 92.8% incidence of AVM rupture, whereas a higher E: of 7.0x10(4) dyne/cm(2) resulted in only a 3.6% incidence of AVM rupture. A dramatic reduction in rupture incidence was observed when increasing fibrosis of the nidus was modeled during the latency period. CONCLUSIONS: It was found that the theoretical occurrence of AVM hemorrhage after radiosurgery was low, particularly when radiation-induced fibrosis of nidus vessels was considered. When rupture does occur, it would appear from a theoretical standpoint that the occlusion of intranidal fistulas or larger-caliber plexiform vessels could be a significant culprit in the generation of critical intranidal hemodynamic surges resulting in nidus rupture. The described AVM model should serve as a useful research tool for further theoretical investigations of cerebral AVM radiosurgery and its hemodynamic sequelae.

MRI of thermally denatured blood: methemoglobin formation and relaxation effects.

Focal regions of T1-shortening have been observed in magnetic resonance imaging (MRI)-monitored thermal ablations of perfused tissues. The aims of this study were two-fold: to find evidence for heat-induced conversion of hemoglobin (Hb) to methemoglobin (mHb), and to investigate the effects of heat treatment of in-vitro blood components upon their MR relaxation times. Spectrophotometric studies were performed to confirm the heat-induced formation of methemoglobin. Preparations of whole and fractionated blood, previously submitted to elevated temperatures of 40 degrees C to 80 degrees C, were imaged and the relaxation times were calculated. Optical absorption spectra of samples containing free Hb, heated to 60 degrees C, showed increased light absorption at 630 nm, evident of mHb presence. Short T1 values in whole blood (1.13 s) and packed red blood cell (0.65 s) compartments, heated at 60 degrees C, compared to their baseline values (1.62 s and 0.83 s, respectively), were attributed to mHb formation. In relation to MRI-guided thermal interventions, these results suggest a possible explanation for observation of hyperintense regions on T1-weighted images.

Correlation between MRI-based stereotactic thalamic deep brain stimulation electrode placement, macroelectrode stimulation and clinical response to tremor control.

In this study we compared the position of the electronically active contact of the thalamic (Vim) deep brain stimulation (DBS) electrode to the stereotactic location of its tip. Fifteen patients with either Parkinson's disease (PD) or essential tremor (ET) underwent stereotactic, MRI-based placement of the Medtronic quadripolar DBS electrode. An overall improvement of 69% was achieved in the tremor scores during a period of 1-13 months after implantation of the DBS electrode. Eleven patients with ET showed 70% clinical improvement of tremor, compared to a 58% response observed in the 4 patients with PD. The electrode tip center was 11.2 +/- 1.54 mm lateral to the third ventricular wall, 5.38 +/- 1.02 mm anterior to the posterior commissure and 2.9 +/- 3.57 mm inferior to the level of AC-PC line. The most significant deviation from the planned stereotactic target was observed in the Z-coordinate. In our group of patients, stimulation settings favored the contacts closer to the AC-PC line, correcting the electrode tip position to 0.80 +/- 2.84 mm (p < 0.001) inferior to the level of the AC-PC line. In our experience, thalamic DBS offers a reversible and adjustable 'lesion' to compensate for the anatomic variabilities encountered in the positioning of the DBS electrode tip.

Stereotactic radiosurgery of cerebral arteriovenous malformations: appearance of perinidal T(2) hyperintensity signal as a predictor of favorable treatment response.

The purpose of this study was to analyze the significance of perinidal T(2) hyperintensity appearance after radiosurgery of arteriovenous malformations (AVMs), as a predictor of treatment response. Our initial experience with linear accelerator (LINAC) radiosurgery at University of California, Los Angeles, between 1990 and 1997 involved treatment of 129 patients affected by cerebral AVMs. Based upon availability of neuroimaging follow-up, 48 patients with 50 AVMs were selected for review. Forty (80%) of the AVMs underwent complete obliteration or significant reduction on follow-up MRI, on average 20 months after radiosurgery. Thirteen (72%) of 18 obliterated AVMs were associated with perinidal T(2) hyperintensity signal, on average 18 months (6-49) after radiosurgery. Ten (20%) of 50 AVMs (average volume 23.1 cm(3), ranging 7.5-46.5) were unchanged. Furthermore, only 3 AVMs in this group showed reversible T(2) signal changes. In patients with complete nidal obliteration, appearance of T(2) hyperintensity signal achieves 72% sensitivity in predicting successful treatment response.

Delayed internal capsule infarctions following radiofrequency pallidotomy. Report of three cases.

The authors report on a series of patients with idiopathic Parkinson's disease (IPD) who underwent stereotactic radiofrequency (RF) pallidotomies, three of whom suffered delayed postoperative strokes. These three belonged to a group consisting of 42 patients with medically intractable IPD in whom 50 pallidotomies were performed. All three patients had significant previous vascular disease and were in a high-risk group for cerebral infarction. A postoperative magnetic resonance (MR) image was obtained immediately after the pallidotomy was performed to document the placement of the RF lesion and to rule out any hematoma. The delayed strokes occurred on postoperative Days 10, 51, and 117 in patients with previous vascular disease (Group 1, 11 patients). No strokes occurred in the group with the vascular disease risk factor (Group 2, 11 patients) or in the group with no risk factors for vascular disease (Group 3, 20 patients). This observation is statistically significant (p < 0.05). The T2-weighted MR images showed the lesions as high-intensity signals extending to the posterior limb of the internal capsule ipsilateral to the pallidotomy site. The poststroke T1-weighted images obtained in two patients showed persistent contrast enhancement of the RF lesion and no enhancement around the stroke lesion. Clinically and radiographically, these discrete new lesions represent delayed infarctions, suggesting that RF lesioning can induce delayed injury in adjacent tissue. Patients with previously identified vasculopathy may be at risk for delayed capsular infarction following RF pallidotomy.

Presence of herpes simplex DNA in surgical tissue from human epileptic seizure foci detected by polymerase chain reaction: preliminary study.

OBJECTIVES: To determine whether herpes simplex virus causes monofocal epilepsy and to assess the presence of herpes simplex virus 1 (HSV-1) and HSV-2 in surgical specimens from patients with epilepsy by using polymerase chain reaction and Southern blot analysis. BACKGROUND: Herpes simplex virus is a common neurotropic virus capable of latency within the central nervous system; it has a predilection for the temporal lobe. Central nervous system infection with HSV has been associated with seizure activity. DESIGN AND METHODS: Surgical specimens were removed from 50 patients as part of a treatment protocol for monofocal epilepsy. Neuropathological classification was done, and adjacent sections were screened for HSV by using polymerase chain reaction. Tissues obtained post mortem from the temporal lobe cortex of persons with Alzheimer disease (n=17), Parkinson disease (n=14), or nonneurological disease (n=17) served as controls. RESULTS: Twenty (40%) of the 50 epilepsy cases and 2 (4%) of the 48 control cases had at least one sample that tested positive for HSV (P<.001). Sixty-seven percent (8/12) of the epilepsy cases with heterotopia were positive for HSV. CONCLUSIONS: There was a statistically significant difference in the frequency of HSV-positive surgical specimens from monofocal seizure epicenters compared with nonepilepsy control specimens. These data suggest an association of the virus with seizure activity. All specimens positive for HSV (surgical specimens and control specimens) should be examined to determine the activity or latency state of the virus and cellular localization.

Endoscopic-assisted clipping of cerebral aneurysms.

Our experience suggests that, with current technology, it is possible to visualize, dissect, and clip cerebral aneurysm using only the endoscope for visualization. Each of the endoscopes requires little or no brain retraction and could be introduced through a bur hole. The penscope would need the largest opening (1.0 x 1.5 cm), because work is done alongside the scope. However, it overcomes the inherent problem of bur hole surgery for aneurysms: what to do in case of a rupture. Working through a slightly larger opening allows the introduction of other instruments outside of and parallel to the penscope, such as suction and aneurysm clips. The penscope is, therefore, most currently suited for aneurysm surgery.

The side-effects and complications of posteroventral pallidotomy.

The side-effects and complications of posteroventral pallidotomy are analysed in 138 consecutive patients who underwent 152 pallidotomies. Transient side-effects, lasting less than three months, appeared in 18% of the patients, that is, 16.5% of the surgical procedures. Long term complications, lasting more than 6 months, were noted in 10% of the patients, that is, 9.2% of the surgical procedures. Sixteen complications occurred alone or in various combinations in 14 patients and included fatigue and sleepiness (2), worsening of memory (4), depression (1), aphonia (1), dysarthria (3), scotoma (1), slight facial and leg paresis (2) and delayed stroke (2). Complications such as dysarthria and paresis could be attributed to MR- or CT-verified pallidal lesions lying too medially and encroaching on the internal capsule. Two of the patients with deterioration in memory had some memory impairment before surgery, and the aphonic patient had dysphonia preoperatively. The study suggests that stereotactic MRI and careful impedance monitoring and macro-stimulation of the posteroventral pallidum area should be sufficient for minimizing the risk of complications; the stereotactic lesion should be centered within the posterior ventral pallidum without involvement of internal capsule. It is concluded that pallidotomy is a safe procedure if performed on cognitively alert patients, and it seems that both the incidence and especially the severity of complications are lower for posteroventral pallidotomy than for thalamotomy.

Sequential postoperative appearance of radiofrequency pallidotomy lesions on MRI.

We analyzed 10 radiofrequency (RF) lesions over time in 9 patients who had follow-up MRI 1 h to 43 weeks following stereotactic pallidotomies performed for medically intractable idiopathic Parkinson's disease. Pallidotomies were performed under MRI guidance, microelectrode recording, and electrical stimulation with neurological monitoring. We compared the MRI taken within 1 h after surgery for each patient to their respective follow-up MRI to determine the changes in size and signal characteristics of RF lesions over time. The postoperative follow-up MRI of RF lesions roughly fell into 4 time periods: 1 h (n = 10), 2 months (n = 3), 6 months (n = 3), and 10 months (n = 4). The average volume (+/- SD, mm3) of these lesions at each phase were as follows: 1 h = 124.35 +/- 58.48; 2 months = 50.5 +/- 30.71; 6 months = 32.36 +/- 21.07; 10 months = 53.19 +/- 28.91. The steep decline in the size of the lesion stabilizes by the 2-month period. Thereafter, the lesion size at 6 and 10 months remains stable. Eventually, the center of coagulative necrosis completely disappears, and the lesions persists as a cystic cavity. The contrast uptake of these RF lesions appears to resolve by the 6-month period. Immediate postoperative images show strong enhancement with gadolinium. There is a lesser degree of enhancement at 2 months, and no appreciable enhancement by 6 months. Interestingly, the patients with better outcome tended to have larger RF lesions. However, this difference was not statistically significant.