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Non-invasive or minimal invasive imaging techniques, such as CTA and MRA, are widely used and lead to an increasing number of incidentally diagnosed intracranial aneurysms. This review answers questions regarding pathogenesis, risk of rupture and treatment options. In conclusion, treatment guidelines based on the individual's risk profile are presented.
The aim of the present study was to compare eyeblink conditioning in cerebellar patients with lesions including the territory of the superior cerebellar artery (SCA) and in patients with lesions restricted to the territory of the posterior inferior cerebellar artery (PICA). The cerebellar areas known to be most critical in eyeblink conditioning based on animal data (i.e. Larsell lobule H VI and interposed nucleus) are commonly supplied by the SCA. Eyeblink conditioning was expected to be impaired in SCA, but not in PICA patients. A total of 27 cerebellar patients and 25 age-matched controls were tested. Cerebellar lesions were primarily unilateral (n = 20). Most patients suffered from ischaemic infarctions of the SCA (n = 11) or the PICA (n = 13). The other patients presented with cerebellar tumours (n = 2) and cerebellar agenesis (n = 1). The extent of the cortical lesion (i.e. which lobuli were affected) and possible involvement of the cerebellar nuclei was determined by 3D-MRI. As expected, the ability to acquire classically conditioned eyeblink responses was significantly reduced in the group of all cerebellar patients compared with the controls. In the patients with unilateral cerebellar lesions, conditioning deficits were present ipsilaterally. In SCA patients with lesions including hemispheral lobules VI and Crus I, eyeblink conditioning was significantly reduced on the affected side compared with the unaffected side. No significant difference between the affected and unaffected sides was present in patients with lesions restricted to the common PICA territory (i.e. Crus II and below). Conditioning deficits were neither significantly different in SCA patients with pure cortical lesions compared with SCA patients with additional nuclear impairment nor in SCA patients with unilateral lesions compared with SCA patients with bilateral lesions. To summarize, unilateral cortical lesions of the superior cerebellum appear to be sufficient to reduce eyeblink conditioning in humans significantly.
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The differential role of the cerebellar cortex and nuclei has rarely been addressed in human lesion and functional brain imaging studies. One important reason is the difficulty of defining the localization of the cerebellar nuclei and extent of possible lesions based on CT or MR scans. The present MRI investigation was specifically designed to study the anatomy of the deep cerebellar nuclei. In both basal ganglia and cerebellar nuclei of healthy human subjects the amount of iron is high compared to the rest of the brain. Clusters of iron are paramagnetic and, therefore, tend to cause local inhomogenities in a magnetic field. The iron-induced susceptibility artefacts were used to visualize the cerebellar nuclei as hypointensities on MR images. A three-dimensional atlas of the dentate (D), interposed (I), and fastigial (F) nuclei is presented in standard proportional stereotaxic space coordinates based on findings in a healthy 26-year-old female. A three-dimensional axial volume of the cerebellum was acquired using a T1-weighted fast low-angle shot (FLASH) sequence on a Siemens Sonata 1.5 Tesla MR. To increase the signal to noise ratio the sequence was acquired 5 times and averaged. Each volume was registered, resampled to 1.00 x 1.00 x 1.00-mm3 voxel size and spatially normalized into a standard proportional stereotaxic space (the MNI-space) using SPM99. Localization of cerebellar nuclei were confirmed by comparison with postmortem MRI and histological microsections of another brain.
Recent advances in hardware technology, noninvasiveness, lack of radiation and high diagnostic accuracy combine to allow the usage of magnetic resonance imaging (MRI) for disease screening in asymptomatic people. 175 volunteers were examined by means of a comprehensive 60-minute MR-screening-protocol covering four organ systems: the brain, the arterial vasculature, the heart and the colon. In 28% of the cases vascular pathology (cerebral, peripheral or cardiovascular) was detected. In up to 17% of the single examination parts relevant incidental findings were seen. The outlined comprehensive MR-protocol is an accurate and patient-friendly imaging tool for the detection of vascular pathology as well as colonic polyps. The socio-economic relevance of this screening exam has to be further investigated in larger patient cohorts.
BACKGROUND AND PURPOSE: In clinically non-functional pituitary macroadenomas, prospective follow-up magnetic resonance imaging (MRI) was conducted after transsphenoidal surgery both to study the changes of the sellar contents at the post-operative site over time and to assess the amount of residual adenoma tissue. METHODS: A total of 50 patients with clinically non-functional pituitary macroadenomas were treated by transsphenoidal tumour resection and were examined by MRI before and directly after surgery (early MR) and 3 months (intermediate MR) and 1 year after surgery (late MR). Changes in the sellar contents over time and the degree of tumour excision were studied on T1-weighted enhanced and unenhanced scans. All patients underwent complete neuro-ophthalmological and endocrinological assessments before and 3 months after surgery. For the interpretation of the post-operative images the results of the endocrinological examinations after surgery were also taken into account. RESULTS: The maximum size of tumour extension on coronal T1-weighted images ranged from 1.2 cm to 5.0 cm (mean 2.3 cm). Despite tumour resection, early post-operative images still showed a persistent mass in the sella in 83% that was usually caused by post-operative haemorrhage, fluid collection and implanted fat material. However, rapid improvement in visual symptoms was noted in 89%. Changes in the sellar region at the early post-operative site markedly hindered the interpretation of MR images for detecting residual tumour tissue, which was suspected in half of the patients (1 intrasellar, 13 suprasellar, and 11 parasellar). Regression of the post-operative mass in the sella was present 3 months after surgery, resulting in a 50% change in the volume of the coronal sellar extension, which also improved the reliability in interpreting the post-operative MR images. On the intermediate MR images residual tumour tissue was detected in 30% of the patients (4 intrasellar, 2 suprasellar and 9 parasellar). Because the suprasellar mass descended over time, an increasing rate of tumour remnant within the sella was seen 3 months following surgery. Before surgery the pituitary gland was visible superiorly or posterosuperiorly to the macroadenomas in 35 patients. However, at the early post-operative site the remaining gland was only visible in 12 patients. Under the condition that endocrinological function tests confirmed adequate hormonal function, the remaining gland was detectable by MRI in 36 patients 3 months after surgery. CONCLUSION: Delayed regression of the sellar contents after transsphenoidal surgery of pituitary macroadenomas was demonstrated by this prospective MR study. Owing to the changes at the post-operative site, it was difficult to interpret early post-operative images and detect residual adenoma tissue. With respect to the delayed regression of the sellar contents, the interpretation of post-operative images for detection of residual adenoma was improved 3 months after surgery. At this time, residual adenoma tissue was found in 30% of clinically non-functional macroadenomas, mostly at the parasellar and, after descent from the suprasellar space, at the intrasellar site.
Optimal management of patients with unruptured intracranial aneurysms (UIAs) remains controversial. Recent studies have found conflicting data regarding the natural history and the treatment outcome of UIAs. Based on the recommendations published by the American Heart Association, the Section of Vascular Neurosurgery of the German Society of Neurosurgery has formed a task force to summarize the available data and to develop a practical framework for the management of UIAs. For UIAs, only evidence from nonrandomized historical cohort comparisons and case series without control subjects are available, supporting only grade C recommendations (options), but no standards (grade A) and no guidelines (grade B). The present recommendations have been developed as a neurosurgical, neuroradiological and neurological consensus. They are based on the existing data of both treatment risks and the risks of the natural history of UIAs.
BACKGROUND AND PURPOSE: We sought to evaluate the effects of reperfusion and craniectomy treatment at different time points after middle cerebral artery (MCA) occlusion on infarct volume and neurological outcome in MCA infarction in rats. METHODS: We used an endovascular technique to obtain MCA occlusion in 182 rats. Thirteen groups with 14 animals each were investigated: control group 1 with no treatment; groups 2 to 7 with only reperfusion or craniectomy at 1, 4, or 12 hours, respectively; and groups 8 to 13 with reperfusion at 1 or 4 hours combined with craniectomy at 1, 4, or 12 hours, respectively. We used infarct volume and neurological performance as study end points in all animals at day 7. RESULTS: Neurological score and infarct volume in animals undergoing early reperfusion at 1 hour were significantly smaller (1.8/79+/-59 mm3) than those in control animals (3.8/225+/-26 mm3) (P<0.01). Reperfusion at 4 hours (2.8/182+/-62 mm3) and 12 hours (3.7/231+/-69 mm3) did not result in significant improvement. Animals undergoing craniectomy at 1, 4, and 12 hours demonstrated significantly better outcome and significantly reduced infarct volume (1.6/96+/-30 mm3, 1.9/109+/-39 mm3, and 2.6/150+/-34 mm3, respectively) (P<0.05). Compared with 1 treatment at a time, combined reperfusion and craniectomy did not result in a significant additional benefit. CONCLUSIONS: Early reperfusion and craniectomy at 1 hour are both effective in large MCA infarction. While reperfusion later than 1 hour was not beneficial, late craniectomy at 4 and 12 hours still resulted in significant improvement of neurological score and reduction of infarction size. Combined treatment at different time points yields no significant additional benefit compared with 1 treatment at a time.
OBJECTS: The objects of the study reported were to recognize different patterns of white matter disease (WMD) in the follow-up of children after surgery, radiation and/or chemotherapy for malignant primary brain tumors and to evaluate statistical data on the incidence of WMD and various risk factors. METHODS: Magnetic resonance imaging (MRI) records were evaluated retrospectively in the routine follow-up (range 6 months to 15 years after surgery) of 44 children with malignant primary brain tumors treated with surgery and radiotherapy and/or chemotherapy. RESULTS: WMD was diagnosed in 28 children and subclassified into circumscribed white matter lesions (WML) and diffuse atrophy. WML were the most common finding ( n=13), followed by atrophy ( n=7) and the combination of both ( n=8). Statistical analysis revealed slightly more frequent atrophy in children younger than 5 years. WML could be linked with supratentorial location of the tumor, follow-up longer than 5 years, and the presence of a ventricular shunt. Intrathecal chemotherapy was also a factor, but because of the small sample size of the group this might not be valid. None of the children had neurological deficits attributed to these findings, but the impact on neuropsychological development was not determined.
HISTORY AND ADMISSION FINDINGS: A seventy-year-old woman was admitted to our hospital under suspicion of an adrenal Cushings's syndrome. Initial laboratory values showed elevated cortisol (834 nmol/l; normal: 180-640) which could not be suppressed after administration of 2 mg dexamethasone (632 nmol/l). Computed tomography of the abdomen showed a 19 x 34 mm mass in the region of the left adrenal gland. INVESTIGATIONS: ACTH levels were normal (42 ng/ml; 17-52). Serum cortisol remained high at 1021 nmol/l after administration of 8 mg dexamethasone. Four more doses of 2 mg dexamethasone were applied on 3 consecutive days, leading to a mild suppression of serum cortisol to 705 nmol/l, with urine cortisol levels dropping from 1915 to 101 nmol/l/24 h. The CRH-test produced a rise of serum cortisol from 895 to 1475 nmol, with ACTH rising from 42 to 68 pg/ml, a laboratory constellation consistent with the diagnosis of centrally located Cushing's syndrome (Cushing's disease). MRI failed to show an adenoma of the pituitary gland so that sinus petrosus sampling was done to confirm the diagnosis (ACTH central/peripheral 7:1; normal range < 2:1). TREATMENT AND COURSE: Serum cortisol rose to 1070 nmol/l and the patient developed pneumonia and contracted tinea. Prior to surgery we lowered the excessive cortisol levels with etomidate and successfully treated the pneumonia with antibiotics. Postoperatively clinical symptoms of Cushing's syndrome disappeared. The patient now presented with total insufficiency of the anterior pituitary. CONCLUSION: Exact hormone testing that may involve sinus petrosus sampling is necessary in diagnosing Cushing's syndrome. Even if radiological procedures cannot show an adenoma of the pituitary, transsphenoidal resection should be considered. Etomidate can lower excessive cortisol levels in seriously ill patients.
We examined the potential of the 'keyhole' technique to improve spatial resolution in perfusion-weighted MRI on whole-body imagers with standard gradient hardware. We examined 15 healthy volunteers. We acquired a high-resolution image with 256 phase-encoding steps before a bolus-tracking procedure. For the dynamic series we collected only 34 lines in the center of k-space. Data reconstruction was performed by both zero-filling and keyhole methods. The dynamic datasets, concentration-time curves calculated from user-defined regions and maps of the cerebrovascular parameters using both reconstruction methods were compared. Using keyhole series, anatomical structures could easily be defined which were not seen on the original dynamic series because of blurring due to ringing artefacts. Comparison of signal-time curves in large regions yielded no significant difference in signal loss during bolus passage. In the parameter maps truncation artefacts were significantly reduced using keyhole reconstruction. The keyhole method is appropriate for enhancing image quality in perfusion-weighted imaging on standard imagers without sacrificing time resolution or information about transitory susceptibility changes. However, it should be applied carefully, because the spatial resolution of the dynamic signal change and the cerebrovascular parameters is less than that afforded by the spatial resolution of the reconstructed images.
We report an unusual case of isolated Langerhans cell histiocytosis of the central nervous system. A 19-year-old man presented with an incomplete ocular palsy. MRI revealed a solitary mass in the pineal gland with marked contrast enhancement. Complete microsurgical excision was followed by local radiotherapy. Histological examination revealed histiocytosis. Unifocal brain involvement by histiocytosis X is rare with few cases in the literature; the most commonly involved areas are the hypothalamus and the pituitary gland.
We conducted an in vitro performance study to test the flow-directed Spinnaker microcatheter for potential endovascular embolizations with Ethibloc as embolic agent. We performed in vitro testing using 50 Spinnaker 1.8F hydrophilic infusion microcatheters of three different types. As embolic agent, different mixtures of Ethibloc and Lipiodol (E/L 1:1, 1:2, 1:3) were used. In an in vitro setting, each catheter was injected to a maximum of ten times (E/L 1:1, n = 20 catheters; E/L 1:2, n = 20; E/L 1:3, n = 10). In addition, we evaluated the thinner Spinnaker 1.5F microcatheter (165/20, n = 10). Five Spinnaker 1.5F catheters were each injected with a mixture of Ethibloc and Lipiodol (E/L 1:2 and 1:3). When a mixture of E/L 1:1 was used, 9 of 20 (45%) Spinnaker 1.8F microcatheters ruptured distally near the tip of the microcatheter, each during injection nos. 5-9. One Spinnaker 1.8F was distally occluded after the fifth injection. With a mixture of E/L 1:2, 4 of 20 (20%) Spinnaker 1.8F microcatheters ruptured distally, during injection no. 6 (n = 2), 7 (n = 1), and 8 (n = 1). With a mixture of E/L 1:3, all ten Spinnaker 1.8F microcatheters could be injected without any problems. All ten microcatheters of the thinner Spinnaker 1.5F ruptured (10-18 cm proximally to the catheter tip). This in vitro study using the flow-directed Spinnaker microcatheter revealed that microcatheters can rupture. The Spinnaker 1.8F can rupture when a mixture of Ethibloc and Lipiodol 1:1 or 1:2 and more than four injections are used. The Spinnaker 1.8F does not rupture when a mixture of E/L 1:3 is used, or with a mixture of E/L 1:1 or 1:2 and injecting to a maximum of four times. The Spinnaker 1.5F microcatheter is not suitable for embolizations using Ethibloc. For embolizations with Ethibloc we therefore recommend the use of a guidewire-directed microcatheter.
Thirty-six lesions in six patients who died from cerebral Aspergillus infection after bone marrow transplantation (BMT) were studied with regard to signal intensity, contrast enhancement, size, and location. The diagnosis was confirmed in all cases by autopsy. Retrospective correlation of histopathological and radiological findings was possible for 14 lesions. Most of the lesions (22/36) had isointense to low signal intensity on T2-weighted images (T2WI). Histopathologically, hemorrhagic necrosis was determined in three of them. Areas of high signal intensity on T1-weighted images (T1WI) were related to gross hemorrhage. Two infarctions showed intravascular accumulation of fungal hyphae with secondary thrombosis of the vessel. The remaining 12 lesions had high signal intensity on T2WI and low on T1WI. Histopathologically, four were infectious and four were unspecific demyelinated lesions. In conclusion, cerebral aspergillosis typically presented with large lesions showing isointense to low signal intensity on T2WI that could have areas of high signal on T1WI. Contrast enhancement was only visible in 15 lesions, and the predominant locations were the subcortical white matter, the cerebellum, and the basal ganglia. Small lesions with high signal on T2WI and low signal on T1WI could not necessarily be related to Aspergillus infection.
In this study we investigated the effect of varying both concentration and dosage of an intravenously administered MR contrast agent on the concentration-time curve in brain tissue. Aside from injection time and injection rate, our model considers the distribution of transit-time between injection site and brain but it is independent from pulse rate, heart volume or other circulation parameters. The width of the transit-time distribution and the concentration-time course in the brain were computed according to indicator dilution theory. We found that increasing the dosage of the administered contrast agent raises the maximum concentration of the agent in the brain, particularly if the injection time is short. Increasing the concentration of the agent (at fixed dosage and injection rate) also increases maximum concentration in the brain capillaries, particularly if the injection time is long. This increase, however, is less than that achieved by raising the dosage.
OBJECTIVE: The purpose of this study was to investigate the potential of perfusion-weighted magnetic resonance imaging for preoperative and postoperative evaluation of cerebral hemodynamics in patients undergoing carotid endarterectomy for carotid artery stenosis. METHODS: We examined 26 patients with angiographically proven stenoses (60%-99%) of the internal carotid artery preoperatively. Perfusion imaging studies were performed by bolus-tracking of a dosage of 0.2 mmol/kg body weight of gadolinium diethylenetriaminepentaacetic acid on a 1.5-T scanner using a T2*-weighted fast low-angle shot sequence. The observed signal intensities were converted pixel by pixel into concentration-time curves. In each patient, the hemispheres were compared and the difference between the normalized first moments (NFMs) and the percentage changes of the regional cerebral blood volume (CBV) were calculated. Three months postoperatively, perfusion-weighted magnetic resonance imaging was performed in 13 patients. RESULTS: In patients with <80% stenosis (n = 10), there was no significant alteration of NFM and regional CBV compared with the contralateral hemisphere (-0.16 +/- 0.7 s, +5.9 +/- 24.6%). In patients with stenoses >or=80% (n = 16), we found an increase in NFM ipsilateral to the stenosis of 1.2 +/- 0.92 s (P < .001) and an increase of CBV of 16.8 +/- 15.2% (P < .005). Three months postoperatively, perfusion parameters were normal in all 13 patients examined. CONCLUSIONS: Perfusion-weighted magnetic resonance imaging is well suited to evaluate the preoperative and postoperative hemodynamic changes in patients with carotid artery stenosis. This noninvasive, semiquantitative magnetic resonance technique could prove to be a valuable adjunct in identification of patients who might benefit from carotid endarterectomy.
Various functional imaging modalities can be applied in acute ischaemic stroke to identify functionally impaired, but morphologically preserved tissue (i.e. the penumbra), and to distinguish it from irreversibly damaged tissue. Flow thresholds for irreversible tissue destruction resulting in functional impairment, as determined by positron emission tomography, perfusion and diffusion-weighted magnetic resonance imaging, single-photon computed tomography and xenon computed tomography, were comparable and ranged between 5 and 12 ml/100 g per min for the lower and 14 and 22 ml/100 g per min for the upper limit of penumbra. These imaging modalities help to select patients for thrombolytic therapy and provide evidence for the effect of this treatment on critically perfused tissue. They can also serve as surrogate markers in the evaluation of therapeutic efficacy. Further progress in interventional neuroradiology has been achieved with intra-arterial thrombolysis, which has become a treatment option beyond the 3-h therapeutic window in acute ischaemic stroke. Angioplasty and stenting of stenosis of arteries that supply the brain with blood have reached a point in their development at which a randomized trial to compare these treatments with vascular surgery is warranted.
Intracavernous carotid artery aneurysms causing a carotid-cavernous fistula (CCF) are rare. These aneurysms usually cause neurological symptoms due to gradual expansion without rupture. If they do rupture they most often lead to a CCF instead of bleeding into the subarachnoid space. A patient is described with a ruptured intracavernous aneurysm causing a CCF resulting in acute onset of unilateral ophthalmoplegia. Selective coil embolisation of the aneurysm led to complete occlusion of the CCF with preservation of the internal carotid artery; symptoms resolved completely.