Surgical management of giant anterior aneurysm.

BACKGROUND: Patients with intracranial anterior circulation aneurysms are subjected to surgical operation because of rupturing of the sac of the aneurysm leading to spontaneous subarachnoid hemorrhage (which occurs in most of the cases) or because of the neurological complaints caused by the mass or pulsation effect of the aneurysms against the surrounding brain structures. Direct surgical treatment of these giant aneurysms is always a challenging procedure but it makes feasible both the clipping of the neck of the aneurysm and the reduction of its mass effect. METHODS: A case series of 47 giant anterior circulation aneurysms, operated during a time span of 23 years (1972-1994) in our Institution is presented. RESULTS: In 31 cases the occlusion of the neck of the aneurysm could be achieved by applying single or multiple clips; in the remaining 16 cases the occlusion of the aneurysm was obtained by the aid of different methods. The operative mortality was 12.7%. CONCLUSIONS: Endovascular techniques for giant aneurysms occlusion are extremely useful in a combined approach. Due to their low morbidity these treatments can achieve a major role although some long term follow-up studies are still needed for a better understanding of their role.

A computer assisted toolholder to guide surgery in stereotactic space.

A computer assisted toolholder, integrated with an anatomical graphic 3-D rendering programme, is presented. Stereotactic neuroanatomical images are acquired, and the same reference system is employed to represent the position of the toolholder on the monitor. The surgeon can check the orientation of different approach trajectories, moving the toolholder in a situation of virtual reality. Angular values expressed by high precision encoders on the five joints of the toolholder modify "on line" the representation of the configuration of the toolholder within the three dimensional representation of the patient's anatomy.

Cell kinetic investigations in craniopharyngioma: preliminary results and considerations.

In vitro determination of 3H-thymidine labeling index (LI%) was carried out in craniopharyngiomas from 16 patients submitted to repeated surgical procedures. This study showed a poor correlation between LI% values and prognosis, but allowed to detect a high LI% variation in the same tumor investigated in serial different times. The spatial distribution of S-phase proliferative cells in squamous epithelium of cystic components suggests a rationale for intracavitary treatment of cystic and mixed craniopharyngioma and may help explain its success.

Hemangioblastomas: clinical characteristics, surgical results and immunohistochemical studies.

A surgical series of 59 patients with cerebellar or spinal cord hemangioblastomas or von Hippel-Lindau's (VHL) syndrome is analyzed. The presence of the tumor is easily detected by Computerized Tomography (CT) and Nuclear Magnetic Resonance (NMR), but angiography is still necessary for a correct surgical planning. The value of a sharp distinction among patients with single hemangioblastomas and the ones with Lindau's disease and VHL syndrome is stressed. In fact patients with single cerebellar or spinal hemangioblastomas have a good prognosis, while patients with disseminated hemangioblastomas have a rather poor outlook. Neuropathological studies with immunohistochemical techniques have been performed to identify the nature of the stromal cells of the hemangioblastomas: their origin from glial, endothelial and monociticphagocitic elements seems excluded.

Reversal of oculomotor disorders after intracranial aneurysm surgery.

Forty-nine patients with oculomotor nerve palsy due to intracranial aneurysm were examined. The reversal of third nerve palsy is related to modality of onset and surgical timing: "early" surgery (within 14 days from the onset of oculomotor palsy) promises a better prognosis for ocular function; recovery starting within the first month will probably be complete. A full recovery is probably seen only with conduction block (neuroapraxia) or minor axonal changes (axonolysis). Clinical features of third nerve palsy due to intracranial aneurysms versus other causes of oculomotor palsy are discussed.

Adrenal medulla autograft in caudate nucleus as treatment for Parkinson disease.

The personal experience of four Parkinson's disease patients operated on with adrenal medulla autograft in the caudate nucleus is reported. Results on long term, possible only in two patients, are moderately fair.

Amelanotic leptomeningeal melanoblastosis. Case report.

Leptomeningeal melanoblastosis is a rare phakomatosis; the amelanotic variant has not till now been described. In this paper we report the case of a young man suffering from amelanotic leptomeningeal melanoblastosis manifested as medullary syndrome and secondary intracranial hypertension. The diagnosis of leptomeningeal melanoblastosis was hypothesized on the basis of CSF and neuroradiological findings and it was finally confirmed by the histopathology.

Surgical treatment of intracranial dermoid and epidermoid cysts in children.

Between 1956 and 1987 operations were performed on 36 patients below the age of 20 years for epidermoid and dermoid cysts of the central nervous system. Seventeen tumors were intracranial intradural lesions (47%): 12 were located in the supratentorial region (71%) and 5 were located in the infratentorial region (29%). Ten of these tumors (59%) were seated along the midline structures. The clinical presentation was consistent with the location of the tumors. The neuroradiological diagnosis was mostly made with the aid of pneumoencephalography, computed tomography (CT), nonionic contrast medium CT cisternography, and magnetic resonance imaging. Complete removal of the tumor contents was performed in all cases but one, although the completeness of removal of the tumor capsule could not be exactly estimated in some patients. At late follow-up only two tumor recurrences were observed. Radical removal of the tumor capsule of these congenital tumors, even when it is connected to vital neurovascular structures, seems advisable in patients who become symptomatic within the first two decades of life.

Influence of surgery and antiepileptic drugs on seizures symptomatic of cerebral tumours.

One hundred and twenty-eight adult patients presenting with and operated on for supratentorial neoplasms were studied. Sixty-five had preoperative seizures and were treated with antiepileptic drugs (AEDs). Among the 63 patients without preoperative epileptic fits, 41 were given AEDs (either phenobarbital or phenytoin) as prophylactic treatment and 22 were not treated. The preoperative epilepsy course was considered with respect to tumour site and histological type. Early and late postoperative seizure occurrence was considered in the different groups of patients. The results suggest the usefulness of a short term preventive treatment with AEDs after surgery in patients without preoperative seizures. In patients with preoperative epilepsy, AEDs should be continued after surgery. However long-term AEDs treatment should not be recommended in patients without preoperative epilepsy. In fact, no significant difference in late seizure occurrence was found between preventively treated and untreated patients.

Guided microsurgery by computer-assisted three-dimensional analysis of neuroanatomical data stereotactically acquired.

Stereotactic acquisition of neuroradiological data, followed by identification of cerebral structures and three-dimensional rendering, has been successfully applied to guided microsurgical resection of deep-seated cerebral lesions. The method described utilizes data from magnetic resonance, computed tomography, and digital angiography and allows the surgeon to 'wire frame' the lesion volume and the position of cerebral vessels and structures of high functional relevance. Three-dimensional rendering of surgical instrumentation around the reconstructed anatomy allows for planning and simulation of the trajectory of approach.

Computer-assisted planning of stereotactic neurosurgical procedures.

To extend the advantages of stereotactic localization to open procedures, a computational device with a graphic output is introduced. It is designed to be used in the operating room, where it processes neuroradiological information (CT, MR, and angiography) acquired under stereotactic conditions. The surgeon can interact with neuroanatomical data, extracting borders of structures of surgical relevance. The resulting sets of outlines, shown tridimensionally within the reference of a stereotactic head holder, are presented with respect to the planned approaching trajectory. Color-coded high-resolution graphics show the relationship between lesions and normal brain structures and guide the surgeon's access to deep-seated lesions through small exposures.

Spinal meningiomas: review of 174 operated cases.

The long-term results obtained in a series of 174 patients operated on for spinal meningiomas are critically analyzed. This series was similar to those of other authors with regard to age, sex, location of the tumors, and clinical presentation. Before surgery, about 70% of the patients were included in Groups I and II (mild neurological impairment), and about 30% of the patients were classified in Groups III and IV (significant to severe neurological impairment, up to paraplegia). Complete tumor removal was achieved in 96.5% of the patients, and surgical mortality was about 1%. Microsurgical technique, which was adopted in the last 29 cases, proved to be very effective in reducing undue damage to the spinal cord and in minimizing the postoperative neurological deficits. Of the 174 patients who underwent surgery, 156 underwent late follow-up study for an average of 15 years (2 patients died in the immediate postoperative period, and 16 patients were lost to follow-up). Twenty-nine patients died of causes unrelated to the spinal meningioma; of the remaining 126 patients, 92% were categorized in Groups I and II, and only 8% in Groups III and IV. The rate of recurrence was 6% (9 patients) among the 150 patients who had complete tumor removal, and the rate of regrowth was 17% (1 patient with anaplastic meningioma) among the 6 patients treated by subtotal removal. The early diagnosis of the disease and the use of microsurgical technique appeared as the most relevant factors for further improvement of the surgical results.

Positive end-expiratory pressure in supine and sitting positions: its effects on intrathoracic and intracranial pressures.

The effects of positive end-expiratory pressure (PEEP) on central venous and intracranial (ICP) pressures were evaluated in 10 patients with posterior fossa tumors, in both supine and sitting positions. With patients in the supine position, intrathoracic PEEP-dependent venous hypertension was clearly transmitted to the intracranial compartment but without intracranial hypertension. On the contrary, with patients in the sitting position PEEP had no influence in almost half of our patients. In patients with radiological or clinical signs of increased ICP, however, the combination of head flexion and rotation with institution of PEEP caused a dangerous increase in ICP, even when the patients were in the sitting position. The need for early withdrawal of cerebrospinal fluid in these patients is stressed.

Computer assisted analysis of neuroradiological data in planning neurosurgical procedures.

A surgical graphic console is presented. It allows the display of multimodal images (CT, MR and digital angiography), and the identification of tridimensional outlines of structures of surgical relevance, within a surgical reference system, together with the trajectory of surgical approach.

Surgical approach to pineal tumours.

During a period of 10 years (1977-1986) 40 cases of tumour of the pineal region have been treated at the Istituto Neurologico "C. Besta"-of Milan. Out of these 40 cases, 27 (67.5%) were in the paediatric (10-15 years) or juvenile (15-20 years) age at the time of operation. Since 1983 a specific diagnostic and therapeutic protocol has been adopted and thereafter direct surgical removal of the tumour was performed only when the neuroradiological investigations were highly suggestive of a benign extrinsic lesion. Sixteen cases in this series underwent direct surgical removal; in the remaining 24 cases stereotactic biopsy of the tumour was performed in the first instance. On the basis of the histological diagnosis obtained by this procedure surgical excision of the tumour (9 cases) or radiotherapy (15 cases) was then performed. 25 cases underwent surgical removal of the lesion. In all the cases the infratentorial supracerebellar approach as introduced by Krause and then modified by Stein was adopted. On analysis of the data of this series it was observed that in 25% of the cases completely benign resectable tumours were found; in 25% of the cases astrocytoma (grade I-II) which could be treated at least by partial removal were present; in 30% of the cases radiosensitive lesions were encountered. In the remaining 20% of the cases highly malignant tumours were found which should be treated only by radiotherapy and/or chemotherapy.

Subarachnoid hemorrhage of unexplained cause.

During a 7-year period, we observed 58 patients with signs and symptoms of subarachnoid hemorrhage (SAH) in whom clinical and neuroradiological investigations failed to reveal a reasonable cause of the bleeding. Repeat panangiography was negative in the 2 patients with spasm. Rebleeding episodes soon after admission were rare, and the overall rebleeding rate was 3.4% (equivalent to an annual recurrence of 0.6%). In 1 case, a second extensive angiographic evaluation showed a small cerebral arteriovenous malformation, which was successfully treated surgically. On follow-up, 89% of the patients experienced a good outcome, with return to normal activities. This study confirms a good prognosis for patients with SAH of unknown cause. The necessity of performing a second angiographic study and the role of small infundibular dilations of the cerebral arteries are discussed.

Microsurgical treatment of intramedullary spinal cord tumours.

A series of 81 patients operated for intramedullary spinal cord tumours over a span of 12 years (1975-1986) is presented. The mean age of the patients was about 37 years and 9 patients were in the paediatric age (0-15 years). In 29 cases (36%) the tumours were located within the cervical region; in 34 cases the tumours were located in the thoracic region (42%) and in 18 cases the tumours were located within the medullary cone (22%). Ependymoma accounted for 52% of the cases (42 cases), astrocytoma for 20% (16 cases), lipoma for 7% (6 cases), hemangioblastoma for 6% (5 cases), metastatic tumours for 5% (4 cases); in the remaining 8 cases (10%) rare or very rare spinal tumours were found. The 9 patients in the paediatric age and 8 additional cases who had undergone previous surgery were then excluded from this review. In 59% of the patients with ependymoma and in 90% of the patients with astrocytoma severe neurological deficit were already present before the operation. Total tumour removal was accomplished in 81% of the cases with ependymoma, total or subtotal removal was achieved in 50% of the cases with astrocytoma. At long term follow-up study fair or good functional results were observed in 19 out of 41 cases of ependymoma (46%) and in 3 cases out of 10 of astrocytoma (30%). The surgical outcome was mostly related to the preoperative neurological conditions and to tumour malignancy grade.

Patient characteristics and pre-operative therapeutic modalities.

The International Cooperative Study on the Timing of Aneurysm Surgery included 68 participating centers from 16 different countries. Eight Italian neurosurgical units participated in the Study: Bellaria Hospital, Bologna; Neurological Institute of Milan, Milan; University Hospital, Brescia; University of Milan, Milan; University of Padova, Padova; University of Rome, Rome; Civil Hospital, Verona; and Civil Hospital, Vicenza. The overall case contribution from the Italian centers was 485 cases, 14.1% of the total study population. As compared to the other centers included in the Study, the Italian centers exhibited a higher percentage of patients with impaired consciousness; a later interval of planned surgery from SAH; frequent use of preoperative lumbar drainage, as well as antihypertensives, anticonvulsants, antifibrinolytics, steroids, diuretics and LMW dextran; and less frequent use of sedatives and narcotics. The individual Italian centers differed significantly in regard to patient characteristics and preoperative therapeutic modalities. There was a relatively high number of stuporous or comatose patients admitted to Centers 1, 7 and 8, very few admitted to Centers 5 and 6, and none admitted to Center 2. The different distribution of key prognostic factors prevents a direct comparison of the overall management results of the centers. A stratification of the patients according to a risk scale and/or a prognostic model is required for comparison of the management results.

Surgical findings and postoperative therapeutic modalities.

The 8 Italian centers participating in the International Cooperative Study on Timing of Aneurysm Surgery operated upon 68% of their patients eligible for the study. This low operative rate is mainly explained by the prevailing use of a delayed surgical policy. Only 28% of cases were operated on within 3 days of hemorrhage. Although early surgery was applied in more than 50% of patients from Centers 2, 6 and 7, most other centers operated on approximately 10% of patients within this time interval. Italian centers exhibited a wide variation in planned and actual surgery interval, with only 48% of their patients eventually operated on at the planned time. Differences from planned and actual timing of surgery were less consistent in the units performing early surgery. Preoperative conditions were different between the individual centers. The percent of patients alert at the time of surgery varied from approximately 50% in Centers 3 and 7 to 90% in Center 5. Centers 2 and 6 never operated on comatose patients and rarely stuporous patients. During surgery, induced hypotension was used in 67% of Italian patients. The brain was tight at exposure in 42% of patients from Italian centers; the difference from the other study centers was very significant (p = 0.0009). Consequently major brain resection was more frequently performed in Italy than in the other centers. Brain conditions depended mainly upon timing of surgery and preoperative grade (except for comatose patients) and varied accordingly between the individual centers. Temporary arterial occlusion was rarely used in Italian centers. Intraoperative bleeding from the aneurysm was slightly more frequent than in the other centers. The overall incidence of intraoperative complications was unremarkable. There were significant differences between the Italian and the other centers regarding the use of postoperative routines and medications. In Italian centers ventricular CSF drainage, shunt insertion, ICP monitoring, sedatives and analgesics were less frequently used; lumbar CSF drainage, anticonvulsants, steroids, and diuretics were applied more frequently. In the individual centers the major differences were in the use of antihypertensives, vasopressor agents, diuretics, hypervolemia, and low-molecular weight dextran.