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ARTICLES: C. -P. Chung, H. -Y. Hsu, A. -C. Chao, F. -C. Chang, W. -Y. Sheng, and H. -H. Hu Detection of intracranial venous reflux in patients of transient global amnesia Neurology 2006; 66: 1873-1877 [Abstract] [Full text] [PDF]

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Chih-Ping Chung, Hung-Yi Hsu, A-Ching Chao, Han-Hwa Hu   (15 August 2006)

Detection of intracranial venous reflux in patients of transient global amnesia

Nabil M. Akkawi, Chiara Agosti, Barbara Borroni, and Alessandro Padovani   (15 August 2006)

Reply from the Authors 15 August 2006
Chih-Ping Chung, Neurological Institute, Veterans General Hospital-Taipei, Yang-Ming Medical University #201 Shi-Pai Road, Peitou, Taipei 112, Taiwan, Hung-Yi Hsu, A-Ching Chao, Han-Hwa Hu Send Correspondence to journal: Re: Reply from the Authors hhhu{at}vghtpe.gov.tw Chih-Ping Chung, et al.	We appreciate Dr. Akkawi's comments on our recent study on transient global amnesia (TGA). [1] Our study provided more direct evidence supporting the role of venous reflux in the pathogenesis of TGA by demonstrating the intracranial venous reflux via the left internal jugular vein (IJV), which was caused by compression of the left brachiocephalic vein (BV). We did not intend to conclude that left venous system abnormalities are responsible for all TGA patients. Also, the frequencies and laterality of internal jugular vein valve incompetence (IJVVI) were not the main focus of this study. Our color-coded Doppler ultrasound study in 134 patients with retinal or cerebral ischemia showed that the frequencies of IJVVI were 23.7% on right, 53.9% on left and 22.4% bilaterally (submitting), which is inconsistent with Dr. Akkawi's study using air-contrast sonography (ACS). [4] Their study demonstrated that IJVVI occurred predominantly on the right side. The discrepancy might be due to different ethnic population or different ultrasound methods. Some technical issues should be addressed when using ACS to detect IJVVI, especially in patients with left BV compression. The assumption that the side of injection did not influence detection of IJVVI was based on limited clinical experience. [6] When air-contrast was injected from the right antecubital vein, the air bubbles would not be transmitted to the left IJV even if the left IJV valves are incompetent due to the compression of the left BV. Moreover, we found that there are venous valves in the left BV, which can prevent transmission of the air bubbles to the left IJV. These could cause one to underestimate left IJVVI. The right IJVVI could be overestimated because the air bubbles might appear in the right IJV without IJVVI via the abundant venous collaterals in case of left IJVVI when air-contrast was injected from the left antecubital vein. The venous collaterals have been demonstrated by the upper extremity digital subtractive venography in patents with left BV compression. [1] ACS can not demonstrate the compression of left BV. In addition, performing a Valsalva maneuver (VM) might relieve the compression of left brachiocephalic vein due to pre-VM deep inspiration. Furthermore, we found that IJV venous reflux transmitted intracranially may appear in the absence of IJVVI. In some TGA patients, the retrograde-flow was found only in the upper part of left IJV, not the lower part adjacent to the BV. The retrograde-flow in the upper part of left IJV was from the venous collaterals, possibly via the incompetent vertebral vein or other venous tributaries of left BV. We agree with Dr. Akkawi that future studies on the standardization of ultrasound techniques with respiratory maneuvers for the better detection and quantification of jugular venous reflux are needed to further understand the role of venous system abnormality in the TGA pathogenesis. Reference <>6.Akkawi NM, Agosti C, Borroni B, Rozzini L, et al. Jugular valve incompetence: a study using air constrast ultrasonography on a general population. J Ultrasound Med 2002:21:747-751. Disclosure: The authors report no conflicts of interest.
Detection of intracranial venous reflux in patients of transient global amnesia 15 August 2006
Nabil M. Akkawi, Department of Neurology, University of Neurology Pza Spedali Civili 1, Brescia, Italy, Chiara Agosti, Barbara Borroni, and Alessandro Padovani Send Correspondence to journal: Re: Detection of intracranial venous reflux in patients of transient global amnesia chiarett{at}libero.it Nabil M. Akkawi, et al.	We read with interest the study by Chung et al. [1]This study evaluated the role of intracranial venous reflux in the pathogenesis of Transient Global Amnesia (TGA). It has largely demonstrated the crucial role of the venous system involvement in the pathogenesis of TGA. [2] The relationship between TGA and venous-related precipitating factors, i.e. Valsalva maneuver and the discovery of Internal Jugular Vein Incompetence (IJVI)3 have further supported the venous congestion hypothesis. The present study confirms previous work but clarification is needed. Chung et al found only left jugular vein reflux with TOF–MRA evaluation claiming that TGA pathogenesis is related to left retrograde intracranial venous flow. We agree that the relevance of the venous system in the pathogenesis of TGA was genuinely investigated in this work but we do not agree with the hypothesis that TGA should be only due to left venous system abnormalities. In a recent study, we evaluated IJVI by air-contrast ultrasound venography, demonstrating an increase incidence of IJVI in TGA patients when compared with either healthy controls or patients with TIA. [3] We did not find a solely left side involvement of venous system, but a prevalence of IJVI on the right side. These data had been confirmed both in a larger sample [4] and in an our ongoing study. We have recruited 120 TGA patients and IJVI was found in 85/120 (70.8%). In 63.5% was on the right side, in 10.6% on the left, and in 25.9% bilaterally. The lack of an exclusive relationship between left side involvement and TGA pathogenesis is also supported by recent neuroimaging studies that have shown either right, left, or bilateral alterations of venous system. [5] We thank the authors for their relevant analysis supporting the venous hypothesis, but caution should be taken before suggesting this clear-cut lateralization in a small sample. Future studies are needed to further understand the role of venous system abnormality in TGA pathogenesis. References 1.Chung CP, Hsu HY, Chao AC, Chang FC, Sheng WY, Hu HH. Detection of intracranial venous reflux in patients of transient global amnesia. Neurology. 2006;66:1873-1877. 2.Lewis SL. Aetiology of transient global amnesia. Lancet. 1998;352:397-399. 3.Akkawi NM, Agosti C, Rozzini L, Anzola GP, Padovani A. Transient global amnesia and disturbance of venous flow patterns. Lancet. 2001;357:957. 4.Akkawi NM, Agosti C, Anzola GP, et al. Transient global amnesia: a clinical and sonographic study. Eur Neurol. 2003;49:67-71. 5.Schreiber SJ, Doepp F, Klingebiel R, Valdueza JM. Internal jugular vein valve incompetence and intracranial venous anatomy in transient global amnesia. J Neurol Neurosurg Psychiatry. 2005;76:509-513. Disclosure: The authors report no conflicts of interest.