**1. Introduction**

222 Venous Thrombosis – Principles and Practice

[2] Libby LS, King TE, LaForce FM, Schwarz MI. Pulmonary cavitation following

[3] Urano T, Shibayama Y, Fukunchi K, Nariyama K, Ohsawa N. Interruption of pulmonary

[4] Butler MD, Biscardi FH, Schain DC, Humphries JE, Blow O, Spontnitz WD. Pulmonary

[5] Lennox H Huang, MD, Pulmonary Infarction; Aug 12, 2008 (www.emedicine.com) [6] Wang PW, Kuo PH, Chang YC, Yang PC. A patient with right upper quadrant abdominal pain, hypotension and dyspnoea. Eur Respir J 2002; 20: 238-241. [7] Djordjevic I et all. Difficulties in establishing a timely diagnosis of pulmonary artery

[8] Herbert L. Fred bacterial pneumonia or pulmonary infarction? Chest 1969; 55: 422-425. [9] Morganthaler TI, Ryu JH, Utz JP. Cavitary pulmonary infarct in immunocompromised

[10] Vidal E, LeVeen HH, Yarnoz M, Piccone VA Jr. Lung abscess secondary to pulmonary

[11] Geibel A. et all. Prognostic value of the ECG on admission in patients with acute major

[12] Wilson AG, Joseph AEA, Butland RJA. The radiology of aseptic cavitary pulmonary

arterial flow with inadequate ventilation leads to pulmonary infarction. Virchows

resection for treatment of cavitary pulmonary infarction. Ann Thorac Surg 1997; 63:

sarcoma misdiagnosed as chronic thrombo-emblic pulmonary disease: a case

[1] Robert Baird, Pulmonary Embolism and Infarction; January 19, 2008

pulmonary infarction. Medicine (Baltimore) 1985; 64: 342-348.

**8. References** 

(www.americanchronicle.com)

Arch 1996; 427: 607-612.

report. JMCR 2009; 3:64.

host. Mayo Clin Proc 1995; 70: 66-68.

infarction. Clin Radiol 1986; 37: 327-333.

infarction. Ann Thorac Surg 1971; 11: 557-564.

pulmonary embolism. Eur Respir J 2005; 25: 843-848.

849-850.

Dural ateriovenous fistula (DAVF) is the acquired and progressive arteriovenous (AV) shunt disease on or between the dura matter, and its etiology is still controversial1-4. This disorder occurs not in the whole dura but at very specific locations. DAVF can be divided into two types based on the intervention of the drainage route and affected sinus; sinus type and non-sinus type. The sinus type has the shunt at the sinus wall or dural vein, and includes DAVF at the cavernous sinus (CS), transverse-sigmoid sinus (TS-SS), anterior condylor confluence (ACC), and superior sagittal sinus (SSS). The non-sinus DAVF has the shunt on the dura and directly drains into the pial veins, and includes tentorial, ethmoidal, craniocervical and spinal DAVF. However, even the sinus type DAVF ultimately changes to the isolated sinus with cortical reflux due to progressive sinus occlusion, similar to the non-sinus type. Such seemingly separated and complex pathogeneses of DAVF remain elusive.

## **2. Previous theory about DAVF etiology**

Previous recognition of the etiology of DAVF has been directed to sinus hypertension1,4 and thrombosis5, 8. It is true that such abnormal situations may create the experimental AV shunt1-4. However, if one considers that the sinus hypertension is the initial trigger, it should be caused secondary to the thrombosis or outlet stenosis. It is unreasonable to adopt this theory into non-sinus type, because this type has no correspondence with the sinus. In other hand AV shunt formation can easily create the condition of sinus hypertension. Thus, the conventional discussion over the etiology of AV shunt formation between sinus occlusion and sinus hypertension is just a chicken-or-egg question. We consider that sinus hypertension concerning sinus wall hypertrophy may not be the cause, but rather one factor in the development of DAVF. Our theory based on inflammatory initiation affecting EV can explain both types of DAVF and subsequent development with pathological changes of the drainage route is not contradictory to the previous sinus-oriented theory.

Hypothetical Mechanism of the Formation of Dural Arteriovenous

Fistula – The Role and Course of Thrombosis of Emissary Vein and Sinuses 225

A B

C D

E A Normal site. Emissary vein (EV) and artery (a) is penetrating through a foramen of the parasagittal skull. EV is connected with the venous lacunae (b). Meningeal arteries (c) have no connection with SSS

C AV shunt formation at the level of dural arteriole and penetration into the sinus (initial stage of

E. Maturation of DAVF with the reflux to cortical veins (red arrow) due to sinus occlusion (white arrow). Note the further recruitment of feeders from the other side or transosseous branches (h). Fig. 2. Mechanism of development of the DAVF at the superior sagittal sinus (SSS) as a

D. Shunt development with thrombosis of an emissary vein (asterisk) and recruitment of distal arteries

B Neovascularization (arrow) and vessel dilatation induced by dural inflammation

DAVF). Note the shunt flow draining into the sinus as well as EV (double arrow).

from anterior falx artery (f) and posterior meningeal arteries (g).

representative of the sinus type DAVF.

(d) and cortical vein (e).
