Biomedical subjects

George I Jallo

Publications and source records attributed to George I Jallo.

At least 19 recordsLinked to original sources

PubMed2006

The Strata programmable valve for shunt-dependent hydrocephalus: the pediatric experience at a single institution.

BACKGROUND AND OBJECTIVE: The Medtronic PS Medical Strata valve has pressure flow characteristics that are noninvasively adjusted with a magnetic tool. The objective of this study was to examine its efficacy during our initial experience with it in shunt-dependent children. MATERIALS AND METHODS: A retrospective review of 53 children with a median age of 2.0 years who had 61 Strata valves implanted. CONCLUSION: The Strata valve is efficacious in the treatment of shunt-dependant hydrocephalus in children. The 1-year shunt survival rate of 67.2% is comparable to that previously reported from a multicenter trial. Of the 30 therapeutically aimed adjustments during the study period, 16 (53.3%) resulted in improvement in abnormal signs or symptoms. Our data indicate that adjustments can be used to treat signs or symptoms of cerebrospinal fluid overdrainage or underdrainage, which may obviate the need for additional surgery.

Adolescent↗

PubMed2006

A novel brainstem tumor model: functional and histopathological characterization.

INTRODUCTION: Diffuse pontine gliomas remain a challenging and frustrating disease to treat. The survival rates for these high-grade brainstem tumors (BSTs) is dismal and optimal therapy has yet to be determined. The development of a satisfactory brainstem tumor model is necessary for testing new therapeutic paradigms that may prolong survival. MATERIALS AND METHODS: We report the surgical technique, functional testing, and histopathological features of a novel brainstem tumor model in rats. Female Fischer 344 rats (n=45) were randomized to receive an injection of either 3 microl of 9L gliosarcoma cells (100,000 cells, n=), 3 microl of F98 glioma cells (100,000 cells, n=10), or 3 microl of medium (Dulbecco's modified eagle medium) into the pontine tegmentum. Using a cannulated guide screw system, implanted in the skull of the animal, we injected each group at coordinates 1.4 mm right of the sagittal and 1.0 mm anterior of the lambdoid sutures, at a depth of 7.0 mm from the dura. The head was positioned 5 degrees from horizontal before injection. The rats were post-operatively evaluated for neurological deficits using an automated test. Kaplan-Meier curves were generated for survival and disease progression, and brains were processed postmortem for histopathology. RESULTS AND DISCUSSION: 9L and F98 tumor cells grew in 100% of animals injected and resulted in a statistically significant mean onset of hemiparesis of 16.5+/-0.56 days (P=0.001, log-rank test), compared to animals in the control group which lacked neurological deficits by day 60. The animals with tumor cells implanted demonstrated significant deterioration of function on the automated rod testing. Animals in the control group showed no functional or pathological signs of tumor. Progression to hemiparesis was consistent in all tumor-injected animals, with predictable onset of symptoms occurring approximately 17 days post-surgery. The histopathological characteristics of the 9L and F98 BSTs were comparable to those of aggressive human BSTs. CONCLUSION: The establishment of this animal tumor model will facilitate the testing of new therapeutic paradigms for the treatment of BSTs.

Animals↗

PubMed2006

Clinical presentation and optimal management for intramedullary cavernous malformations.

OBJECT: Intramedullary cavernous malformations (CMs) account for approximately 5% of all intraspinal lesions. The purpose of this study was to define the spectrum of presentation for spinal intramedullary CMs and the results of microsurgery for these benign but clinically progressive lesions. METHODS: Retrospective chart review was performed in 26 patients with histologically diagnosed CMs. All patients had undergone preoperative magnetic resonance (MR) imaging studies. All patients were treated with a laminectomy and microsurgical resection of the malformation. CONCLUSIONS: The MR imaging findings are diagnostic for intramedullary CMs; these lesions abut a pial surface and have a characteristic imaging pattern. Spinal intramedullary CMs present with either an acute onset of neurological compromise or a slowly progressive neurological decline. Acute neurological decline occurs secondary to hemorrhage inside the spinal cord. Chronic progressive myelopathy occurs due to microhemorrhages and resulting gliotic reaction to blood products. Surgery and total removal of the lesion tends to halt progression of symptoms.

Adolescent↗

PubMed2006

Intracranial drug-delivery scaffolds: biocompatibility evaluation of sucrose acetate isobutyrate gels.

INTRODUCTION: Sucrose acetate isobutyrate (SAIB) is a water insoluble, biodegradable gel used for controlled-release oral and subcutaneous drug delivery. We investigated SAIB compatibility in the rat central nervous system (CNS) by implanting solutions of SAIB in adult and in neonatal brains. METHODS: 10-15 microL solutions of SAIB gels in 0-30% ethanol were injected into the cerebral cortex of adult Fischer 344 rats. Control animals were implanted with a 10 mg biodegradable poly anhydride copolymer of poly [bis (p-carboxyphenoxy) propane] anhydride and sebacic acid (PCPP:SA). Adult rats were evaluated for signs of pain and distress, including changes in posture, facial signs, and grooming behavior. 1-2 microL solutions of SAIB gels in 15% ethanol were injected into brains of 12-24 h-old rats. Neonatal rats were evaluated for survival. Adult and neonatal brains were examined by histopathology 3-48 days after implant. RESULTS: Gel implants produced elliptical compression of cortical tissue, cell loss, and inflammation. Cell loss appeared to be confined to the implantation wound and associated neuronal fields. In adult rats, neurophil compression, inflammation, and cell loss appeared similar with the 10-mg PCPP:SA implants and the 10-mg SAIB implants. There was no clinical evidence of pain or distress from SAIB implants. 1-2 microL implants of SAIB-15% ethanol had no effect on survival of neonatal animals. CONCLUSION: Brain implants of SAIB induce a mild to moderate inflammatory response and associated neuronal cell damage. The implants appeared to be biocompatible in adult and neonatal animals. These results suggest that further studies of SAIB as an injectable drug-delivery scaffold for CNS therapeutic agents are warranted.

Animals↗

PubMed2006

Eyebrow surgery: the supraciliary craniotomy: technical note.

OBJECTIVE: Many approaches have been recommended for the surgical treatment of anterior and middle cranial fossa lesions. The frontobasal approach and its many modifications have been proposed and developed for such situated lesions. An alternative approach is the frontolateral craniotomy through a supraciliary skin incision. METHODS: This minimally invasive technique, a 2.5 x 3.0 cm craniotomy, just above the eyebrow through a supraciliary incision, is a simple but elegant modification of the traditional approach to the anterior cranial fossa. RESULTS: A step-by-step description of the approach is offered in this report to facilitate a clear understanding of the lesions treatable with this minimally invasive technique. CONCLUSION: The supraciliary frontolateral keyhole craniotomy is a minimally invasive cosmetic approach that provides excellent exposure to a variety of intracranial lesions. This approach cannot be used for all intracranial pathologies, but is recommended for many anterior and middle cranial fossa lesions.

Adolescent↗

PubMed2006

Intrinsic brainstem epidermoid cyst. Case report and review of the literature.

Brainstem epidermoid cysts are rare lesions, with only 18 reported cases in the literature and only five purely intrinsic epidermoid cysts within this group. The authors present the case of a 3-year-old girl with a history of chronic headaches, progressive diplopia, and relapsing and remitting mild right hemiparesis who was found to harbor an intrinsic brainstem epidermoid cyst at the pontomedullary junction. Initial working diagnoses included intrinsic brainstem astrocytoma and cavernoma. After tumor enlargement and progressive symptoms, a diffusion-weighted (DW) magnetic resonance (MR) imaging sequence was performed and a definitive diagnosis of an intrinsic brainstem epidermoid cyst was made in the patient. The patient underwent a suboccipital craniotomy and complete resection of the cyst with the aid of intraoperative neurophysiological monitoring. Three years after the operation, the patient is neurologically intact and no evidence of tumor recurrence has been found. The rarity of brainstem epidermoid cysts can make their diagnosis difficult; thus a DW MR imaging sequence of the brain is a useful diagnostic modality. Intrinsic brainstem epidermoid cysts can be removed safely, in a manner similar to that used for the surgical treatment of focal tumors.

Central Nervous System Cysts↗

PubMed2006

Local infusion therapy in the monkey brainstem: technical considerations.

This chapter assesses the safety of freehand placement of an infusion catheter (outer diameter, 0.3 mm) in brainstems of cynomolgus monkeys (Macaca fascicularis) for local infusion therapy. A posterior midline approach through the cerebellum and roof of the fourth ventricle was used to implant catheters into a pontine target area. Computer tomography (CT), magnetic resonance imaging (MRI), and histology were used to examine the position of the implants. The freehand placement of a catheter resulted in approximately 5-mm variations in anterior-posterior and dorsal-ventral locations of the targeted implantation site. No evidence of morbidity from the surgery, or from the infusion process was present. In conclusion, small-diameter catheters for chronic drug infusions can be implanted safely into the brainstem, an eloquent region that has been considered surgically inoperable. Infusion systems may offer a minimally invasive, generally applicable tool to provide chronic therapy for central nervous system (CNS) lesions.

Animals↗

PubMed2005

Neuroendoscopy: past, present, and future.

Neuroendoscopy began with a desire to visualize the ventricles and deeper structures of the brain. Unfortunately, the technology available to early neuroendoscopists was not sufficient in most cases for these purposes. The unique perspective that neuroendoscopy offered was not fully realized until key technological advances made reliable and accurate visualization of the brain and ventricles possible. After this technology was incorporated into the device, neuroendoscopic procedures were rediscovered by neurosurgeons. Endoscopic third ventriculostomy and other related procedures are now commonly used to treat a wide array of neurosurgically managed conditions. A seemingly limitless number of neurosurgical applications await the endoscope. In the future, endoscopy is expected to become routine in modern neurosurgical practice and training.

Brain Diseases↗

PubMed2005

Endoscopic third ventriculostomy for tumor-related hydrocephalus in a pediatric population.

OBJECT: Endoscopic third ventriculostomy (ETV) has become a common alternative for managing hydrocephalus in select patients. Nevertheless, there is still controversy regarding the indications for ETV as the primary procedure, given its variable success rates. The purpose of this study is to review the authors' experience with ETV for a variety of patients. METHODS: A total of 43 children underwent ETV between July 1992 and June 2003. Their medical records, operative reports, and imaging studies, when available, were retrospectively reviewed with regard to outcome, complications, and patency rate. Treatment failure was defined as the need to place a shunt within 4 weeks of performing ETV in the patient. There were 20 male and 23 female patients with a mean age of 9.6 years (range 8 weeks-21 years). The overall success rate was 69.8%, and the mean follow-up duration was 24.6 months. Six patients underwent eight repeated ETVs at a mean interval of 25 months, with a patency rate of 62.5% after the second procedure. Only two surgeries were aborted for anatomical reasons. The highest success rates (100% in each instance) were achieved for obstructive hydrocephalus resulting from midbrain/tectal tumor (four patients) and pineal tumor (three patients). CONCLUSIONS: The ETV procedure is an effective management tool for obstructive hydrocephalus in children. It should be considered the primary procedure, rather than ventriculoperitoneal shunts, in carefully selected children. The success rate is dependent on the origin of the hydrocephalus.

Adolescent↗

PubMed2005

Endoscopic third ventriculostomy.

The traditional treatment for all forms of hydrocephalus has been the implantation of ventricular shunt systems; however, these systems have inherent tendencies toward complications such as malfunction and infection. A significant advance in the treatment of hydrocephalus has been the evolution of endoscopy. The recent technological advances in this field have led to a renewed interest in endoscopic third ventriculostomy as the treatment of choice for obstructive hydrocephalus. Although several different endoscopes are available, the authors favor a rigid one to perform a blunt fenestration of the third ventricle floor. This description of the technique stresses the nuances for successful completion of this procedure.

Endoscopy↗

PubMed2005

A novel brainstem tumor model: guide screw technology with functional, radiological, and histopathological characterization.

OBJECT: Survival rates for high-grade brainstem tumors are approximately 10% and optimal therapy has yet to be determined. Development of a satisfactory brainstem tumor model is necessary for testing new therapeutic paradigms that may prolong survival. The authors report the technique, functional progression, radiological appearance, and histopathological features of a novel brainstem tumor model in rats. METHODS: Thirty female Fischer 344 rats were randomized (10 animals/group) to receive an injection of either 3 ml of 9L gliosarcoma cells (100,000 cells), 3 ml of F98 glioma cells (100,000 cells), or 3 ml of medium (Dulbecco modified Eagle medium) into the pontine tegmentum of the brainstem. Using a cannulated guide screw system implanted in the skull of the animal, rats in each group were injected at coordinates 1.4 mm to the right of the sagittal and 1 mm anterior to the lambdoid sutures, at a depth of 7 mm from the dura mater. The angle of the syringe during injection was anteflexed 5 degrees from the vertical. Postoperatively, the rats were evaluated for neurological deficits by using an automated rotarod test. High-resolution [18F]fluorodeoxyglucose-positron emission tomography (FDG-PET) fused with computerized tomography (CT) scans were acquired pre- and postoperatively through the onset of hemiparesis and correlated accordingly. Kaplan-Meier curves were generated for survival and disease progression, and brains were processed postmortem for histopathological investigation. The 9L and F98 tumor cells grew in 95% of the animals in which they were injected and resulted in a statistically significant mean onset of hemiparesis of 16.5 6 0.56 days (p = 0.001, log-rank test), compared with animals in the control group, which had no neurological deficits by Day 45. The FDG-PET studies coregistered with CT scans demonstrated space-occupying brainstem lesions, and this finding was confirmed by histological studies. Animals in the control group showed no functional, radiological, or pathological signs of tumor. CONCLUSIONS: Progression to hemiparesis was consistent in all tumor-injected animals, with predictable onset of symptoms occurring approximately 17 days postsurgery. The histopathological and radiological characteristics of the 9L and F98 brainstem tumors were comparable to those of aggressive primary human brainstem tumors. Establishment of this animal tumor model will facilitate the testing of new therapeutic paradigms for the treatment of these lesions.

Animals↗

PubMed2005

Endoscopic third ventriculostomy for hydrocephalus associated with tectal gliomas.

OBJECT: Tectal gliomas are a distinct form of pediatric brainstem tumor that present in patients with symptoms related to increased intracranial pressure due to obstructive hydrocephalus. The natural history of these lesions is often uniquely indolent. Thus, initial surgical therapies are directed at treatment of hydrocephalus, usually with ventricular shunt placement. Recently, third ventriculostomy has been used in patients with tectal gliomas, both as an initial procedure and after shunt failures. In this report the authors review their experience with the treatment of hydrocephalus in patients with tectal gliomas. METHODS: The authors reviewed 31 consecutive cases of tectal gliomas and compared the success rates of ventricular shunt placement with the success rates of endoscopic third ventriculostomy (ETV). Shunt placement procedures were associated with a significant number of malfunctions, and most patients required shunt revisions. The ETV procedure was attempted both as an initial treatment and after shunt malfunction. Overall, ETV was attempted in 18 patients and was performed successfully in all cases. At the time of follow-up evaluation, 16 patients (89%) were shunt free. CONCLUSIONS: The authors found that ETV could be performed with good long-term success both as an initial treatment and after shunt failure. Overall, ETV was found to be superior to ventricular shunt placement in the management of hydrocephalus associated with tectal gliomas.

Adolescent↗

PubMed2005

Familial Chiari type I malformation with syringomyelia in two siblings: case report and review of the literature.

OBJECTIVE: Familial cases of Chiari malformation with syringomyelia are rare. The majority of the reported series and case reports detail sporadic cases. The authors report two siblings who presented with Chiari type I malformation and syringomyelia (CMI+S). CLINICAL PRESENTATION: We report two sisters who each presented with scoliosis on routine school physicals. Their clinical examination was unremarkable; however, imaging studies demonstrated a Chiari malformation with syringomyelia. Both underwent cervicomedullary decompression, and follow-up imaging studies revealed resolution of the syringomyelia. CONCLUSION: A review of the literature reveals fewer than ten previous reports of familial CMI+S in the past 30 years. Although rare, the existence of familial cases of CMI+S suggests a genetic component to the pathogenesis of this condition in at least a proportion of patients. Neurosurgeons should be aware of the familial aggregation of CMI+S.

Adolescent↗

PubMed2005

Experimental models of brainstem tumors: development of a neonatal rat model.

OBJECTIVE: Brainstem tumor models are required to advance the treatment for diffuse pontine gliomas in children. The feasibility of creating an experimental rodent model by inoculating newborn pups with tumor cells was examined. The study was performed to create an animal model for diffuse brainstem tumors. METHODS: Eighty-two Fischer rat pups aged 12-24 h were anesthetized by hypothermia. The brainstem was injected with saline to identify anatomical coordinates for subsequent tumor cell challenges. The newborn pups were then inoculated with F98 (n=30) or 9L (n=30) glioma cells. Animals were returned to their mother for nursing. Tumor growth was assessed by survival and histopathology. RESULTS: Twenty-one percent of the saline-treated animals (17 out of 82) and 5% of the tumor cell-challenged pups (3 out of 60) were eliminated by their mothers. Inoculations with 9L and F98 cells produced brainstem tumors in 83% (24 out of 29) and 93% of animals (26 out of 28) respectively that were evaluated. CONCLUSIONS: Our results demonstrate that neonatal rat models for brainstem tumors can be prepared using known injection coordinates and orthotopic cell lines. Decreasing rates of maternal removal during the course of the work suggests that the method involves a learning curve.

Animals↗

PubMed2005

Recovery of lower cranial nerve function after surgery for medullary brainstem tumors.

OBJECTIVE: Although optimal treatment for intrinsic focal tumors of the medulla remains controversial, many surgeons advocate radical surgery for patients with these tumors. Postoperative surgical morbidity may include loss of lower cranial nerve function and significant motor deficits. Recovery of lower cranial nerve dysfunction after radical surgery has not been reported previously. METHODS: Forty-one children and adolescents with tumors involving the medulla underwent operations between 1986 and 1997. Nineteen (46%) of these patients experienced loss of lower cranial nerve function requiring tracheostomy, ventilator support, and feeding gastrostomy. A retrospective analysis of this patient population and the time to cranial nerve recovery was undertaken. RESULTS: Thirteen (68%) of the 19 patients with loss of lower cranial nerve function had full recovery of lower cranial nerve function. Two patients (11%) have had significant improvement in their lower cranial nerve function, and four patients (21%) have remained without lower cranial nerve function. CONCLUSION: Lower cranial dysfunction is common after surgery for intrinsic medullary tumors. However, the majority of patients who require tracheostomy or gastrostomy tubes will recover cranial nerve function.

Adolescent↗

PubMed2005

Spinal solitary fibrous tumors: a series of four patients: case report.

OBJECTIVE AND IMPORTANCE: Intraspinal solitary fibrous tumors, which are rare mesenchymal tumors, have previously been reported as case reports. We review our experience and, to our knowledge, the first small institutional series with respect to clinical presentation, diagnosis, surgical management, pathohistological analysis, progression-free survival, and long-term outcome. CLINICAL PRESENTATION: In this retrospective review, four patients (three male and one female) ranging in age from 17 to 59 years (mean, 38.5 yr) had spinal solitary fibromas located throughout the spinal canal. Three tumors were located in the thoracic region and one in the cervical spine. All patients presented with pain and paresthesia. Two patients had an associated spinal deformity. All had gross total resection as confirmed by postoperative imaging studies. INTERVENTION: All four patients underwent surgical treatment for spinal solitary fibromas. None of these patients underwent irradiation or chemotherapy after surgery at our center; therefore, outcome was attributed to surgery alone. There were no surgical deaths, and the 5-year actuarial survival rate was 100%. At the most recent follow-up examination, neurological function was stable or improved in 90% of patients. CONCLUSION: Patients with solitary fibrous tumors have a long survival. These tumors have an indolent course, and radiotherapy or chemotherapy seems to be unnecessary.

Adolescent↗

PubMed2005

Infusion rates and drug distribution in brain tumor models in rats.

OBJECT: The aim of this study was to investigate the optimal delivery rates of chemotherapy for the treatment of central nervous system tumors and to determine whether local delivery can lower toxicity profiles and increase target concentrations of chemotherapy. METHODS: The authors used two brain tumor models in rats. Slow (1 microl/hour) and fast (10 microl/hour) pumps were used to deliver chemotherapy--carboplatin, doxorubicin, and a high-molecular-weight transferrin-doxorubicin conjugate to the brains of normal rats and rats previously injected with F98 or 9L rat brain tumor cells. Brains were cut in 1-mm sections rostral and caudal from the infusion point. Slices were analyzed for doxorubicin and platinum by fluorescence and atomic absorption, respectively. In the normal tissues, the volume of drug distribution is generally greater at the faster flow rate. In abnormal tissues, distribution is similar at slow and fast infusion rates for low-molecular-weight drugs and greater at slow rates for a high-molecular-weight targeted toxin. CONCLUSIONS: After local administration the distribution of chemotherapy appears to be significantly influenced by tumor metabolism. Additional studies are needed to determine the optimal delivery rates for the interaction of the drug with the targeted tumor.

Animals↗

PubMed2005

Neonatal cavernous carotid artery aneurysm: case report.

Neonatal intracranial aneurysms are rare. The authors report the case of a 4-week-old girl who presented with left-eye ptosis and proptosis. Computerized tomography scanning and magnetic resonance imaging demonstrated a mass involving the left cavernous sinus and middle cranial fossa. Cerebral angiography revealed a large complex left cavernous carotid artery (CA) aneurysm. The patient underwent endovascular treatment in which detachable coils and N-butyl cyanoacrylate glue were used to achieve complete obliteration of the aneurysm. To the authors' knowledge, this is the first reported neonatal intracranial aneurysm originating from the cavernous CA and treated endovascularly. The authors review the literature on neonatal intracranial aneurysms.

Arteriovenous Fistula↗