Proliferative index in astrocytic tumours.

The accurate grading of astrocytic tumours is of prime importance because it is critical to the patient management and survival/outcome. Although internationally accepted WHO grading system of CNS tumours is based on histological features of H&E stained sections, yet there are cases where differentiation between grade II and grade III is difficult particularly when the biopsy is small. Proliferative index derived from MIB-1 immunostaining has been found to be useful in the distinction between various grades of malignancy. Formalin-fixed paraffin-embedded surgical specimens from 90 cases of astrocytic tumours, 30 each of low-grade astrocytoma (grade II), anaplastic astrocytoma (grade III), and glioblastoma multiforme (grade IV), were immunostained by standard indirect immunoperoxidase technique using MIB-1 monoclonal antibody. MIB-1 labeling index (MIB-1 LI) was calculated. The mean MIB-1 LI values of astrocytomas, anaplastic astrocytomas and glioblastomas were 1.75 +/- 1.5%, 8.74 +/- 6.2%, and 20.54 +/- 12.2% respectively and there was statistically significant difference between grade II and III (Unpaired "t" test, T value 5.907, p value < 0.001) and grade III and grade IV (T value 4.734, p value < 0.001). The statistical analysis also revealed that the mean MIB-1 LI increased with histological grade of malignancy (One way ANOVA test, p value < 0.001). This investigation further reinforces and corroborates the findings that MIB-1 LI is useful tool in assigning grading to the astrocytic tumours and hence in treatment modalities and should be used routinely.

Central neurocytoma: a clinico-pathological study of eight cases.

Central neurocytomas are benign neuronal tumours generally found in the lateral or third ventricles. They are rare, comprising < 1% of all brain tumours. It is frequently confused with other tumours of the central nervous system particularly oligodendroglioma. The present study was done to analyse the histopathological features including immunohistochemical profile of these rare tumours. Eight cases were taken up for the study. Seven of the cases had an intraventricular location and one was located outside the ventricles. Increased intracranial pressure was the most common presenting symptom. Microscopically all tumours were composed of small uniform cells with perinuclear halos and regular round nuclei. The tumour in extraventricular location showed atypical features. Immunohistochemistry showed positivity for neuronal markers. The present series highlights the characteristic clinical and pathological findings of this rare brain tumour. Immunostaining for neuronal markers are essential for distinguishing them from other small round cell tumours of the brain.

Calvarial malignant fibrous histiocytoma.

Primary malignant fibrous histiocytoma (MFH) of the central nervous system (CNS) is uncommon. We report cases of two young patients of MFH arising from the cranial meninges and involving the adjacent skull and scalp. There was infiltration of the brain in one case. Both the lesions were excised and primary scalp repair was performed.

Raised intracranial pressure in hepatic encephalopathy.

Intracranial hypertension secondary to cerebral edema is the cause of death in 50%-80% of patients with fulminant hepatic failure (FHF). This is rarely seen in chronic hepatic failure. The genesis of cerebral edema in FHF is poorly understood. The grade of encephalopathy and coagulopathy are the most important predictors of outcome in FHF. However, it is important to emphasize that intracranial pressure (ICP) may not reflect clinical course. Decerebrate posturing may be seen with ICP recording of 16 mmHg, while a quarter of the patients may have brain damage without clinical signs of raised ICP. ICP monitoring is therefore vital. The gold standard for ICP monitoring is the intraventricular method. Non-invasive methods like computerized tomography scan and magnetic resonance imaging have poor correlation with ICP. Other methods like transcranial Doppler and jugular venous oximetry measurement of brain metabolites need evaluation. The main indications for ICP monitoring in FHF are (a) patients in grade III or IV encephalopathy and (b) patients undergoing liver transplantation. Generally, patients with an ICP >40 mmHg with cerebral perfusion pressure <50 mmHg for over 2 hours are poor subjects for liver transplant.

Subependymomas in children: a report of five cases including two with osseous metaplasia.

Subependymomas are highly differentiated slow growing gliomas. They are one of the few gliomas which are biologically benign. They are extremely rare in children. However, after going through the histopathology records of our department of fourteen years (1983-1997) we found that five (20%) cases of subependymomas have been diagnosed in children out of a total of twenty-six subependymomas. Two of our cases showed the presence of osseous metaplasia, a hitherto undescribed finding.

Primary central nervous system lymphoma: experience of 46 cases with review of literature.

Primary central nervous system lymphomas (PCNSL) constitutes only 1.0 to 1.5% of all brain tumors. Their incidence has gone up over tenfold in the last 25 years. Though, there has been an association of PCNSL with acquired immune deficiency syndrome (AIDS), yet the increased incidence of PCNSL appears to be real and unrelated to AIDS and organ transplantation. This increased incidence could be because of improvement in diagnostic technology and practice. The outcome remains gloomy despite surgical resection, radiotherapy and intensive adjuvant chemotherapy regimens, as majority of the patients succumb to the disease, with only 30-40% survival in patients under 70 years of age.

Expression of Bcl2 proto-oncogene in primary tumors of the central nervous system.

The present study was addressed to find out the expression of Bcl2 proto-oncogene in tumor tissues derived from 25 patients with primary central nervous system tumors. Brain parenchyma in 8 cases, with deeply located tumor, was also examined for Bcl2 expression which served as control. Both benign and malignant tumors (confirmed by histopathological examination) expressed Bcl2 gene product. Tumors exhibited 2-6 fold increase in Bcl2 expression as compared to the normal parenchyma adjacent to some of these tumors studied. However, no correlation was found between the histopathological types of tumor, glial fibrillary acidic protein positivity and degree of Bcl2 expression. Based on this study, we propose that the overexpression of Bcl2 gene product found in primary CNS tumors may be an important molecular event which is known to make the various types of tumor resistant to chemotherapy or radiotherapy.

Single flap fronto-temporo-orbito-zygomatic craniotomy for skull base lesions.

Surgery was performed, through single flap fronto-temporo-orbito-zygomatic approach in 22 patients with skull base lesions. In two of these patients, this approach was combined with a transpetrosal approach. The pathological spectrum consisted of trigeminal neurofibromas (5), spheno-orbital meningiomas (4), carotico-ophthalmic aneurysms (4), basilar top aneurysms (2), cavernous sinus haemangiomas (2), invasive pituitary tumours (2) and one patient each of metastatic adenocarcinoma of the cavernous sinus, transcranial fungal granuloma and tubercular granuloma of the cavernous sinus. Of the 14 tumours, 10 were excised totally/near totally while a subtotal excision was achieved in four. Removal of the anterior clinoid process facilitated the clipping of all the carotico-ophthalmic aneurysms. One basilar top aneurysm was wrapped and the other clipped. One patient of fungal granuloma died of fungal meningitis and one patient of basilar top aneurysm expired as a result of thalamic infarct. The advantages of this approach included excellent exposure of the skull base lesions, making the dissection distance shorter and wider, minimal brain retraction and easy replacement of the single bone flap.

Traumatic subarachnoid haemorrhage: a clinicoradiological and TCD correlation.

Twenty five consecutive patients with CT proven pure traumatic subarachnoid haemorrhage (tSAH) were studied, prospectively over a 6 month period. They constituted 2% of all head injuries. Most of the patients (88%) had a mild or moderate head injury at the time of admission, with a mean glasgow comma scale (GCS) of 10.68. The CT scan findings were divided into 3 grades. Grade 1 - blood in hemispheric region only (n=4), grade 2 - blood in basal region only (n=11), grade 3 - blood in both hemispheric as well as basal region (n=10). Transcranial doppler ultrasound (TCD) velocities were recorded in all patients by insonating the middle cerebral artery, internal carotid artery and anterior cerebral artery on both sides. All patients were also subjected to digital substraction angiography (DSA). All patients with mild head injury had normal TCD velocity (<100 cm/sec), while TCD velocities of more than 150 cm/sec were seen only in one patient with severe head injury. Patients with severe head injury were found to have grade 3 tSAH on CT. No statistically significant correlation was found between the CT grade and TCD velocities. Angiographic vasospasm was found in 2 patients with severe head injury only. 90.2% of patients had good outcome at discharge.

Posterior fossa dermoid in association with Klippel-Feil syndrome--a short report.

A posterior fossa dermoid cyst in association with the Klippel-Feil syndrome, in a 4 year old child is reported. Early diagnosis to prevent complications like neural compression, cyst rupture and staphylococcal meningitis justifies investigation for posterior fossa dermoids in cases of Klippel-Feil syndrome. Their embryological basis is discussed.

Cerebral abscess with astrocytoma.

A child with a right parieto-occipital astrocytoma, caped by a large acute pyogenic abscess with flimsy capsule, detected at emergency craniotomy, is presented. Patient succumbed to the disease three hours following surgery.

Intramedullary cysticercosis : MRI diagnosis.

Three cases of dorsal intramedullary cysticercosis presenting as spastic paraparesis or paraplegia are reported. A definite preoperative diagnosis, using MRI, was made in two cases while in the third it was strongly suspected. One paraplegic patient regained full function whereas in the other two the deficit persisted even after successful cyst excision. The pathogenesis and recovery are discussed in the light of the MRI findings.

Bilateral fronto-orbito-zygomatic craniotomy--a combined extended frontal and orbitozygomatic approach.

In extensive skull base lesions involving the spheno-ethmoido-clival region and extending into both the cavernous sinuses and infratemporal regions, a combination of approaches is usually required, either in the same operation or at a second stage. The bilateral fronto-orbito-zygomatic craniotomy described in this report is a combination of an extended frontal approach and fronto-orbito-zygomatic craniotomy. This gives a wide exposure of the spheno-ethmoido-clival regions of both the cavernous sinuses and both the infratemporal regions. The exposure is thus greatly improved with minimal frontal lobe retraction. The single bone piece can be speedily replaced obviating the need for a complicated reconstruction technique and gives a superior cosmetic result. The operative technique is described in detail.

Calcified falx meningioma.

A totally calcified mid third falcine meningioma in an elderly male patient is presented. An uneventful enmasse excision was performed. Advantages of positioning on ipsilateral side for paramedian extracerebral lesions are highlighted.

Postoperative hypertensive-hypervolaemic-haemodilution (Triple H) therapy in the treatment of vasospasm following aneurysmal subarachnoid haemorrhage.

Twenty five patients with post operative ischaemic deficits, following clipping of intracranial aneurysms, were studied. Hypertensive-hypervolaemic-haemodilution (triple H) therapy was given to all patients using colloids and crystalloids. CVP was used to monitor the fluid therapy. Dopamine was needed in 22 patients to elevate the systemic blood pressure. Vasospasm was confirmed in 20 patients with transcranial doppler studies (TCD). 20 (80%) patients survived, 10 (40%) with good outcome, 7 (28%) with fair, 2 (8%) with poor outcome and 1 (4%) with vegetative state. There were 5 (20%) deaths, 4 of which occurred due to infarct. All these patients had poor Hunt and Hess grade at admission, high Fisher grade haemorrhages in the initial CT scan and/or required prolonged temporary clipping at surgery. One death occurred due to central venous line induced septicaemia. The duration of 'triple H therapy' amongst the survivors varied from 2-7 days with an average of 4.6 days. The complications of 'triple H therapy' included hypokalaemia (3 patients), haemorrhagic infarct (1 patient) and septicaemia (1 patient). It is concluded that 'triple H therapy' is useful in treating vasospasm induced ischaemic deficits. It worsens brain oedema in presence of acute infarcts and hence is contraindicated in such patients. A further study involving a larger number of patients with strict haemodynamic and ICP monitoring is suggested to determine the usefulness of individual components of 'triple H therapy'.

Current concepts in the management of pyogenic brain abscess.

Current philosophy of treatment of brain abscess includes aspiration, appropriate antibiotics, treatment of sequelae and eradication of the primary source. Early clinical suspicion and diagnosis with CT is crucial. Small abscesses (<3 cm) in cerebritis or capsular stage located deep in clinically stable, poor surgical risk patients with diagnosis firmly supported by CT, may be treated with medical treatment only. Biweekly CT scan must be done to monitor the treatment response. CT or ultrasound guided aspiration should be performed in the event of clinical deterioration, failure of reduction in size or enlargement of abscesses. Encapsulated abscess (>3 cm), presence of significant neurological deficit or mass effect, doubt in the diagnosis and presumed resistant organisms are best treated with aspiration. Excision is required in large superficial abscesses resistant to multiple aspirations, post-traumatic abscess with a foreign body or fistula and multiloculated abscess of nocardial or actinomycotic aetiology. Results are directly related to the sensorium at the time of presentation. Stereotactic aspiration of all the loculi of multiloculated abscess in single or staged aspiration, and more completed drainage and lavage with endoscopic stereotactic evacuation may cut down indications of excision of brain abscess in future. It is concluded that, with diagnostic and technical advancements, a trend of adequate drainage of brain abscess via minimally invasive surgery is emerging. Confirmation of diagnosis and monitoring of treatment response with magnetic resonance spectroscopy may allow greater number of patients in future to be managed with medical treatment only.

Molecular basis of cholesterol feedback lesion in CNS tumours.

An important feature of malignant transformation of tumours is the loss of cholesterol feedback inhibition mechanism (cholesterol-feedback lesion) that regulates mevalonate pathway recognized to play a crucial role in cellular growth, death and differentiation. Recently, it was shown that Receptor-C(k)-dependent signalling regulates genes involved in maintaining cellular cholesterol homeostasis through a transcription factor sterol response element binding protein (SREBP) having affinity for sterol regulatory element (SRE) present in the promoter region of these genes. The present study revealed that CNS tumours exhibit overexpression of Receptor-C(k) gene product which was accompanied by their inability to express SREBP gene product and this phenomenon has the inherent capacity to initiate the cholesterol feedback lesion in these tumours. Based upon these and our earlier studies, we propose for the first time that this loss of cholesterol feedback control may be responsible for the initiation of these tumours.

Anterior surgical approaches to the sub-axial cervical spine.

Anterior cervical spine surgery has come of age, as a golden route for treating anteriorly placed cervical compressions ranging from simple prolapsed disc to long segment pathologies like ossification of posterior longitudinal ligaments and cervical spondylotic myelopathy. Numerous technical modifications of the procedure are described. The role of stabilisation established for several pathologies, is still debateable in surgery for cervical disc. Bone is the ideal tissue for fusion. Hydroxyapetite implants are goods, but costly for our set up. Methylmethacrylate has a limited role in elderly patients with malignancy and a short life expectancy. Anterior cervical instrumentation has mushroomed over the last decade. Acceptable as methods of immediate stabilisation, the choice of the system varies with the surgeon. The authors use simple titanium plates with locking screws for the purpose.

Midline and far lateral approaches to foramen magnum lesions.

Twenty patients with foramen magnum lesions were operated upon in the last 5 years at Postgraduate Institute of Medical Education and Research, Chandigarh. The common presenting features were quadriparesis, quadriplegia, diminished sensations, neck pain and respiratory insufficiency. The lesions encountered were meningiomas, neurofibromas, posterior inferior cerebellar artery aneurysms, neurenteric cyst and chordoma. Patients with posterior or posterolaterally placed lesions were operated by the midline posterior approach while those with anterior or anterolateral lesions were managed by the far lateral approach. All mass lesions were excised completely and the aneurysms were clipped. Seventeen patients made good neurological recovery while three died. The latter three patients presented very late. The merits of various surgical approaches to the foramen magnum are discussed.

Pure extradural approach for skull base lesions.

Lesions in the parasellar and paracavernous regions can be removed by various skull base approaches involving basal osteotomies. A major complication of intradural skull base approaches is CSF leak and associated meningitis. We have managed 5 patients with skull base lesions with a pure extradural approach using wide basal osteotomies. The operative techniques are described.