Variations of perforating arteries of anterior communicating artery in cases with anterior communicating artery aneurysms: a cadaveric anatomical study.

PURPOSE: In terms of postoperative morbidity and mortality, preservation of the perforating arteries branching from the anterior communicating artery (ACoA) during clipping is particularly imperative in patients with ACoA aneurysm. In the present study, we aimed to investigate whether perforating arteries originated from ACoA were pushed away in a different location in patients with ACoA aneurysm. Furthermore, if they did so, we aimed to identify the direction in which they were dislocated and how the perforating arteries could be preserved during clipping. METHODS: Herein, we categorized 40 brains obtained from cadavers into two groups. The first (n = 26) and second (n = 14) groups included cases without and with ACoA aneurysms, respectively. After completing the preparation procedure, the brains were dissected using surgical microscope and the relevant anatomical region was examined and photographed. Finally, statistical analyses were performed on the data and the results were documented. RESULTS: In the aneurysms with posterior and superior projections, the perforators appeared to be pushed away inferiorly and were frequently noted at the anteroinferior part of the aneurysm neck. Most of the cases, where one of the A1s was larger at one side, the perforating arteries arose from the larger A1 side. CONCLUSION: The mortality and morbidity associated with damage to the perforators can be reduced by approaching the patient from the dominant A1 side and pursuing the perforators primarily at the anteroinferior part of the aneurysm neck in the aneurysms with superior and posterior projections.

Perimesencephalic subarachnoid hemorrhage: Etiologies, risk factors, and necessity of the second angiogram.

AIM: In this paper, we aim to present our experience with a series of patients with PMSAH. In addition, the clinical course of perimesencephalic subarachnoid hemorrgade (PMSAH) is discussed with an evaluation of etiologies, risk factors, and the necessity for a second angiogram on follow-up. MATERIALS AND METHODS: The data for this study were obtained retrospectively from patients who were treated at the Uludag University, School of Medicine, Department of Neurosurgery, Division of Neurovascular Surgery's clinic with a diagnosis of PMSAH between January 1980 and March 2002. RESULTS: We identified a total of 24 patients, 12 male. The mean age at the time of hemorrhage was 53 ± 12 years. In all patients, the onset was typical with a sudden severe headache. Five of the patients were Hunt-Hess Grade I, 15 were Grade II, and 4 were Grade III. The initial 4-vessel angiography was normal in 23 cases. Twenty-two had a second 4-vessel angiography, and all were normal. We observed acute hydrocephalus in 5 patients (20.8%). We did not observe re-bleeding during the follow-up of our patients. CONCLUSION: Patients with PMSAH have a particularly excellent outcome, and there is no need to evaluate these patients with repeat angiography.

Effect of Pre/Postconditioning at Temporary Clipping.

Intracranial aneurysms and their treatment is one of the leading problems of neurosurgery that create high mortality and morbidity. The technique of safe clipping is as generally used depends on the temporary occlusion of the cerebral vasculature during surgery. However, there is no exact data about temporary clipping or timing of this procedure. Preconditioning by exposure to sublethal hypoxic stress, hours or days before severe hypoxia, decreases cell death, and this resistance of the brain to injury is known as ischemic tolerance. Brief alternating periods of reperfusion-reocclusion at the beginning of reperfusion is defined as postconditioning. Cerebral ischemic pre/postconditioning protects against stroke, but is clinically feasible only when the occurrence of stroke is predictable. Brief, repetitive occlusion and release of the main trunk of a vessel during early aneurysm surgery or before long-lasting temporary artery occlusion may protect the brain against later possible vasospasm/ischemia.

The artery of Percheron revisited: a cadaveric anatomical study.

BACKGROUND: The artery of Percheron (AOP) is a single thalamoperforating arterial trunk that provides bilateral supply to the paramedian thalami and the rostral midbrain. As this rare anatomical variant artery may be involved in endovascular procedures or encountered surgically during basilar terminus aneurysms, the present study was warranted. METHOD: Thirty-four adult (20 male and 14 female) formalin-fixed cadaveric brains underwent dissection of the 68 posterior cerebral arteries. Observations were made of the presence and the variations of the thalamoperforating arteries as well as the presence of the AOP. FINDINGS: Thalamoperforating arteries arose from the superior or posterior surfaces of the P1 segment at a mean of a 1.87 mm (range, 0.39-5.25 mm) distance from the basilar apex and entered the brain through the posterior perforated substance. The average number was 4.25 (range 1-9), and the mean diameter was 0.73 mm (range 0.46-1.16 mm). Thalamoperforating arteries were classified into four different types according to their origin at the P1 segment: type I (bilateral multiple, n = 19), 55.8 %; type II (unilateral multiple, unilateral single, n = 4), 11.7 %; type III (bilateral single, n = 7), 20.5 %; type IV [one side with a single branch, the other side with no branches (the AOP), n = 4], 11.7 %. In three separate specimens with ruptured basilar artery aneurysms, the origin of the thalamoperforating arteries was incorporated not only into the posterior aspect of the aneurysm neck but also into the fundus. CONCLUSIONS: In about one tenth of cases the possibility of the presence of a single arterial trunk that supplies the two paramedian thalamic territories should be taken into consideration during treatment planning of basilar terminus aneurysms. Furthermore, our data show that the thalamoperforating arteries may take off from both the aneurysm neck and the fundus.

Anatomical aspects in the transsphenoidal-transethmoidal approach to the optic canal: an anatomic-cadaveric study.

BACKGROUND: Determining anatomic landmarks during a transsphenoidal-transethmoidal approach to the optic canal region is of critical importance. METHODS: Sella-parasella sphenoid bone blocks were extracted from adult cadavers. Anatomic dissections were performed in the optic canal region using a surgical microscope in 30 samples. Quantitative measurements were done using photographic techniques. For histological evaluation, coronal and longitudinal cross-sections were taken from the bilateral optic canal in seven decalcified samples. RESULTS: Optic protuberance (OP), carotid protuberance (CP), medial opticocarotid recess (MOCR) and lateral opticocarotid recess (LOCR) were defined as lateral landmarks determining the width of the opening in the extended transsphenoidal-transethmoidal approach. Among all anatomic markers, LOCR was the most determinant lateral marker with tubercular recess the most prominent central marker. OPs showing the optic canal direction and inter-recessal sulci had similar distinguishing rates in the sphenoid sinus base. Inter-recessal sulci formed by OPs and CPs were observed between MOCR and LOCR in most samples. In histologic sections, the dural sheath was thicker inferolaterally to the optic nerve compared to superiorly and medially; collagen arrangement was dense and irregular. CONCLUSION: Although LOCRs and tubercular recesses are safe and prominent markers in extended transsphenoidal-transethmoidal approaches, other anatomic markers should also be taken into consideration to perform an efficient optic canal approach and optic canal decompression. Other factors for safe dissection are the length of the optic canal, bone thickness, adherence of dural structures and the course of the intradural ophthalmic artery.

Cerebellar granulocytic sarcoma: a case report.

Granulocytic sarcoma is a rare tumor composed of immature granulocytic cells that is usually associated with acute myelogenous leukemia. Intraparenchymal cranial localization without skull, meningeal, or bone marrow invasion is extremely rare. The mechanisms of intraparenchymal cranial localization of GS remains unknown, as only 10 cases with cerebellar granulocytic sarcoma have been previously reported. Herein, we report a four year old boy with cerebellar localization of granulocytic sarcoma.

Surgical limits in transnasal approach to opticocarotid region and planum sphenoidale: an anatomic cadaveric study.

BACKGROUND: The significance of medial and lateral opticocarotid recesses and the planum sphenoidale region in skull base pathologies for the transsphenoidal-transplanum approach were evaluated. METHODS: The sphenoid bone block samples were extracted from adult cadavers. Dissections and measurements in the opticocarotid and planum sphenoidale regions were performed in 29 samples using a surgical microscope. For histologic evaluation, oblique sections through the bilateral opticocarotid regions were obtained and examined in eight samples. RESULTS: Optic, carotid prominences, and medial and lateral opticocarotid recesses can be identified as lateral markers intraoperatively to the extent of the exposure. The lateral opticocarotid recess was observed to be prominent in all samples. In all samples, the groove formed by optic and carotid prominences between the medial and lateral opticocarotid recesses was seen. This groove was designated the inter-recess sulcus. In the transsphenoidal-transplanum approach, the area needed for a reliable bone resection was measured as a mean of 237.32 ± 30.96 mm(2). The mean angle between optic nerves was 115.41 ± 18.39 degrees. The mean anteroposterior length of the planum sphenoidale was 14.84 ± 1.52 mm. In histologic sections, collagenous ligaments between the anterior part of cavernous sinus and the adventitia layer of internal carotid artery were more frequent and regular than the inferior part of optic nerve. CONCLUSIONS: The lateral opticocarotid recess is a reliable and persistent indicator for extended transsphenoidal surgery. To approach the opticocarotid region near the internal carotid artery and optic nerve, a careful dissection is needed to minimize surgical injuries to the optic nerve and carotid artery. Other factors determining a reliable bone resection are the anteroposterior length of the planum sphenoidale and the distance and width of the angle between optic nerves. Attention should be given to individual anatomic variations of the region when planning and performing transsphenoidal-transplanum surgery.

Citicoline and postconditioning provides neuroprotection in a rat model of ischemic spinal cord injury.

BACKGROUND: Ischemic spinal cord injury is a chain of events caused by the reduction and/or cessation of spinal cord blood flow, which results in neuronal degeneration and loss. Ischemic postconditioning is defined as a series of intermittent interruptions of blood flow in the early phase of reperfusion and has been shown to reduce the infarct size in cerebral ischemia. Our study aimed to characterize the relationship between the neuronal injury-decreasing effects of citicoline and ischemic postconditioning, which were proven to be effective against the apoptotic process. METHOD: Spinal cord ischemia was produced in rats using an intrathoracic approach to implement the synchronous arcus aorta and subclavian artery clipping method. In our study, 42 male Sprague-Dawley rats (309 +/- 27 g) were used. Animals were divided into sham operated, spinal ischemia, citicoline, postconditioning, and postconditioning citicoline groups. Postconditioning was generated by six cycles of 1 min occlusion/5 min reperfusion. A 600 mmol/kg dose of citicoline was given intraperitoneally before ischemia in the citicoline and postconditioning citicoline groups. All rats were sacrificed 96 h after reperfusion. For immunohistochemical analysis, bcl-2, caspase 3, caspase 9, and bax immune staining were performed. Caspase 3, caspase 9, bax, and bcl-2 were used as apoptotic and antiapoptotic markers, respectively. FINDINGS: The blood pressure values obtained at the onset of reperfusion were significantly lower than the preischemic values. A difference in immunohistochemical scoring was detected between the caspase 3, caspase 9, bax, and bcl-2 groups. When comparisons between the ischemia (groups 2, 3, 4, and 5) and sham groups (group 1) were performed, a significant increase in caspase 3, caspase 9, bax, and bcl-2 was detected. When comparing the subgroups, the average score of caspase 9 was found to be significantly higher in ischemia group 2. The average score of bcl-2 was also found to be significantly higher in postconditioning and citicoline group 5. CONCLUSIONS: It is thus thought that combining citicoline with postconditioning provides protection by inhibiting the caspase pathway and by increasing the antiapoptotic proteins.

Anatomy of the floor of the third ventricle in relation to endoscopic ventriculostomy.

Neuroanatomical structures that form the floor of the third ventricle (FTV) and neighboring tissues are important in the context of third ventriculostomy (TV) procedures. Thorough knowledge of the anatomical and histological organization of the region would be useful in understanding and preventing surgical complications. Taking the third ventricle region as a model, we aimed to simulate TV and make measurements of 23 cadaver brains, as well as perform histological examinations of the third ventricular floor on five cadaver brains. During the endoscopic TV, we examined the degree to which the structures surrounding the FTV were affected by surgical simulation. To make a clinical comparison, the distance between the center of the FTV and the basilar apex was measured on cranial magnetic resonance images (MRIs) of 15 subjects with normal ventricular systems and 15 subjects with moderately enlarged ventricles. Histological examination revealed that the ependymal cells and arachnoid membrane formed the inner and outer surfaces of the third ventricle floor, respectively, whereas the stroma was made up of glial cells exclusively. This region was gliotic and avascular. When cadaver brains with normal and hydrocephalic ventricles were compared, there were significant differences in the distance between the center of the floor and the basilar apex (P < 0.001). On the basis of our study, the optimal site for TV fenestration and balloon inflation is just anterior to the mamillary bodies to avoid injury to neighboring structures.

Investigation of neuroprotective effects of cyclooxygenase inhibitors in the 6-hydroxydopamine induced rat Parkinson model.

AIM: Recent experimental and clinical studies on Parkinson's disease point out the pivotal role of inflammation in the pathogenesis of neurodegeneration and the possible positive effects of nonsteroidal anti-inflammatory drug therapies. Our aim in this study was to investigate the preventive effects of nonsteroidal anti-inflammatory drugs in the 6-hydroxydopamine (6-OHDA) induced rat model of Parkinson's disease. MATERIAL AND METHODS: Twenty-one female Wistar-Albino rats (200-250g) were used in this study. The rats were divided in three groups: Saline group (n: 7, 2 ml), Acetylsalicylic acid group (n: 7, 100 mg/kg), and Meloxicam group (n: 7, 50 mg/kg). An hour after administration, the rats received a unilateral intranigral injection of 6-OHDA to produce the Parkinson model lesion. Rotational tests were performed two weeks later as follow-up. Immunohistochemical tests were performed in all groups to determine the severity of the lesion in the substantia nigra. RESULTS: Administration of drugs an hour before the lesions were created did not protect the degeneration of dopaminergic neurons in the substantia nigra. CONCLUSION: Oral usage of low repeated doses of nonsteroidal anti-inflammatory drugs may possibly slow down the progression of the disease.

Neuronal protective effects of focal ischemic pre- and/or postconditioning on the model of transient focal cerebral ischemia in rats.

We investigated the neuroprotective effects of pre- and postconditioning on infarct volume in the transient middle cerebral artery occlusion (MCAo) model in rats. Thirty-two male rats were divided into occlusion, preconditioning, postconditioning and both pre- and postconditioning groups. MCAo (120 minutes) was monitored with continuous cerebral tissue oxygen (O2) pressure (PtiO2). Pre-conditioning comprised 10 minutes of MCAo, 24 hours prior to the 120 minute MCAo. The postconditioning algorithm was 30 seconds of reperfusion followed by 30 seconds of MCAo. This cycle was repeated 3 times at the onset of reperfusion. Comparison of infarct volumes showed a significant difference between the conditioned groups and occlusion group. Although there was better protection in the preconditioning group compared with the other two conditioned groups, the results did not reach statistically significant levels. The results suggest that preconditioning, postconditioning and pre/post conditioning have protective effects on cerebral ischemia.

Sylvian cistern dermoid cyst presenting with dysgeusia.

It is rare for a patient with a dermoid cyst (DC) to present with taste dysfunction. A 58-year-old man presented with an altered sense of taste. Magnetic resonance imaging of the brain showed a mass lesion in the right insula with compression effect. The tumour was resected and was found to be a DC. The postoperative course was uneventful, and the patient resumed his usual taste sensation within the early postoperative period. To the best of our knowledge, this is the first report of a sylvian cistern DC that presented with dysgeusia.

Phase-contrast cine MRI versus MR cisternography on the evaluation of the communication between intraventricular arachnoid cysts and neighbouring cerebrospinal fluid spaces.

INTRODUCTION: The objective of this study was to evaluate the role of phase-contrast cine magnetic resonance imaging (PC-MRI) in detecting possible communications between intraventricular arachnoid cysts (IV-ACs) and cerebrospinal fluid (CSF) spaces based on MR cisternography (MRC) comparison. MATERIALS AND METHODS: Twenty-one patients with IV-AC were examined by PC-MRI and MRC. In order to determine the communication of IVAC with its neighbouring CSF spaces, PC-MRI was employed. The communication of IV-ACs with the ventricular system was examined on at least two anatomic planes. Precontrast images and PC-MRI were followed by the intrathecal administration of 0.5-1 ml gadopentetate dimeglumine. Early and delayed MRC were then carried out. Results of PC-MRI were compared with findings of MRC (McNemar's test). RESULTS: In seven IV-ACs, no communication was detected by PC-MRI. In 14 IVACs, a pulsatile CSF flow into the IV-ACs was observed. All the IV-ACs, which have been determined as non-communicating (NC) on the PC-MRI, showed NC character on MRC as well. Six cases suggesting a communication on PC-MRI showed no communication on MRC. MRC revealed eight communicating (38%) and 13 NC (62%) IV-ACs among a total of 21 cases. The sensitivity and specificity of PC-MRI imaging in demonstrating the communication between the IV-ACs and the CSF were 100% and 54%, respectively. CONCLUSION: PC-MRI is an effective method for evaluating NC IV-ACs. In order to decide about the management of IV-ACs, which are communicating according to the PC-MRI, the results should be confirmed with MRC if suspected jet flow is depicted.

Analysis of intracranial pressure changes during early versus late percutaneous tracheostomy in a neuro-intensive care unit.

BACKGROUND: We aimed to investigate intracranial pressure (ICP) changes during early versus late bedside percutaneous tracheostomy (PT) in a neuro-intensive care unit (NICU). METHODS: This study included 30 patients admitted to our NICU for head trauma, subarachnoid haemorrhage, intracerebral haematoma or brain tumour with a Glasgow Coma Score (GCS) less than 8. These patients also underwent ICP monitoring. Bedside PT was performed either early (within 7 days of ventilation) or late (after 7 days of ventilation) via the Griggs system. In all patients; ICP, systemic blood pressure, heart rate, oxygen saturation (Sat O(2)) and arterial blood gases were recorded 5 min before the procedure, during skin incision, during tracheal cannulation, as well as 5 min and 10 min after the procedure. FINDINGS: Thirty patients, 18 male and 12 female, with various intracranial pathologies between ages 18 and 78 (mean 38.7 +/- 20) were identified. The admission GCS ranged between 4 and 11 (median 7). Physiological variables did not differ significantly between the two groups. In the early group, ICP values measured 5 min before the procedure, during skin incision, during tracheal cannulation, as well as 5 min and 10 min after the procedure were 15.1 +/- 5.2, 22 +/- 10.1, 28.4 +/- 13.7, 17.3 +/- 7.1, 13.8 +/- 5.0 mmHg, respectively. In the late group, these values were 14.2 +/- 4.5, 17.2 +/- 5.5, 21.5 +/- 8.0, 15.1 +/- 5.3 and 12.4 +/- 4.1 mmHg. There was no significant difference between the early or late groups in terms of ICP increases during these predetermined 5 time points. CONCLUSIONS: In patients with decreased intracranial compliance, a relatively minimally invasive procedure such as PT may lead to significant increases in ICP. The timing of PT does not seem to influence ICP, mortality, pneumonia or early complications. During the PT procedure, ICP should be closely monitored and preventive strategies should be instituted in an attempt to prevent secondary insult to an already severely injured brain.

Comparison of prognostic scores and surgical approaches to treat spinal metastatic tumors: a review of 57 cases.

Surgical treatment of metastatic spinal cord compression with or without neural deficit is controversial. Karnofsky and Tokuhashi scores have been proposed for prognosis of spinal metastasis. Here, we conducted a retrospective analysis of Karnofsky and modified Tokuhashi scores in 57 consecutive patients undergoing surgery for secondary spinal metastases to evaluate the value of these scores in aiding decision making for surgery. Comparison of preoperative Karnofsky and modified Tokuhashi scores with the type of the surgical approach for each patient revealed that both scores not only reliably estimate life expectancy, but also objectively improved surgical decisions. When the general status of the patient is poor (i.e., Karnofsky score less than 40% or modified Tokuhashi score of 5 or greater), palliative treatments and radiotherapy, rather than surgery, should be considered.

MR imaging in the detection of diffuse axonal injury with mild traumatic brain injury.

PURPOSE: To evaluate the occurrence and distribution of mild traumatic brain injury (MTBI) caused by diffuse axonal injury (DAI) using magnetic resonance (MR) imaging and to attempt to correlate MR findings with post-concussion symptoms (PCS). PATIENTS AND METHODS: Forty MTBI patients (mean age: 32.5 years) with normal cranial computed tomography (CT) findings were examined with standard MR protocol including T(1)-weighted, T(2)-weighted, fluid attenuated inversion recovery (FLAIR), gradient echo (GRE) and diffusion-weighted (DW) sequences. MR imaging was performed within 24 hours of injury. The lesions were classified as DAI based on their location and morphologic appearance. RESULTS: In MR imaging of five (12.5%) of the patients, the lesions compatible with DAI were observed. Four patients (10%) had the foci of low signal intensity compatible with hemorrhagic shear injury on the GRE sequence, and five (12.5%) patients had high signal intensity on FLAIR and DW sequence. CONCLUSION: MR imaging can be helpful in revealing DAI lesions in patients with normal CT scan findings after MTBI. FLAIR, GRE and DW sequences are superior to conventional spin-echo images in detecting DAI lesions.

Pituitary apoplexy as a cause of internal carotid artery occlusion.

Occlusion of intracranial arteries by pituitary apoplexy with resulting infarction is a rare occurrence. A 50-year-old man who presented with a history of sudden onset of frontal headache and visual impairment was admitted to another medical centre and MRI revealed a non-enhancing sellar lesion with suprasellar and infrasellar extension. Thereafter, the patient's consciousness deteriorated progressively and he showed signs of herniation; he was then referred to our centre for further evaluation. CT scanning revealed infarction of the left internal carotid artery territory. Transcranial resection of the tumour followed by a large decompressive craniotomy restored the blood flow in the internal carotid artery. Histological examination revealed the tumour to be a pituitary adenoma that contained formed blood elements. The patient's neurological status did not improve and he died on the ninth postoperative day despite vigorous treatment for controlling intracranial pressure. This case study documents a rare presentation of pituitary apoplexy that caused signs of raised intracranial pressure due to mechanical obstruction of an internal carotid artery with resulting infarction.

Clinical importance of the basal cavernous sinuses and cavernous carotid arteries relative to the pituitary gland and macroadenomas: quantitative analysis of the complete anatomy.

BACKGROUND: It is unusual to encounter hemorrhagic complications caused by arterial or venous damage during TSS. Problems with these structures can lead to permanent disability or death. Our aim was to quantitatively analyze anatomical and radiologic relationships among the BCS, the CCA, and the pituitary gland, as these structures are accessed during TSS. METHODS: Forty-nine formaldehyde-fixed, sellar-parasellar tissue blocks from adult cadavers were used to simulate accessing the BCSs via TSS. In each specimen, size of the pituitary gland and specific characteristics of each BCS and the horizontal segment of each CCA were recorded. Nine other specimens were used for histologic investigation and microanatomical measurements. To attest correlation between clinical data and cadaveric measurements, coronal MRI scans of 22 healthy adults as well as of 28 patients with macroadenomas were analyzed. RESULTS: In cadaveric specimens, distances between both CCAs in the BCS were 17.1 +/- 4.0 mm anteriorly, 20.3 +/- 4.2 mm medially, and 18.8 +/- 4.6 mm posteriorly. In this study, the anterior medial space of the BCS was dominant in 12 specimens on the right side and in 5 specimens on the left; the posterior medial space of the BCS was dominant in 23 specimens on the right side and in 9 specimens on the left side. The right medial BCS was dominant in 35 specimens. On histologic coronal sections, some part of the carotid artery's (CA's) diameter was located below the line passing from the basal dural layer ranging from 5.3% to 65.4%. In normal-sella images, distances between both CCAs were 15.4 +/- 1.8 mm anteriorly, 16.0 +/- 2.8 mm medially, 16.2 +/- 3.4 mm posteriorly. On coronal normal-sella images, some part of the CA's diameter was located below the line passing from the basal dural layer ranging from 16.4% to 66.7%. In macroadenomas, distances between both CCAs were 22.0 +/- 3.6 mm anteriorly, 21.5 +/- 3.8 mm medially, and 20.7.2 +/- 3.7 mm posteriorly . On coronal images, in only 6 of 28 macroadenomas, some part of the CA's diameter was located below the line passing from the basal dural layer ranging from 12.5% to 100%. CONCLUSIONS: Our results indicate that a working area of 15.0 +/- 2.6 x 10.3 +/- 2.1 mm is safe during TSS. The position of the CCA posterior segment was notably more caudal than the anterior segment with respect to the basal dura, which should be taken into account during extended exposure. Also, preoperative recognition of the anatomical variations is beneficial for detection of the boundaries of dissection, which is particularly important in the BCS, where variable course of CCAs may transform the anatomical configuration. Slowly growing pituitary adenomas stretch out both CCAs considerably from medial to lateral directions, and they cause widening of intercarotid distances in all segments. Processing of fixation, decalcification, and paraffin embedding for the cadaveric tissue in contrast to physiologically hydrated tissues may change the accuracy of measurements. These measurements are significantly different than those in the radiologic images when arterial blood under pressure is in the CCA as well as when venous blood fills the cavernous sinus as is the case in vivo. In clinical practice, these facts must be taken into consideration in the cadaveric measurements.

Unusual complications and presentations of intracranial abscess: experience of a single institution.

BACKGROUND: Complicating events and unusual presentations associated with intracranial abscess are rare but potentially fatal conditions. This study was undertaken to shed light on the unusual complications and presentations of intracranial abscess treated at a single institution. METHODS: We retrospectively reviewed 116 cases of intracranial abscesses that were treated at our institution over the last 10 years and identified 11 (9.4%) cases with unusual complications. RESULTS: These complications consisted of (1) rupture within the abscess, (2) hemorrhage into the abscess, (3) hemispheric infarction due to ICA thrombosis, (4) acute visual loss due to pituitary abscess, (5) acute neurologic deterioration due to rapid gas formation within the abscess, (6) acute hydrocephalus, (7) trigeminal neuralgia, (8) fungal abscess developing secondary to intracranial extension of a temporal bone tumor, (9) Cryptococcus abscess with different morphology, (10) pontine infarction, and (11) sigmoid sinus thrombosis. Sinusitis accompanied 8 (72.7%) of the cases, and there were 5 (45.4%) mortalities. Culture results were unyielding in 4 patients, whereas Streptococcus species were identified in 4 and fungi in the rest. CONCLUSION: Intracranial abscesses and their complications still continue to be challenging entities in the neurosurgical practice. Our experience may provide an informational source for those who are taking care of patients with intracranial abscess.

Meningiomas with conventional MRI findings resembling intraaxial tumors: can perfusion-weighted MRI be helpful in differentiation?

INTRODUCTION: To investigate the contribution of perfusion-weighted MRI to the differentiation of meningiomas with atypical conventional MRI findings from intraaxial tumors. METHODS: We retrospectively analyzed 54 meningiomas, 12 glioblastomas and 13 solitary metastases. We detected 6 meningiomas with atypical features on conventional MRI resembling intraaxial tumors. The regional cerebral blood flow (rCBV) ratios of all tumors were calculated via perfusion-weighted MRI. The signal intensity-time curves were plotted and three different curve patterns were observed. The type 1 curve resembled normal brain parenchyma or the postenhancement part was minimally below the baseline, the type 2 curve was similar to the type 1 curve but with the postenhancement part above the baseline, and the type 3 curve had the postenhancement part below the baseline accompanied by widening of the curve. Student's t-test was used for statistical analysis. RESULTS: On CBV images meningiomas were hypervascular and the mean rCBV ratio was 10.58+/-2.00. For glioblastomas and metastatic lesions, the rCBV ratios were 5.02+/-1.40 and 4.68+/-1.54, respectively. There was a statistically significant difference in rCBV ratios between meningiomas and glioblastomas and metastases (P<0.001). Only one of the meningiomas displayed a type 2 curve while five showed a type 3 curve. Glioblastomas and metastases displayed either a type 1 or a type 2 curve. None of the meningiomas showed a type 1 curve and none of the glioblastomas or metastases showed a type 3 curve. CONCLUSION: Differentiating meningiomas with atypical conventional MRI findings from malignant intraaxial tumors can be difficult. Calculation of rCBV ratios and construction of signal intensity-time curves may contribute to the differentiation of meningiomas from intraaxial tumors.