Structural fragility and inflammatory response of ruptured cerebral aneurysms. A comparative study between ruptured and unruptured cerebral aneurysms

BACKGROUND AND PURPOSE

Despite technical advances in endovascular and microsurgical treatment, patients with aneurysmal subarachnoid hemorrhage still have a high mortality and morbidity rate. To improve the treatment results in patients with aneurysms, we must better understand the pathophysiology of cerebral aneurysms and the mechanisms leading to their rupture. Therefore, we studied the pathological differences between unruptured and ruptured aneurysms.

METHODS

Ruptured (n=44) and unruptured (n=27) aneurysms were obtained at surgery. The aneurysmal endothelium was scored from 0 (normal) to 5 (complete disruption) by using a scanning electron microscope. The aneurysmal wall was evaluated by immunohistochemical methods. The wall structure was scored from 1 (dense collagen and rich, smooth muscle cells) to 5 (hyaline-like structure). The degree of inflammatory cell invasion into the wall was also scored from 0 (very few cells) to 3 (many cells).

RESULTS

Ruptured aneurysms manifested significant endothelial damage (score of 3.7 versus 0.8; Mann-Whitney U test, P<10(-3)), significant structural changes of the wall (3.7 versus 1.7, P<10(-5)), and significant inflammatory cell invasion (2.2 versus 0.8, P<10(-4)) compared with unruptured aneurysms. There was a significant correlation between the score for wall structure and the score for inflammatory cell invasion (Rs=0. 63; Spearman rank correlation test, P<10(-5)). The pathophysiology of several symptomatic unruptured aneurysms was similar to that of ruptured aneurysms.

CONCLUSIONS

We conclude that the pathophysiology of unruptured, asymptomatic and ruptured aneurysms is different. The wall of ruptured aneurysms was found to be fragile, possibly because macrophage infiltration into the aneurysmal wall resulted in loss of smooth muscle cells and in degradation of matrix proteins.

Nigral degeneration following striato-pallidal lesion in tissue type plasminogen activator deficient mice

Tissue type plasminogen activator (tPA) has been suggested as a key factor in excitotoxic neuronal death in the hippocampus. Transneuronal degeneration of the substantia nigra pars reticulata (SNR) neurons after striato-pallidal lesions is attributable to excess excitatory glutamatergic inputs into the SNR following inhibitory GABAergic deafferentation and tPA may contribute to the mechanism of transneuronal degeneration of the SNR. To examine this possibility, we studied pathological changes in the SNR following striato-pallidal lesions produced by electrocoagulation in tPA-deficient mice. There was no difference in the degree of SNR degeneration, or in microglial activation and proliferation in the degenerating SNR of tPA-deficient and control mice. Our results indicate that tPA does not contribute to transneuronal degeneration in the SNR following striato-pallidal lesions in mice.

Restenosis following carotid endarterectomy--clinical profiles and pathological findings

Restenosis following carotid endarterectomy is not a rare condition. Among 122 endarterectomies we experienced, five restenoses (4.1%) were encountered and treated by the second surgery. The present report clarifies the clinical profiles and pathological findings of restenosis following carotid endarterectomy. Mean age of restenosis group (59 years old) was not significantly different from the group without restenosis (62 years old). Average duration between the first endarterectomy and the second surgery was 17 months (8-30 months). Initial symptoms were transient ischemic attack in three sides, minor stroke in one side, and asymptomatic in one. Degree of stenosis was tight (> or = 90%) in two and moderate (70-89%) in three. It is interesting to note that no ulcer was noted in the first endarterectomy specimen. At surgery for restenosis, two cases had symptoms and another two cases were asymptomatic, though all had neck bruits. Four of five lesions were treated by short venous graft from common carotid artery to distal internal carotid artery and another lesion was treated by second endarterectomy and Dacron patch graft. Pathology was studied in four and all showed myointimal hyperplasia. Three of four restenosis tissues showed mutant form p53 by immunohistochemistry. The present study indicates that restenosis following carotid endarterectomy is not a rare status. Short venous bypass across the stenotic portion is the treatment of choice. Monoclonal growth of smooth muscle with mutant form p53 might be related to the restenosis.

[Examination of the stability of chloral hydrate and its preparation by capillary electrophoresis]

Stabilities of chloral hydrate in an aqueous solution and its medicated syrup were examined by high performance capillary electrophoresis. Analysis of the concentration of chloral hydrate indicated that there was no obvious change in the concentration of chloral hydrate both in the aqueous solution and in the syrup preparation after keeping them for 3 months at room temperature or at 60 degrees C. The lowering of pH was more obvious in the syrup solution than in the aqueous solution, and this tendency was estimated to be due to the formation of hydrochloric acid. We propose that the stabilities of the preparation of chloral hydrate should be monitored by observing pH changes.

Enhancement of vascular permeability by specific activation of protease-activated receptor-1 in rat hindpaw: a protective role of endogenous and exogenous nitric oxide

1. To clarify the role of the first thrombin receptor/protease-activated receptor (PAR)-1 in an inflammatory process, we tested and characterized the effect of intraplantar (i.pl.) administration of the highly specific PAR-1 agonist TFLLR-NH2 in rat hindpaw. 2. TFLLR-NH2 administered i.pl. at 0.01-0.03 micromol per paw enhanced vascular permeability in the hindpaw and produced paw oedema in a dose-dependent manner. This effect was almost completely abolished by repeated pretreatment with compound 48/80 to deplete inflammatory mediators in mast cells. 3. The NO synthase inhibitor N(G)-nitro-L-arginine methyl ester or N-iminoethyl-L-ornithine, preadministered i.pl., stereospecifically potentiated the i.pl. TFLLR-NH2-induced permeability increase, while the NO donor sodium nitroprusside or NOC-18, given i.pl., suppressed the effect of TFLLR-NH2. 4. These findings demonstrate that specific activation of PAR-1 produces increased vascular permeability accompanied by oedema formation in the rat hindpaw, predominantly via mast cell degranulation, and that endogenous and exogenous NO plays a protective role in the PAR-1-mediated inflammatory event.

How should a subarachnoid hemorrhage grading scale be determined? A combinatorial approach based solely on the Glasgow Coma Scale

OBJECT

The purpose of this study was to present a combinatorial approach used to develop a subarachnoid hemorrhage (SAH) grading scale based on the patient's preoperative Glasgow Coma Scale (GCS) score.

METHODS

There are 4094 different combinations that can be used to compress the 13 scores of the GCS into two to 12 grades. Break points, the positions in the scale in which two adjacent scores connote a significantly different outcome, are obtained by a direct comparison of the GCS and the Glasgow Outcome Scale (GOS). Guided by the break points, the number of combinations to be considered can be limited. All possible combinations are statistically analyzed with respect to intergrade differences in outcome. Single combinations, with the maximum number of grades having maximum intergrade outcome differences for each corresponding set of adjacent grades, must be selected. The authors verified the validity of this combinatorial approach by retrospectively analyzing 1398 consecutive patients with aneurysmal SAH who underwent surgery within 7 days of the last hemorrhage episode. The patients' GCS scores were assessed just before surgery and their GOS scores were estimated 6 months post-SAH. The combinatorial approach yields only one acceptable grading scale: I (GCS Score 15); II (GCS Scores 11-14); III (GCS Scores 8-10); IV (GCS Scores 4-7); and V (GCS Score 3).

CONCLUSIONS

The combinatorial approach, guided by the break points, is so simple and systematic that it can be used again in the future when revision of the grading scale becomes necessary after development of new and effective treatment modalities that improve patients' overall outcome.

[Four cases of abducens palsy caused by a vascular lesion of the vertebrobasilar system]

Several pathological conditions are responsible for abducens palsy, but a lesion of the vertebral artery (VA) has rarely been recognized as one of the causes. It has been reported that a high percentage of cases of abducens palsy are involved with ruptured dissecting aneurysms of the VA. We investigate the vertebrobasilar anatomy in 4 patients, suffering with abducens palsy. One patient revealed a fusiform dilatation of the vertebral artery on the same side as the abducens palsy. Three patients were noted to have stenosis of the vertebral artery from the origin of the posterior inferior cerebellar artery (PICA) to the union. Finally, four patients were found to have abnormal vertebrobasilar anatomy, which was on the same side as the abducens palsy. It is conceivable that changes of vertebrobasilar circulation may cause abducens palsy through direct compression, or ischemic events.

Mobile fluoroscopic open stereotaxy for MRI-negative angiographic microlesions

The approach to the deep-seated angiographic microlesion is often difficult, particularly when it is not demonstrated by computed tomography (CT) or magnetic resonance imaging (MRI). We have developed a method to localize these lesions for open stereotactic surgery employing mobile fluoroscopy. Prior to craniotomy, the patient's head is fixed in a stereotactic frame in a position optimal for the routine microscopic surgery. Following the injection of contrast media, the location of the lesion is marked on the fluoroscope monitor. Under fluoroscopic control, the scalp is marked using radiopaque pointer on each side of the patient's head so that the scalp marks and the target lesion overlap each other on the fluoroscope monitor. Thus the imaginary line connecting these scalp marks passes through the lesion. An additional pair of scalp marks is obtained by changing the projection angle of the fluoroscope. By simple calculation, the coordinates of the lesion are obtained as the nearest point to these two imaginary lines, each of which connects a pair of scalp marks. After craniotomy, the lesion is approached using an open stereotactic technique. The first patient had an aneurysm 1.5 mm in diameter that arose from the feeder of the arteriovenous malformation. The second patient had a small residual nidus of arteriovenous malformation 1.5 cm in diameter in the deep frontal lobe, not recognizable by CT or MRI because of artifacts from a previous surgery. Both patients were successfully operated by employing the present method. This method requires only a conventional stereotactic frame and a mobile fluoroscope, and provides simple and reliable localization of the small lesions recognizable only by cerebral angiography.

Stenting of the extracranial carotid artery in a high-risk population

SUMMARY

The results of nine patients with carotid stenosis in a high-risk surgical population that were treated by stent supported angioplasty are reported. There were eight males and one female between the ages of 53 to 74. A balloon expandable stent was deployed by a transfemoral approach. Technical success was achieved in all cases. There were no periprocedural complications. The mean % stenosis decreased from 84% to 5.2% after stenting. No arterial dissection was recorded and smooth contour of the vessel was demonstrated in all patients. We have observed long term patency for over 6 months in seven patients. Mean angiographic stenosis was 20% and 21% at 3 and 6 months, respectively (range, 5 to 32%). No further stenosis was recorded. Carotid stenting is an alternative strategy to carotid endoarterectomy (CEA) for high-risk patients, for whom the complications of CEA may exceed the potential benefits.

Increased vascular permeability by a specific agonist of protease-activated receptor-2 in rat hindpaw

The present study examined the effect of intraplantar (i.pl.) administration of a selective agonist of protease-activated receptor (PAR)-2, SLIGRL-NH2(PP6-NH2), on vascular permeability in rat hindpaw. PP6-NH2, administered i.pl. at 10-100 nmol per paw, enhanced vascular permeability and caused oedema formation in rat hindpaw. SLIGRL (PP6-OH) and trypsin, by i.pl. administration, also elicited an increase in vascular permeability, although i.pl. administration of the mixture of constituent amino acids of PP6-OH at an equivalent dose did not. The PP6-NH2-induced increase in vascular permeability was abolished by repeated pretreatment with compound 48/80 to deplete bioactive amines in mast cells. These findings suggest that the activation of PAR-2 induces acute inflammation, at least partially, via mast cell degranulation in rat hindpaw.

Selection of severely head injured patients for mild hypothermia therapy

OBJECT

The authors have analyzed the efficacy of inducing mild hypothermia (34 degrees C) in 62 severely head injured patients to control fulminant intracranial hypertension.

METHODS

All 62 patients fulfilled the following criteria: 1)persistent intracranial pressure (ICP) greater than 20 mm Hg despite fluid restriction, hyperventilation, and high-dose barbiturate therapy; 2) an ICP lower than the mean arterial pressure; and 3) a Glasgow Coma Scale (GCS) score of 8 or less on admission. The patients were divided into three groups based on computerized tomography findings: extracerebral hematoma (34 patients with subdural and/or epidural hematoma), focal cerebral lesion (20 patients with localized brain contusion and/or intracerebral hematoma), and diffuse swelling (eight patients with no focal mass lesion). Mild hypothermia prevented ICP elevation in 35 (56.5%) of the 62 patients whose ICP was greater than 20 mm Hg despite conventional therapies. Among those 35 patients whose ICP was controlled by mild hypothermia, 12 (34.3%) achieved functional recovery (good outcome or moderate disability). However, functional recovery was observed in only five (10.9%) of the 46 patients whose ICP was greater than 40 mm Hg after conventional therapies. Of 40 patients with an admission GCS score of 5 to 8, there were 11 (27.5%) who achieved functional recovery. On the contrary, mild hypothermia was not effective in 22 patients with an admission GCS score of 3 or 4. In the patients with focal cerebral lesions, ICP was controlled by mild hypothermia in 17 patients (85%) and patient outcome was intimately related to the extent of the damage. Among 18 patients with extracerebral hematoma who had a midline shift of 9 to 12 mm, raised ICP could be successfully controlled by mild hypothermia in 16 patients (88.9%) and three (16.7%) achieved functional recovery. However, ICP could not be controlled in patients with extracerebral hematoma who had a midline shift of 13 mm or more. In patients with diffuse swelling, ICP elevation could not be prevented at all by mild hypothermia.

CONCLUSIONS

The authors conclude that mild hypothermia is effective for preventing ICP elevation in patients without diffuse brain swelling in whom ICP remains higher than 20 mm Hg but less than 40 mm Hg after conventional therapies.

[Japan Coma Scale as a grading scale of subarachnoid hemorrhage: a way to determine the scale]

BACKGROUND

The grading scale for subarachnoid hemorrhage (SAH) with inter-grade outcome differences is essential for evaluating the effectiveness of newly developed therapeutic modalities. Although Hunt's grade and WFNS scale have been widely used, these grading scales do not meet this requirement. We previously proposed a revised WFNS scale based solely on the Glasgow Coma Scale (GCS) that has intergrade outcome differences of high-level significance. The Japan Coma Scale (JCS) has been long and widely used in Japan. The purpose of this study is to show whether it is possible to determine a reasonable SAH grading scale based on the JCS and to show a way to determine an SAH grading scale.

PATIENTS AND METHODS

We retrospectively analyzed 1398 consecutive cases of aneurysmal SAH operated on within Day 7 of the latest onset. The preoperative JCS and GCS were evaluated just before the surgery and the Glasgow Outcome Scale (GOS), analyzed with numerical transformation (1 = dead to 5 = good recovery), was estimated at 6 months after the onset. All 510 possible combinations of scores of JCS were statistically tested under the following 2 assumptions; (1) JCS = 0 and JCS = 100 fall into a single independent grade. (2) No other single JCS score should fall into a single grade.

RESULTS

The outcome differences between JCS 0 and 1, and 100 and 200 are significant. The outcome difference between JCS 30 and 100 is relatively higher than any other set of 2 scores of JCS. Only 5 combinations are practical among the candidates to be analyzed. Out of 510 combinations, the following combination shows the highest inter-grade outcome differences; I (JCS = 0, n = 375, mean GOS = 4.78) II (JCS = 1, 2; n = 310; mean GOS = 4.47) III (JCS = 3-30; n = 476; mean GOS = 3.96) IV (JCS = 100; n = 96; mean GOS = 3.10) V (JCS = 200, 300; n = 141; mean GOS = 2.33). In JCS, the mean outcome of JCS = 3 is worse than those of JCS = 10, 20, and 30. The outcome difference between JCS 0 and 1 is only significant in patients over 60 years old.

CONCLUSION

Taking all the 510 possible combinations of JCS into consideration, we obtained a reasonable combination containing 5 grades. Although this grading scale showed good inter-grade outcome differences, JCS is not preferable to GCS as a consciousness evaluation system in the acute phase of SAH. We emphasize the importance of this way to determine a grading scale with a combinatorial approach, which can be applicable for re-evaluating the grading scales in the future.

Asymmetrical regulation of blood pressure in the rat medulla

The effects of microinjection of serotonin-1 (5-HT1) antagonist methiothepin and 5-HT1 agonist buspirone into the nucleus reticularis parvocellularis were investigated in the anaesthetized rats. Methiothepin produced an increase in arterial blood pressure when injected into the left side, but it did a decrease when injected into the right side. On the contrary, buspirone produced a decrease in arterial blood pressure when injected into the left side, but it did an increase when injected into the right side. These findings provide the clue to clarify that there is a reciprocal regulation of arterial blood pressure between the left and right sides in the rat medulla.

Asymptomatic hypothalamic hamartoma associated with an arachnoid cyst--case report

A 42-year-old male presented with the complaint of mild left facial numbness. Magnetic resonance imaging demonstrated a solid tumor in the interpeduncular cistern and a huge arachnoid cyst in the left middle cranial fossa. The tumor appeared isointense to the surrounding cerebral gray matter on T1-weighted images and hyperintense to that on T2-weighted images. The tumor was partially resected. Histological findings were characteristic of hamartoma. The mild left facial numbness was probably due to compression of the left trigeminal nerve by the arachnoid cyst. Asymptomatic hypothalamic hamartomas may occur in adults with atypical clinical presentations.

Monitoring of cerebrospinal fluid pressure during embolization of AVM

We experienced that therapeutic embolization of a large cerebral arteriovenous malformation (AVM) led to venous outflow obstruction resulting in intracranial hypertension in a patient who had undergone external decompression. To evaluate hemodynamic changes after embolization, we monitored the cerebrospinal fluid pressure in the next four patients who underwent endovascular treatment. The embolization of a medium AVM resulted in a slight increase in the cerebrospinal fluid pressure. In two medium AVMs, embolization produced slight decreases in the cerebrospinal fluid pressure. In a small AVM, we did not observe any changes in the cerebrospinal fluid pressure during the endovascular treatment. We discuss the mechanism of changes in the intracranial pressure after embolization and conclude that monitoring of the cerebrospinal fluid pressure immediately yields useful information for hemodynamic changes during endovascular treatment.

Traumatic laceration of the intracranial vertebral artery causing fatal subarachnoid hemorrhage: case report

A 36-year-old man who had been drinking alcohol had a fatal subarachnoid hemorrhage immediately after suffering a moderate craniofacial injury. Autopsy revealed a 3-mm longitudinal laceration of the left intracranial vertebral artery proximal to the posterior inferior cerebellar artery. There was no finding of arterial dissection. We discuss the mechanisms of the traumatic laceration of the vertebral artery in relation to traumatic dissection of the vertebral artery.

Traumatic subarachnoid hemorrhage as a predictable indicator of delayed ischemic symptoms

This report provides findings of an investigation of the influence of traumatic subarachnoid hemorrhage on the development of delayed cerebral ischemia caused by vasospasm. The authors prospectively studied 130 patients with closed-head trauma, who exhibited subarachnoid blood on admission computerized tomography (CT) scans. Ten (7.7%) of these patients developed delayed ischemic symptoms between Days 4 and 16 after the head injury. They consisted of three (3.0%) of 101 patients with small amounts of subarachnoid blood and seven (24.1%) of 29 patients with massive quantities of subarachnoid blood on admission CT scans. In each of the 10 patients, severe vasospasm was demonstrated by angiography performed soon after development of ischemic symptoms. There was a close correlation between the main site of the subarachnoid blood and the location of severe vasospasm. In seven of the patients, follow-up CT scans showed development of focal ischemic areas in the cerebral territories corresponding to the vasospastic arteries. These results demonstrate that traumatic subarachnoid hemorrhage, especially if massive, is a predictable indicator of delayed ischemic symptoms.

Electrophysiological changes in substantia nigra after striatal infarction

The GABAergic efferent pathway from the striatum exerts inhibitory control on the substantia nigra pars reticulata (SNR) neurones. We studied sequential changes in spontaneous single-unit activities in the ipsilateral SNR 1 h, 1 day, 7 days and 14 days after striatal infarction induced by middle cerebral artery occlusion (MCAO) in rats. Compared with a sham-operated group, there was no change in the firing rate 1 h after MCAO, and one day after MCAO the mean firing rate decreased. The firing rate of SNR neurones at 7 and 14 days after MCAO was significantly reduced compared with the sham-operated group. Only two neurones (sham-operated group and 1 h after MCAO group) fired with high frequency. Histological examination revealed degeneration of the ipsilateral SNR 7 and 14 days after MCAO. Our results indicated that SNR neuronal degeneration accompanied by striatal ischaemia does not simply depend on hyperexcitation due to the activation of a disinhibition mechanism.

Expression of bone-related protein messenger RNA in human meningiomas: possible involvement of osteopontin in development of psammoma bodies

Meningiomas often contain concentric calcified foci, referred to as psammoma bodies. Since calcium phosphate deposits in both psammoma bodies and bone tissues, we examined whether messenger (m) RNA of bone-related extracellular matrix proteins and bone morphogenetic proteins (BMP) were expressed in human meningioma tissues. Northern blotting demonstrated the expression of osteopontin (OPN), matrix Gla protein (MGP), osteonectin (ON) and BMP-4 mRNA but not bone sialoprotein, osteocalcin and BMP-2 mRNA. In situ hybridization revealed that most OPN mRNA-expressing cells were located around the psammoma bodies in meningothelial whorls. Moreover, combination of in situ hybridization and immunohistochemistry on serial sections showed that the OPN mRNA-expressing cells were CD68-positive, suggesting they were macrophages. Immunohistochemistry with anti-OPN antibody and von Kossa staining on the adjacent section showed that the deposition site of OPN protein was consistent with that of calcium phosphate. Neither MGP nor ON mRNA expression appeared to correlate with the calcification. The present result suggests that OPN produced by CD68-positive macrophages may play a significant role for development of psammoma bodies in meningiomas.

A new animal model of cerebral infarction: magnetic embolization with carbonyl iron particles

A new animal model of cerebral infarction was developed by magnetic embolization with carbonyl iron particles. An electromagnet was placed upon the lateral portion outside the orbit of Mongolian gerbils and charged with a current intensity of 2 A, 3 V (400 G) for 10 min. By intracardiac injection of iron particles at the beginning of the electric charge, infarction was selectively produced in the cerebral cortex. Two days after the operation, microhemorrhaging was seen in the necrotic region. Multiple scattered infarctions accompanied with microhemorrhagic signs closely resembled embolic infarction encountered in the human brain.

Endoscopic-image display system mounted on the surgical microscope

This report describes a newly developed endoscopic-image display system which is mounted on the optical unit of the surgical microscope. This system permits the neurosurgeon to watch the endoscopic image through one of the eye lenses of a surgical microscope during application of neurosurgical endoscopy under open microsurgical procedures. It frees the neurosurgeon from the major conventional inconvenience that he has to discontinue watching the microscopic view in order to look at the endoscopic images through the ocular of the endoscope or on the video monitor.

Mechanical detachable coil as a therapeutic alternative for cerebral aneurysm

Endovascular treatment for unruptured cerebral aneurysms has been recognized as a useful alternative. Various types of intravascular materials embolizing aneurysms were classified into one of two groups. One was retrievable after the placement, whereas the other was irretrievable. The former which has involved detachable coils is preferred, because it can be repositioned repeatedly, while it forms the most effective arrangement. In this report, we present a compromised patient who was a 68 year-old female suffering angina pectoris and was treated with an interlocking detachable coil. Technical points are discussed here compared with Guglielmi's detachable coil.