Sen Yamagata

The introduction of microvascular surgery to hepatic artery reconstruction in living-donor liver transplantation : its surgical advantages compared with conventional procedures

&NA; Microvascular surgery for the reconstruction of the graft artery has been used since the 8th case in our series of 14 liver transplantations using living-related donors, and the clinical results have been compared between the first seven cases (the Loupe group) and the last seven cases (the Micro group). Seven arteries in 7 grafts were reconstructed with the use of loupe magnification in the Loupe group, while 8 arteries in 7 grafts were anastomosed with microscopic techniques in the Micro group. Statistically, there was no difference between the two groups in general background, including age, body weight and primary disease of the recipient, and in medical and surgical factors possibly relating to postoperative thrombosis of the hepatic artery.In two cases in the Loupe group, one or two additional reconstructions were necessary to obtain sufficient blood flow, while 8 arteries were anastomosed in the Micro group without any arterial complication in the postoperative period. There was no difference in time required for completing the arterial reconstruction (45.1±18.1 min in the Loupe versus 44.4±6.9 min in the Micro [mean±SEM]). Postoperative ultrasonic Doppler duplex study demonstrated a temporary decrease in the arterial flow in 2 cases of the Loupe group, and partial thrombosis of the artery was suspected. Additionally there were two episodes of hepatic artery thrombosis in 1 case of the Loupe group, in which emergent revision for thrombectomy and reanastomosis was performed at the first episode. This illustrated the higher incidence of arterial complications in the Loupe group compared with the Micro group (4 episodes/7 arteries in the Loupe versus 0/8 arteries in the Micro, P<0.05). In the present series there were no graft failures or arterial complications in the three deaths in the series. The clinical improvements achieved by micro-vascular surgery in living-donor liver transplantation suggest an alternative technical strategy for dealing with problematic arterial reconstruction in adult liver transplantation.

Independent predictors for recurrence of chronic subdural hematoma: a review of 343 consecutive surgical cases.

OBJECTIVE Chronic subdural hematoma (CSDH) is a common form of intracranial hemorrhage with a substantial recurrence rate. We focused on determining independent predictors associated with the recurrence of CSDH. METHODS We retrospectively reviewed 343 consecutive surgical cases of CSDH. Univariate and multivariate analyses were performed to describe the relationships between recurrence of CSDH and factors such as sex, age, hypertension, diabetes mellitus, heart disease, cerebrovascular disease, atrial fibrillation, antiplatelet or anticoagulant therapy, and bilateral CSDH. RESULTS Sixty-one patients experienced a recurrence of CSDH. Univariate and multivariate analyses found that bilateral CSDH was an independent risk factor for the recurrence of CSDH. Although antiplatelet and anticoagulant therapy had no significant effect on recurrence of CSDH, the time interval between the injury and the first operation for patients with antiplatelet and/or anticoagulant therapy was shorter than that for patients without it (29.9 versus 44.2 days). CONCLUSION Bilateral CSDH was an independent predictor for the recurrence of CSDH. Antiplatelet or anticoagulant drugs might facilitate the growth of CSDH. These results may help to identify patients at high risk for the recurrence of CSDH.

Milrinone for the treatment of cerebral vasospasm after subarachnoid hemorrhage: report of seven cases.

OBJECTIVEThe intra-arterial infusion of papaverine has been used for dilation of spastic cerebral vessels after aneurysmal subarachnoid hemorrhage, although its efficacy is controversial. Milrinone is an inotropic drug that dilates vessels by phosphodiesterase inhibition in a mechanism similar to that of papaverine. We examined the effects of intra-arterial and subsequent intravenous administration of milrinone on patients with symptomatic cerebral vasospasm. METHODSSeven patients with cerebral vasospasm were enrolled in this study. Milrinone was delivered intra-arterially via catheter at a rate of 0.25 mg/min. The total delivered dose was between 2.5 and 15 mg. Radiological measurement of the middle cerebral artery diameter and cerebral blood flow was carried out before and after arterial infusion. Intravenous treatment followed at 0.50 or 0.75 &mgr;g/kg/min for up to 2 weeks from the onset of subarachnoid hemorrhage. RESULTSDilation of the vasospastic vessels occurred in all patients. The rate of cerebral blood flow was calculated in six patients and was increased in all. Subsequent intravenous infusion was effective in preventing a recurrence of symptomatic vasospasm in four of the seven patients. CONCLUSIONIt is suggested that milrinone was effective and safe for the treatment of cerebral vasospasm after subarachnoid hemorrhage in the patients in this series. Intra-arterial infusion with adjunctive intravenous infusion holds promise as a clinically advantageous treatment regimen.

Effects of Hypoxia on the Activity of the Dopaminergic Neuron System in the Rat Striatum as Studied by In Vivo Brain Microdialysis

The purpose of the present study is to clarify the effects of hypoxia on the activity of the dopaminergic neurons in the brain and its mechanism of action. For this purpose, the effects of hypoxia on the extracellular levels of 3,4‐dihy‐droxyphenylethylamine (dopamine) were examined in the rat Striatum using in vivo brain microdialysis in the presence or absence of pretreatment with either tetrodotoxin (a blocker of voltage‐dependent sodium channels) or nomifensine (a blocker of dopamine reuptake). Exposure to various degrees of hypoxia (15, 10, and 8% O2 in N2) increased dopamine levels in striatal dialysates to 200, 400, and 1,100%, respectively, of the control value. On reoxygenation, dopamine levels in the dialysates rapidly returned to the control level. Reexposure to hypoxia increased the dopamine levels to the same extent as during the first exposure. After addition of tetrodotoxin (40 mUM) to the perfusion fluid or pretreatment with nomifensine (100 mg/kg, i.p.), exposure to hypoxia no longer increased the dopamine levels. These results suggest that although hypoxia induces an increase in the extracellular dopamine levels (hence, an apparent increase in the activity of the dopaminergic neurons), this increase is not the result of an increase in dopamine release itself, but rather the result of inhibition of the dopamine reuptake mechanism.

Characterization of atherosclerotic plaque of carotid arteries with histopathological correlation: Vascular wall MR imaging vs. color Doppler ultrasonography (US)†

To investigate whether the vessel wall MRI of carotid arteries would differentiate at‐risk soft plaque from solid fibrous plaque by identifying liquid components more accurately than color Doppler ultrasonography (US).

Association Between Carotid Atherosclerosis Plaque With High Signal Intensity on T1-Weighted Imaging and Subsequent Ipsilateral Ischemic Events

BACKGROUND:An association between magnetic resonance imaging detection of intraplaque hemorrhage and the risk of cerebral ischemic events has been described. However, few studies have followed patients with intraplaque hemorrhage. OBJECTIVE:We used 3-dimensional gradient-echo black-blood T1-weighted imaging (screening BB [S-BB]) as a magnetic resonance imaging sequence to evaluate acute cerebrovascular stroke. The association between S-BB high signal plaques and the risk of subsequent ipsilateral ischemic events was investigated. METHODS:A total of 928 consecutive patients hospitalized for a stroke or transient ischemic attack according to the Trial of Org 10172 in Acute Stroke Treatment (TOAST) classification were evaluated. Recurrence was retrospectively evaluated in S-BB–positive patients and patients with severe stenosis (SS) (≥70%) by magnetic resonance angiography. Based on clinical and imaging findings, recurrence was defined as a carotid artery stroke or transient ischemic attack that developed after hospital discharge as an initial event. RESULTS:Sixty-six patients were S-BB positive and 62 patients had severe stenosis (S-BB positive with SS, 32 patients; S-BB negative with SS, 30 patients; S-BB positive without SS, 34 patients). During a mean follow-up period of 9.1 months, 7 S-BB–positive patients with SS (18.7%) and 1 S-BB-negative patient with SS (3%) had a recurrent event (P = .051). In the S-BB–positive group, in 34 patients without SS, the recurrence rate was 14.7% (5/34); the difference in the recurrence rate between S-BB–positive group with and without SS was not significant (P = .34). CONCLUSION:Patients with carotid artery lesions and intraplaque hemorrhage tend to be at higher risk of a subsequent ipsilateral ischemic event. Risk evaluation of carotid artery disease should include plaque characteristics.

Effects of transient forebrain ischemia and reperfusion on function of dopaminergic neurons and dopamine reuptake in vivo in rat striatum.

To clarify functional changes of dopaminergic neurons and dopamine (DA) reuptake during and after ischemia, extracellular DA levels in striatum were determined using in vivo brain microdialysis in a 4-vessel occlusion model of male Wistar rats with and without pharmacological interventions. Without interventions, the extracellular DA levels markedly increased during ischemia, but upon reperfusion, rapidly returned to control level. Infusion of tetrodotoxin, a blocker of voltage-dependent Na+ channels, was without effect on the DA surge during ischemia, but decreased the DA levels after reperfusion to the same extent as in control rats. Pretreatment with nomifensine, an inhibitor of DA reuptake, was also without effect on the surge, but reduced the rate of DA decline after reperfusion to one-fifth of the rate without the pretreatment. When nomifensine was administered 40 min after reperfusion, extracellular DA levels increased to the same extent as in control rats. Infusion of high K+ 1 h after reperfusion induced a smaller increase in extracellular DA levels than that in control rats. It took 96 h for this reduced response to high K+ stimulation to recover after reperfusion. These results suggest that the DA surge during ischemia is mainly derived from action potential-independent DA release (means dysfunction of dopaminergic neurons), although activity of DA reuptake is completely inhibited. After reperfusion, the basal function of dopaminergic neurons and activity of DA reuptake rapidly recover, but the neurons are functionally disturbed to release less DA in response to a given stimulus for several days.

Evaluation of carotid artery atherosclerotic plaque distribution by using long-axis high-resolution black-blood magnetic resonance imaging.

OBJECT The goal of this study was to evaluate the usefulness of long-axis black-blood MR (BB-MR) imaging for assessing plaque morphology and distribution in patients with atherosclerotic carotid artery (CA) stenosis. METHODS Sixty-eight carotid arteries in 67 patients who were scheduled to undergo CA endarterectomy or CA stent placement due to atherosclerotic stenosis were included in this study. The patients had undergone CA BB-MR imaging and digital subtraction (DS) angiography within 3 weeks of revascularization. The DS angiography studies were performed using the transfemoral artery approach with selective common CA catheterization. The BB-MR images were acquired using a 1.5-T whole-body MR imaging unit, and T1-weighted images parallel to the long axis of the artery at 1-mm intervals were obtained. Plaque distribution was evaluated by measuring the distance between the CA bifurcation and the point that appeared to be the distal extent of the plaque on BB-MR imaging (D-MR imaging) and DS angiography images (D-DS angiography). RESULTS Plaque distribution was clearly shown in 88.2% of the cases using long-axis BB-MR images, except for 8 arteries with poor image quality. In 4 arteries, D-DS angiography could not be obtained because the distal plaque end could not be confirmed. In 56 vessels, both the D-DS angiography and D-MR imaging could be measured; the mean D-MR imaging (19.75 +/- 6.85 mm [standard deviation]) was significantly longer than the average D-DS angiography (16.32 +/- 7.07 mm). CONCLUSIONS Long-axis BB-MR imaging can provide a noninvasive and accurate way to show CA plaque distribution; it is of great use not only for stroke risk assessment in patients with CA atherosclerosis but also for preoperative evaluation in patients requiring CA endarterectomy or CA stent placement.

Treatment of a giant aneurysm of the cavernous internal carotid artery associated with a persistent primitive trigeminal artery: case report

A case of an unruptured giant aneurysm of the cavernous portion of the left internal carotid artery associated with a persistent primitive trigeminal artery (PTA) is presented. The usual surgical approach to giant aneurysms at this site, including ligation of the ipsilateral internal carotid artery (ICA) and an extracranial-intracranial (EC-IC) bypass, was inadequate because of continued blood supply to the aneurysm via the PTA from the vertebrobasilar system. The patient was successfully treated with a combination of EC-IC bypass surgery, ICA ligation, and simultaneous intravascular balloon obliteration of the ICA just distal to the junction of the PTA and immediately proximal to the aneurysmal neck. Follow-up radiological investigations showed thrombosis of the aneurysm.

Cerebral infarction due to an embolism after cervical pedicle screw fixation.

Study Design. Case report and clinical discussion. Objective. We report a rare case of delayed onset of cerebral infarction caused by an embolism after cervical pedicle screw (CPS) fixation. Summary of Background Data. CPS has a risk of vertebral artery (VA) injury. CPSs sometimes breach the transverse foramen without rupture of the VA. Most breaches are not considered harmful. Methods. We present a case in a 71-year-old man who underwent an operation for CPS fixation and laminoplasty for cervical spondylomyelopathy. He presented symptoms of hemiparesis 3 days after the operation. The left C4 pedicle screw was proven to breach the transverse foramen. An angiogram showed a thrombus cranial to the screw. Results. The patient underwent anticoagulation therapy without removal of screw. After 2 weeks, the thrombus had disappeared. Subsequently, the pedicle screws were removed. At final follow-up, the patient complained of a grade 4/5 hemiparesis, facial nerve palsy, and hearing loss in his left ear. Conclusion. To our knowledge, this is the first case report of delayed onset of cerebral infarction caused by an embolism after CPS fixation. When a CPS perforates the transverse foramen, even if no apparent VA injury occurs during the operation, the surgeon must take care not to risk cerebral infarction because of an embolism.