Results of Mechanical Thrombectomy 6 Hours after Stroke Onset: Analysis of Multiple Stroke Centers in Fukushima Prefecture.

Objective: The purpose of this study was to examine the efficacy and safety of mechanical thrombectomy in patients with acute occlusion of a large cerebral artery in the anterior circulation beyond 6 hours of the time last known to be well using the real-world clinical data collected from non-urban areas of Japan. Methods: We analyzed a retrospective multicenter database collected at 10 thrombectomy capable primary stroke centers in Fukushima Prefecture. In all, 188 patients were presenting a large cerebral artery occlusion in the anterior circulation, that is, internal carotid and middle cerebral artery (M1 and M2 segment). In all, 158 patients received mechanical thrombectomy within 6 hours from symptom onset (early time window), and 30 patients exceeded 6 hours (late time window). We compared the patient background, outcomes, and safety variables between the two groups. The modified Rankin Scale (mRS) score of 0-2 at 90 days after treatment and the incidence of symptomatic intracranial hemorrhage were compared between groups to evaluate treatment efficacy and safety. Results: There was no significant difference in the proportion of mRS score 0-2 at 90 days after treatment (51.3 vs. 46.7%: P = 0.644). However, symptomatic intracranial hemorrhage was more frequent in the late time window group (7.0 vs. 16.7%: P = 0.081). Symptomatic intracranial hemorrhage was a significant factor of a poor functional outcome in the late time window group (P = 0.022). Conclusion: This study reflects the real-world results of mechanical thrombectomy in the non-urban areas of Japan. The treatment efficacy in the late time window patients was equivalent to that in the early time window patients. On the other hand, the incidence of symptomatic intracranial hemorrhage showed a trend to high in patients beyond 6 hours, which was a significant factor related to a poor functional outcome.

Hemifacial Spasm Caused by Compression of a Vertebral Artery Aneurysm Consequently Improved by Stent-assisted Coil Embolization.

Objective: We described a rare hemifacial spasm (HFS) caused by compression of a vertebral artery (VA) aneurysm that was consequently improved by stent-assisted coil embolization. Case Presentation: A 60-year-old man presented with a chief complaint of left HFS that had persisted for 1 month. It had initially appeared in the orbicularis oculi, spread to the orbicularis oris, and severely disrupted his quality of life. Both MRI and MRA revealed a wide-necked aneurysm of the left VA (neck 8.5 mm, dome 6.0 mm) compressing the left facial nerve root exit zone (REZ). We performed stent-assisted coil embolization because the VA was dominant at this side of the aneurysm and we tried to preserve normal antegrade flow. The HFS disappeared immediately after embolization without complications. After 6 month follow-up, the patient had no recurrence of symptoms and MRA showed no recurrence of the aneurysm. Conclusion: Stent-assisted coil embolization was effective for treating HFS caused by compression of a VA aneurysm and it might be the treatment of choice for this type of aneurysmal HFS.

Utility and the limit of motor evoked potential monitoring for preventing complications in surgery for cerebral arteriovenous malformation.

OBJECTIVE: To evaluate the usefulness of motor evoked potential (MEP) monitoring and mapping in arteriovenous malformation surgery. METHODS: Intraoperative MEP monitoring was performed in 21 patients whose AVMs were located near the motor area or fed by arteries related to the corticospinal tract to detect blood flow insufficiency and/or direct injury to the corticospinal tract and/or to map the motor area. RESULTS: In 4 of 16 patients monitored for blood flow insufficiency, the MEP changed intraoperatively. In 2 patients, the changes were attributable to temporary occlusion of the feeding artery (anterior choroidal or lenticulostriate artery): 1 patient had a venous infarction around the internal capsule caused by thrombosis of the draining vein and the other bled intraoperatively from the nidus. In 17 patients, the MEP was monitored to rule out direct injury. In 1 patient, the MEP changed on coagulation of fragile vessels around the nidus in the precentral gyrus; it recovered after coagulation was discontinued. In 1 of 5 patients with MEP changes, the MEP did not recover; permanent hemiparesis developed in this patient because of venous infarction. In 1 of 11 patients subjected to MEP mapping of the motor area, we found translocation to the postcentral sulcus. CONCLUSION: In arteriovenous malformation surgery, MEP monitoring facilitates the detection of blood flow insufficiency and/or direct injury of the corticospinal tract and mapping of the motor area. It contributes to reducing the incidence of postoperative motor paresis.

Evoked potentials elicited on the cerebellar cortex by electrical stimulation of the rat spinocerebellar tract.

BACKGROUND: In the current study, as a first step to develop a monitoring method of cerebellar functions, we tried to record evoked potentials on the cerebellar cortex by electrical stimulation of the rat SCT, which is located in the Inf-CPed. METHODS: The experimental study was performed on rats. Unilateral muscular contractions of quadriceps femoris muscle were elicited by electrical stimulation. The evoked potentials were recorded from the surface of the ipsilateral cerebellum and the contralateral primary sensory cortex. RESULTS: The highly reproducible potentials obtained from the ipsilateral cerebellar hemisphere were named SCEP. The SCEP exhibited one negative peak with a latency of 11.7 +/- 0.3 milliseconds (N(11)). Short-latency somatosensory evoked potential was recorded from the contralateral primary sensory cortex with a latency of 19.1 +/- 0.6 milliseconds. Coagulation of the ipsilateral Inf-CPed caused disappearance or marked reduction of the SCEP N(11), but it did not change the SSEP. On the other hand, sectioning of the ipsilateral dorsal column resulted in the disappearance of the SSEP, but it did not affect the SCEP N(11). CONCLUSIONS: Reproducible SCEP was recorded from the rat cerebellar hemisphere by electrical stimulation of the quadriceps femoris muscle. We posit that the SCEP differs from the SSEP, which ascends via the dorsal column, and that it is conducted by the dorsal SCT located in the Inf-CPed. Our results suggest that it may be possible to detect the dysfunction of the Inf-CPed electrophysiologically by using SCEP.

Cerebral medulloepithelioma with long survival.

An 8-year-old boy presented with a rare cerebral medulloepithelioma manifesting as headache, nausea, and vomiting. Neuroimaging demonstrated a mass containing a cyst in the left frontal lobe. Gross total resection of the tumor with a 1-cm margin was performed under intraoperative monitoring. The histological diagnosis was medulloepithelioma. Stereotactic radiotherapy (total dose 20 Gy) was given to the brain up to 1 cm from the surgical margin. Follow-up neuroimaging 5 years later showed no signs of recurrence. He now attends junior high school, with normal mental and physiological development. Medulloepitheliomas are rare, highly malignant embryonal tumors of the central nervous system. Combined gross total tumor resection and radiotherapy are recommended to obtain the most favorable outcome.

Blood flow disturbance in perforating arteries attributable to aneurysm surgery.

OBJECT: The object of this study was to investigate patients with cerebral infarction in the area of the perforating arteries after aneurysm surgery. METHODS: The authors studied the incidence of cerebral infarction in 1043 patients using computed tomography or magnetic resonance imaging and the affected perforating arteries, clinical symptoms, prognosis, and operative maneuvers resulting in blood flow disturbance. RESULTS: Among 46 patients (4.4%) with infarction, the affected perforating arteries were the anterior choroidal artery (AChA) in nine patients, lenticulostriate artery (LSA) in nine patients, hypothalamic artery in two patients, posterior thalamoperforating artery in five patients, perforating artery of the vertebral artery (VA) in three patients, anterior thalamoperforating artery in nine patients, and recurrent artery of Heubner in nine patients. Sequelae persisted in 21 (45.7%) of the 46 patients; 13 (28.3%) had transient symptoms and 12 (26.1%) were asymptomatic. Sequelae developed in all patients with infarctions in perforating arteries in the area of the AChA, hypothalamic artery, or perforating artery of the VA; in four of five patients with posterior thalamoperforating artery involvement; and in two of nine with LSA involvement. The symptoms of anterior thalamoperforating artery infarction or recurrent artery of Heubner infarction were mild and/or transient. The operative maneuvers leading to blood flow disturbance in perforating arteries were aneurysmal neck clipping in 21 patients, temporary occlusion of the parent artery in nine patients, direct injury in seven patients, retraction in five patients, and trapping of the parent artery in four patients. CONCLUSIONS: The patency of the perforating artery cannot be determined by intraoperative microscopic inspection. Intraoperative motor evoked potential monitoring contributed to the detection of blood flow disturbance in the territory of the AChA and LSA.

Rebleeding from ruptured intracranial aneurysms in North Eastern Province of Japan. A cooperative study.

OBJECT: Rebleeding from ruptured intracranial aneurysms is a major cause of death and disability. With regard to the factors that precipitate the rebleeding and influence the time course after initial bleeding, previous reports differ in their results, and the number of patients investigated was not sufficient for valid conclusions. This study was thus designed to clarify the factors related to rebleeding from ruptured intracranial aneurysms in a large group of patients of the North Eastern Province of Japan. METHODS: We found 181 patients with rebleeding after hospitalization among 5612 cases of ruptured intracranial aneurysms from January 1997 to December 2001 in 33 major hospitals in the North Eastern Province of Japan. We analyzed the data with respect to the time course after bleeding and rebleeding, the arterial blood pressure, the situation when rebleeding occurred, the methods of neuroimaging, the level of consciousness, the treatment and the outcome. RESULTS: Of 181 patients who were hospitalized, rebleeding occurred in 65 (35.9%) within 3 h and 88 (48.6%) within 6 h after the initial subarachnoid hemorrhage (SAH). The consciousness level before the rebleeding varied widely in distribution, but belonged to the drowsiness or less [Japan coma scale (JCS) single-digit] in 83 patients (45.8%), but after rebleeding, JCS triple-digits (semicoma to coma) included 152 patients (84.0%). Systolic arterial blood pressure prior to rebleeding was most commonly between 120 and 140 mmHg. Rebleeding did occur more frequently during angiography (totally 29 patients, 20%) and much less frequently during 3D-CTA and MRA procedures (a single case). Treatment consisted of aneurysm neck clipping in 72 patients (40.0%), endovascular therapy with coils in 4 patients (2.2%) and conservative ones in 103 patients (56.9%). As to outcome, 109 patients with rebleeding (60.2%) died in 3 months following initial SAH. CONCLUSION: Rebleeding occurs more frequently in the earlier period after the initial SAH than previously believed. Thus, more aggressive pharmacologically induced systemic arterial hypotension appears to be important for preventing rebleeding but ultimate outcome of more aggressive hypotension is yet to be determined. If feasible, in order to avoid catheter-angiography related rebleeding, evaluations solely with 3D-CTA and MRA should be in consideration and earlier surgical intervention seems essential as rebleeding does occur often within the first 3 h of onset.

High-frequency monopolar electrical stimulation of the rat cerebral cortex.

OBJECTIVE: Intraoperative monitoring of the motor-evoked potential has been widely used in patients undergoing neurosurgery. Direct stimulation of the brain with high-frequency monopolar stimulation (HFMS) is one of the most common methods to produce motor-evoked potential. We studied the influence of HFMS on the rat cerebral cortex. METHODS: We applied 1.5, 15, 30, 40, or 50 mA of HFMS to the rat sensorimotor cortex by a short sequence of five monopolar, monophasic, anodal rectangular 500-Hz pulses. We delivered one short five-pulse train 100 times every 5 seconds and examined pre- and post-stimulation electroencephalograms and histological changes at the stimulation site. RESULTS: We observed no spike waves after HFMS in any of the rats. There was no change in the power spectrum or frequency content in any of the rats exposed to HFMS. Histologically, there was significant swelling of the dendrites in rats sacrificed immediately after exposure to 40- and 50-mA stimulation; the 50-mA stimulation group also exhibited slight swelling of the mitochondria. These findings were not obtained in any of the rats sacrificed 30 days after stimulation. CONCLUSION: In rats exposed to a stimulation intensity of 30-mA or less, no morphological or electrophysiological changes were observed. However, the possibility that HFMS may affect neural tissue cannot be ruled out.

Intraoperative monitoring of blood flow insufficiency during surgery of middle cerebral artery aneurysms.

OBJECT: The usefulness of motor evoked potential (MEP) monitoring to detect blood flow insufficiency (BFI) in the cortical branches of the middle cerebral artery (MCA) and lenticulostriate arteries (LSAs) during MCA aneurysm surgery was investigated based on the correlation between MEP and somatosensory evoked potential (SEP) monitoring. METHODS: Fifty-three patients with MCA aneurysms underwent surgery accompanied by intraoperative MEP and SEP monitoring. There was no postoperative motor paresis in 43 patients in whom MEP and SEP results remained unchanged. In the other 10 patients, nine manifested transient MEP changes; in five of these, SEP changes did not occur. The transient MEP changes were thought to be attributable to BFI of the MCA cortical branches in two patients, the LSA in three, and either the MCA branches or the LSA in four patients. Of these nine patients, six did not present with postoperative motor paresis; transient motor paresis was recognized in the other three. In the 10th patient, MEP waves disappeared and did not recover. This patient's SEPs remained at 70% of the control level, and he developed severe hemiparesis. A postoperative computerized tomography scan revealed a new low-density area in the corona radiata and putamen. CONCLUSIONS: Blood flow insufficiency in both the LSA and MCA cortical branches that perfuse the corticospinal tract can be detected by intraoperative MEP monitoring. Somatosensory evoked potential monitoring is not reliable enough to detect BFI in the MCA branches and the LSAs.

3D-CT arteriography and 3D-CT venography: the separate demonstration of arterial-phase and venous-phase on 3D-CT angiography in a single procedure.

Although 3D-CT angiography provides valuable anatomic information regarding lesion and their surrounding vessels and bony structures, it cannot demonstrate lesions, arteries, and veins, separately. The separate demonstration of arterial-phase 3D-CT angiography (3D-CT arteriography) and venous-phase 3D-CT angiography (3D-CT venography) will facilitate the understanding of the vascular anatomy within lesions, thus, allowing improvement of diagnostic accuracy and potentially a safer surgical approach. We describe 3D-CT arteriography and 3D-CT venography by using a multidetector row helical CT.

Management of poor-grade patients with aneurysmal subarachnoid hemorrhage in the acute stage: Importance of close monitoring for neurological grade changes.

BACKGROUND: The optimal management of poor-grade patients with aneurysmal subarachnoid hemorrhage (SAH) remains controversial. We evaluated therapeutic outcomes to identify appropriate treatments for SAH patients admitted with a poor grade. METHODS: We retrospectively studied 136 patients admitted within 6 hours after SAH onset with a poor Hunt & Kosnik Grade (IV and V). RESULTS: Of 136 poor-grade patients, 20 with massive intracerebral or subdural hematoma underwent urgent hematoma evacuation and aneurysmal neck clipping. Seven of these achieved a favorable outcome (good recovery or moderate disability). Another 7 patients with prominent hydrocephalus or massive intraventricular hematoma underwent urgent continuous ventricular drainage. Of these, 4 manifested spontaneous grade improvement and underwent neck clipping; the other 3 died resulting from rebleeding. The remaining 109 patients whose poor grade was primarily because of SAH were observed without immediate surgery. In 43 patients of 109, the grade improved within 24 hours after hospitalization and within 38 hours in the other 4 patients. Aneurysmal neck clipping was performed in these 47 patients and a favorable outcome was achieved in 25 patients. The remaining 62 patients did not improve and the outcome was unfavorable. CONCLUSIONS: Poor-grade SAH patients should be treated according to the pathogenesis underlying their poor grade. Close monitoring for a grade change over the first 24 hours after hospitalization is mandatory in patients whose poor grade is primarily because of the SAH and helps to determine the appropriateness of surgery.

Monitoring and preventing blood flow insufficiency due to clip rotation after the treatment of internal carotid artery aneurysms.

The authors report a case in which anterior choroidal artery (AChA) blood flow insufficiency due to aneurysm clip rotation was detected intraoperatively by motor evoked potential (MEP) monitoring and ischemia was successfully avoided. The patient had an incidentally discovered aneurysm for which occlusion of its neck was performed through a standard frontotemporal craniotomy without changing the MEP amplitude. After it was confirmed that the surrounding arteries were not stenotic, the brain retractor on the frontal lobe was released; MEP amplitude subsequently decreased. Rotation of the clip toward the frontal base by repositioning of the frontal lobe caused the AChA stenosis at the origin of its branches. On reorienting the clip toward the frontal lobe, the AChA stenosis was released and MEP amplitude recovered. To prevent repeated clip rotation, a large amount of gelatin (Spongel) was inserted between the frontal base and the clip. The authors confirmed that clip rotation did not occur after repositioning of the frontal lobe. Motor evoked potential amplitude was maintained until dural closure. Postoperatively, the patient demonstrated no neurological deficit and there was no newly developed low-density area on computerized tomography scans.

Intraoperative monitoring of blood flow insufficiency in the anterior choroidal artery during aneurysm surgery.

OBJECT: The lack of a specified intraoperative method for monitoring anterior choroidal artery (AChA) blood flow insufficiency (BFI) led the authors to devise a method for checking the BFI in this artery during aneurysm surgery. To this end, the authors relied on the intraoperative motor evoked potentials (MEPs) elicited by electrical stimulation of the hand motor cortex. METHODS: The study population consisted of 108 patients with internal carotid artery (ICA) aneurysms who underwent surgery via a standard frontotemporal craniotomy. After the dura mater had been opened, a grid electrode strip with 16 small electrodes was inserted subdurally into the hand motor cortex from the edge of the craniotomy. To check BFI in the AChA, the hand motor cortex was stimulated at an intensity level between 10 and 18 mA. The MEPs were successfully recorded from the contralateral thenar muscles in all 108 patients. There was no postoperativemotor paresis in 88 patients in whom the MEPs remained unchanged during the performance of various surgical maneuvers. Among the other 20 patients, 19 manifested transient MEP changes, but 15 of those patients experienced no postoperative motor paresis. In four patients who exhibited transient MEP changes, either after aneurysm clipping or during temporary occlusion of the ICA and/or AChA, hemiparesis occurred postoperatively but disappeared within 24 hours. In one patient with an ICA-posterior communicating artery aneurysm, the MEP disappeared and did not reappear by the time of dural closure. Severe hemiplegia developed in this patient and a computerized tomography scan obtained postoperatively revealed a new low-density area in the internal capsule. CONCLUSIONS: The findings of this study suggest that the monitoring method that is introduced here is safe and reliable for detecting intraoperative BFI in the AChA.