Carotid endarterectomy is an effective surgical option for the prevention of stroke. However, the indications and risks associated with this procedure vary between individual surgeons and institutions. The aim of this review is to analyze the current indications for intervention and recent operative experience at a single institution, the Mayo Clinic. Recent trials are assessed and integrated with our management policy. Important aspects of anesthesia, monitoring, and operative technique are described along with rationale for their use. Outcome of patients operated on in the last 25 years is assessed with respect to grade. In the period from 1972 to 1995 there have been 3831 cases. Overall major morbidity and mortality is 1.8% for 3665 patients with primary stenosis. For 113 patients with recurrent stenosis it is 8.5%. Comparison with a previous interim review in 1986 demonstrates a modest improvement in the more recent cases. It is proposed that improvements in anesthesia and perioperative care are principally responsible for this improvement. The importance of institutional audit of results is emphasized because surgical morbidity is a major factor in decision-making.
The protective effect of prior ischemia on focal cerebral infarction produced by permanent middle cerebral artery (MCA) occlusion was studied in a gerbil model. Forebrain ischemia for 2 and 5 minutes at an interval of 48 hours was used as the prior ischemic insult. Forty-eight hours after the second forebrain ischemia, the MCA was occluded. Progression of ischemic change caused by the MCA occlusion was delayed in the early ischemic period in animals with prior ischemia, as compared to animals without prior ischemia. The mean infarct volume 24 hours after the MCA occlusion was the same in animals with and without prior ischemia. Ischemic tolerance was acquired in this model, but had no effect on the extent of infarction caused by permanent ischemia.
The effect of retrograde perfusion of the cerebral vein (RPCV) with antioxidant LY231617 on neuronal injury after transient ischemia in rat brain was examined. Transient ischemia was caused by left middle cerebral artery (MCA) occlusion and reperfusion. Rats were assigned to three groups: Group A (n = 6), MCA occlusion only; Group B (n = 8), RPCV with saline (flow rate 4.95 ml/hr) into the left inferior cerebral vein; and Group C (n = 6), RPCV with LY231617 (20 mg/kg/hr, flow rate 4.95 ml/hr). RPCV in Groups B and C was performed simultaneously with occlusion. Both occlusion and RPCV were performed for 30 minutes in awake animals. Seven days later, all rats were investigated for rotational behavior elicited by apomorphine (1.0 mg/kg), and then immunohistochemical analysis of brain specimens was carried out using calcineurin as a neuronal marker in the striatum to detect the ischemic damaged area. The number of turns to the left (lesioned side) in both Groups B (42 ± 12) and C (46 ± 14) was significantly lower (p < 0.01) than in Group A (222 ± 45), but there was no significant difference between Groups B and C. The percentage ischemic damaged area in both Groups B (17.9 ± 6.2%) and C (1.6 ± 1.0%) was significantly less (p < 0.01) in Group A (51.1 ± 2.1%). RPCV with and without LY231617 during occlusion was effective for attenuating reperfusion injury.
Proton magnetic resonance spectroscopy (1H MRS) was evaluated for distinguishing between radiation necrosis and recurrent glioma in 11 patients after high-dose radiotherapy. Six patients had a histological diagnosis of recurrent glioma. Four patients had a histological diagnosis of radiation necrosis and one had a clinical course consistent with the diagnosis of radiation necrosis. 1H MRS showed cases of radiation necrosis had two characteristic 1H MRS patterns: markedly increased lactate/creatine and phosphocreatine (Cr) ratio and decreased choline-containing compounds/Cr ratio compared to that of recurrent glioma; or all the major metabolites were completely diminished. The N-acetyl aspartate signal was not helpful for differential diagnosis. 1H MRS is a potentially useful method for differentiating tumor recurrence from radiation necrosis in patients treated for malignant glioma.
Visual evoked potentials (VEPs) to photic stimulation of the eyes were used to identify the optic tract and thus determine the location of the globus pallidus internus (GPi) in eight patients with Parkinson''s disease who then underwent posteroventral pallidotomy. Distinct waves appeared at 1 or 2 mm below the target (4 to 5 mm below the intercommissural line) and the amplitude significantly increased at 5 or 6 mm below, strongly suggesting that the electrode was in contact with the optic tract. In the medio-lateral direction, potentials were successively recorded in an area of 4 to 8 mm length, indicating the width of the optic tract. The trajectory at the mid point showed the most significant potentials which suggested the center of the optic tract. The site of the first lesion was placed 0 to 2 mm lateral to this trajectory and 5 mm above the point at which the amplitudes of responses increased. The actual lesion site significantly differed from the tentative target in a medio-lateral direction by 1 to 5 mm (mean 3.0 ± 1.5 mm, n = 6). The Unified Parkinson''s Disease Rating Scale score significantly improved and magnetic resonance imaging taken 2 or 3 weeks after the operation showed a lesion within the GPi in each patient. Recording of VEPs greatly facilitates accurate determination of the GPi.
A 36-year-old male presented with headache, vomiting, and gait disturbance. Examination found marked anemia, renal failure, markedly choked disks, and hypertensive encephalopathy. Magnetic resonance imaging demonstrated diffuse swelling of the brainstem and cerebellum, and obstructive hydrocephalus. Treatment with steroid, glycerol, and antihypertensive drugs resulted in a slow decrease in the brain swelling and cerebral edema. However, hydrocephalus and intracranial hypertension persisted, requiring a shunt operation. Hypertensive encephalopathy is usually improved by the treatment of hypertension, but shunt operation may be required to treat exacerbated intracranial pressure associated with obstructive hydrocephalus.
A 57-year-old male presented with a traumatic dissecting aneurysm of the distal, extracranial internal carotid artery (ICA). Stent placement resulted in complete occlusion of the aneurysm and preservation of the carotid blood flow. He also had an atherosclerotic stenosis of the ipsilateral middle cerebral artery, which was uneventfully treated by angioplasty 3 months after stent placement. Endovascular reconstruction of the ICA with a stent may be the best way to occlude dissecting aneurysms, especially in patients who cannot tolerate ICA occlusion, are at risk from delayed ischemia, or have wide-necked or multiple aneurysms.
A 47-year-old female presented with an unusual cystic meningioma. Computed tomography and magnetic resonance imaging showed a cystic tumor with marked edema in the left parietal region of the brain, resembling a metastatic tumor. The tumor was totally removed. Histological examination revealed meningioma with dense lymphoplasmacytic infiltrates.
A 24-year-old female presented with basilar invagination and kyphoscoliosis of the cervical spine associated with a large intercarotid paraganglioma. She had suffered from pharyngeal discomfort from the age of 9 years due to the tumor. The tumor had originated from the right carotid body and extended in the parapharyngeal space compressing the upper cervical spine. Presumably the slowly growing tumor had caused the kyphoscoliosis and disturbed osseous development of the occipito-atlanto-axial complex, resulting in anterior basilar invagination, hypoplasia of the clivus, and aplasia of the posterior arch of the atlas.
A 19-year-old female presented with an unusual glial cyst of the thalamus that caused development of acute hydrocephalus due to hemorrhage and manifested as headache and fainting attacks. Computed tomography showed a large cystic mass lesion in the left thalamus with intracystic hemorrhage. The cyst was subtotally removed. Microscopic examination revealed mild gliosis with marked hemosiderin deposits. The inner surface of the cystic wall lacked an epithelial lining. The diagnosis was glial cyst. Magnetic resonance (MR) imaging 2 months after surgery showed a residual cyst in the left thalamus. However, after 12 months she was asymptomatic, neurologically intact, and MR imaging showed no regrowth of the cyst. Treatment of glial cyst must provide sufficient communication between the cyst and the cerebral ventricles rather than attempt total removal of the cyst, which may present a considerable challenge.
A method for cerebral revascularization using latissimus dorsi muscle free flap transfer is described. Latissimus dorsi muscle is harvested with thoracodorsal vessels after completion of craniotomy and exposure of superficial temporal vessels. The size of muscle belly which is harvested is dependent on the area where the revascularization is necessary. Microvascular anastomoses of superficial temporal vessels and thoracodorsal vessels are performed in end-to-end fashion. A 31-year-old male patient with moyamoya syndrome was treated by this method. Postoperative angiography demonstrated successful revascularization in the affected hemisphere, with improved perfusion reserve capacity shown by cerebral blood flow study. This type of encephalo-myo-synangiosis (with free muscle flap) is a possible method when vascular reconstruction of an extensive ischemic area which involves anterior and posterior cerebral artery territories is needed in a patient with moyamoya disease or other similar ischemic conditions.