Early recurrence from stereotactic aspiration of a colloid cyst of the third ventricle.

The case of a 66 year old woman who underwent successful stereotactic aspiration of a symptomatic colloid cyst of the third ventricle, but who had recurrence after only 5 weeks, is presented. Stereotactic aspiration is a well established technique for the treatment of colloid cysts, however disagreement exists regarding its efficacy. Two factors, both from pre-operative CT, help to predict success from aspiration: the cyst's density and size. The literature reports that recurrence after successful stereotactic aspiration should not occur for many years.

Computer-assisted and frameless stereotaxy: the initial Australian experience.

The trends towards minimally invasive surgery coupled with the increasing use of computer software and hardware have led to an increasing use of stereotactic neurosurgery as a part of mainstream neurosurgery. Computer-assisted and frameless stereotactic systems allow the performance of stereotactic procedures without the need for the mechanical linkage to a stereotactic frame. St Vincent's Hospital, Sydney, has used the Radionics Operating Arm System since March 1994 in 106 cases for stereotactic biopsy, localization of superficial lesions and volumetric resection of tumours. The Operating Arm System uses mechanical digitizers and has the advantages of being able to be used for both framed-based and frameless stereotactic procedures, simplicity of use, and the arm as a 'mouse' software program allowing the surgeon control of the computer program within the sterile operative field.

Endoscopic transsphenoidal approach to the pituitary fossa technical note.

A new technique combining transnasal endoscopy with the direct transnasal transsphenoidal approach to the pituitary fossa is described and preliminary results of its use on 8 patients presented. The advantages of this procedure are: it avoids many of the 'route of access' complications of other transsphenoidal approaches such as dental problems, nasal deformity and dysfunction; the brilliant illumination and manoeuvrability of the endoscope overcomes the visualisation problems associated with transnasal approaches and eliminates the need for releasing incisions at the base of the ala; there is less septal dissection and therefore less bleeding; and re-operation should be easier following this approach.

Stereotactic biopsy of cerebral lesions in acquired immunodeficiency syndrome.

The efficacy, mortality and morbidity of CT directed stereotactic biopsy of a cerebral lesion in 32 Human Immunodeficiency Virus (HIV) infected patients between July 1991 and June 1994 who had an atypical presentation for toxoplasmosis or who were failing or intolerant of empirical antitoxoplasmosis treatment was evaluated. An histological diagnosis was able to be made in 85%: progressive multifocal leucoencephalopathy (PML) in 13, primary cerebral lymphoma in 10, toxoplasmosis in 3 and HIV encephalitis in one. Non-specific reactive changes or gliosis were seen in 5 patients. There was no mortality, and morbidity occurred in 2 patients: one intraventricular haemorrhage and one transient third nerve palsy. Correct diagnosis made by image-directed stereotactic biopsy of central nervous system (CNS) disease in acquired immunodeficiency syndrome (AIDS) patients may improve outcome, particularly in those diseases where effective treatment strategies already exist and become increasingly available in the future.

Spinal epidural leiomyoma occurring in an HIV-infected man. Case report.

A case of spinal epidural leiomyoma is reported in a 52-year-old man infected with the human immunodeficiency virus (HIV). The tumor arose in the epidural region at the T-3 vertebral level, and the patient presented with radicular pain in the right T-3 dermatome. While soft-tissue tumors such as Kaposi's sarcoma and lymphomas have been well documented in association with HIV infection, this is the first reported case of primary spinal leiomyoma. Isolated cases of leiomyomas and leiomyosarcomas in unusual locations have been reported, notably in pediatric HIV-positive patients, perhaps indicating a causal relationship. This case may represent further evidence of such an association.

Stereotactic management of intrinsic brain stem lesions.

Between 1981 and 1991, seventy-two cases of brain stem lesions have undergone CT or MRI-directed stereotactic surgery using the Brown-Roberts-Wells or Cosman-Roberts-Wells stereotactic systems. In 16 cases, the pre-operative diagnosis of haematoma had been made and the procedure was for therapeutic aspiration. In fifty-six cases, the pre-operative diagnosis was uncertain although intrinsic tumour was suspected. Histological diagnosis was obtained in fifty-four of these and unexpected findings of haematomas, granulomas, leucoencephalopathy, demyelinating disease, vasculitis and radiation necrosis occurred in over 15% of the cases. There were no operative deaths and morbidity was low. Advances in neuroradiological imaging with CT and MRI have increased the detection rate of brain stem lesions and image-directed stereotactic biopsy makes it possible in most cases to obtain histological diagnosis with relatively low morbidity which is important for treatment and prognosis. MRI-directed biopsies can compliment CT-guided biopsies in most cases where the lesion is not adequately delineated on the CT image.

Open stereotactic selective amygdalo-hippocampectomy for drug resistant epilepsy.

Selective removal of the medio-basal temporal structures has been introduced as an alternative to standard temporal lobectomy in the treatment of intractable temporal lobe epilepsy not related to gross structural lesions. Various approaches have been described for the surgical excision of the amygdalo-hippocampal complex, each of them presenting advantages and limitations. The recently introduced computer-assisted technique of volumetric stereotactic excision of deep-seated intracerebral lesions combines precision of targeting with elimination of unnecessary cortical trauma and may potentially provide an alternative method in the treatment of temporal lobe epilepsy. We present our experience of stereotactic volumetric selective amygdalo-hippocampectomy in six patients with medically intractable temporal lobe epilepsy. The criteria for selection, the pre-operative evaluation and the operative technique are discussed. All patients had a cessation or considerable reduction in seizure frequency while the morbidity was minimal.

Image directed stereotactic surgery for brain stem lesions.

Advances in neurological imaging may have increased the diagnostic accuracy and the detection rate of intrinsic brain stem lesions, but a histological diagnosis is still an essential requirement for rational and appropriate management. Open exploration allows biopsy and resection in cases where an exophytic component is present. The surgical inaccessibility and the resultant morbidity of these approaches, however, associated with a low diagnostic yield in cases with no visible surface abnormality, are important limiting factors. A series of 45 brain stem lesions stereotactically approached with CT or MRI guidance is presented. A transcortical frontal pre-coronal trajectory was used in all of them. Haematoma was preoperatively diagnosed in 10 cases and the procedure was for therapeutic aspiration. Of 35 cases where the diagnosis was uncertain, although intrinsic tumour was suspected, positive results were obtained in 33, while unexpected findings of granuloma, lymphoma, angioma, leucoencephalopathy, vasculitis and radiation necrosis were found in over 10% of the cases. There were no operative deaths and the morbidity was low. In no case was there a permanent neurological deterioration directly related to the procedure, although there was a transient deterioration in two patients and one patient required early reaspiration of a haematoma. Image directed stereotactic approaches to brain stem lesions can combine a high degree of accuracy (offering positive histological diagnoses) with a low operative morbidity. MRI directed biopsies can complement CT guided ones thus increasing the number of suitable cases and improving the success rate. The frontal precoronal transcortical trajectory provides safe access to the majority of the brain stem targets.

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.

Radical excision of craniopharyngioma by the temporal route: a review of 50 patients.

Attempts at radical excision of craniopharyngioma have been made increasingly possible by progress in neuroradiological imaging and the use of microscopic technique. Between 1977 and 1990, 50 patients of The National Hospital for Neurology and Neurosurgery, London, have undergone radical surgical excision of craniopharyngioma by the temporal route, with a small anterior temporal resection. Surgical mortality was 4%. Thirty-eight (76%) patients remain well at average follow-up of 30 months; 15% had major complications (hypothalamic damage, subdural haematoma, scalp collections requiring shunt drainage). There were three recurrences in those patients where the initial operations were considered as complete microscopic excision. It is concluded that maximal control of tumour recurrence by removal of all tumour accessible and visible to the surgical microscope is best achieved by a radical excision at the first operation.

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.

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.

Cerebrospinal fluid rhinorrhea following acoustic neurinoma surgery. Technical note.

The authors describe a method of preventing cerebrospinal fluid (CSF) rhinorrhea following surgery for acoustic neurinoma. Mastoid air cells exposed during craniectomy are skeletonized and packed with bone dust, then covered with Surgicel soaked with Tisseel fibrin glue. The use of this technique has reduced the number of acoustic neurinoma cases requiring secondary mastoidectomy for CSF leakage from 16% to 5%.

Diagnosis of a posterior fossa tumour by magnetic resonance imaging.

The application of magnetic resonance imaging as a diagnostic tool for diseases of the central nervous system is described in the case of a 17-year-old girl who presented with neurological symptoms in January 1986. A comparison is made with the results of computed tomography in the diagnosis of the disease, which proved to be a grade-III glioma that appeared as a lesion of the posterior fossa. The patient recovered uneventfully after radiotherapy. It is suggested that MRI should be considered seriously as a first line of investigation in any suspected lesion of the posterior fossa.