Safety of perioperative subcutaneous heparin for prophylaxis of venous thromboembolism in patients undergoing craniotomy.

OBJECTIVE: To determine whether perioperative subcutaneous heparin is safe to use for patients undergoing craniotomy and to determine the incidence of venous thromboembolism in patients undergoing craniotomy. METHODS: Perioperative prophylaxis with subcutaneous heparin, 5000 U every 12 hours, was begun at induction of anesthesia for craniotomy and continued for 7 days postoperatively or until the patient was ambulating. Entry criteria to the study included patient age over 18 years and no evidence of deep vein thrombosis (DVT) preoperatively as judged by lower limb duplex ultrasound. Patients were excluded if they had duplex evidence of DVT or clinical evidence of pulmonary embolus (PE) preoperatively, had hypersensitivity to heparin or related products, had sustained a penetrating head injury, or refused informed consent. Any patient undergoing craniotomy was eligible, including patients with a ruptured aneurysm or arteriovenous malformation and those with spontaneous intracranial hemorrhage. Patients underwent duplex study 1 week after surgery and 1 month of clinical follow-up. Records were also kept on 68 nonstudy patients who refused consent. All patients were treated with lower limb pneumatic compression devices. RESULTS: One hundred six patients were treated. No differences were noted between study and nonstudy patients in some individual risk factors for DVT or PE, such as obesity, smoking, paralysis, infection, pregnancy or postpartum state, varicose veins, heart failure, or previous DVT or PE. Significantly more (43 of 106) patients in the study group had a history of risk factors for DVT or PE, particularly malignancy, however, compared with nonstudy patients (20 of 68 patients; chi2, P < 0.01). There were no differences between groups in intraoperative blood loss, transfusion requirements, or postoperative platelet counts. Four clinically significant hemorrhages occurred during surgery in patients receiving heparin. Three resulted from intraoperative aneurysm rupture and one from intraventricular bleeding during resection of an arteriovenous malformation. These events were believed to be related to known complications of these operations, not to heparin. Of the study patients, two developed symptomatic DVT and one developed a nonfatal PE during the 1-month postoperative period. One additional study patient developed DVT below the popliteal veins, which was not treated. Four study patients developed DVT 1 to 2 months after surgery. In nonstudy patients, three developed DVT and two developed PE (one fatal, one nonfatal). CONCLUSION: Perioperative heparin may be safe to administer to patients undergoing craniotomy, but a larger study is needed to demonstrate efficacy.

Identification of the sensory/motor area and pathologic regions using ECoG coherence.

An electrophysiologic mapping technique which enables identification of the central sulcus and pathologic cortical regions is described. Electrocorticographic recordings of 1 min duration were recorded from 25 patients who were undergoing resection of tumors in the sensory-motor region or being evaluated for temporal lobectomy for epilepsy. Analysis of the patterns of subdural inter-electrode coherence revealed low coherence across the central sulcus for 11/12 cases where its location could be verified with direct cortical stimulation and/or somatosensory evoked potential mapping. Regions of high coherence identified the location of tumors in the sensory-motor region for 10/10 cases. Over the temporal lobe, localized areas of high coherence were evident in 8/9 epilepsy patients, but were not indicative of the location of mesial temporal lobe tumors or inter-ictal spiking, when present. We conclude that analysis of cortical coherence patterns may be helpful for revealing the location of pathologic processes relative to critical cortical areas.

Quantitative imaging study of extent of surgical resection and prognosis of malignant astrocytomas.

OBJECTIVE: This study used quantitative radiological imaging to determine the effect of surgical resection on postoperative survival of patients with malignant astrocytomas. Previous studies relied on the surgeons' impressions of the amount of tumor removed, which is a less reliable measure of the extent of resection. METHODS: Information concerning possible prognostic factors was collected for 75 patients undergoing magnetic resonance imaging or computed tomography preoperatively and within 10 days postoperatively. Image analysis of the neuroradiological studies was conducted to quantify pre- and postoperative total tumor volumes and enhancing volumes. Univariate and multivariate proportional hazards models were used to analyze the regression of survival regarding 22 covariates that might affect survival. The covariates that were entered included age, gender, tumor grade, cumulative radiation dose, chemotherapy, seizures as a first symptom, Karnofsky performance status at presentation, pre- and postoperative total and enhancing tumor volumes, ratio of pre- to postoperative total and enhancing tumor volumes, tumor location, surgeon's impression of the degree of resection, and subsequent surgery. RESULTS: There were 23 patients with anaplastic astrocytomas and 52 with glioblastomas multiforme. The estimated mean survival time was 27 months for patients undergoing gross total resection, 33 months for subtotal resection, and 13 months for open or stereotactic biopsy. Five factors that were significant predictors of survival in multivariate analysis were tumor grade, age, Karnofsky performance status, radiation dose, and postoperative complications (P < 0.05). In univariate analysis, tumor grade, radiation dose, age, Karnofsky status, complications, presence of enhancing tumor in postoperative imaging, and postoperative volume of enhancing tumor were significantly associated with survival (P < 0.05). CONCLUSION: We conclude that the most important prognostic factors affecting survival of patients with anaplastic astrocytomas and glioblastomas multiforme are tumor grade, age, preoperative performance status, and radiation therapy. Postoperative complications adversely affect survival. Aggressive surgical resection did not impart a significant increase in survival time. Surgical resection may improve survival, but its importance is less than that of other factors and may be demonstrable only by larger studies.

Frameless stereotaxy with real-time tracking of patient head movement and retrospective patient-image registration.

The accuracy of a novel frameless stereotactic system was determined during 10 surgeries performed to resect brain tumors. An array of three charge-coupled device cameras tracked the locations of infrared light-emitting diodes on a hand-held stylus and on a reference frame attached to the patient's skull with a single bone screw. Patient-image registration was achieved retrospectively by digitizing randomly chosen scalp points with the system and fitting them to a scalp surface model derived from magnetic resonance (MR) images. The reference frame enabled continual correction for patient head movements so that registration was maintained even when the patient's head was not immobilized in a surgical clamp. The location of the stylus was displayed in real-time on cross-sectional and three-dimensional MR images of the head; this information was used to predict the locations of small intracranial lesions. The average distance (and standard deviation) between the actual position of the mass and its stereotactically predicted location was 4.8 +/- 3.5 mm. The authors conclude that frameless stereotaxy can be used for accurate localization of intracranial masses without resorting to using fiducial markers during presurgical imaging and without immobilizing the patient's head during surgery.

A frameless stereotactic approach to neurosurgical planning based on retrospective patient-image registration. Technical note.

A frameless stereotactic device interfacing an electromagnetic three-dimensional (3-D) digitizer to a computer workstation is described. The patient-image coordinate transformation was found by retrospectively registering a digitizer-derived model of the patient's scalp with a magnetic resonance (MR) imaging-derived model of the same surface. This procedure was performed with routine imaging data, eliminating the need to obtain special-purpose MR images with fiducial markers in place. After patient-image fusion was achieved, a hand-held digitizing stylus was moved over the scalp and tracked in real time on cross-sectional and 3-D brain images on the computer screen. This device was used for presurgical localization of lesions in 10 patients with meningeal and superficial brain tumors. The results suggest that the system is accurate enough (typical error range 3 to 8 mm) to enable the surgeon to reduce the craniotomy to one-half the size advisable with conventional qualitative presurgical planning.

Epidural lipomatosis in steroid-treated patients.

Epidural lipomatosis is a condition in which excess adipose tissue is deposited circumferentially about the spinal cord in the epidural space. It is most frequently seen in patients on chronic steroid treatment for a variety of medical problems and can present as nonspecific back pain, radiculopathy, or frank spinal cord compression. Diagnosis and treatment have generally relied on multi-level decompressive laminectomy after myelography and computed tomography. The immunocompromised state and the reported postoperative mortality (22%) of these patients, however, suggests that nonoperative therapy may be preferable whenever possible. Five cases of epidural lipomatosis are reported, and previous literature is reviewed for presentation, evaluation, and treatment of this condition.

Fibrinolytic activity in experimental intracerebral hematoma.

In an attempt to investigate the role of tissue fibrinolytic activity in the resolution of intracerebral hematoma, an experimental model of intracerebral hematoma was developed in the rat. The fibrinolytic activity was studied using a histochemical fibrin slide technique. A total of 59 adult male rats were studied. Twenty-nine rats were used for developing the intracerebral hematoma model via injection of autologous whole blood into the left frontal lobe; in the remaining 30 rats, the intracerebral hematomas were studied sequentially. Intracerebral hematoma formation was unsuccessful in six (21%) of 29 rats. Four rats died in the immediate postoperative period and two showed no intraparenchymal clot. Intense fibrinolytic activity was demonstrated in the blood vessel walls of the normal brain, especially in the meninges, choroid plexus, and ependymal cell layer. In the initial stages of hematoma resolution, fibrinolytic activity was not seen in the hematoma or parenchyma except in the preexisting blood vessels. However, 3 to 5 days later, fibrinolytic activity was observed in the capillary buds surrounding the hematoma and among the infiltrating mononuclear cells. This activity increased for 7 to 10 days following formation of the hematoma and decreased after 21 to 28 days. It is concluded that tissue fibrinolytic activity associated with newly formed blood vessels appears to be important in lysis of intracerebral hematomas.

The effect of fetal hypothalamus grafts on weight gain resulting from lesions of the ventromedial hypothalamus.

Bilateral ventromedial hypothalamic lesions in female adult rats which resulted in hyperphagia and rapid weight gain were followed by placement of fetal brain tissue in the anterior third ventricle. The treatment group received fetal hypothalamus grafts, and fetal cortical tissue of identical age was grafted into the control group. A significant reduction in average daily weight gain was noted from 4 to 12 weeks following transplantation in the treatment group. At 12 weeks posttransplantation, the animals were sacrificed for histological analysis. Examination of the hypothalamus grafts revealed neurons, ependymal clusters, and axonal processes which appeared to infiltrate the surrounding hypothalamic parenchyma.