Development of a linear ion trap mass spectrometer capable of analyzing megadalton MALDI ions

Detecting megadalton matrix-assisted laser desorption/ionization (MALDI) ions in an ion trap mass spectrometer is a technical challenge. In this study, megadalton protein and polymer ions were successfully measured by MALDI linear ion trap mass spectrometer (LIT-MS) for the first time. The LIT-MS is comprised of a Thermo linear ion trap mass analyzer and a highly sensitive charge-sensing particle detector (CSPD). A newly designed radio frequency (rf) scan mode with dipolar resonance ejection techniques is proposed to extend the mass range of LIT-MS up to one million Thomson (Th). We analyze high mass ions with mass-to charge (m/z) ratios ranging from 100 kTh to 1 MTh, including thyroglobulin, alpha-2-macroglobulin, immunoglobulins (e.g., IgG and IgM), and polymer (∼ 940 kTh) ions. Besides, it is also very challenging for ion trap mass spectrometry to detect megadalton ions at low concentrations. By adopting high affinity carboxylated/oxidized detonation nanodiamonds (oxDNDs) to enrich IgM molecules and form antibody-nanodiamond conjugates, we have successfully reached ∼ 5 nM (5 μg/mL) concentration which is better than that by the other techniques.

District-wise estimation of Basic reproduction number (R0) for COVID-19 in India in the initial phase

SARS-CoV-2 or COVID-19 was introduced into India by multiple sources generating local clusters and leading to the nationwide spread. A retrospective study has been conducted on the epidemiological features and spatial spread of COVID-19 in India during February 2020–March 2021. For each district, the cumulative number of confirmed COVID-19 cases were fitted to exponential growth model for the initial phase of the outbreak (the first 7–15 days). From the estimated growth rate, epidemiological parameters like the Basic reproduction number (R₀) and epidemic doubling time (τ) were determined. Using Q-GIS software, we have generated the all India distribution maps for R₀ and τ. COVID-19 spread rapidly covering majority of the districts of India between March and June 2020. As on 1st March 2021, a total of 715 out of 717 districts have been affected. The R₀ range is at par with the global average. A few districts, where outbreaks were caused by migrant workers coming home, intense transmission was recorded R₀ > 7. We also found that the spread of COVID-19 was not uniform across the different districts of India. The methodology developed in the study can be used by researchers and public health professionals to analyze and study epidemics in future.

Isophthaloyl-Based Selective Fluorescence Receptor for Zn (II) Ion in Semi-Aqueous Medium

A novel Isophthaloyl-based symmetrical (12E,21E)-N1',N3'-bis(2-hydroxybenzylidene) isophthalohydrazide, receptor (1) was synthesized and characterized using various spectroscopic technique. The reorganization ability of receptor (1) was evaluated in semi-aqueous medium and shows significant enhancement in fluorescence intensity for Zn (II) ion over various metal ions in CH₃CN:H₂O (1:1, v/v). The 1:2 binding stoichiometry between receptor (1) and Zn (II) ion was established using Job's plot and the proposed complex structure was calculated by applying Density Functional Theory (DFT) method. The binding constant (K_a) of receptor (1) with Zn (II) ion was established with the Benesi-Hildebrand plot, Scatchard and Connor's plot and the values are 1.00 × 10⁴ M^-1, 1.05× 10⁴ M^-1 and 1.05× 10⁴ M^-1 respectively. The limit of detection (LOD) and limit of quantification (LOQ) of receptor (1) and Zn (II) ion was 0.292 μM and 0.974 μM respectively. The binding mode was due to photo-induced electron transfer (PET) and the coordination of Zn (II) ion with C = N hydroxyl group of receptor (1). Electrochemical analysis of metal free receptor (1) and with Zn (II) ion also confirmed the formation of complex.

Adult neural stem cell isolation from whole rat brain and neurosphere culture and differentiation

Historically, it was thought that neurogenesis ceased by the end of development, but it is currently understood that neurogenesis continues throughout the life of an individual. This continued growth arises from neural stem or progenitor cells (NSCs) located in specific regions of the adult brain, including the subventricular zone and the dentate gyrus of the hippocampus. Increased understanding of the nature of these cells and their reaction to environmental stimuli is of paramount importance in the effort to discern their role and potential use in repair following neurological disruption. Neurosphere suspension culture is identified as an effective way of actualizing a self-renewing population of neural stem cells. This study demonstrated that adult rat neural stem cells could be effectively induced to differentiate into cells of astrocytic lineage through exposure to fetal bovine serum (FBS), and that the same population of precursor cells could be induced toward neuronal lineage through exposure to dibutyryl cyclic adenosine monophosphate (dcAMP). There were also observations noted regarding difficulty inducing cell attachment following enzymatic digestion of neurospheres, and potential effects on various types of assays, including migration assays (Fig. 7, Ref. 31). Keywords: neural, stem cell, neurosphere, adult rat, cell culture, cell differentiation.

Bioinformatics characterization of envelope glycoprotein from Kyasanur Forest disease virus

Background & objectives

Kyasanur Forest disease (KFD) is a febrile illness characterized by haemorrhages and caused by KFD virus (KFDV), which belongs to the Flaviviridae family. It is reported to be an endemic disease in Shimoga district of Karnataka State, India, especially in forested and adjoining areas. Several outbreaks have been reported in newer areas, which raised queries regarding the changing nature of structural proteins if any. The objective of the study was to investigate amino acid composition and antigenic variability if any, among the envelope glycoprotein (E-proteins) from old and new strains of KFDV.

Methods

Bioinformatic tools and techniques were used to predict B-cell epitopes and three-dimensional structures and to compare envelope glycoprotein (E-proteins) between the old strains of KFDV and those from emerging outbreaks till 2015.

Results

The strain from recent outbreak in Thirthahalli, Karnataka State (2014), was similar to the older strain of KFDV (99.2%). Although mutations existed in strains from 2015 in Kerala KFD sequences, these did not alter the epitopes.

Interpretation & conclusions

The study revealed that though mutations existed, there were no drastic changes in the structure or antigenicity of the E-proteins from recent outbreaks. Hence, no correlation could be established between the mutations and detection in new geographical areas. It seems that KFDV must be present earlier also in many States and due to availability of testing system and alertness coming into notice now.

Differences in Type I interferon response in human lung epithelial cells infected by highly pathogenic H5N1 and low pathogenic H11N1 avian influenza viruses

Influenza A virus infection induces type I interferons (IFNs α/β) which activate host antiviral responses through a cascade of IFN signaling events. Herein, we compared highly pathogenic H5N1 and low pathogenic H11N1 avian influenza viruses isolated from India, for their replication kinetics and ability to induce IFN-β and interferon-stimulating genes (ISGs). The H5N1 virus showed a higher replication rate and induced less IFN-β and ISGs compared to the H11N1 virus when grown in the human lung epithelial A549 cells, reflecting the generation of differential innate immune responses during infection by these viruses. The non-structural 1 (NS1) protein, a major IFN-antagonist, known to help the virus in evading host innate immune response was compared from both the strains using bioinformatics tools. Analyses revealed differences in the composition of the NS1 proteins from the two strains that may have an impact on the modulation of the innate immune response. Intriguingly, H5N1 virus attenuated IFN-β response in a non-NS1 manner, suggesting the possible involvement of other viral proteins (PB2, PA, PB1/PB1-F2) of H5N1 in synergy with NS1. Preliminary analyses of the above proteins of the two strains by sequence comparison show differences in charged residues. The insight gained will be useful in designing experimental studies to elucidate a probable role of the polymerase protein(s) in association with NS1 in inhibiting the IFN signaling and understanding the molecular mechanism governing the difference.

High Mass Ion Detection with Charge Detector Coupled to Rectilinear Ion Trap Mass Spectrometer

Conventional linear ion trap mass analyzers (LIT-MS) provide high ion capacity and show their MS ⁿ ability; however, the detection of high mass ions is still challenging because LIT-MS with secondary electron detectors (SED) cannot detect high mass ions. To detect high mass ions, we coupled a charge detector (CD) to a rectilinear ion trap mass spectrometer (RIT-MS). Immunoglobulin G ions (m/z ~150,000) are measured successfully with controlled ion kinetic energy. In addition, when mass-to-charge (m/z) ratios of singly charged ions exceed 10 kTh, the detection efficiency of CD is found to be greater than that of SED. The CD can be coupled to LIT-MS to extend the detection mass range and provide the potential to perform MS ⁿ of high mass ions inside the ion trap. Graphical Abstract ᅟ.

Development of a novel rapid micro-neutralization ELISA for the detection of neutralizing antibodies against Chandipura virus

BACKGROUND

Chandipura virus (CHPV) is a leading cause of acute encephalitis with high mortality in paediatric population in India. A micro-neutralization ELISA (MN-ELISA) assay was developed for the detection of neutralizing antibodies (Nab) against CHPV. This novel method gives read-out in the form of ELISA optical density (OD) values and has a shorter turn-around time (TAT) as compared to the conventional cytopathic effect (CPE)-based neutralization assay (MN-CPE). The assay was developed using an Indian strain of CHPV. During the development of the assay different parameters such as cell count, dilution of primary and secondary antibodies and time point for the test termination were optimized. The new and conventional assays were run in parallel where known positive and negative human serum samples were used as test controls. The conventional MN-CPE was terminated at 48h post-infection (p.i.) and stained with Amido black, while in the new assay, MN-ELISA was terminated at pre-determined 18h p.i. and the infected cells were fixed with acetone, followed by in-situ ELISA. Results of both the assays were compared. The sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) of the new test was 100% when compared with the conventional MN-CPE method as a 'gold standard'. The MN-ELISA showed two-fold higher antibody titer in one sample and one sample was additionally positive than MN-CPE ELISA.

CONCLUSION

The MN-ELISA is rapid, more sensitive and read-out of results is by measurement of OD, which could be more accurate than manual observation of reduction in CPE. This novel test could be used as an alternative to the conventional MN-CPE based assay in sero-surveillance and in future vaccine studies.

Incidence of Postoperative Pain after Single Visit and Two Visit Root Canal Therapy: A Randomized Controlled Trial

INTRODUCTION

Root Canal Treatment (RCT) has become a mainstream procedure in dentistry. A successful RCT is presented by absence of clinical signs and symptoms in teeth without any radiographic evidence of periodontal involvement. Completing this procedure in one visit or multiple visits has long been a topic of discussion.

AIM

To evaluate the incidence of postoperative pain after root canal therapy performed in single visit and two visits.

MATERIAL AND METHODS

An unblinded/ open label randomized controlled trial was carried out in the endodontic department of the Dental Institute, where 78 patients were recruited from the regular pool of patients. A total of 66 maxillary central incisors requiring root canal therapy fulfilled the inclusion and exclusion criteria. Using simple randomization by biased coin randomization method, the selected patients were assigned into two groups: group A (n=33) and group B (n=33). Single visit root canal treatment was performed for group A and two visit root canal treatment for group B. Independent sample t-test was used for statistical analysis.

RESULTS

Thirty three patients were allotted to group A where endodontic treatment was completed in single visit while 33 patients were allotted to group B where endodontic treatment was completed in two visits. One patient dropped-out from Group A. Hence in Group A, 32 patients were analysed while in Group B, 33 patients were analysed. After 6 hours, 12 hours and 24 hours of obturation, pain was significantly higher in Group B as compared to Group A. However, there was no significant difference in the pain experienced by the patients 48 hours after treatment in both the groups.

CONCLUSION

Incidence of pain after endodontic treatment being performed in one-visit or two-visits is not significantly different.

Measuring masses of large biomolecules and bioparticles using mass spectrometric techniques

Mass spectrometric techniques can measure the masses and fragments of large biomolecules and bioparticles.

An in vitro comparison of bond strengths of Gutta-percha/AH Plus, Resilon/Epiphany self-etch and EndoREZ obturation system to intraradicular dentin using a push-out test design

Aim:

To evaluate and compare the push-out bond strengths of three obturation materials; Gutta-percha/AH Plus, Resilon/Epiphany self-etch (SE) and EndoREZ obturation system to intraradicular dentin.

Materials and Methods:

Sixty single-canal anterior teeth were prepared and assigned to experimental groups (n = 20), designated as Group I: Gutta-percha/AH Plus, Group II: Resilon/Epiphany SE and Group III: EndoREZ sealer/EndoREZ points. After obturation, each tooth was prepared for push-out assessment with root slices of 2 mm thickness using universal testing machine.

Statistical Analysis:

Two way analysis of variance and Scheffe's test.

Results:

Gutta-percha/AH Plus root fillings showed significantly highest bond strength. Also, root segment location did not have a significant influence on bond strength.

Conclusion:

The adhesiveness quality to root dentin promoted by newer methacrylate resin-based obturation systems like Resilon/Epihany SE and EndoREZ is compromised even when teeth with simple anatomic features were obturated under well-monitored laboratory conditions.

Stereotactic approach to skull-base lesions

With improved knowledge of the anatomy and increased collaboration between the neurosurgeon and the otolaryngologist, successful surgical resection of skull-based tumors is being achieved with reduced mortality and morbidity. In spite of this, there remains a group of patients in whom an alternate surgical approach of stereotaxis may be indicated. This group of patients includes those in whom only biopsy is required, or those in whom brachytherapy using high-intensity (125)I is planned because the patients' general condition is not good enough to undergo open surgical resection of the tumor or the tumor is unresectable or the patient refuses open surgery. This article presents a preliminary report on stereotactic approach to skull base lesions with special emphasis on the technique.

Morphometric and allozyme variation in Culex tritaeniorhynchus mosquito populations from India

Four populations of Culex tritaeniorhynchus (Giles) (Diptera: Culicidae), collected from Bellary, Cuddalore, Pune, and the Microbial Containment Complex laboratory culture in India were analyzed for morphological and allozyme variation. Multivariate analysis based on eight morphological characteristics and three morphometric indices was used to investigate the morphological variations among the four populations. Principal component analysis of the data suggested that siphon, saddle, and anal gills related variables were most important. Discriminant factor analysis of morphological data revealed that the four populations form significantly different clusters which can be differentiated from each other based on siphon, saddle, and pectin teeth related variables. Allozyme electrophoresis of the four populations revealed that the mean heterozygosity per locus value had high variation, ranging from 0.0879 to 1.794. Fst values between 0 and 0.519 suggested genetic differentiation within these populations. Fis values ranged from 0 to 1 with most of the values closer to 1. The allelic frequencies and Nei's genetic identity values showed that genetic differences between populations were small, but significant. Some of the morphological and allozyme variations in the Cx. tritaeniorhynchus populations could be partly attributed to the environmental conditions. The findings suggested that transition of morphological characters and allozyme variations in Cx. tritaeniorhynchus populations seem to be consequences of influence and selection by the environmental conditions. These results indicated that populations of Cx. tritaeniorhynchus in non-endemic areas of Japanese encephalitis (JE) virus infection have higher adaptability as compared to endemic areas of JE infection.

A DNA vaccine that encodes rabies virus glycoprotein lacking transmembrane domain enhances antibody response but not protection

Rabies virus (RV) glycoprotein (gp) consists of three domains: cytoplasmic, transmembrane and ectodomain. It occurs in a complete, membrane-bound form within the infected cell, but it is released from them in a deleted, secreted form lacking the transmembrane domain. This study was performed to test the importance of the transmembrane domain for the capability of the RV gp gene, introduced into mice via a recombinant plasmid (DNA vaccine), to induce immune response and protection against challenge. Although the antibody response to the secreted form of gp was higher than that to complete gp, the protective efficacy of the respective DNA vaccine against challenge was not better than that of the DNA vaccine inducing complete gp. This indicates that the transmembrane domain of RV gp is important for generating protection against rabies and should be present in RV DNA vaccines.

Endoscopic neuroanatomy through the sphenoid sinus

OBJECT

The aim of the study was to perform endoscopic anatomical studies of skull base structures through the sphenoid sinus in order to better understand endoscopic approaches to skull base lesions.

METHODS

Anatomical studies were performed on six cadavers using sinus endoscopes. The sphenoid sinus was entered via a sublabial nasoseptal approach. Stepwise removal of bone surrounding the sphenoid sinus was done to expose the suprasellar area, the retrosphenoid area and the cavernous sinus. The suprasellar dissection exposed the anterior communicating artery (ACom) complex, optic apparatus, pituitary stalk, lamina terminalis, third ventricle and pituitary gland. The retrosphenoid dissection exposed the mamillary bodies, basilar artery and its branches, the mid-brain, the pons, and the third, fifth, sixth, seventh and eighth cranial nerves. The cavernous sinus dissection exposed the carotid artery, and the third, fourth, fifth and the sixth cranial nerves.

CONCLUSION

Through the sphenoid sinus, most of the structures in the suprasellar area, cavernous sinus and retrosphenoid area can be reached.

Interstitial brachytherapy for skull base tumors

1. Irrespective of the histology, all tumors responded to 125I permanent BT. 2. There were no intra- or postprocedural complications, making this modality extremely safe. 3. There were no acute or late complications attributable to continuous LDR radiation with 125I permanent BT. 4. The dose distribution can be tailored to fit the tumor shape by seed placement at the desired location and by selecting the seed strength. 5. Unlike any other radiation therapy procedure, with SBT, the placement of the 125I seed or seeds is verifiable at each step of the procedure on the CT screen, making the treatment more accurate. 6. The procedure is performed under local anesthesia, and the patient is observed overnight at the most, making it safe and cost-effective. 7. Most skull base tumors are located close to the brain, cranial nerves, or blood vessels. Tolerance of these vital structures to high doses of radiation when given continuously at a LDR makes this treatment method safe.

Anatomical structures in the Leksell pallidotomy target

OBJECTIVE

Because interruption of pallidal outflow signals by pallidotomy is believed to play an important role in the motor improvement in Parkinson's disease, the anatomical relationship of the two major pallidofugal tracts, namely the ansa lenticularis (AL) and the fasciculus lenticularis (FL) to the Leksell pallidotomy target (LPT) were studied.

METHODS

Magnetic resonance (MR) scans of 20 patients with Parkinson's disease were studied. The scans were obtained in the inversion recovery and fast spin echo sequences and viewed in the reverse video mode.

RESULTS

The pallidofugal tracts appeared as bands of high intensity on MR scan. FL was wide and extended from the posterior half of the globus pallidus interna (GPi) medially into the internal capsule. AL was narrow, parallel and posterior to the anterior commissure, parallel to and 3 mm above the optic tract, and just beneath the FL. The part of the FL immediately lateral to the internal capsule overlapped the lateral end of the AL. The center of this overlapping area was termed the 'operlapping point' (OP). In all cases, the OP was within the range of LPT.

CONCLUSION

It is concluded that the structures in the LPT are FL and AL; and therefore, this procedure could also be known as 'fasciculoansatomy'.

Magnetoencephalographic patterns of epileptiform activity in children with regressive autism spectrum disorders

BACKGROUND

One-third of children diagnosed with autism spectrum disorders (ASDs) are reported to have had normal early development followed by an autistic regression between the ages of 2 and 3 years. This clinical profile partly parallels that seen in Landau-Kleffner syndrome (LKS), an acquired language disorder (aphasia) believed to be caused by epileptiform activity. Given the additional observation that one-third of autistic children experience one or more seizures by adolescence, epileptiform activity may play a causal role in some cases of autism.

OBJECTIVE

To compare and contrast patterns of epileptiform activity in children with autistic regressions versus classic LKS to determine if there is neurobiological overlap between these conditions. It was hypothesized that many children with regressive ASDs would show epileptiform activity in a multifocal pattern that includes the same brain regions implicated in LKS.

DESIGN

Magnetoencephalography (MEG), a noninvasive method for identifying zones of abnormal brain electrophysiology, was used to evaluate patterns of epileptiform activity during stage III sleep in 6 children with classic LKS and 50 children with regressive ASDs with onset between 20 and 36 months of age (16 with autism and 34 with pervasive developmental disorder-not otherwise specified). Whereas 5 of the 6 children with LKS had been previously diagnosed with complex-partial seizures, a clinical seizure disorder had been diagnosed for only 15 of the 50 ASD children. However, all the children in this study had been reported to occasionally demonstrate unusual behaviors (eg, rapid blinking, holding of the hands to the ears, unprovoked crying episodes, and/or brief staring spells) which, if exhibited by a normal child, might be interpreted as indicative of a subclinical epileptiform condition. MEG data were compared with simultaneously recorded electroencephalography (EEG) data, and with data from previous 1-hour and/or 24-hour clinical EEG, when available. Multiple-dipole, spatiotemporal modeling was used to identify sites of origin and propagation for epileptiform transients.

RESULTS

The MEG of all children with LKS showed primary or secondary epileptiform involvement of the left intra/perisylvian region, with all but 1 child showing additional involvement of the right sylvian region. In all cases of LKS, independent epileptiform activity beyond the sylvian region was absent, although propagation of activity to frontal or parietal regions was seen occasionally. MEG identified epileptiform activity in 41 of the 50 (82%) children with ASDs. In contrast, simultaneous EEG revealed epileptiform activity in only 68%. When epileptiform activity was present in the ASDs, the same intra/perisylvian regions seen to be epileptiform in LKS were active in 85% of the cases. Whereas primary activity outside of the sylvian regions was not seen for any of the children with LKS, 75% of the ASD children with epileptiform activity demonstrated additional nonsylvian zones of independent epileptiform activity. Despite the multifocal nature of the epileptiform activity in the ASDs, neurosurgical intervention aimed at control has lead to a reduction of autistic features and improvement in language skills in 12 of 18 cases.

CONCLUSIONS

This study demonstrates that there is a subset of children with ASDs who demonstrate clinically relevant epileptiform activity during slow-wave sleep, and that this activity may be present even in the absence of a clinical seizure disorder. MEG showed significantly greater sensitivity to this epileptiform activity than simultaneous EEG, 1-hour clinical EEG, and 24-hour clinical EEG. The multifocal epileptiform pattern identified by MEG in the ASDs typically includes the same perisylvian brain regions identified as abnormal in LKS. When epileptiform activity is present in the ASDs, therapeutic strategies (antiepileptic drugs, steroids, and even neurosurgery) aimed at its control can lead to a significa

Direct identification of ventrointermediate nucleus of the thalamus on magnetic resonance and computed tomography images

OBJECTIVE

The ventro-intermediate (Vim) nucleus of the thalamus is a commonly used target for the treatment of tremor. The thalamic fasciculus contains myelinated fibers, believed to play a role in the generation of tremor, that converge into a dense bundle at the inferior aspect of the Vim nucleus, making it visible on magnetic resonance (MR) and computed tomography (CT) images. This structure, therefore, can be visualized directly and targeted for thalamotomy.

METHODS

Thalamotomies were performed on nine patients (who have a follow-up of 13-23 months) with parkinsonian and essential tremors using MR and CT images. The tremor target was hypointense on MR images obtained in inversion recovery sequence and hypointense on CT images. It was therefore visualized, directly targeted, and probed. Stimulation studies were done to physiologically confirm accuracy of the probe placement and then a radiofrequency lesion was made.

RESULTS

Stimulation of the target identified as the Vim nucleus on MR and CT images produced responses similar to those expected from the Vim nucleus. After this site was lesioned tremor disappeared in all nine patients.

CONCLUSION

The Vim nucleus of the thalamus is visible on MR and CT images. Destruction of this target abolishes parkinsonian and essential tremors.

Isolation of dominant seizure foci by multiple subpial transections

Dominant seizure foci (DSF) are seizure foci that do not respond to multiple subpial transections (MST). DSF were isolated in 15/31 patients who underwent MST in the past 6 years. These patients had MST over both hemispheres (6 patients) or over multiple lobes of one hemisphere (9 patients). DSF measured 0.5-1 cm in diameter and numbered 1-4 (in each patient). Their excision resulted in dramatic improvement in EEG over wide areas of the cortex. The longest postoperative follow-up is 67 months, with a median of 21 months. Nine of 15 patients are free of seizures, 3/15 have rare seizures, 2/15 have > 90% reduction in seizure frequency, and 1/15 has > 70% reduction in seizure frequency with improvement in motor and speech functions. In summary, DSF are resistant to MST and influence the electrical activity of the surrounding cortex. MST combined with excision of DSF resulted in good seizure control in this series, which included patients with multilobar and bihemispheric seizure foci.

Surgical treatment of intractable seizures with multilobar or bihemispheric seizure foci (MLBHSF)

BACKGROUND

Patients with multilobar or bihemispheric seizure foci (MLBHSF) are generally not considered candidates for major resective surgery because of the high risk of complications. A combination of relatively less invasive surgical procedures were used to treat 19 patients with intractable seizures with MLBHSF.

METHODS

Epileptogenic areas were identified via standard techniques. Locations of the seizure foci were in two lobes of a hemisphere in 11 patients, three lobes of a hemisphere in four patients, four lobes of a hemisphere in one patient, and both hemispheres in three patients. All 19 patients had multiple subpial transections; in addition, seven patients had small topectomies and nine patients had amygdala hippocampotomies.

RESULTS

The longest follow-up is 54 months and the median for follow-up is 33 months. Nine patients (47%) are either free of seizures or have only rare seizures; eight patients (41%) have greater than 90% reduction in seizure frequency; one patient (6%) has complete cessation of myoclonic seizures and secondary generalization, and greater than 50% reduction in partial complex seizures; and one patient (6%) has greater than 50% reduction in seizure frequency. There were no permanent operative complications.

CONCLUSION

Though the follow-up is relatively short and the number of patients is small, these results are encouraging, because the majority of patients in this group were poor surgical candidates.

Neuroradiologic applications of central nervous system SPECT

Single photon emission computed tomography (SPECT) of the central nervous system (CNS) has many potentially useful interventional neuroradiologic applications. CNS SPECT allows easy and safe evaluation of the collateral circulation during internal carotid balloon test occlusion. The cerebrovascular distribution of intracarotid amobarbital sodium, which is used in the Wada test, can be accurately determined with simultaneous injection of a radiopharmaceutical. Easy and safe evaluation of the extent and distribution of vasospasm associated with subarachnoid hemorrhage or cerebral angiography is also possible with CNS SPECT. Images obtained after administration of acetazolamide can be compared with baseline images to evaluate cerebrovascular reserve before carotid endarterectomy. Seizure foci can be identified if peripheral intravenous injection is performed during an ictus. Thallium-201 imaging can be used to direct stereotactic brain biopsy to check for tumor recurrence. Radiologists need to familiarize themselves and their clinical colleagues with the many uses of this imaging technique.

Posttraumatic intradiploic meningoencephalocele. Case report

A case of posttraumatic intradiploic meningoencephalocele is reported. The patient presented with a progressively enlarging lump in the left parietal area approximately 8 months after a blunt trauma. Magnetic resonance imaging showed an intradiploic cyst containing cerebrospinal fluid and brain tissue. These findings were confirmed at surgery. In addition, the cyst was found to have a lining of arachnoid membrane.

Nonresective treatment of pineoblastoma: a case report

BACKGROUND

Stereotactic biopsy followed by cytoreductive surgery and/or radiation are the standard treatment for pineoblastoma. We are reporting a patient with a relatively large pineoblastoma, who was treated with a combination of nonresective treatment modalities.

METHOD

The patient is a 20-year-old woman who presented with signs and symptoms of raised intracranial pressure. Magnetic resonance imaging (MRI) showed a large tumor in the pineal region and hydrocephalus. She was emergently treated by placement of a ventriculoperitoneal shunt. Three days later she underwent a stereotactic biopsy, which showed the tumor to be pineoblastoma. She was then further treated with the following treatment modalities: permanent implantation of high activity I125 seeds, external radiation, and chemotherapy.

RESULTS

At 10 months' follow-up, MRI showed complete disappearance of the tumor. At 18 months' follow-up, the patient is asymptomatic, neurologically intact, and her MRI scans show no evidence of intracranial or intraspinal tumor.

CONCLUSIONS

Though the follow-up is relatively short, the results of the nonresective approach in this patient have been excellent.

Stereotactic location and excision of seizure focus with xenon-enhanced CT

A case of intractable seizures, originating in the motor cortex, was successfully treated with excision of the seizure focus after precise location of the focus on depth electrode recordings. The depth electrode was placed stereotactically with coordinates from xenon-enhanced CT images. Prior attempts at treating the seizures with ablation of seizure foci had resulted in disappearance of seizure activity on electrocorticography study without cessation of clinical seizures.

Modifications of transnasal and transoral stereotactic procedures--technical notes

Stereotactic transnasal and transoral procedures have been reported by different authors in the past. In this paper, several modifications of these methods are described. The modifications are: transnasal approach to the frontal skull base and suprasellar regions; and transoral approaches to the clivus, the petroclival junction, medial part of the cerebellopontine angle and the lateral mass of C-1. Eleven patients were operated on using these modifications. The procedures were for biopsy and brachytherapy. No complications resulted from the procedures.

Minimally invasive surgical approach for intractable seizure

Minimally invasive procedures (multiple subpial transection, topectomy and amygdalahippocampotomy) were used to treat 24 patients with intractable seizures. The seizure foci were in both hemispheres in 3 patients, all 4 lobes of a hemisphere in 1 patient, 3 lobes of a hemisphere in 5 patients, 2 lobes of a hemisphere in 11 patients and the temporal lobe alone in 4 patients. The longest follow-up is 41 months, with a median of 18 months. Sixteen patients have a follow-up of more than 1 years, with excellent results in 10 (66%) and good in the remaining 6 (38%). There were no permanent complications These results are encouraging, because the majority of the patients were poor candidates for surgery.

Response of extra-axial tumors to stereotactically implanted high-activity 125I seeds

125I seeds can deliver a very high dose of radiation (100-500 Gy) to a well-circumscribed area over their average life of 87 days, which enable them to destroy slow-growing extra-axial tumors after permanent implantation. Stereotactic implantation of 125I seeds was performed in 26 patients with extra-axial tumors, with a median follow-up of 32 months. No acute morbidity or mortality resulted from the procedure. Cranial nerve involvement in 5 patients was the only delayed complication. One patient developed radionecrosis outside the range of 125I dose distribution, which was felt to be due to the hyperfractionated external radiation the patient had received prior to 125I seed placement. All 26 patients showed tumor regression. The results indicate that this form of treatment is relatively safe and effective in the management of extra-axial tumors.

Stereotactic volumetric radiofrequency lesioning of intracranial structures for control of intractable seizures

Computed tomography (CT) scans provide three-dimensional information about intracranial structures, which can be used to place stereotactically guided radiofrequency (RF) lesions and destroy a targeted volume of tissue. This technique was used for lesioning of the corpus callosum (CC) or the amygdala-hippocampus complex (AHC) in 9 patients with intractable seizures. The procedures were monitored by intraoperative CT scans. Lesions were made in the AHC in 7 patients and the CC in 2 patients. In addition, multiple subpial transection (MST) was performed in 6 patients. The longest follow-up is 29 months with a median of 19 months. Five patients (56%) are free of seizures, 3 patients (33%) have greater than 90% reduction in seizure activity and 1 patient (11%) has greater than 50% but at most 90% reduction in seizure activity. There were no complications except for temporary hemiparesis following MST in 1 patient. The results suggest that stereotactic volumetric RF lesioning of the AHC and the CC may be safe and effective in controlling intractable seizures.

Electroconvergent cautery

A new cautery system known as the electroconvergent cautery system is described. This cautery system uses a radiofrequency current of 13.56 MHz. The current is passed through an amplifier, an impedance matching system, and a loading and tuning coil into a probe. After the probe tip is touched to the tissue, the mismatch of impedance between the probe tip and the generator is minimized to almost zero, resulting in high-current density at the probe tip, which causes pinpoint heating of the tissue at the point where it is touched by the probe without spread of heat to the surrounding tissue. This heat can cut and vaporize tissue and coagulate vessels. The probe can also be used to coagulate vessels with standard surgical forceps. Because convergence of energy is used for tissue heating, a grounding pad is not needed. The system can also be used under cerebrospinal fluid or saline.

Magnetic resonance angiography in the diagnosis of traumatic vertebrobasilar complications: a report of two cases

Although conventional arteriography is usually performed to study the vertebrobasilar system, we report two cases of traumatic vertebrobasilar vascular occlusion that were diagnosed by magnetic resonance angiography. This enabled us to promptly treat the patients. Our experience suggests that magnetic resonance angiography may be a useful diagnostic tool in the setting of acute vertebrobasilar complications, associated with cervical spine trauma.

Electromagnetic field focusing instrument augments resection of meningiomas

The electromagnetic field focusing (EFF) surgical instrument creates an oscillating electromagnetic field that induces eddy currents in the tissue, which converge at the point of contact. This energy creates a focal spark capable of vaporizing tissue. The EFF instrument was used to resect 17 meningiomas in 14 patients. The effectiveness of the EFF probe in resecting tumor tissue was compared with that of the Cavetron ultrasonic surgical aspirator (Model 100) in 11 patients. The EFF system was superior to the Cavetron ultrasonic surgical aspirator in tumor excision in all but two cases, in which the EFF grounding tip was poorly tuned. Surgical time and blood loss were reduced by subjective analysis in all but these two cases, especially in the rubbery or calcified meningiomas resistant to aspiration. No complications were directly attributable to use of the EFF. Drawbacks encountered with the EFF system include buildup of "char" on the tip, requiring scraping, and intense heat at the tip, which occasionally melted the insulating sheath, requiring replacement.

Role of brachytherapy in the management of the skull base meningioma. Treatment of skull base meningiomas

BACKGROUND

The treatment of primary and recurrent skull base meningiomas presents a formidable surgical problem.

METHODS

Fifteen patients with primary and recurrent skull base meningiomas were treated by means of interstitial irradiation with iodine 125 (125I) seed implantation. The physical characteristics of 125I enabled the authors to administer a minimum tumor dose ranging from 100 to 500 Gy at a low dose rate of 0.05-0.25 Gy per hour.

RESULTS

All 15 patients are alive at a median follow-up of 29 months. Of the 15 patients, 2 with calcification and 2 without calcification achieved only partial responses. The remaining 11 patients achieved a complete response. No early or late complications were observed.

CONCLUSIONS

From these data, the authors conclude that interstitial irradiation with 125I seeds is an effective, safe, and simple method in the treatment of both recurrent and primary skull base meningiomas.

Intracranial skip metastasis from parotid and facial skin tumors: mechanism, diagnosis, and treatment

Perineural and endoneural tumor spread is a form of metastatic disease in which the primary tumors spread along neural pathways and gain access to noncontiguous regions. Although rare, this type of skip metastasis into the cranial cavity occurs from tumors of the parotid gland and facial skin. Recognition of this process, evaluation of the patient with proper diagnostic procedures, and its treatment are presented.

Continuous low dose rate brachytherapy with high activity iodine-125 seeds in the management of meningiomas

The purpose of this study was to evaluate if meningiomas can be effectively treated with brachytherapy using permanent implantation of high activity I-125 seeds. Thirteen patients with intracranial meningiomas were treated by means of permanent stereotactic implantation of one or more high-activity I-125 seeds. The physical characteristics of I-125 enabled us to deliver a minimum tumor dose ranging from 100 Gy to 500 Gy at a low dose rate of 5 cGy to 25 cGy per hr. Indications for this procedure included recurrence after initial surgery or as primary modality of treatment in patients who were not candidates for surgery. All 13 patients are alive at a median follow-up of 25 months. Nine of 13 patients achieved complete resolution of the tumor and in the remaining four, more than 50% reduction in tumor volume was noted at the last follow-up. No late complications were observed. We conclude from this initial data that localized high dose irradiation delivered at a low dose rate using I-125 permanent implantation is an effective, safe, and simple method in the treatment of both recurrent and primary intracranial meningiomas.

Thermal profiles of electrocauteries, the Nd:YAG laser, and the electromagnetic-field focusing system

Electromagnetic-field focusing (EFF) is a method of converging induced eddy current onto a pointed tip of a tuned length return circuit in the near field of a resonator, which results in the production of high temperature. Previously reported applications of this method include various devices for local hyperthermia and a precision surgical device. The latter is currently being used in human clinical trials under two investigational device exemptions from the Food and Drug Administration. In the present work, the thermal profile produced in a uniform, tissue-simulating phantom by the hand-held probe of the surgical EFF system is compared with those produced by mono- and bipolar electrocauteries and by a contact Nd:YAG laser. At the equivalent power setting and 2-cm insertion depth, the EFF probe was shown to have a tighter thermal profile than the monopolar electrocautery or the contact Nd:YAG laser. This finding is consistent with earlier histologic evidence that brain cortical tissue cut by the surgical EFF probe had minimal thermal damage in the tissue surrounding the incision.

Bourneville's tuberous sclerosis associated with double outlet right ventricle and infundibular pulmonary stenosis

The cardiac manifestation usually associated with tuberous sclerosis is rhabdomyoma of the heart. We report a rare association with cyanotic congenital heart disease in the form of double outlet right ventricle with infundibular pulmonary stenosis.

Stereotactic external beam irradiation system

Stereotactic localization is of vital importance in treating small intracranial lesions either with interstitial or external beam irradiation. This article describes a simple, fast, accurate, and verifiable system that can be used with a standard computerized axial tomography (CAT) scanner and linear accelerator for stereotactic external beam irradiation.

Brachytherapy: a viable alternative in the management of basal meningiomas

Thirteen patients with intracranial meningiomas of the skull base were treated with one or more high-activity iodine-125 seeds. In 11 patients, the seeds were implanted stereotactically under local anesthesia. A minimum dose of 100 to 500 Gy was delivered to the tumor at a dose rate of 5 to 25 cGy/h. Indications for this procedure included recurrence after initial surgery or as the primary modality of treatment in patients who were not candidates for surgery. All 13 patients are alive at a median follow-up of 15 months. Nine of 11 patients (82%) without calcification in their meningiomas achieved complete response. The remaining 4 patients-2 with calcification and 2 without--achieved partial response. No early or late complications were observed. We conclude from our experience that both recurrent and primary meningiomas of the skull base can be treated effectively with permanent iodine-125 brachytherapy.

Free-standing, stereotactic, microsurgical retraction technique in "key hole" intracranial procedures

Free-standing, stereotactic, microsurgical retraction technique involves integration of a standard image-guided stereotaxis, an operating microscope and free-standing micro-retractors, data acquisition from computed tomography (CT) images, trajectory determination, and obtaining tumor configuration "in line" with the trajectory using standard CT computer program. The free-standing stereotactic micro-retractors are directed to the lesion using the stereotactic frame. The remainder of the procedure is carried out independent of the stereotactic frame. The technique allows unobstructed access to deep lesions through a "key-hole" opening with excellent visualization of the lesions, and accurate retractor placement. Independent retractor movement also allows visualization of the different corners of the wound. Experience with the first 15 consecutive procedures for stereotactic excision of deep lesions using the Patil frame is reported. Based on this preliminary experience, this technique is free of obstruction, accurate and safe.

Accuracy of thalamotomy target determination using axial images only

The target point for thalamotomy is generally determined in relationship to the intercommissural line. Standard axial computed tomography (CT) images can show both the anterior and posterior commissures. However, these commissures may not always be visible on the same axial image, as the plane in which the two commissures are located may not be the same as the plane of scanning. Mathematical calculations were performed to determine the degree of error that would occur if the target point determination was performed using axial images alone, even when the two commissures were not in the same plane as the CT images. The degree of error was found to be directly proportional to the distance between the plane of scanning for the two commissures. For each millimeter separation of these planes an error of approximately 0.11 mm in the z-coordinate (caudo-cephaled distance) and 0.04 mm in the y-coordinate (antero-posterior distance) was observed. These errors were felt to be negligible, especially since the final target point determination is based on physiological responses.

Axial herniation with brain stem deformity as a cause of sleep apnea

A patient with an intracerebral hematoma and associated edema in the high right hemisphere parasagittal convexity had several episodes of apnea at night and during the day when she was asleep. On computed tomography (CT) scan, the hematoma demonstrated no evidence of brainstem compression. Sagittal magnetic resonance image (MRI), revealed the hematoma and edema mass resulted in central herniation with axial deformity of the brainstem. This is believed to be the cause of the apneic episodes. Treatment with mannitol and steroids promptly relieved the symptom.

Percutaneous discectomy using the electromagnetic field focusing probe. A feasibility study

The EFF probe has the capability of sharply focusing the eddy currents produced in tissue secondary to the electromagnetic field it generates. This sharp convergence of eddy current produces intense heat at the point of contact of the probe to the tissue, which can vaporize tissue. The probe diameter can be as small as required which makes it easy to be navigated into disc space for disc vaporization. Four discs were vaporized in three pigs by inserting the probe into the disc and vaporizing it. The vertebral columns were removed and transverse sections through the disc were made. Excellent disc vaporization was observed with vaporization of 70-80% of the nucleus. As the probe can be of flexible material it could be turned in different directions to vaporize necessary disc material.

Intraoperative calibration of the Patil stereotactic system during computed tomography (CT) guided stereotactic procedures--a technical note

A method for intraoperative calibration of the Patil stereotactic system is described. After adjusting the z and y coordinates, a marker is placed in the pivot block and a CT scan is obtained. The presence of the marker in the indicator block on the same horizontal line as the target, on the image of the target, would indicate that the y and z coordinates adjustments are accurate. After the arc is attached with the x coordinate adjusted, a CT scan is obtained with the arc vertical and the probe holder at zero angle (from the vertical) position. The presence of the middle of the probe holder in the same vertical line as the target would indicate accurate x coordinate adjustment. This technique, which can be applied also to other stereotactic systems, allows the surgeon to check not only the accuracy of the system but also the accuracy of the procedure prior to inserting the probe into the brain.