Validation of the modified radiosurgery-based arteriovenous malformation score in a linear accelerator radiosurgery experience in Hong Kong.

The modified radiosurgery-based arteriovenous malformation (AVM) score (modified AVM score or Pollock-Flickinger AVM score [PFAS]) is a simplified grading system developed to predict outcome after gamma knife radiosurgery for cerebral AVM. The purpose of this study was to test the PFAS in a cohort of patients managed with linear accelerator (LINAC) radiosurgery. We analyzed 70 consecutive patients with cerebral AVM treated with LINAC radiosurgery in Hong Kong. The scores were determined by the following equation: Modified AVM score=(0.1×volume [cm(3)])+(0.02×age [years])+(0.5×location). The location values are as follows: hemispheric/corpus callosum/cerebellar=0; basal ganglia/thalamus/brainstem=1. A total of 74% of patients presented with ruptured AVM before radiosurgery. The overall obliteration rate was 86%. Five (7%) patients developed new permanent neurological deficits from delayed bleeding or radiation-induced complications. Modified AVM score correlated with the percentage of patients with AVM obliteration without new neurological deficits (≤1, 96%; 1.01-1.50, 78%; 1.51-2.00, 90%; >2, 50%; Spearman's rho 0.354, p=0.003). In conclusion, the modified AVM score is a good predictor of patient outcome after LINAC radiosurgery in our cohort. The modified AVM score can be used to guide treatment selection for cerebral AVM and stratify patients for future comparative analyses.

Ischemic events after carotid interventions in relationship to baseline cerebrovascular reactivity.

BACKGROUND: We aimed to investigate whether baseline cerebrovascular reactivity could predict subsequent ischemic event after intervention and identify the patient group for more aggressive medical and interventional management paradigms. METHODS: Patients with more than 70% cervical carotid stenosis (from ultrasonography) were reviewed. Patients, who had baseline cerebrovascular reactivity test before intervention and had either carotid endarterectomy (CEA) or carotid angioplasty and stenting (CAS) performed, were recruited for analysis. Transcranial Doppler ultrasonography was used to examine the reactivity of the middle cerebral artery in response to 5% carbon dioxide in oxygen. The mean follow up period was 66 months. FINDINGS: Twenty-six patients had symptomatic carotid stenosis and ten patients had asymptomatic carotid stenosis. There were four subsequent ischemic events during follow up. None of the nine patients with impaired baseline ipsilateral cerebrovascular reactivity had subsequent ischemic event. CONCLUSIONS: In this current study, impaired baseline cerebrovascular reactivity did not predict the subsequent stroke risk after carotid intervention. Cerebrovascular reactivity testing may not serve as an indicator for aggressive medical and surgical treatments.

Effects of illness duration on memory processing of patients with temporal lobe epilepsy.

PURPOSE: To examine the effects of illness duration on the neural processing of memory in patients with temporal lobe epilepsy (TLE) by using functional MRI. METHODS: Twenty-three TLE patients (16 left, seven right) performed a complex visual scene-encoding task during functional MRI. Region-of-interest (ROI) analyses were used to quantity functional activation in the mesial temporal and frontal lobes. The patients' verbal and visual memory performances were evaluated by standardized neuropsychological tests. Analyses included group comparison and correlations of duration of epilepsy with functional activation and memory performance. RESULTS: Compared with normal controls, TLE patients demonstrated reduced activation bilaterally in the mesial temporal lobe (p=0.003), and the reduction was more pronounced on the ipsilateral side of the seizure focus. Moreover, a longer duration of illness was associated with fewer voxels activated in both the left (p=0.038) and right (p=0.017) mesial temporal lobe. Furthermore, the duration of illness was found to be significantly and negatively correlated with both verbal (p=0.020) and visual (p=0.000) memory functioning. CONCLUSIONS: TLE seems to affect the memory processes in the mesial temporal lobes progressively (i.e., the longer the duration of illness, the lower the brain activation). In turn, the reduction of brain activation negatively affects memory functioning. Finally, the reduction is not limited to the side of seizure but also is observed in the contralateral hemisphere.

Language lateralization of Chinese-English bilingual patients with temporal lobe epilepsy: a functional MRI study.

Functional MRI was used to examine language lateralization of Chinese characters and English words associated with temporal lobe epilepsy (TLE) in Chinese-English bilinguals with left or right TLE. The results suggest that the neural basis of processing Chinese and English seems to be different, as normal controls demonstrated left hemispheric lateralization in reading English words but bi-hemispheric lateralization in reading Chinese characters. This difference in the neural bases of Chinese and English processing was found to affect the patterns in change-of-language processing associated with TLE. That is, whereas left-TLE patients were more likely than right-TLE patients to demonstrate a bi-hemispheric language involvement in reading English, both left- and right-TLE patients demonstrated primarily bilateral hemispheric involvement for reading Chinese characters.

Complete obliteration of intracranial arteriovenous malformation with endovascular cyanoacrylate embolization: initial success and rate of permanent cure.

BACKGROUND AND PURPOSE: Endovascular treatment with cyanoacrylate embolization is an option when complete obliteration of the nidus of an intracranial arteriovenous malformation (AVM) is the goal. Our purpose was to evaluate the rates of initial success and permanent cure of such treatment in a Chinese population. METHODS: Twenty-seven consecutive patients with an intracranial AVM underwent endovascular embolization with cyanoacrylate between June 1995 and May 1997. Twenty-six patients had cerebral AVMs and one had a cerebellar AVM. Curative embolization was attempted in 10 patients in whom 1) the nidus was not larger than 3 cm, 2) the number of feeders did not exceed three, and 3) the nidus was accessible with the tip of the catheter. We used a flow-directed microcatheter and a 20-25% mixture of cyanoacrylate in contrast medium. Long-term outcomes were observed angiographically and clinically. RESULTS: Complete embolization was achieved in six patients. No procedure-related complications occurred during attempted curative embolization. Follow-up angiography performed at 17-32 months showed complete obliteration of the AVM nidus in the six patients after initial embolization. These patients remained asymptomatic 5-7 years after treatment. The rate of permanent cure of the initially complete embolization was 100% (six of six). The success rate of endovascular cure for patients treated with curative intent was 60% (six of 10). The overall cure rate was 22% (six of 27). CONCLUSION: The overall initial cure rate of intracranial AVM with cyanoacrylate embolization was 22%. Initial angiographic evidence of complete embolization indicated permanent cure in these patients.

Intracranial aneurysms treated with Guglielmi detachable coils: midterm clinical and radiological outcome in 97 consecutive Chinese patients in Hong Kong.

BACKGROUND AND PURPOSE: Use of Guglielmi detachable coils (GDCs) has proved to be a promising endovascular treatment for intracranial aneurysms. This study aimed to evaluate midterm clinical and radiologic outcomes of this treatment in Hong Kong Chinese patients, 68% of whom had small aneurysms (< or =5 mm). METHODS: We included 97 consecutive patients in whom GDCs were placed with curative intent. The patients presented with subarachnoid hemorrhage (n = 80) or mass effect (n = 17). The aneurysms measured 5 cm +/- 2.8 mm; 68% were < or =5 mm. All patients were followed up clinically for an average of 54.5 +/- 20.9 months and radiologically with sequential digital subtraction angiography at 6 and 18 months. RESULTS: Total occlusion of the aneurysm was successfully achieved in 71.1% of patients after the initial treatment and in 82.5% after subsequent treatments. The retreatment rate was 17.5%. Procedure-related complication and mortality rates were 11.3% and 0%, respectively. The overall mortality was 5%, including mortality due to treatment failure in 1%. Neurologic outcomes were excellent in 77% of patients. Improved neurologic status, unchanged status, and deteriorated status was noted in 61.5%, 22%, and 16.5% of patients, respectively, at the end of the follow-up period. Intrinsic differences existed between Chinese and Western patients regarding the size of the aneurysm at presentation, periprocedural complications, and progression patterns of anatomic outcomes. CONCLUSION: Endovascular coiling with GDCs is a reasonably effective and safe treatment for intracranial aneurysms in this group of Hong Kong Chinese patients, with favorable clinical and radiologic outcomes.