In this paper, we describe in detail our surgical approach for the precise exposure of the distal cervical segment of the internal carotid artery (ICA) in carotid endarterectomy (CEA). We also evaluate the validity of our surgical procedure by retrospectively reviewing 12 consecutive cases with high cervical ICA stenosis. With precise head and neck position and careful dissection based on the anatomical features under microscope observation, CEA was accomplished safely without invasive techniques.

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Carotid endarterectomy (CEA) is the main treatment for the cervical internal carotid artery stenosis, which is an important cause of transient ischemic attacks and strokes. The operation requires careful attention to technical details, and certain specific principles are essential to achieve a consistently favorable outcome. It is important to expose the distal internal carotid artery adequately to permit direct visualization of the entire extent of an atherosclerotic plaque. An anatomical understanding of the deep cervical fascia of which carotid sheath consists helps to achieve a successful removal of plaque for high cervical lesions. The deep cervical fascia fuses with the periosteum along the superior nuchal line of the occipital bone, over the mastoid process and along the entire base of the mandible. Between the angle of the mandible and the anterior edge of sternocleidomastoid muscle, the fascia is particularly strong. However, this should be dissected thoroughly to expose the internal carotid artery as high as the entrance of carotid canal. These procedures allow a good approach to the high-positioned carotid stenosis.

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In this article, we present a non-invasive approach to the high cervical internal carotid artery lesion based on the anatomical features of the parotid gland and the carotid sheath.

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We retrospectively studied the endosaccular coil embolization of 88 patients with 89 large (maximum diameter ≥10 mm) unruptured intracranial aneurysms (UIAs). The mean aneurysm and neck size were 12.7 ±2.9 mm and 5.7±1.8 mm, respectively. Frequent locations were the paraclinoid segment of the internal carotid artery and posterior communicating artery in the anterior circulation and the basilar artery bifurcation in the posterior circulation. Twenty-one aneurysms (23.6%) presented with the clinical symptoms due to the mass effect. All of the procedures were completed. Embolization techniques used were conventional (simple, balloon-assisted, or double-catheter) techniques in 66 aneurysms and the stent-assisted technique in 23 aneurysms.
Overall immediate anatomical outcomes showed complete occlusion (CO) in 50.6%, residual neck (RN) in 29.2%, and residual aneurysm (RA) in 20.2%. Overall radiological follow-up results of the 71 aneurysms showed unchanged in 26.8%, improved in 11.3%, minor recurrence in 22.5%, and major recurrence in 39.4%. The final anatomical outcomes of the aneurysms radiologically followed up were CO in 47.9%, RN in 31.0%, and RA in 21.1%. The stent-assisted technique improved the immediate anatomical outcomes and decreased the risk of recurrence in the short term compared with the conventional techniques. Procedure-related complications occurred in 15.9% of the aneurysms. Four aneurysms (4.5%) had ischemic complications, and two aneurysms (2.2%) had hemorrhagic complications. Only four patients had clinical worsening of the mRS of >1 at the latest clinical follow-up. The permanent morbidity and mortality rates were 3.4% and 1.1%, respectively. The mean clinical follow-up period after endovascular therapy was 34.9±2.9 months (13 days–9.54 years). No patients suffered from aneurysmal subarachnoid hemorrhage (SAH) during the clinical follow-up periods. Permanent clinical worsening of the mass effect occurred in three patients with visual symptoms. Two aneurysms showed transient asymptomatic perianeurysmal edema that improved after administration of steroid therapy. Basilar artery dissection and renal artery injury due to the migration of the femoral sheath guidewire occurred once in each case. Twenty-one aneurysms (23.6%) underwent endosaccular coil re-embolization without any complications. No patients underwent surgical clipping or parent artery scarification. The mean duration between the initial treatment and the first re-embolization was 18.2 months (0.5–48.4 months).
Endosaccular coil embolization of the large UIAs is effective and safe. But recurrence and aneurysm growth after endosaccular coil embolization are significant concerns, and patients with visual symptoms may be candidates for parent artery occlusion or surgical clipping.

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We studied hemorrhagic complications of coil embolization for very small (less than 3 mm in maximum diameter) intracranial aneurysms from April 2006 to Dec. 2011. We treated 272 intracranial aneurysms (78 ruptured, 194 unruptured), including 12 very small aneurysms (five ruptured, seven unruptured), during this period. There were one rupture during coil embolization among 260 intracranial aneurysms larger than 3 mm in maximum diameter (0.4%), However, there were two ruptures of very small 12 aneurysms (16.7%, p<0.05). The rupture rate of very small aneurysms during coil embolization is remarkably high compared with that of aneurysms with maximum diameter larger than 3 mm. The main cause of intraoperative rupture was supposed to be unstableness of the microcatheter for the long axis of the very small aneurysms. Therefore, the coils were pushed out in an unexpected direction and resulted in rupture.
Preshaping of the tip of the microcatheter to fit the long axis of the very small aneurysms is very important to prevent this serious complication.

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Nonionic iodinated contrast-induced encephalopathy is a rare complication in neuroendovascular therapy and is supposed to be caused by the osmotic disruption of the blood-brain barrier resulting from repeated contrast injections into a single vessel. But its exact etiological mechanisms remain uncertain. We report a unique case of contrast-induced encephalopathy after coil embolization of unruptured aneurysm. An abnormal high signal intensity lesion on arterial spin-labeled perfusion weighted imaging-magnetic resonance imaging (PWI-MRI) persisted until more than one year after the procedure without any neurological sequelae or any obvious organic abnormalities recognized on MRI.
A 66-year-old woman with an incidentally found unruptured left paraclinoid aneurysm was treated with endovascular balloon-assisted coil embolization. The procedure was successfully accomplished using about 80 ml of contrast medium (iomeprol) injected into the left internal carotid artery. However, she manifested prolonged consciousness disturbance, aphasia, and right hemi-paresis directly after the procedure and seizure on the next day. Immediate computed tomography revealed the cortical enhancement in the left cerebral hemisphere. Diffusion weighted imaging-MRI six hours and two days after the procedure revealed no particular abnormality. Her clinical symptoms completely resolved four days after the procedure with administration of steroid, glycerin and edaravone. She was discharged with no neurological deficit, but the abnormal high signal intensity lesion in the left temporo-parietal lobe was demonstrated on the serial PWI-MRI from two days to 12 months after the procedure.
We speculate that some further mechanisms such as ischemia, immunological response or a genetic factor may be involved in this case, thus increasing her susceptibility to neurotoxic effects of the contrast medium.

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Proton MR spectroscopy (MRS) is valuable for identifying metabolic changes occurring during brain ischemia. Although it has been shown that N-acetylaspartate (NAA) measurement by MRS is useful to detect neuronal damage in the acute stage of cerebral ischemia, the clinical significance and the availability of the NAA measurement in the chronic stage of cerebral ischemia are still obscure. We examined a serial change of NAA/Creatinin (Cr) ratio in patients who underwent EC-IC bypass in the chronic stage of ischemia and investigated the influence of revascularization surgery on the brain metabolism. Nine patients who underwent EC-IC bypass, five patients with symptomatic occlusive main cerebral arteries who received conservative treatment, and three healthy volunteers were studied. ¹H-MRS was obtained using Philips Achieva 3.0T. Multi-voxcel spectra were recorded using a SE-2D-CSI sequence (TR/TE=2000/288 ms). The volume of interest was placed in the frontal white matter of both hemispheres axially above the lateral ventricles. Surgery was done on average 45 days after onset. ¹H-MRS was performed before and one week, one month and three months after surgery, and the serial change of ischemia/contralateral side ratio (I/C ratio) of NAA/Cr between the bypass group and conservative treatment group was compared. In the healthy volunteer group, neither laterality of NAA/Cr nor the serial change was seen. Six patients in the bypass group had significant lower NAA/Cr on the affected side compared to the contralateral side at one month after onset. In these patients, the I/C ratio of NAA/Cr increased 11 percentage point three months after surgery. All patients in the conservative treatment group also had significantly lower NAA/Cr on the affected side, but I/C ratio of NAA/Cr increased three percentage points at three months after onset. The improvement range of I/C ratio of NAA/Cr was significantly higher in the bypass surgery group.
The present study demonstrated that decreased NAA/Cr shown in the chronic stage of cerebral ischemia is reversible. MRS may provide useful information of impaired metabolic states that can be treated with revascularization surgery.

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Recent advancement of three-dimensional computed tomographic angiography (3D-CTA) allows high-spatial-resolution images for the diagnosis of cerebral aneurysms. Prior to operative intervention, the best possible strategy can be developed with the precise knowledge of the shape and location of the lesions in relation to the bone structure and the vascular arrangement, using 3D-CTA. However, replacing conventional digital subtraction angiography (DSA) in order to develop the best treatment strategy remains controversial.
In 47 patients with symptomatic cerebral aneurysms, such as subarachnoid hemorrhage or cranial nerve palsy, between April, 2008 and December, 2011, we developed the treatment strategy with computer simulation using only 3D-CTA images of 64- or 320-detector row CT. Thirty-four of the 47 underwent neck clipping of the aneurysms, 3D-CTA clearly showed not only the exact locations of the aneurysms, but also neighboring bone structure such as the anterior clinoid process. Venous arrangements were more clearly shown with 320-detector row CT. In the seven other patients, subsequent DSA was done prior to neck clipping. Coil embolization was employed for the three other patients following the use of 3D-CTA. Two patients underwent parent artery occlusion with EC-IC bypass after DSA.
In most cases of the cerebral aneurysms, 3D-CTA seems to be a reliable and less invasive method to develop the operative strategy. The 320-detector row CT can show more precise venous arrangements. If patients have cerebral vasospasm, conventional DSA is still necessary.

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Most IC-PC ANs could be safely clipped via the pterional approach. However, if ANs are larger or the anterior clinoid process (ACP) can hide the anatomy at the proximal neck, clinoidectomy is sometimes necessary for complete exposure and safe clipping.
We examined 57 cases of IC-PC ANs treated with clipping. The ACP was resected in 11 of the 57 cases, which included different techniques for extradural resection for seven cases and intradural resection for four cases, respectively.
We recommend extradural clinoidectomy for all ANs close to 1 cm. However, if an AN is less than 1 cm, and satisfactory proximal carotid control or visualization of the neck is obscured by the ACP, then intradural partial clinoidectomy is an effective alternative method.

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Appropriate and adequate training for carotid endarterectomy (CEA) and bypass surgery is crucial for neurosurgical residents. We have developed new vessel models for CEA and high-flow bypass. The new vessel model for simulating CEA contains a plaque in the vessel, and surgeons can dissect the plaque from the vessel wall and perform insertion and removal of an internal shunt. Suturing the vessel model feels realistic. Patch angioplasty can also be performed using this vessel. Using 4- and 8-mm diameter vessel models, simulation of high-flow bypass (radial and external carotid artery bypass) can be performed.
Simulation training for neurosurgical residents and medical students using these vessel models may provide useful sensate experience similar to that encountered in real CEA and high-flow bypass.

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A 57-year-old female presented left-sided weakness, but her deficit improved for a few days. MRI performed a week later after onset showed infarctions in the head of the right caudate nucleus and the cortex of the right frontal lobe. MRI and DSA revealed an irregular dilatation with the pseudolumen in the right ICA C1-2 portion. She was diagnosed with ischemic stroke due to intracranial internal carotid artery dissection. After conservative therapy including Cilostazol and blood pressure control, the size of ICA dissection remained unchanged. However, the follow-up angiography six months after onset revealed aneurysmal dilatation of the C1-2 portion. Therefore, we stopped Cilostazol. An ischemic attack recurred in the subcortex of the right frontal and temporo-parietal lobe seven months after onset.
To prevent both the recurrence of ischemic attack and occurrence of subarachinoid hemorrhage due to the rupture of the aneurysm, we planned to trap the dissecting ICA aneurysm with the use of STA-MCA double bypass under motor evoked potential (MEP) monitoring. However, MEP amplitudes decreased during surgery after trapping of the ICA. Therfore, we were obliged to treat the dissecting aneurysm with proximal occlusion to avoid ischemic complication.
The postoperative course was uneventful. Motor paresis deteriorated immediately after surgery, but she recovered after 72 hr.

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