Richard Leblanc

Preoperative Embolization of Brain and Spinal Hemangioblastomas

Large hemangioblastomas can be difficult to resect because of excessive bleeding. We report our experience with two patients whose large hemangioblastomas were embolized preoperatively and were totally resected with minimal blood loss and satisfactory postoperative outcome. Embolizations were carried out within 3 days of surgery, with the patient under general anesthesia, with 150- to 250-microns Contour emboli. A 65-year-old woman with progressive, severe myelopathy from a 4.5 x 2.1 x 1.4 cm intramedullary hemangioblastoma at T4 underwent embolization of the left T2 and T3 intercostal arteries; a 29-year-old man with Lindaus syndrome and posterior fossa hemorrhage from a 3.8 x 1.8 x 1.8 cm right cerebellar hemangioblastoma underwent embolization of the right posterior inferior cerebellar artery, two right anterior inferior cerebellar arteries, and a dural branch of the right vertebral artery. Embolization led to the complete obliteration of the tumoral blush without neurological sequelae. Both lesions were completely resected with a blood loss of 50 to 100 ml, with bleeding occurring mainly from the pseudocapsule of the lesion. Preoperative embolization of hemangioblastomas is a useful and relatively safe procedure that reduces blood loss at the time of surgery and allows complete resection.

Magnetic resonance spectroscopy guided brain tumor resection : Differentiation between recurrent glioma and radiation change in two diagnostically difficult cases

BACKGROUND It is often difficult to differentiate a recurrent glioma from the effects of post-operative radiotherapy by means of conventional neurodiagnostic imaging. Proton magnetic resonance spectroscopic imaging (1H-MRSI), that allows in vivo measurements of the concentration of brain metabolites such as choline-containing phospholipids (Cho), may provide in vivo biochemical information helpful in distinguishing areas of tumor recurrence from areas of radiation effect. PATIENTS AND METHODS Two patients who had undergone resection and post-operative radiotherapy for a cerebral glioma became newly symptomatic. Computed tomographic (CT) and magnetic resonance imaging (MRI) performed after the intravenous infusion of contrast material, and in one case, [18F]fluorodeoxyglucose positron emission tomography (PET), could not differentiate between the possibilities of recurrent glioma and radiation effect. The patients underwent 1H-MRSI prior to reoperation and the 1H-MRSI results were compared to histological findings originating from the same locations. RESULTS A high Cho signal measured by 1H-MRSI was seen in areas of histologically-proven dense tumor recurrence, while low Cho signal was present where radiation changes predominated. CONCLUSIONS The differentiation between the recurrence of a cerebral glioma and the effects of post-operative irradiation was achieved using 1H-MRSI in these two patients whose conventional neurodiagnostic imaging was equivocal for such a distinction. Where these two conditions are present, metabolite images from 1H-MRSI, such as that based on Cho, can be co-registered with other imaging modalities such as MRI and may also be integrated with functional MRI or functional PET within a multimodal imaging-guided surgical navigation system to assure maximal resection of recurrent tumor while minimizing the risk of added neurological damage.

Three-dimensional Computed Tomographic Angiography of Cerebral Aneurysms

We describe our technique and results of dynamic, reconstructed, three-dimensional (3-D) computed tomographic (CT) angiography in our first 18 patients with either complex aneurysms, producing subarachnoid hemorrhage or the compression of neighboring structures, or small asymptomatic aneurysms, and assess the role of this technique in treatment planning. A dynamic, infused CT scan producing 1.5-mm cuts of the area of interest was performed, and the two-dimensional images were reconstructed in three dimensions with the ISG Allegro system (ISG Technologies, Toronto, Ontario, Canada). Results were compared with intra-arterial digital subtraction angiography and magnetic resonance angiography. All aneurysms over 3 mm and half of the aneurysms less than or equal to 3 mm were demonstrated by 3-D CT angiography. The neck of the aneurysm, its relationship to the parent artery and associated branches, and its relationship to surrounding bony structures, such as the anterior clinoid, were also demonstrated. This was especially useful for ophthalmic aneurysms. The 3-D image could be rotated on the screen to mimic the operative approach. The active, filling portion and the thrombosed part of partially thrombosed, giant aneurysms could be seen on the same image, and the active, filling portion could be better appreciated with 3-D CT angiography than with magnetic resonance angiography. A partially treated, acrylic-coated aneurysm that could not be completely assessed otherwise has been demonstrated by this technique. 3-D CT angiography is useful in the evaluation of aneurysms, especially when the local anatomy is obscured or distorted by its mass or by the anterior clinoid.(ABSTRACT TRUNCATED AT 250 WORDS)

Language Localization with Activation Positron Emission Tomography Scanning

We report the first instance of the use of 3-dimensional magnetic resonance imaging anatomically correlated to positron emission tomography (PET) scanning to identify language areas in a patient with an arteriovenous malformation (AVM) in the posterior speech region. The patient was a 24-year-old right-handed woman with an angiographically proven AVM (3-4 cm) in the left mid-posterior second temporal convolution in whom a left intracarotid injection of sodium Amytal produced significant language disruption. A baseline PET cerebral blood flow study identified the AVM, and an activation PET scan performed during the reading and speaking of simple words showed increased activity in the left parastriate cortex (the second visual area), in the left posterior third frontal convolution (Brocas area), and in the left inferior and midtemporal gyri (Wernickes area). Increased activity was also noted in the right and left transverse temporal (Heschls) gyri, in the left precentral gyrus, in the left medial superior frontal gyrus (the supplementary motor area), and in the right cerebellum. We conclude that activation PET scanning is useful in the preoperative assessment of patients who harbor cerebral AVMs in classically described speech regions.

Familial Cerebral Aneurysms: A Study of 13 Families

Despite the recent interest in familial cerebral aneurysms, the epidemiology, natural history, pattern of inheritance, screening of asymptomatic relatives, and the search for a biochemical marker remain problematic. To assess these issues, we report the results of our prospective study of 30 patients with 38 aneurysms (27 ruptured) and of the angiographic screening of asymptomatic relatives, all from 13 families seen consecutively since 1986. Women were over-represented (77%), and patients with multiple aneurysms (17%) were under-represented, compared with sporadic cases. Only 16% of the aneurysms were at the anterior communicating artery. Aneurysms occurred at the same or at the mirror site in 10 of 16 siblings (62%) and in 50% of mother-daughter pairs versus 20% for randomly selected, sporadic aneurysm patients. Rupture occurred in the same decade in 10 of 12 siblings (83%) versus the expected 21% for randomly selected, sporadic aneurysms. The average age at rupture was 47.2 years, and 60% of patients with a ruptured aneurysm were 50 years of age or younger. Seventy percent of patients died or were disabled from aneurysmal rupture. Screening of 41 individuals, including 2 dizygous twins, identified 1 aneurysm and 2 infundibula. A specific pattern of inheritance could not be ascertained from the pedigrees. The presence of an aneurysm was not associated with a specific human leukocyte antigen haplotype or antigen, and collagen Type III was qualitatively and quantitatively normal. Until a biological marker is identified, angiographic screening by intra-arterial digital subtraction or magnetic resonance angiography remains the only way to identify patients at risk of harboring a familial cerebral aneurysm.

Surgical treatment of intractable epilepsy associated with schizencephaly.

With the advent of magnetic resonance imaging, there has been an increased recognition of schizencephaly during life, especially in epileptic patients. We report our experience with the assessment and treatment of three patients with medically intractable seizures associated with this condition. The three men were aged 24 to 37 years. Two had delayed developmental milestones and hemiparesis or hemiplegia. One had normal development and a normal neurological examination. Seizures began between the ages of 15 and 19 years and lasted for 5 to 22 years before surgery. All had partial simple or generalized seizures with predominant electroencephalographic and electrocorticographic epileptic activity localized to temporal and frontal lobes on the side of the lesion. Neuropsychological assessment indicated widespread dysfunction maximal at the areas of predominant electroencephalographic abnormality. Magnetic resonance imaging demonstrated anterior parasagittal, parietal, and Rolandic cerebral clefts, with ventricular diverticuli, gray matter heterotopia, polymicrogyria, and a true agenesis of the corpus callosum in individual patients. The patients underwent temporal (one patient) and frontotemporal (two patients) lobectomies without additional neurological deficits or neuropsychological deterioration. Postoperative follow-up showed reduction in seizure frequency. We conclude that the surgical treatment of epilepsy is well tolerated in such patients, and their seizures can be alleviated by resection of epileptogenic areas.

Cerebral Aneurysms and Polycystic Kidney Disease: A Critical Review

The pathogenic basis of the association between adult polycystic kidney disease (APKD) and cerebral aneurysms is unknown. We have compared cerebral aneurysms in 79 patients with APKD gleaned from the literature to the sporadic aneurysm cases reported by the Cooperative Study to determine if there are significant biological differences between these two groups. Sixty-eight patients had a single aneurysm and 11 (14%) had multiple aneurysms. In APKD patients with subarachnoid hemorrhage from a single aneurysm there was a significant over-representation of males (72%, p less than 0.01); and the APKD group had more aneurysms of the middle cerebral artery (37%, p less than 0.05). The peak decennial incidence and mean age of rupture of APKD-associated aneurysms was younger (mean age 39.7 years, p less than 0.01) and over 77% of APKD-associated aneurysms had ruptured by age 50 versus 42% for sporadic aneurysms (p less than 0.001). Cerebral aneurysms co-existed with APKD in the absence of hypertension in 25% of 45 cases where the presence or absence of hypertension was recorded. These biological differences and the occurrence of aneurysms in normotensive APKD patients suggests an etiology which may be independent of hypertension and that APKD-associated aneurysms may be genetically determined. It is hypothesized that cases of inherited, familial cerebral aneurysms could be linked to a genetic defect resembling that which occurs on chromosome 16 in APKD.

Epilepsy from Cerebral Arteriovenous Malformations

Twenty-seven patients with epilepsy as the only manifestation of a cerebral AVM were seen at the MNI/MNH from 1973 to 1981. The nine females and eighteen males between the ages of fourteen and fifty-four years (mean 25.2 years) had epilepsy for an average of 3.5 years prior to the diagnosis of AVM. Seven patients had primarily generalized seizures, ten patients had partial seizures with complex symptoms, fourteen patients had partial seizures with elementary symptoms, and thirteen patients had secondarily generalized seizures. Although there was no history of intracranial hemorrhage, seven patients had negative hemispheric signs (hemiatrophy, hemianopia, dysphasia, hemiparesis), two had impaired mentation, and two were ataxic. The EEG, normal in ten cases,showed non-epileptiform activity in six cases, and focal epileptiform activity in eleven cases. Angiographic and/or histological examination revealed eight small (less than 2 cm in diameter) and nineteen large lesions. Fifteen AVMs involved the frontal lobe, ten the temporal lobe five the parietal lobe, and one the occipital lobe. Angiography failed to demonstrate three frontal and three temporal AVMs. Plain CT scanning demonstrated a high or low density lesion without a mass effect in sixteen cases, enlargement of the ipsilateral ventricle or Sylvian fissure in seven cases, and diffuse ventricular enlargement in three cases. CT scanning was performed after the intravenous injection of contrast material in nineteen cases and demonstrated vascular enhancement in fifteen cases and an abnormal blood vessel in six cases. Two angiographically occult AVMs demonstrated vascular enhancement with infusion CT scanning, thereby demonstrating the vascular nature of the lesion where angiography had failed to do so.

Hemodynamic and metabolic effects of cerebral arteriovenous malformations studied by positron emission tomography

Seventeen patients with an intracranial arteriovenous malformation were studied with positron emission tomography. Cerebral blood flow, cerebral blood volume, oxygen extraction fraction, and glucose and oxygen metabolism were evaluated in both hemispheres, excluding the area of the malformation itself. Patients were divided into three groups according to the size of their malformation, and results obtained were compared with studies in healthy volunteers. The glucose metabolism was significantly (p less than 0.01) decreased in the ipsilateral hemisphere in all patients. The cerebral blood volume was significantly increased (p less than 0.001) ipsilaterally in the three groups, and contralaterally in patients with medium- and large-sized arteriovenous malformations. The cerebral blood volume to cerebral blood flow ration, an index of vascular mean transit time, was significantly increased (p less than 0.005) ipsilaterally in patients with medium- and large-sized malformations and contralaterally in patients with large ones. Cerebral blood flow, oxygen extraction fraction, and oxygen metabolism were within the normal range bilaterally in all three groups, but oxygen extraction fraction tended to be higher in patients with larger lesions. The lack of significant change in oxygen metabolism suggests that oxygen metabolism in cortical areas remote from the arteriovenous malformation has been maintained by compensatory hemodynamic mechanisms. These data reveal widespread metabolic and hemodynamic consequences of arteriovenous malformations and suggest that they are associated with impairment of glucose metabolism, both in ipsilateral regions remote from the lesion and in the contralateral hemisphere in patients with large lesions.

Surgical Considerations in Cerebral Amyloid Angiopathy

In cerebral amyloid angiopathy, the contractile elements of the leptomeningeal and cortical arteries are replaced by noncontractile amyloid beta protein. The incidence of amyloid angiopathy increases with advancing age. It is associated with Alzheimers disease and spontaneous cerebral hemorrhage. The latter can have the characteristic acute computed tomographic appearance of a hematoma at the cortex-white matter junction with extension of blood into the subarachnoid, subdural, and intraventricular spaces. Multiple hemorrhages are frequent. Additional bleeding can occur after evacuation of the hematoma, and postoperative hemorrhage can occur after cortical biopsy. To elucidate the role of surgery in this condition, we have reviewed 20 consecutive operated cases of cerebral amyloid angiopathy. A first group of 8 patients with senila dementia underwent cortical biopsy without resultant hemorrhage. A second group of 6 patients in good clinical condition had delayed evacuation of a spontaneous cerebral hematoma from cerebral amyloid angiopathy because of the radiological misdiagnosis of a hemorrhage within a tumor. One patient died of a pulmonary embolism, and another had subsequent multiple hemorrhages that were ultimately fatal. A third group of 6 patients in poor neurological condition had the acute evacuation of a spontaneous cerebral hematoma to relieve intracranial hypertension. All died or were severely disabled. One had repeated hemorrhages which added a progressively more severe organic dementia onto an initial hemiplegia.(ABSTRACT TRUNCATED AT 250 WORDS)