Microsurgical resection of brainstem, thalamic, and basal ganglia angiographically occult vascular malformations.

OBJECTIVE: To evaluate the clinical results for patients who underwent resection of angiographically occult vascular malformations (AOVMs) of the brainstem, thalamus, or basal ganglia, successfully resected after it exhibited rebleeding and presented to a pial surface. METHODS: Between January 1990 and May 1998, 56 patients with 57 deep AOVMs underwent 63 operations, at Stanford University Medical Center, to treat AOVMs of the brainstem (42 AOVMs), thalamus (5 AOVMs), or basal ganglia (10 AOVMs). The surgical approach was suboccipital midline (27 operations), far lateral suboccipital (10 operations), transsylvian (9 operations), interhemispheric transcallosal or infracallosal (8 operations), infratentorial supracerebellar (6 operations), or subtemporal (3 operations). Four patients experienced recurrent bleeding from the same lesion after surgical resection, requiring a second operation. One patient required a planned second operation, using a different approach, to completely resect the lesion, and one patient underwent two surgical procedures to resect two separate brainstem AOVMs. One patient initially underwent exploration but not resection of her AOVM, because it did not present to a pial or ependymal surface. The AOVM was successfully resected after it exhibited rebleeding and presented to a pial surface. RESULTS: The immediate outcomes after surgery were unchanged for 31 patients (55%), worsened for 16 (29%), and improved for 9 (16%). The long-term outcomes were unchanged for 24 patients (43%), compared with their presenting grade, worse for 3 (5%), and improved for 29 (52%). Patients who had undergone previous radiotherapy or radiosurgery to treat these lesions experienced more difficult postoperative courses, and radiation necrosis was observed for two patients. CONCLUSION: AOVMs of the brainstem, thalamus, and basal ganglia can be safely removed, with a long-term neurological morbidity rate of only 5% and a complete lesion resection rate of 93% after the initial planned resection. The use of cranial base surgical approaches and intraoperative electrophysiological monitoring contributes to successful clinical outcomes.

Lactate and free fatty acids after subarachnoid hemorrhage.

The hypothesis that lactate and free fatty acids (FFA) are elevated in the first minutes after subarachnoid hemorrhage (SAH) is tested. Adult rats were subjected to an endovascular SAH through the right internal carotid artery while under anesthesia. The brains were frozen in-situ at 15, 30, 60 min, and 24 h post-hemorrhage. Regional measures of tissue lactic acid and FFA were made in the hippocampi, ipsilateral cortex, contralateral cortex, and cerebellum. Lactic acid levels were significantly elevated from sham animals in each region within the first hour (p<0.0001 cerebellum, right, and contralateral cortex, p<0.01 hippocampus), but did not change significantly over the first hour. At 24 h post-hemorrhage, there was no significant difference in the lactic acid levels from controls. Similarly, total FFA were significantly higher in each region as compared to sham operated controls within the first hour (p<0.001 cerebellum, p<0.05 hippocampus, p<0.05 contralateral cortex, p<0.0001 ipsilateral cortex). By 24 h, there was no significant difference in FFA levels from shams. The data indicate that aerobic metabolism fails and cellular damage with degradation of cell membranes occurs in the first minutes after SAH, and lasts for at least 1 h. However, this process is stabilized within 24 h in our model. Although the largest effect was seen in the ipsilateral cortex, all areas of the brain were effected.

Pathological changes in surgically resected angiographically occult vascular malformations after radiation.

OBJECTIVE: The goal of this study was to evaluate the pathological changes associated with radiation treatment (stereotactic radiosurgery or conventional irradiation) of angiographically occult vascular malformations (AOVMs). METHODS: Eleven patients underwent surgical resection of an AOVM in the mesial temporal lobe, brain stem, thalamus, or basal ganglia after previous radiation treatment. The indications for surgery were recurrent symptomatic bleeding from the lesion in 10 patients and recurrent intractable seizures in 1 patient. Radiation was used as the initial therapy because the risk of surgical resection was deemed too high. Three patients received conventional radiation therapy of 3000 to 5400 rads at an outside institution. One patient received radiosurgery with the gamma knife at another institution using a dose of 15 Gy to the margin. The remaining 7 patients received stereotactic radiosurgery with a helium-ion particle beam. The dose range was from 18 to 26 Gy equivalents. The interval from radiation to surgical resection ranged from 1 to 10 years, with a mean of 3.5 years. These lesions were compared with 10 nonirradiated cavernous malformations. RESULTS: One irradiated lesion was identified pathologically as a true arteriovenous malformation despite being angiographically occult. This lesion did not demonstrate significant changes in the vasculature but did have radiation necrosis of the surrounding brain 5 years after 25 Gy equivalents of helium-ion radiosurgery. Two other specimens were too small to identify the type of vascular malformation adequately. Of the remaining eight malformations identified as cavernous malformations, six showed a combination of marked fibrosis of the vascular channels, fibrinoid necrosis, and ferrugination. However, the fibrinoid necrosis was the only finding unique to the irradiated lesions compared with nonirradiated controls. All the irradiated lesions still had patent vascular channels; none were completely thrombosed. CONCLUSION: Radiosurgery or conventional radiation therapy did not cause histologic vascular obliteration in intracranial AOVMs evaluated 1 to 10 years (mean 3.5 yr) after radiation delivery. It should be recognized that these patients are irradiation failures who may not be representative of all irradiated patients. However, recurrent bleeding from AOVMs may relate to poor radiation response in some patients.

Fusiform P1 segment artery aneurysm in a pediatric patient: technical case report.

We present an unusual aneurysm in a pediatric patient. Due to the fusiform nature of the aneurysm and the small size of the patient, a unique surgical solution was applied. One year of clinical follow-up is also provided.

Giant aneurysms of the anterior circle of Willis: management outcome of open microsurgical treatment.

BACKGROUND: There is no uniform agreement to date regarding the optimal management of giant aneurysms (GAs) of the anterior circle of Willis. Endovascular therapeutic techniques have yielded unacceptable rates of aneurysm growth and recanalization (endosaccular) or high rates of complications (distal parent vessel occlusion). Despite size, frequent thrombosis and calcification (incollapsibility), and splaying of parent vessels, these aneurysms are readily amenable to direct surgical exposure and control of parent vessels intracranially. Published series have not considered these lesions separately and have often reflected a mixture of management strategies for these and other GAs. METHODS: Thirty-eight consecutive patients with symptomatic GAs of the anterior circle of Willis were managed by the senior author over a 7-year period. Twenty-six of these patients (68%) presented with subarachnoid hemorrhage (SAH). Temporary occlusion was performed under a protocol to enhance brain protection. Direct clip reconstruction or trapping was used in all instances, with intraoperative angiographic control. Revascularization procedures and suture vascular reconstructions were not used in any case. RESULTS: All patients were considered for direct microsurgical treatment. One patient refused surgery, and two patients were deemed a prohibitive medical risk. Thirty-five patients were treated surgically with complete obliteration of the aneurysm in 34 cases (97%), and patency of all parent arteries in 30 cases (86%). Overall mortality was 6% in the surgical cohort, with good or excellent clinical outcome in 71%. Mortality and poor outcome occurred exclusively in the setting of recent hemorrhage. CONCLUSIONS: The results are compared to the natural history of these lesions and to outcome (safety and effectiveness) of currently available endovascular techniques. This experience supports direct microsurgical intervention as the primary therapeutic modality for these lesions.

Giant aneurysms of the proximal anterior cerebral artery: report of three cases.

Aneurysms of any size involving the A1 segment of the anterior cerebral artery are unusual, but giant aneurysms in this location are exceedingly rare, with only five cases previously reported in the literature. We report three cases of A1 segment giant aneurysms presenting with mass effect that were successfully treated. A discussion of the salient features of diagnosis and treatment are presented, along with a brief review of the literature describing these aneurysms. The role of newer imaging modalities, including magnetic resonance imaging, magnetic resonance angiography, and intraoperative angiography, is discussed. The three patients were treated by direct exploration, trapping, and endaneurysmal decompression. Giant A1 segment aneurysms present a unique opportunity to safely trap and decompress the aneurysm with definitive cure.

Natural history of claudicants with critical hemodynamic indices.

We reviewed the records of approximately 1,500 patients seen in the Vascular Laboratory of the Cincinnati Veterans Affairs Medical Center from 1980 to 1987 and identified 23 patients (25 limbs) who met all of the following criteria: 1) an ankle/brachial index less than or equal to 0.35; 2) an ankle or transmetatarsal pulse volume recording less than or equal to 3 mm in amplitude; and 3) no history of ischemic rest pain or gangrene. These patients were followed in the Vascular Laboratory for periods ranging from 11 to 127 months (mean 45.2 months). The study was terminated in March 1991 or when revascularization or amputation was required for limb-threatening symptoms or if the patient expired. Thirteen extremities (52%) showed no progression to limb-threatening symptoms. Claudication actually improved in three, remained unchanged in eight, and progressed in two. Twelve (48%) extremities developed limb-threatening conditions, with rest pain occurring in three, ischemic ulceration in six and gangrene in three. Eight of these limbs underwent revascularization and only one ultimately required major amputation. Another extremity presented with extensive gangrene and underwent a primary above-knee amputation. Three other patients did not undergo revascularization because of death in one and refusal in two others. Patients with intermittent claudication who have critical hemodynamic indices are at much greater risk for developing symptomatic limb-threatening ischemia. Close follow-up is mandatory since nearly half of these patients will eventually require operation for limb salvage. Patients who are unlikely to comply with a regular follow-up program may be considered for early revascularization to prevent complications of limb-threatening ischemia.

Concurrent intradural and extradural meningiomas of the cervical spine.

A case of an extradural spinal meningioma presenting with a separate intradural meningioma at the same cord level is reported. Review of the English literature on spinal epidural meningiomas reveals a high incidence of concurrent intradural tumors in patients with epidural meningiomas. This leads to the conclusion that the intradural space should be evaluated carefully when an epidural meningioma is encountered.

Protection against postischemic spinal cord injury using a new 21-aminosteroid.

Ischemic spinal cord injury following repair of the thoracoabdominal aorta is an unpredictable and devastating complication. Recently, a new class of agents has been developed, the 21-aminosteroids, which have been demonstrated to reduce ischemic neurologic injury in several animal models. We performed this study to determine if the 21-aminosteroid U-74006F exerted a protective effect in a rabbit model of spinal cord ischemia. Nineteen New Zealand rabbits were anesthetized and then subjected to 25 min of temporary infrarenal aortic occlusion. Nine rabbits were given 3.0 mg/kg U-74006F iv 10 min prior to clamping the aorta, followed by 0.75 mg/kg every hour for 6 hr beginning 1 hr after the clamp was removed. Ten rabbits received equivalent doses of an aqueous buffered vehicle. The rabbits were neurologically graded upon awakening and then daily using the following scale: grade 0 = complete paralysis, grade 1 = partial deficit, grade 2 = normal. In the U-74006F-treated group, five animals were normal, one had a partial deficit, and three were paraplegic. In the vehicle group, only one animal was normal and nine were paraplegic. The difference between the mean neurologic grading scores of the two groups was statistically significant (P = 0.013). It is believed that U-74006F acts at the cell membrane level during reperfusion by inhibiting lipid peroxidation and lipid hydrolysis. Our data suggest that this agent may significantly reduce the incidence of postischemic spinal cord injury following temporary aortic occlusion.