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G Chacko

Publications and source records attributed to G Chacko.

At least 19 recordsLinked to original sources
PubMed2004

Intratumoral abscess: an unusual complication of ventriculoperitoneal shunt infection.

INTRODUCTION: Ventriculoperitoneal shunts were routinely used in the past in children with posterior fossa tumors and hydrocephalus. They can, however, cause a multitude of problems. CASE REPORT: This report highlights a previously unencountered phenomenon of a pyogenic abscess forming within a posterior fossa ependymoma as a result of shunt infection. The shunt was exteriorized and the child treated with antibiotics before surgery was done. Only a partial excision of the tumor was possible, as the inflammatory response caused by the abscess had obliterated tissue planes.

Amikacin↗
PubMed2003

Intraoperative ultrasound in determining the extent of resection of parenchymal brain tumours--a comparative study with computed tomography and histopathology.

BACKGROUND: Radical excision of parenchymal brain tumours is generally associated with a better long-term outcome; however, it is difficult to ascertain the extent of resection at surgery. We used intra-operative ultrasound [IOUS] to help detect residual tumour and define the tumour-brain interface. METHODS: Thirty-five patients with parenchymal brain lesions including 11 low-grade and 22 high-grade tumours and 2 inflammatory granulomata were included in the study. The IOUS was used to localize tumours not seen on the surface, define their margins and assess the extent of resection at the end of surgery. Multiple samples from the tumour-brain interface which were reported as tumour or normal tissue on IOUS were submitted to histopathology. The IOUS findings were compared with a postoperative contrast enhanced computed tomogram [CT] and with histopathology. RESULTS: All tumours irrespective of histology were hyperechoic on IOUS. IOUS was useful in localizing those tumours not seen on the surface of the brain. In 71.4% of cases IOUS was useful in defining their margins, however in the remaining cases the margins were ill-defined. The tumour margins were ill-defined in those treated previously by radiation. With regard to the extent of excision, after excluding the cases who were irradiated, it was found that in the 28 patients who had parenchymal neoplasms, there was concordance between the ultrasound findings and the postoperative CT scan in 23 cases. Of the 79 samples taken from the tumor-brain interface which were reported as tumour on ultrasound, 66 had histopathological evidence of tumour while 13 samples were negative for tumour. On the other hand, in the tissue sent from 17 sites where the IOUS showed no residual tumour, 2 were positive for tumour on histopathology while 15 were negative. INTERPRETATION: In conclusion, IOUS is a cheap and useful real-time tool for localizing tumours not seen on the brain surface, for defining their margins and for determining the extent of resection.

Adult↗
PubMed2003

The 'capsule' of pituitary macroadenomas represents normal pituitary gland: a histopathological study.

The goal of trans-sphenoidal pituitary adenoma surgery is radical excision of the tumour with preservation of endocrine function. Our hypothesis was that, even in macroadenomas extending into the suprasellar cistern, the 'capsule' of the tumour is the compressed normal pituitary gland. The biopsy material from 126 patients with pituitary macroadenomas were retrospectively reviewed to look for the presence of normal adenohypophysis. Fourteen patients with macroadenomas operated trans-sphenoidally were studied prospectively, sampling tissue from the periphery of the tumour for histopathology. From the retrospective data, we found that normal adenohypophysis was more often found at histopathology in the extracapsular excisions, rather than in the intracapsular excisions. In the 14 patients studied prospectively, normal adenohypophysial tissue was found histologically at all sites sampled except in areas where the tumour was invasive. In conclusion, while an extracapsular excision would offer the best chance for a surgical cure, preserving parts of the capsule may preserve normal and possibly functioning gland.

Adenoma↗
PubMed2003

Diagnostic validity of the Ki-67 labeling index using the MIB-1 monoclonal antibody in the grading of meningiomas.

BACKGROUND: About 10% of meningiomas behave aggressively and are graded atypical or malignant with important therapeutic and prognostic implications. Routine histological parameters are inconsistent in the assessment of their aggressive behavior. AIMS: The aim of this study was to find a threshold level of the MIB-1 labeling index (MIB-1 LI) with the highest diagnostic validity in predicting histological atypia in a meningioma. SETTING AND DESIGN: This was a retrospective study of all atypical and malignant meningiomas diagnosed at our center between January 1995 and June 2000 and which were identified from the General Pathology Registry. MATERIAL AND METHODS: These meningiomas were assessed histologically with respect to the individual criteria of atypia. They were categorized according to the WHO 2000 classification as benign, atypical and anaplastic meningiomas, WHO Grades I, II and III respectively and by immunohistochemical analysis using the MIB-1 monoclonal antibody. STATISTICAL ANALYSIS: The diagnostically useful cut-off level for the prediction of atypia was estimated by calculating the sensitivity and specificity of the MIB-1 LI at various levels and a receiver operated characteristic (ROC) analysis was performed. The correlation between the individual histological parameters was studied and the MIB-1 LI was obtained using Fisher's exact test. RESULTS: Of the 40 meningiomas studied 21 were benign, 16 atypical and 3 anaplastic. Atypical tumors had a higher MIB-1 LI than benign tumors, with diagnostic validity highest at a threshold of 7%, with a sensitivity of 0.86 and a specificity of 0.93, giving a likelihood ratio of 17. The MIB-1 LI correlated well with mitotic activity and the other individual criteria in the WHO 2000 definition of atypia in a meningioma. MIB-1 LI did not, however, correlate well with brain invasion. CONCLUSION: The MIB-1 LI has the highest validity in the diagnosis of atypia in meningiomas at a threshold level of 7%. The MIB-1 LI used in conjunction with histological features can help in making a recommendation regarding potentially aggressive behavior in meningiomas.

Adolescent↗
PubMed2002

Endolymphatic sac tumor: a rare cerebellopontine angle tumor.

Endolymphatic sac tumors (ELST) are rare papillary tumors of the temporal bone. Previously named as aggressive papillary middle ear tumors, they have recently been shown to arise from the endolymphatic sac. They are a rare in cerebello-pontine angle (CPA). We present a case of an ELST who presented as a CPA tumor with hydrocephalus. He underwent a ventriculo-peritoneal shunt initially. On exploration of the CP angle, the tumor was found to be extremely vascular. He was re-explored following embolization, and a subtotal excision of the tumor was done. Extensive petrous bone infiltration and vascularity of the tumor makes total excision almost impossible with high risk of cranial nerve deficits, excessive blood loss and CSF leak. This tumor should be considered in the differential diagnosis of vascular CPA tumors which erode the petrous temporal bone. The relevant literature is reviewed.

Adult↗
PubMed2002

Hemorrhagic necrosis of pituitary adenomas.

A clinicopathological study of 41 cases of pituitary apoplexy in a series of 324 surgically treated pituitary adenomas is presented. In 23 patients, the predominant operative finding was hemorrhage with or without necrosis. However, there were 15 (37.7%) cases where pale, necrotic tissue with no evidence of hemorrhage was found at surgery. Pale, necrotic material was particularly found when there was a long interval between the acute clinical event and surgery. It is concluded that the pale, necrotic debris represents one stage in the resorption process of blood after hemorrhagic necrosis of pituitary adenomas. This entity needs to be kept in mind especially since the material closely resemble the pultaceous material seen in craniopharyngiomas and epidermoid cysts.

Adenoma↗
PubMed2002

Skull base chondroblastoma: a case report.

Chondroblastoma is a rare tumor of the skull. Temporal bone is the commonest site of involvement in the skull. We present a thirty one year old man who presented with painless swelling over the left temporal bone, which was near totally excised after preoperative embolization. Management of this unusual tumor and its complications are discussed.

Adult↗
PubMed2001

Determination of Ki-67 labeling index in pituitary adenomas using MIB-1 monoclonal antibody.

Proliferative activity of 94 pituitary adenomas was assessed by the determination of the growth fraction, using MIB-1 monoclonal antibody in formalin fixed, paraffin embedded sections. This index was correlated with clinical and radiological evidence of invasiveness. The mean Ki-67 labeling index for all pituitary adenomas was 0.84% (range 0-17.45%). Hardy stage E tumours (1.44%) had a higher Ki-67 labeling index (LI) as compared with Hardy stage 0 tumours (0.36%). The difference in the Ki-67 labeling indices between invasive and non-invasive adenomas was not statistically significant. Hence, the Ki-67 labeling index is not a reliable indicator of invasiveness in pituitary adenomas.

Adenoma↗
PubMed2000

The calcified intracorporeal vacuole: an aid to the pathological diagnosis of solitary cerebral cysticercus granulomas.

Fifty four cases of single small (<20 mm) enhancing CT lesions (SSECTLs) of the brain that were excised between 1987 and 1995 were reviewed histologically. In 28 cases the entire cysticercus or its parts were found. In the remaining 26 cases, most had a histological picture suggestive of a parasitic granuloma. In six of these 26 cases, small ovoid masses corresponding in morphology to the intracorporeal vacuoles of a cysticercus were seen lying free in the cavitary space of the granuloma. This lends further strength to the contention that SSECTLs of the brain are caused by cysticercus, and that in the event of a surgical excision, absence of obvious parasitic parts should necessitate a closer search, as calcareous residues of the parasite might be the only evidence of the cysticercal aetiology in the granuloma.

Adolescent↗
PubMed1999

Cerebral hemodynamic effects of phenylephrine and L-arginine after cortical impact injury.

OBJECTIVE: To determine the effects of a pressor agent (phenylephrine and L-arginine) on the abnormal cerebral hemodynamics and on neurologic outcome after a severe cortical impact injury in rats. DESIGN: Prospective, randomized study. SETTING: University laboratory. SUBJECTS: Male Long-Evans rats, weighing 300 to 400 g, fasted overnight. INTERVENTIONS: The animals were anesthetized with isoflurane, and a severe cortical impact injury (velocity, 5 m/sec; deformation, 3 mm) was produced in the right parietal cortex. Five minutes after impact injury, one of the following three treatments were infused: 1 mL saline intravenously for 10 mins, 300 mg/kg L-arginine in 1 mL saline intravenously for 10 mins, or 0.3 microg/kg/min phenylephrine intravenously for 3 hrs. Mean arterial pressure, intracranial pressure (ICP), cerebral perfusion pressure (CPP), and laser Doppler flow (LDF) at the impact site and in the contralateral parietal cortex were monitored for 3 hrs after the impact injury. Histologic examination of the brain was performed at 2 wks after injury in a separate group of L-arginine- and saline-treated animals. MEASUREMENTS AND MAIN RESULTS: The immediate response to the impact injury was an increase in ICP, and a decrease in mean arterial pressure, CPP, and LDF. In the saline-treated animals, LDF decreased to <25% of the baseline values at the impact site and stayed at that level for the entire 3-hr monitoring period. On the contralateral side, LDF decreased initially and recovered gradually to approximately 50% of the preimpact baseline value. Infusion of both phenylephrine and L-arginine increased LDF back to near-baseline levels. However, phenylephrine increased ICP significantly, whereas ICP with L-arginine did not change. L-arginine treatment reduced the contusion volume from a median value of 5.28 mm3 to 0.63 mm3. CONCLUSIONS: Phenylephrine increased cerebral blood flow (CBF) by increasing CPP. L-arginine, however, increased CBF without changing CPP. The improvement in CBF was accompanied by a decrease in neurologic injury. Although the pressor agents are used currently to increase CBF after traumatic brain injury, other strategies may also increase CBF without the potential adverse effects of induced hypertension.

Animals↗
PubMed1999

Cysticercosis of the cerebellopontine angle cistern mimicking epidermoid inclusion cyst.

We report a case of a cystic lesion in the left cerebellopontine (CP) angle cistern. The magnetic resonance (MR) imaging features closely resembled an epidermoid inclusion cyst, and was interpreted as such. However, at surgery and on histopathological examination the lesion was found to be a cysticercus cyst. It may be impossible to distinguish between the two by imaging. The MR imaging findings of cysticercosis, epidermoid and other common differentials are discussed.

Adult↗
PubMed1999

Medullomyoblastoma: A case report.

Medullomyoblastoma is a rare tumour seen in childhood. We report a medullomyoblastoma occurring in the cerebellar vermis of a 4 year old boy. The light microscopic features, immunohistochemistry and histogenesis are described.

Cerebellar Neoplasms↗
PubMed1998

Induction of acute translational response genes by homocysteine. Elongation factors-1alpha, -beta, and -delta.

The thiol amino acid homocysteine (HC) accumulates in homocystinuria and homocyst(e)inemia, and is associated with a wide variety of clinical manifestations. To determine whether HC influences the cell's program of gene expression, vascular endothelial cells were treated with HC for 6-42 h and analyzed by differential display. We found a 3-7-fold, time-dependent induction of a 220-base pair fragment, which demonstrated complete sequence identity with elongation factor-1delta (EF-1delta), a member of the multimeric complex regulating mRNA translation. Fibroblasts from cystathionine beta-synthase -/- individuals also showed up to 3.0-fold increased levels of mRNA for EF-1alpha, -beta, and -delta when compared with normal cells, and treatment of normal cells with the HC precursor, methionine, induced a 1.5-2.0-fold increase in EF-1alpha, -beta, and -delta mRNA. This induction was completely inhibited by cycloheximide and reflected a doubling in the rate of gene transcription in nuclear run-on analyses. In HC-treated endothelial cells, pulse-chase studies revealed a doubling in the rate of synthesis of the thiol-containing protein, annexin II, but no change in synthesis of the cysteineless protein, plasminogen activator inhibitor-1. Thus, HC induces expression of a family of acute translational response genes through a protein synthesis-dependent transcriptional mechanism. This process may mediate accelerated synthesis of free thiol-containing proteins in response to HC-induced oxidative stress.

Amino Acid Sequence↗
PubMed1998

Sacral haemangioma as a cause of coccydynia.

We report a 55-year-old woman with coccydynia due to a sacral mass. The histological diagnosis was haemangioma. The MRI findings and the unusual location of this lesion are discussed.

Diagnosis, Differential↗
PubMed1998

Argyrophilic nucleolar organizer region proteins (AgNORs) as an index of clinical and radiological invasiveness in pituitary adenomas.

Sixty-eight patients with pituitary adenomas were classified into groups based on their invasiveness and functional status. Mean argyrophilic nucleolar organizer region proteins (AgNOR) counts obtained from 200 cells showed no correlation with the invasive status of pituitary adenomas. However, the functional tumours showed significantly higher AgNOR counts than non-functional tumours.

Adenoma↗
PubMed1998

Primary sphenoid and petrous apex esthesioneuroblastoma: case report.

A 62-year-old woman presented with raised intracranial pressure and features of a right cerebellopontine angle tumour with extension into the right middle cranial fossa. The patient died before a surgical excision could be performed. The autopsy revealed a primary esthesioneuroblastoma of the sphenoid sinus eroding the petrous bone and extending into the middle cranial fossa with metastatic tumour in the liver, and paratracheal and hilar lymph nodes. Although rare, esthesioneuroblastoma must be considered in the differential diagnosis of petrous-sphenoid lesions.

Brain↗