Multiple sequential molecular abnormalities in the evolution of human gliomas

We have examined a series of 13 benign and 27 malignant human gliomas for evidence of molecular abnormalities of proto-oncogene and putative tumour suppressor gene loci. The results indicated that specific molecular lesions were associated with increasing grades of malignancy. Thus, loss of genetic material on chromosome 17 was present with approximately equal frequency in both benign and malignant gliomas, whereas loss of loci on chromosome 10 was seen only in malignant gliomas. Only the most malignant tumours, known as glioblastoma multiforme, had more than one molecular abnormality in the same tumour. These findings may contribute to our understanding of glial tumour development, as well as improve the accuracy of tumour diagnosis.

Retinoblastoma gene deletions in human glioblastomas

The retinoblastoma susceptibility gene, RB, is the best characterised of the tumour suppressor genes, or 'anti-oncogenes'. Abnormal function of the RB protein is thought to result in loss of an inhibitory effect on cell growth, and thus contribute towards the development of certain human cancers. One group of human cancers of particular interest in relationship to retinoblastoma gene function are the gliomas, which are central nervous system tumours thought to originate from the neuroectoderm, the embryological tissue which also gives rise to retinoblastomas. We have therefore examined a group of benign and malignant gliomas for evidence of structural alterations of the RB gene. Four out of nine (44%) glioblastomas, the most malignant gliomas, showed loss of heterozygosity of a locus within this gene. In addition, one of these hemizygous tumours showed deletion of part of the RB protein-coding region, and this abnormality was also present in cells cultured from the tumour. These findings suggest that RB gene abnormalities may contribute to the development of glioblastomas.

Relocatable frame for stereotactic external beam radiotherapy

A non-invasive head fixation system is described which is accurately relocatable and enables the transfer of stereotactic positions between a variety of radiodiagnostic images and therapeutic procedures. The system can be simply and repeatedly applied for planning stereotactic radiation therapy from one or more diagnostic images and for repeated treatment with a conventional linear accelerator. In addition, the long-term effects of therapy can be objectively monitored by relocating the frame and repeating images in an identical way, months or years later.

Photodynamic therapy of a mouse glioma: intracranial tumours are resistant while subcutaneous tumours are sensitive

Subcutaneous and intracranial VMDk tumours were treated with photodynamic therapy (PDT) using a new sensitiser, m-THPP. Subcutaneous tumours were highly sensitive to PDT but intracranial tumours were much more resistant, requiring a 30-fold increase in sensitiser dose to produce equivalent levels of necrosis. Resistance of intracerebral tumours was not due to failure of the sensitiser to enter tumours. Necrosis of intracranial tumours was increased when mice breathed 100% oxygen during PDT while subcutaneous tumour necrosis was unaffected.

Artificial urinary sphincter insertion in congenital neuropathic bladder

A series of 44 patients with neuropathic bladder dysfunction due to congenital myelodysplasia underwent implantation of an artificial urinary sphincter (AUS); in 26 patients a reconstructive procedure was performed at the same time. Five patients who initially had AUS implantation alone developed detrusor hyper-reflexia and required a clam cystoplasty. Forty patients (90%) are continent, 2 are occasionally damp and 2 are wet and awaiting further surgery; 66% of patients who underwent AUS insertion and reconstruction were found to have significant residual urine and they perform intermittent self-catheterisation (ISC). In patients with a good bladder capacity and normal compliance and detrusor hyper-reflexia controlled by anticholinergic drugs, cystoplasty is not necessary at the time of AUS insertion.

Stereotactic biopsy of cerebral lesions in patients with AIDS

Central nervous system involvement with AIDS is not uncommon. The indications and timing of brain biopsy remains controversial. Stereotactic CT-guided biopsy offers a safe and effective means of establishing a diagnosis in any patient with a cerebral mass lesion and has less morbidity and mortality than freehand biopsy or exploratory craniotomy. Eleven patients with AIDS have undergone CT-directed stereotactic biopsy between May 1987 and November 1990 with one death from intracerebral haemorrhage. Histological diagnosis of the biopsy specimens showed multifocal leucoencephalopathy, toxoplasmosis, lymphoma and non-specific changes. Biopsy is recommended for patients with an atypical presentation, negative serology, progressive clinical deterioration and differential response of lesions to empirical therapy.

The initial experience with the Cosman-Roberts-Wells stereotactic system

The Cosman-Roberts-Wells stereotactic instrument is a recently developed modification, based on an arc-radius design, of the Brown-Roberts-Wells stereotactic frame utilizing the existing fixation and fiducial components of the Brown-Roberts-Wells stereotactic system to localize and verify target data. The design modification has been made with a view to facilitating technical approaches both in stereotactic biopsy and in stereotactic craniotomy, whilst encompassing the same stereotactic space. Initial experience with the Cosman-Roberts-Wells instrument is reported. Over a 5-month period 55 procedures were performed which included 40 stereotactic biopsies, five CT-guided stereotactic craniotomies, three stereotactic placements of a Bennett Ball for thalamotomy, three stereotactic implantations of intracranial electrodes for recording in drug-resistant epilepsy, three aspirations of cyst or haematoma and one implantation of a Gutin catheter for interstitial brachytherapy. There was minimal morbidity and no mortality related to operation. This frame offers rapid targeting without the need to pre-determine entry points, as well as allowing direct lateral passes and unimpeded stereotactic craniotomy.

Activity and toxicity of carboplatin and iproplatin in relapsed high-grade glioma

A total of 15 patients with relapsed high-grade glioma were treated with carboplatin (400 mg/m2) or iproplatin (300 mg/m2). All had received previous radiotherapy, and 12 had previously undergone chemotherapy. One of the ten patients treated with carboplatin and one of the five treated with iproplatin achieved a partial remission as determined by repeat computerised tomographic (CT) scan. Myelosuppression was considerable, as three patients developed grade IV neurotoxicity, which was fatal in one case. Although carboplatin and iproplatin showed activity against malignant glioma, the study was closed because of unacceptable toxicity.

Cell proliferation in serial biopsies through human malignant brain tumours: measurement using Ki67 antibody labelling

Cell proliferation was assessed in brain tumours using the monoclonal antibody Ki67 which recognizes a nuclear antigen expressed by proliferating cells. Using a novel stereotactic biopsy procedure, serial 1 cm biopsies were taken along a trajectory through six malignant brain tumours. Specimens were also obtained from 10 other brain tumours during conventional surgery. The percentage of Ki67 positive cells was determined as a fraction of the total number of tumour cells present. The Ki67 index for anaplastic astrocytomas and glioblastomas was significantly higher (Ki67 index range 11-18%) than that for benign or low grade tumours. Significant variation in proliferation was measured along the biopsy track through individual tumours (e.g. 0-12.3%) which correlated well with histological appearance. The Ki67 indices of normal brain were very low. In general the Ki67 indices increased with increasing histological grade and also appear to be a useful indicator of the active tumour volume and margin. This method provides spatial information about tumour proliferation which may be used to decide between different treatments and relate to prognosis.

Multicentric malignant glioma

Multicentre gliomas are a well recognized entity but the occurrence of such tumours both above and below the tentorium remains uncommon. We report the case of an 11-year-old boy who underwent stereotactic biopsy of a brain stem ring enhancing tumour with histology of an anaplastic astrocytoma (Grade 3). Nine months following his radiotherapy a large left frontal mass was biopsied and found to be a malignant glioma (Grade 4). Advances in neuroradiological imaging will readily show multiple cerebral lesions and multicentre glioma should be considered in the differential diagnosis of such lesions and biopsy is indicated.

Urinary continence in spinal injury patients following complete sacral posterior rhizotomy

Complete sacral posterior rhizotomy was carried out in 15 spinal injury patients in conjunction with implantation of sacral anterior root stimulators. All patients were incontinent pre-operatively and had video-pressure cystometry before and at regular intervals after surgery. Detrusor hyper-reflexia was totally abolished in all but 1 patient following rhizotomy and 87% no longer require any form of incontinence appliance. Deafferentation produced adverse changes in vesicourethral function and even when rhizotomy was complete, continence could not be guaranteed. The pre-operative state of the bladder neck and distal sphincter mechanism had an important bearing on future continence and those patients with a closed bladder neck and no previous sphincterotomy had the greatest chance of becoming continent after deafferentation. The majority of patients in this series are now fully continent, representing a transformation in their quality of life; it is recommended, however, that to optimise the success of rhizotomy precise pre-operative evaluation and selection of patients are essential.

Lumbosacral evoked potentials and vesicourethral function in patients with chronic suprasacral spinal cord injury

Persistent detrusor acontractility despite normal somatic reflex activity in some patients with high spinal cord injury is an enigma. Previous work has suggested disordered integration of afferent activity in sacral roots or the sacral spinal cord. Forty male patients with chronic stable suprasacral cord lesions were studied by filling and voiding videocystometrography, and recording lumbosacral evoked potentials from posterior tibial nerve stimulation. Only five of 15 patients with decreased detrusor contractility had abnormal lumbosacral evoked potentials. Similar abnormalities were found in four of 11 patients with efficient hyperreflexic bladders. The finding of normal lumbosacral evoked potentials in the majority of patients with suprasacral cord injuries and decreased detrusor contractility supports the argument that the pathophysiology of this specific form of neurogenic bladder dysfunction is multifactorial.

The VM model of glioma: preparation of multicellular tumour spheroids (MTS) and their response to chemotherapy

A cell line, 497-P(1), derived from the VM spontaneous murine astrocytoma has been used to develop an in vitro therapeutic model of human glioma. In this study we describe the preparation of MTS from this cell line. The in vitro chemosensitivity of 497-P(1) MTS has been examined and compared to the sensitivity of the monolayer culture. BCNU and CCNU both produced growth delay in MTS at doses below the ID50 of the monolayer culture. MTS, however, were considerably more resistant to vincristine and procarbazine when compared to the monolayer culture.

Proton MR spectroscopy of intracranial tumours: in vivo and in vitro studies

Proton magnetic resonance spectroscopy (1H MRS) was used to investigate intracranial tumours in vitro and in vivo. Biopsy specimens were studied from 47 patients, 11 of whom were also examined in vivo. Analysis was based on the signals from N-acetylaspartate (NAA), phosphocreatine plus creatine (Cr), choline-containing compounds (Cho), alanine (Ala), and lactate. Biopsy data from 26 astrocytomas showed that the NAA/Cr ratio differs significantly in all grades from its value in normal white matter and that the Cho/Cr ratio differs significantly in grade IV tumours from its value in the other grades. Meningiomas have an unusually high Ala/Cr ratio. Spectra obtained in vivo are consistent with in vitro results from the same patients, and their lactate signal provides additional information about abnormal metabolism. We conclude that 1H MRS has a clear role in the diagnosis and biochemical assessment of intracranial tumours and in the evaluation and monitoring of therapy.

Use of relocatable stereotactic frame to integrate positron emission tomography and computed tomography images: application in human malignant brain tumours

A stereotactic head frame has been developed which is accurately relocatable over an extended period of time, is non-invasive, and yet is rigidly fixed relative to the patient's skull. Eight patients with malignant brain tumours were studied by positron emission tomography scanning using 18FUDR and computed tomography scan. Serial biopsies were performed and were studied by routine histological methods and using the monoclonal antibody Ki67.

The chemotherapeutic response of a murine (VM) model of human glioma

Using a cell line derived from the VM spontaneous murine astrocytoma, a reliable in vitro-in vivo model of human malignant glioma has been developed. In this paper we examine the effects of cytotoxic drugs with known activity against other animal brain tumour models and human disease on the in vivo VM model. The drugs BCNU, CCNU and vincristine produced significant volume reduction in tumours growing at a subcutaneous location in syngeneic animals. Procarbazine was ineffective. Similarly, BCNU, CCNU and vincristine produced small but statistically significant increases in survival of VM mice bearing the intracerebral tumour, but procarbazine was again ineffective. The modest, but significant, response of the VM model to the nitrosoureas mimics the human situation more closely than previously described animal models.

Analyses of single-trial N1 amplitude and latency variability and their influence on the average evoked potential

Sixteen adult subjects listened to tone pips superimposed on Bach concertos and either attended to the tones or to the music. Auditory evoked potentials (EPs) were recorded to the tones in both conditions from C3 and C4 each referenced to linked ears. Although the expected Condition X Hemisphere interaction was not found, a main effect for Condition showed that N1 amplitude in the average EPs (AEPs) was greater in the Tones condition. P2 showed no significant main effects or interactions. The AEP was used as a template to identify N1 in each single-trial wave form. The difference in AEP amplitude between conditions was subsequently found to be due primarily to enhanced N1 amplitude in the single-trial wave forms, and not to a decrease in latency variability. This template-matching procedure appears to be a valid method for identifying N1 in single-trial wave forms based on the following findings: (1) multiple regression analyses demonstrated that 90-99% of the variance of the amplitude of N1 in the average EP could be accounted for by a weighted linear combination of single-trial amplitude and latency variability; (2) the values of the correlation coefficients between the AEP template and the single-trial EPs were generally very high, averaging approximately +0.91; (3) the distributions of the latency of N1 in the single-trial EPs were not flat as would be expected if random noise were being identified as N1.

The development of an animal model of glioma for use in experimental neuro-oncology

A cell line, 497-P(1), derived from the VM spontaneous murine astrocytoma has been used to develop an in vitro in vivo model of human glioma. This paper describes the growth characteristics of tumours produced after intracerebral or subcutaneous inoculation of 497-P(1) cells into syngeneic VM mice. The results show that cell line 497-P(1) provides the basis for a reproducible animal model of glioma which fulfils many of the criteria required for experimental therapy studies.

Experience in 300 cases of CT-directed stereotactic surgery for lesion biopsy and aspiration of haematoma

Despite advances in imaging of the brain, an accurate diagnosis of brain lesions requires tissue sampling and histological verification. A series of CT-directed procedures has been performed in 300 patients with deep sited, multiple, diffuse, extensive, small or inflammatory lesions, brain stem haematomas and tumours presenting with epilepsy. A positive diagnosis was obtained in 271 cases (92.8%), no diagnosis in 21 cases (7.2%). Therapeutic results were also obtained in eight cases (2.7%) of brain stem haematoma aspiration. Complications occurred in 14 cases (4.7%) including one death (0.3%). Because of the importance of an accurate diagnosis in order to avoid inappropriate therapy, together with the relative safety of the technique, CT-directed stereotactic biopsy should be considered in all patients harbouring deep seated, multiple, diffuse, small or inflammatory brain lesions.

Application of CT-directed stereotaxy in the determination of functional neurosurgical targets in the diencephalon and cerebral hemisphere

The descriptions of two techniques allowing for CT target determination in functional neurosurgery are presented, the first for thalamic and peri-thalamic explorations in the treatment of dyskinesiae and chronic pain, the second for the implantation of multiple hemispheric depth electrodes in the assessment of chronic drug-resistant epilepsy.

Lack of relationship of conus reflexes to bladder function after spinal cord injury

A series of 20 patients with acute complete suprasacral cord lesions underwent serial urodynamic assessment of vesicourethral function and serial measurement of sacral reflex latency times (SRL) and reflex threshold throughout a follow-up period of 42 to 83 weeks (mean 50). No correlation was found between any pattern of SRL latencies or reflex thresholds and subsequent bladder behaviour. The reproducibility of sacral reflex latencies was found to be poor (mean variation of serial measurements from initial reading 21%) and could not be explained on the basis of "dynamic" neurological recovery. Studies using the bladder as a stimulus site were unreliable. The value of SRL studies in detecting subtle neurophysiological changes is discussed.