Protective effect of phenytoin and its enhanced action by combined administration with mannitol and vitamin E in cerebral ischaemia

The efficacy of antioxidants in functional recovery of spinal cord injured rats: an experimental study

A total of 30 female Sprague-Dawley rats (180-220 g) subjected to spinal cord injury (SCI) were divided into three groups of ten rats each. Group 1 served as control (SCI + Saline), Group 2 received daily dose of ascorbic acid 2,000 mg/kg body weight and group 3 rats received alpha tocopherol daily with the dose of 2,000 mg/kg body weight for 14 days. The Spontaneous coordinate activity (SCA), Basso, Beattie, and Bresnahan (BBB) and Tarlov locomotor scores were used to assess functional recovery of SCI rats. Compared to group 1, group 2 showed statistically insignificant improvement in the SCA, BBB and Tarlov scores at the end of the study. Compared to group 1, group 3 showed statistically significant improvement in the SCA (P < 0.001), BBB (P < 0.001) and Tarlov (P < 0.01) scores at the end of the study. In conclusion, the administration of alpha-tocopherol enhances the reparative effects against SCI and it is more effective than ascorbic acid.

Neuroprotective effects of L-carnitine and vitamin E alone or in combination against ischemia-reperfusion injury in rats

BACKGROUND

Neurological injury because of transient cerebral ischemia is a potential complication of cardiovascular surgery. In this study, the neuroprotective effects of L-carnitine, vitamin E, and the combination of these agents on ischemia/reperfusion (I/R) injury were determined in a rat model of transient global cerebral I/R.

METHODS

Rats were pretreated with L-carnitine (100 mg/kg, i.v.) and vitamin E (50 mg/kg, i. v.), alone or in combination and then subjected to cerebral I/R induced by a four-vessel-occlusion technique for a duration of 15 min followed by 15 min of reperfusion. Malondialdehyde (MDA) levels, superoxide dismutase (SOD) activity, and glutathione (GSH) levels were measured in the cerebral tissues. Histopathological examinations were also carried out under light and electron microscopy.

RESULTS

The results showed that I/R elevated MDA levels, which were accompanied by a reduction in SOD activities and GSH levels. Surviving neurons was markedly decreased in CA1 and CA3 subfield of hippocampus in I/R animals. L-carnitine, vitamin E, and their combination restored MDA levels and SOD activities, with a tendency to increase surviving neurons in CA1 and CA3 subfield. Combined treatment of L-carnitine and vitamin E had better GSH levels than individual treatment of these agents.

CONCLUSIONS

The results suggest that L-carnitine has a potent neuroprotective effect against cerebral-I/R-induced injury in rat brain that is comparable to that of vitamin E. However, the combined use of L-carnitine and vitamin E does not further protect from neuronal injury, although it provides an increase in GSH levels.

Possible neuroprotective effects of lecithin and alpha-tocopherol alone or in combination against ischemia/reperfusion insult in rat brain

A close correlation exists between ischemia/reperfusion (I/R)-induced insult and the release of free radicals. Lecithin is a polyunsaturated phosphatidylcholine that corresponds to the phosphatidylcholine molecule. Phosphatidylcholines are high-energy functional and structural elements of all biologic membranes. alpha-Tocopherol is the major lipid-soluble chain-breaking antioxidant in the body tissues and effectively protects against neuronal damage. Therefore, we studied the effect of lecithin (300 mg/kg, p.o., 14 days) and alpha-tocopherol (200 mg/kg, p.o., 14 days), alone or in combination, on the brain redox state during I/R. Adult male Wistar rats were subjected to global ischemia by the occlusion of the two carotid arteries 24 h after the last dose of drug administration. Reperfusion was carried out 1 h after induction of ischemia and lasted for another hour. Brain lipid peroxides (MDA) and glutathione (GSH) contents, as well as superoxide dismutase (SOD) and catalase (CAT) activities were assessed. The results showed that I/R elevated brain lipid peroxides content which was accompanied by a reduction in both antioxidant enzyme activities, however, brain GSH level remained unaltered. Lecithin, alpha-tocopherol and their combination restored MDA content, as well as CAT activity with a slight tendency to normalize SOD activity. We conclude that lecithin has a possible neuroprotective effect partly through its antioxidant action which is comparable to that of alpha-tocopherol.

Phenytoin-induced hyperglycaemia may confound rat cerebroprotection models

1. The anticonvulsant phenytoin (PHT) has been used with variable success in animal models of cerebral ischaemia. Although PHT has been reported to alter glucose regulation in man, this potential effect has been largely ignored in animals. Because hyperglycaemia strongly influences the outcome of cerebral ischaemia, we sought to systematically delineate the effects of PHT on serum glucose in several rat strains. 2. We studied the PHT dose-response curve for serum PHT and glucose concentrations and several physiological variables. Phenytoin induces a significant, concentration-dependent hyperglycaemia, even in the ranges commonly used for humans and in animal models. 3. Hypothermia of several degrees was observed during PHT administration, but no hypotension or bradycardia was found. 4. Both hyperglycaemia and hypothermia must be considered when PHT is studied as a neuroprotective agent in animal models.

The effect of mannitol on experimental cerebral ischemia, revisited

The effect of 20% mannitol on ischemic neuronal injury was examined in male Wistar rats (n = 80) that were randomly divided into forebrain and focal ischemia groups. The animals were further subdivided into control, treatment with mannitol before ischemia (1 g/kg of body weight, 12 min before ischemia), and treatment with mannitol after ischemia (0.25 g/kg of body weight, beginning 20 min after ischemia and then every 6 h for 48 h) groups. Physiological parameters were carefully monitored and maintained within normal limits. The administration of mannitol after ischemia was found to produce a statistically significant improvement in ischemic neocortical injury and selective neuronal necrosis in the neocortex in the forebrain and focal models, respectively. However, treatment with mannitol after ischemia was shown not to favorably alter histopathological outcome in hippocampal levels 2 through 7 in the forebrain model nor did not reduce infarct volume in the focal ischemia group. Treatment with mannitol before ischemia did not produce statistically significant reductions in neuronal injury in either model. These results do not support the findings of previous investigations, which have demonstrated that mannitol affords a significant degree of neuroprotection when administered either before or immediately after vessel occlusion in models of forebrain and focal cerebral ischemia. The neuroprotective effect of mannitol demonstrated in the neocortex of both forebrain and focally ischemic rats may support the theory that the main mechanisms responsible for neocortical injury in ischemia differ from those in the striatum hippocampus. Finally, mannitol's ability to reduce ischemic neuronal injury most effectively when administered after rather than before the production of ischemia is consistent with a possible beneficial influence on the development of delayed cerebral edema.

Effect of balloon angioplasty on high grade symptomatic vasospasm after subarachnoid hemorrhage

Of 455 cases of ruptured intracranial aneurysm treated with radical surgery from January 1987 to March 1992, 19 cases with high grade symptomatic vasospasm were treated by percutaneous transluminal balloon angioplasty (PTA). The indication for PTA was high grade symptomatic vasospasm which does not respond to conservative medical treatment. Of the 36 segments of vasospastic arteries, severe vasospasm (angiographical constriction more than 50% of diameter on admission) was observed in 67%. PTA dilated these vasospastic arteries significantly (diameter of more than 75% of diameter on admission) in 83%. Follow up angiography revealed neither recurrence of vasospasm nor chronic atherosclerotic changes. Clinical improvement within 24 hours after PTA was observed in 63% of cases (7 of 17 cases with consciousness disturbance, 5 of 16 cases with motor weakness and one of 7 cases with aphasia). Outcomes at the time of discharge were excellent in 10 cases, good in 3, fair in 4, and lethal in 2. SPECT study before and after PTA confirmed improvement of cerebral blood flow in 3 out of 5 cases investigated. PTA for high grade symptomatic vasospasm after subarachnoid hemorrhage is considered an effective treatment method for the patient who does not respond to medical therapy. Immediate improvement of angiographical and clinical findings were frequently observed immediately after PTA. Exact indication and timing of PTA should be postulated after much more cases have been treated with this methal.

Hypothermic circulatory arrest and other methods of cerebral protection during operations on the thoracic aorta

Current surgical techniques in operations on the thoracic aorta frequently require exclusion of the cerebral circulation for varying periods. During these periods, hypothermic circulatory arrest (HCA), selective cerebral perfusion (SCP), and retrograde cerebral perfusion (RCP) can be used for cerebral protection. Hypothermia is the principle component of these methods of protection. The main protective effect of hypothermia is based on reduction of cerebral energy expenditures and largely depends on adequate suppression of cerebral function. It is most effective at deep hypothermic levels (13 degrees C to 15 degrees C). Measures that preserve autoregulation of cerebral blood flow help increase the margin of safety with all methods of protection. There is solid experimental and clinical data indicating the safe limits and outcome following HCA. Current applications of SCP and RCP are fairly recent developments and do not have comparable supporting data. SCP can be used without deep hypothermia and allows prolonged periods of cerebral protection, but is complex in application. RCP is simpler, but always requires deep hypothermia. Present clinical data do not allow separation of its protective effect from that of HCA alone. Recent modifications in the application of HCA include monitoring of cerebral O2 extraction, and selective use of supplemental SCP to limit arrest times to less than 50 minutes, or RCP to prevent embolic strokes, as indicated. These changes appear to have reduced the overall mortality, the severity of embolic strokes, and stroke-related mortality.

Effects of the conventional anticonvulsants, phenytoin, carbamazepine, and valproic acid, on sodium-potassium-adenosine triphosphatase in acute ischemic brain

The effects of phenytoin, carbamazepine and valproic acid on alterations in sodium-potassium-adenosine triphosphatase activity during ischemia were studied in the rat brain. Pretreatment with phenytoin and carbamazepine prevented a reduction of this activity, which, without either treatment, was observed in the cerebral hemisphere exposed to 30-minute ischemia resulting from unilateral middle cerebral artery occlusion. Valproic acid, on the other hand, did not principally affect the ischemic impairment of this membrane-bound enzyme activity. These results lend support to the previously proposed use of phenytoin in cerebral ischemia, but also suggest the therapeutic availability of another common anticonvulsant, carbamazepine, for treatment of the insult.

Direct clipping of basilar trunk aneurysms using temporary balloon occlusion

In the surgical treatment of basilar trunk aneurysms, there is still considerable technical difficulty in gaining both proximal artery control and a sufficient operative field. The authors describe their experience in five patients with basilar trunk aneurysms treated using temporary balloon occlusion and intraoperative digital subtraction angiography. With the patient under general anesthesia, a heparinized angiography catheter was guided into the dominant vertebral artery by means of the Seldinger technique. A silicone balloon catheter was introduced coaxially through the angiography catheter to the basilar artery just proximal to the aneurysm. The balloon was inflated tentatively to evaluate the appropriate inflation volume, then the balloon catheter was withdrawn back into the angiography catheter to prevent thrombus formation. After exposure of the aneurysm, the occlusion balloon was advanced again and inflated temporarily within the basilar artery to prevent premature rupture and to facilitate dissection of the aneurysm. The mean duration of temporary balloon occlusion was 22 minutes. There were no patients with postoperative deficits attributable to the temporary occlusion. The results of aneurysm clip placement were confirmed by intraoperative digital subtraction angiography immediately after clipping. No patient suffered from distal embolism or other complications related to vessel catheterization. From this experience, it is concluded that this intraoperative endovascular technique can contribute to the success of surgery for complex cerebral aneurysms, particularly for basilar trunk aneurysms in which proximal vascular control is difficult.

Combined endovascular and neurosurgical approach for paraclinoid internal carotid artery aneurysms

The authors review the surgical management of nine complex paraclinoid aneurysms treated with the endovascular balloon catheter technique. With the patient under general anesthesia, the balloon catheter was guided into the feeding artery of the aneurysm by the Seldinger technique. After the aneurysm was exposed, the balloon was inflated temporarily to prevent premature rupture and to facilitate the dissection of the aneurysm. For the larger paraclinoid aneurysm, the double-lumen catheter was introduced into the cervical internal carotid artery (ICA). After temporarily trapping the aneurysm by balloon occlusion of the cervical ICA and clipping the intracranial ICA distal to the aneurysm, retrograde aspiration was performed to collapse the aneurysm. The complete collapse of the large aneurysm by this technique allows an easier dissection of the aneurysm and a safer application of suitable clips. Such a retrograde suction decompression method was used in six large aneurysms. Intraoperative digital subtraction angiography was performed in all cases after the aneurysmal clipping; in three aneurysms, repositioning the clip was required. Only one case of embolic complication was related to the vessel catheterization in this series, which was discovered during the operation. An embolectomy was performed immediately, and there were no postoperative sequelae. We conclude that the combined endovascular and neurosurgical approach, particularly for the large ICA aneurysms, which are difficult to control proximally, can be a useful method of treatment. To prevent complications related to thrombus formation, further refinement in the balloon catheter itself is still needed.

Permissible temporary occlusion time in aneurysm surgery as evaluated by evoked potential monitoring

To clarify the permissible time for temporary vascular occlusion during aneurysm surgery, we have undertaken a retrospective analysis of the results of intraoperative median nerve somatosensory evoked potential (SEP) monitoring in 97 patients with middle cerebral artery (MCA) (46 patients) or internal carotid artery (ICA) (51 patients) aneurysms. All patients underwent temporary vascular occlusion, lasting from 2 to 70 minutes, under the administration of a mixed solution of 20% mannitol with phenytoin and vitamin E. The mean occlusion time was 20.3 minutes for the MCA patients and 15.8 minutes for the ICA patients. The SEP disappeared during occlusion in 42 patients (30 MCA and 12 ICA). All but three eventually recovered the SEP to the baseline level after recirculation, and none of the 39 patients had postoperative sequelae. The time period from the start of occlusion until the complete loss of the SEP averaged 8.6 minutes among these 39 patients, and the occlusion time from total SEP loss until recirculation averaged 12 minutes. In the remaining 3 of the 42 patients (all 3 being ICA aneurysm patients), however, the SEP did not recover after recirculation and all 3 patients showed postoperative sequelae. In two of these three patients, vascular occlusions were performed at the multiple sites (i.e., at the ICA, MCA, anterior cerebral artery, and posterior communicating artery) and the SEP disappeared rapidly after the occlusion.(ABSTRACT TRUNCATED AT 250 WORDS)

Acute revascularization for progressing stroke

The effectiveness of acute stage vascular reconstruction in cases of progressing stroke is reported. The clinical material consists of 28 cases of progressing stroke in the anterior circulation upon which vascular reconstruction was performed. Following admission, brain protective substances (500 ml mannitol, 500 mg vitamin E, 500 mg phenytoin) and dextran, were administered to the patients, and induced hypertension was also performed. Changes in symptoms were then observed and vascular reconstruction was carried out in cases where symptoms progressed. The vascular lesion was on the internal carotid artery in 8 cases and on the middle cerebral artery in 20 cases. Complete disappearance of neurological symptoms was obtained in 12 cases, whereas only mild neurological symptoms remained but a return to normal social life was possible in 11 other cases. Symptoms remained in three cases and there were two fatalities. In a long-term follow-up study, there were no cases of aggravation of symptoms due to ischaemic stroke. Moreover, the reconstruction was judged as effective on the basis of cerebral blood flow and metabolism. We concluded that acute vascular reconstruction for progressing stroke under the administration of brain protective substances is effective in preventing the progression of neurological symptoms.

Treatment of proximal vertebral artery stenosis. Vertebral to subclavian transposition

For vascular reconstruction in cases of atherosclerotic stenosis at the origin of the vertebral artery, we use vertebral to subclavian artery transposition. We discuss the advantages and effectiveness of such treatment based on a study of 32 cases. We have experienced neither surgical mortality nor morbidity and the outcome at the time of discharge has been favourable. Follow-up revealed no deaths, however, three cases exhibited symptoms of cerebral ischaemia. One had a supratentorial completed stroke, and the other two hat TIA or RIND, but without any notable lesion in the angiograms. There were no cases of cerebral infarction of the posterior fossa. We believe that this method should be the first choice for treatment of cases without lesions of the subclavian artery for the following reasons: serious operative complications have not been encountered, surgical invasion is minimal, temporary occlusion of the common carotid artery is unnecessary, the operation can be done by occluding only the vertebral artery, and unlike various bypass operations, anastomosis is required at only one location and is consequently technically uncomplicated. Following anastomosis the cerebral blood pathway is physiological.

Phenytoin affects metabolism of free fatty acids and nucleotides in rat cerebral ischemia

We investigated the effects of phenytoin on the rate of enzymatic release of free fatty acids and on the levels of energy metabolites and nucleoside phosphates in ischemic brain. Phenytoin (10 mg/kg i.v.) was administered 30 minutes before the onset of ischemia induced in 30 male Wistar rats by occluding the basilar and both common carotid arteries. The rats' brains were frozen in situ after 0, 5, or 30 minutes of ischemia or 10, 30, or 60 minutes of recirculation following 30 minutes of ischemia (n = 5 at each time). Nucleoside triphosphate levels were higher in the phenytoin-treated rats than in corresponding untreated rats at each time during and after ischemia. Phenytoin significantly attenuated the accumulation of lactate and free fatty acids (arachidonic acid and stearic acid) during ischemia and accelerated their recovery during recirculation. These results suggest that phenytoin has favorable protective effects on ischemic brain and that phenytoin may inhibit calcium-mediated phenomena, especially the inositol cycle, in cerebral ischemia.

Actions of brain-protecting substances against both oxygen and glucose deprivation in the guinea pig hippocampal neurons studied in vitro

A study was made of the protective effects of several drugs (mannitol, phenytoin, vitamin E and dexamethasone) on the electrical activities of guinea pig hippocampal neurons in vitro when they were treated with a bathing medium deprived of both oxygen and glucose. Using guinea pig hippocampal slices, antidromic field potentials in the granular cell layer of the dentate gyrus were recorded stimulating mossy fibers. A model of ischemia in vivo in the slices was achieved by removing both oxygen and glucose from the perfusing medium. In standard medium, after 10 min of both oxygen and glucose deprivation, the field potentials exhibited minimum recovery with an amplitude of 6% of the control after 60 min. The protective effect of the drugs was evaluated by recovery of the field potential amplitude of the 60 min post-deprivation response and histological examination of the brain slice tissue. Drugs were added during 30 min of pre-deprivation and during deprivation. In this experiment we demonstrated that (1) phenytoin and vitamin E clearly showed protective action against neuronal damage caused by both oxygen and glucose deprivation in guinea pig hippocampal slices, (2) combined application of these drugs was more effective, and (3) mannitol showed no protective action in vitro. It was also demonstrated that (4) the dentate antidromic field response can be a useful index of cell death.

Surgical treatment of multiple aneurysms. Review of experience with 372 cases

We review the surgical results in 372 cases of multiple intracranial aneurysms over a 25-year period in which one of us (JS) performed 2,000 direct operations for aneurysms. All patients were classified into four groups according to the location of the aneurysm: Group 1: multiple aneurysms including anterior communicating artery aneurysm (157 cases); Group 2: multiple aneurysms of unilateral anterior circulation (72 cases); Group 3: multiple aneurysms of bilateral anterior circulation (110 cases); Group 4: multiple aneurysms including vertebro-basilar artery aneurysms (33 cases). In multiple aneurysm cases, our policy has been to treat all aneurysms, ruptured and unruptured, in a one-stage operation whenever possible. About 90% of patients in both Group 1 and 2 were treated by one-stage operations, while 60% of patients in Group 3 and 42% of patients in Group 4 were operated on in the same manner. Excellent and good results in from 73% to 81% of cases were obtained in patients in Group 1, Group 2 and Group 3. Morbidity was 14-19% and mortality was 6-8%. These results were comparable to the results with a single aneurysm of the anterior circulation. On the other hand, the surgical results in Group 4 were poor with a mortality of 27%. Poor results were attributable to the postoperative rebleeding from the untreated vertebro-basilar aneurysms, which were thought to be unruptured aneurysms preoperatively. Furthermore, it was clarified that the results of early one-stage operations (within one week from onset) in patients with multiple aneurysms were satisfactory. In this group, there was good recovery in 84% of patients, 7% were disabled and 9% died.(ABSTRACT TRUNCATED AT 250 WORDS)