FROM THE DEPARTMENT OF DIAGNOSTIC RADIOLOGY (DIRECTOR: PROF. H. LODIN), AKADEMISKA SJUKHUSET, UNIVERSITY OF UPPSALA, S-750 14 UPPSALA, SWEDEN.
FIBROUS SEPTA IN THE STRAIGHT DURAL SINUS
ERIC BERGQUIST
The presence of septa in the straight sinus has received only scant attention in the literature. GRAY'S Anatomy (1962) states that the straight sinus is traversed by a few transverse bands. Numerous septa in the dural sinuses in the region of the confluens sinuum, similar to those present in the cavernous sinus, were observed at cerebral angiography by TONNIS & SCHIEFER (1959). KRAYENBUHL & Y A~ARGIL (1965) reported that the straight sinus may be duplicated ('spaltfOrmig') but do not discuss the anatomic basis. In the course of an investigation concerning the tentorial notch (BERGQUIST 1973), one or more septa in the upper part of the straight sinus were incidentally observed and a systematic search thus seemed to be warranted.
Material and Methods. During routine autopsies performed at the Department of Pathology the straight sinus in 145 cases (83 men and 62 women, 30 to 93 years old) was opened after removal of the tentorium of the cerebellum and adjacent parts of the falx. In 15 cases, before the tentorium was removed and the straight sinus opened, a 50 % suspension of Micropaque in water was injected into the lower part of the sinus, which was exposed by removing the left half of the vault and the left cerebral hemisphere. Following optimal filling of the sinus, lateral films were taken. Submitted for publication 30 August 1974.
331
Downloaded from acr.sagepub.com by guest on July 24, 2015
332
ERIC BERGQUIST
b
a
Fig. 1. Septa in the upper part of the straight sinus. A wire is introduced into the posterior canal.
Results Transverse septa or synechiae were found in 44 of the 145 straight sinuses (from 30 men and 14 women). Septa crossing the sinus in the transverse direction, dividing it completely or partially into an anterior and a posterior canal, were observed in 31 cases (21 per cent). A single septum was present in 28 cases, varying greatly in length (2 to 5 mm in 1I cases, 6 to IO mm in 9, 11 to 20 mm in 5 and over 20 mm in 3 cases). In a further 3 cases two septa were present (12 and 3 mm long in each of 2 cases, and 6 and 4 mm long in the third case). The septa (Fig. 1) were found in all parts of the sinus. In 5 cases the septum was situated behind the opening of the great vein of Galen into the straight sinus. These septa, which varied in length between 6 and 23 mm, divided the upper part of the sinus into two canals, the great vein of Galen invariably joining the anterior one. The inferior sagittal sinus mainly drained into the same canal; however, a small aperture in the upper part of the septum would seem to permit drainage to the posterior canal. Proximally positioned septa separated the lacuna at the origin of the straight sinus from other parts of the sinus. Thread-like synechiae no more than I mm thick were found in 15 cases (10 per cent); in 4 of them the synechiae were multiple, and in addition a septum occurred in 2 cases, 7 mm and 3 mm long, respectively. Like the septa, the synechiae were observed in all parts of the sinus. Septa were identified on the autopsy films in 5 of 15 examined cases. In 9 of the other 10 cases no septum was found on exploration of the sinus. In the remaining case a thin septum in the lower part of the straight sinus existed; this could not be identified on the film, probably because it was obscured by the fairly concentrated contrast medium. The septa appeared on the films as narrow longitudinal filling defects in the sinus (Fig. 2). In one case with a long septum in the upper part of the sinus, the film gave incomplete information concerning the septum, because the cannula through which
Downloaded from acr.sagepub.com by guest on July 24, 2015
FIBROUS SEPTA IN THE STRAIGHT DURAL SINUS
Fig. 2
333
Fig. 3
Fig. 2. Lateral film of the straight sinus (autopsy case). Same case as in fig. 1 a. The septum causes a long filling defect in the upper part of the sinus; its anterior part is divided by the septum into an upper and a lower canal. Fig. 3. Lateral film of the straight sinus (autopsy case). The cannula through which the contrast medium was injected is placed in the anterior upper canal and only the lower posterior part of a long septum (-+) is demonstrated, giving a false impression of the width of the straight sinus.
the contrast medium was injected had been placed in the anterior canal; there was only a narrow opening in the upper part of the septum and the contrast medium did not pass through it to the posterior canal. Consequently, only the lower part of the septum was demonstrated on the film (Fig, 3). The synechiae were not visible at radiography. Discussion
The straight sinus develops from the lower part of the sagittal venous plexus (STREETER 1918, PADGET 1957). O'CONNEL (1934) reported single or multiple 'platforms' subdividing the lumen of the superior sagittal sinus into dorsal and ventral parts. The longest platform was 8 em, The orifices of the superior cerebral veins joining the superior sagittal sinus were always located below any nearby platform. O'CONNEL was of the opinion that the platforms persist as evidence of the original plexiform character of the superior sagittal sinus. The septa in the straight sinus reported here would seem to be of the same nature as these platforms, since the straight sinus develops from the same plexus as the superior sagittal sinus. In addition, the observed thread-like synechiae had the same appearance as the so-called cords of Willis-strands of endothelium traversing the lumen of the superior sagittal sinus-which are also generally considered to be remnants of the sagittal plexus. Anatomically the septa, which were present in about one fifth of the cases, varied greatly in length, position and number from one subject to another, and all must be viewed as normal anatomic variants. If a septum was present in the upper part of the straight sinus, however, the great vein of Galen and the major part of the inferior
Downloaded from acr.sagepub.com by guest on July 24, 2015
334
ERIC BERGQUIST
a
b
Fig. 4. Clinical case. a) Left carotid angiography. A septum has given the straight sinus a two-channelled appearance. b) Right carotid angiography. The straight sinus seems to be single-channelled and not as wide as in (a). c) Vertebral angiography. The straight sinus seems to be single-channelled and its width corresponds to that seen in (a). No septum is seen; probably obscured by the contrast medium.
c
sagittal sinus invariably drained in front of the septum. This may be compared with the position of the orifices of the superior cerebral veins in relation to the platforms in the superior sagittal sinus (O'CONNEL). A septum may appear as a defect in the straight sinus filled with contrast medium, i.e. it may resemble a thrombus. The possible presence of septa in this sinus should be borne in mind so as to avoid an erroneous diagnosis of a thrombus. A blood clot, however, generally gives rise to an increase in the circulation time. Furthermore, it seems possible that in the presence of a septum the straight sinus may vary in appearance at different angiographic examinations in one and the same patient. This may be illustrated by the following clinical case. At carotid angiography on the left side the straight sinus had a two-channelled appearance (Fig. 4 a), while on the right side only the anterior canal filled, the sinus thus appearing narrower
Downloaded from acr.sagepub.com by guest on July 24, 2015
FIBROUS SEPTA IN THE STRAIGHT DURAL SINUS
335
than at the left angiography (Fig. 4 b); at vertebral angiography the sinus appeared to be broad and single-channelled and seemed to contain more contrast medium than at the carotid angiographies (Fig. 4 c). Various factors were probably responsible for the varying appearances. It was observed at postmortem radiography that when a septum was present the straight sinus could have a two-channelled appearance. At the left carotid angiography in the patient, thestraight sinus appeared to have two channels and the presence of a septum could therefore be considered proven. The filling of the straight sinus was more complete at the vertebral angiography than at the carotid angiographies and probably obscured the septum. This indicates that the septum was thin. These findings may be compared with the autopsy case in which a thin septum, subsequently seen on dissection, could not be identified on the films because it was obscured by the contrast medium. The different appearances of the straight sinus on the left and right carotid angiograms may have been due to differing topography of the veins draining into the deep venous channels on the left and right sides; in addition, the septum may have caused a deviant flow.
SUMMARY Postmortem exploration of the straight sinus supplemented in some cases by radiography revealed the presence of single or multiple septa or synechiae in the sinus in 44 of 145 cases. A septum should not be mistaken for a thrombus. The septa are of roentgenologic significance because of their ability to alter the appearance of the sinus from one cerebral angiography to another in one and the same patient.
ZUSAMMENFASSUNG Die postmortale Exploration des Sinus rectus, in einigen Fallen durch Rontgenuntersuchungen ergranzt, zeigte das Vorkommen einzelner oder multipler Septen oder Verwachsungen in den Sinus von 44 von 145 Hillen. Ein Septum sollte nicht mit einem Thrombus verwechselt werden. Die Septen sind wegen ihrer Fahigkeit, das Bild des Sinus von einer zerebralen Angiographie zur anderen bei ein und demselben Patienten zu andern, von rontgenologischer Bedeutung.
RESUME L'examen postmortem du sinus droit, complete dans certains cas par la radiographic, a montre la presence de cloisons uniques ou multiples ou de synechies dans le sinus dans 44 cas sur 145. II ne faut pas prendre une cloison pour un thrombus; les cloisons ant un interet radiologique car elles peuvent modifier I'aspect du sinus d'une angiographie cerebrale it I'autre chez un meme malade.
REFERENCES BERGQUIST E.: Tentorial notch and adjacent major vessels in carotid angiography. Acta radiol. (1973) Suppl. No. 327.
Downloaded from acr.sagepub.com by guest on July 24, 2015
336
ERIC BERGQUIST
GRAY'S ANATOMY. Thirty-third Edition. Longrnans, Green & Co Ltd, London 1962. KRAYENBUHL H. und YA§ARGIL M. G.: Die zerebrale Angiographie. Zweite Auflage. Georg Thieme Verlag, Stuttgart 1965. O'CONNEL J. E. A.: Some observations on the cerebral veins. Brain 57 (1934), 484. PADGET D. H.: The development of the cranial venous system in man, from the viewpoint of comparative anatomy. Carnegie Inst. Washington, Pub!. 611. Contrib. to Embryo!. 36 (1957), 79. STREETER G. L.: The developmental alterations in the vascular system of the brain of the human embryo. Carnegie Inst. Washington, Publ. 271. Contrib. to Embryol. 8 (1918), 5. TONNIS W. und SCHIEFER W.: Zirkulationsstorungen des Gehirns im Serienangiogramm. Springer Verlag, Berlin-Gottingen-Heidelberg 1959.
Downloaded from acr.sagepub.com by guest on July 24, 2015
FIBROUS SEPTA IN THE STRAIGHT DURAL SINUS
ERIC BERGQUIST
The presence of septa in the straight sinus has received only scant attention in the literature. GRAY'S Anatomy (1962) states that the straight sinus is traversed by a few transverse bands. Numerous septa in the dural sinuses in the region of the confluens sinuum, similar to those present in the cavernous sinus, were observed at cerebral angiography by TONNIS & SCHIEFER (1959). KRAYENBUHL & Y A~ARGIL (1965) reported that the straight sinus may be duplicated ('spaltfOrmig') but do not discuss the anatomic basis. In the course of an investigation concerning the tentorial notch (BERGQUIST 1973), one or more septa in the upper part of the straight sinus were incidentally observed and a systematic search thus seemed to be warranted.
Material and Methods. During routine autopsies performed at the Department of Pathology the straight sinus in 145 cases (83 men and 62 women, 30 to 93 years old) was opened after removal of the tentorium of the cerebellum and adjacent parts of the falx. In 15 cases, before the tentorium was removed and the straight sinus opened, a 50 % suspension of Micropaque in water was injected into the lower part of the sinus, which was exposed by removing the left half of the vault and the left cerebral hemisphere. Following optimal filling of the sinus, lateral films were taken. Submitted for publication 30 August 1974.
331
Downloaded from acr.sagepub.com by guest on July 24, 2015
332
ERIC BERGQUIST
b
a
Fig. 1. Septa in the upper part of the straight sinus. A wire is introduced into the posterior canal.
Results Transverse septa or synechiae were found in 44 of the 145 straight sinuses (from 30 men and 14 women). Septa crossing the sinus in the transverse direction, dividing it completely or partially into an anterior and a posterior canal, were observed in 31 cases (21 per cent). A single septum was present in 28 cases, varying greatly in length (2 to 5 mm in 1I cases, 6 to IO mm in 9, 11 to 20 mm in 5 and over 20 mm in 3 cases). In a further 3 cases two septa were present (12 and 3 mm long in each of 2 cases, and 6 and 4 mm long in the third case). The septa (Fig. 1) were found in all parts of the sinus. In 5 cases the septum was situated behind the opening of the great vein of Galen into the straight sinus. These septa, which varied in length between 6 and 23 mm, divided the upper part of the sinus into two canals, the great vein of Galen invariably joining the anterior one. The inferior sagittal sinus mainly drained into the same canal; however, a small aperture in the upper part of the septum would seem to permit drainage to the posterior canal. Proximally positioned septa separated the lacuna at the origin of the straight sinus from other parts of the sinus. Thread-like synechiae no more than I mm thick were found in 15 cases (10 per cent); in 4 of them the synechiae were multiple, and in addition a septum occurred in 2 cases, 7 mm and 3 mm long, respectively. Like the septa, the synechiae were observed in all parts of the sinus. Septa were identified on the autopsy films in 5 of 15 examined cases. In 9 of the other 10 cases no septum was found on exploration of the sinus. In the remaining case a thin septum in the lower part of the straight sinus existed; this could not be identified on the film, probably because it was obscured by the fairly concentrated contrast medium. The septa appeared on the films as narrow longitudinal filling defects in the sinus (Fig. 2). In one case with a long septum in the upper part of the sinus, the film gave incomplete information concerning the septum, because the cannula through which
Downloaded from acr.sagepub.com by guest on July 24, 2015
FIBROUS SEPTA IN THE STRAIGHT DURAL SINUS
Fig. 2
333
Fig. 3
Fig. 2. Lateral film of the straight sinus (autopsy case). Same case as in fig. 1 a. The septum causes a long filling defect in the upper part of the sinus; its anterior part is divided by the septum into an upper and a lower canal. Fig. 3. Lateral film of the straight sinus (autopsy case). The cannula through which the contrast medium was injected is placed in the anterior upper canal and only the lower posterior part of a long septum (-+) is demonstrated, giving a false impression of the width of the straight sinus.
the contrast medium was injected had been placed in the anterior canal; there was only a narrow opening in the upper part of the septum and the contrast medium did not pass through it to the posterior canal. Consequently, only the lower part of the septum was demonstrated on the film (Fig, 3). The synechiae were not visible at radiography. Discussion
The straight sinus develops from the lower part of the sagittal venous plexus (STREETER 1918, PADGET 1957). O'CONNEL (1934) reported single or multiple 'platforms' subdividing the lumen of the superior sagittal sinus into dorsal and ventral parts. The longest platform was 8 em, The orifices of the superior cerebral veins joining the superior sagittal sinus were always located below any nearby platform. O'CONNEL was of the opinion that the platforms persist as evidence of the original plexiform character of the superior sagittal sinus. The septa in the straight sinus reported here would seem to be of the same nature as these platforms, since the straight sinus develops from the same plexus as the superior sagittal sinus. In addition, the observed thread-like synechiae had the same appearance as the so-called cords of Willis-strands of endothelium traversing the lumen of the superior sagittal sinus-which are also generally considered to be remnants of the sagittal plexus. Anatomically the septa, which were present in about one fifth of the cases, varied greatly in length, position and number from one subject to another, and all must be viewed as normal anatomic variants. If a septum was present in the upper part of the straight sinus, however, the great vein of Galen and the major part of the inferior
Downloaded from acr.sagepub.com by guest on July 24, 2015
334
ERIC BERGQUIST
a
b
Fig. 4. Clinical case. a) Left carotid angiography. A septum has given the straight sinus a two-channelled appearance. b) Right carotid angiography. The straight sinus seems to be single-channelled and not as wide as in (a). c) Vertebral angiography. The straight sinus seems to be single-channelled and its width corresponds to that seen in (a). No septum is seen; probably obscured by the contrast medium.
c
sagittal sinus invariably drained in front of the septum. This may be compared with the position of the orifices of the superior cerebral veins in relation to the platforms in the superior sagittal sinus (O'CONNEL). A septum may appear as a defect in the straight sinus filled with contrast medium, i.e. it may resemble a thrombus. The possible presence of septa in this sinus should be borne in mind so as to avoid an erroneous diagnosis of a thrombus. A blood clot, however, generally gives rise to an increase in the circulation time. Furthermore, it seems possible that in the presence of a septum the straight sinus may vary in appearance at different angiographic examinations in one and the same patient. This may be illustrated by the following clinical case. At carotid angiography on the left side the straight sinus had a two-channelled appearance (Fig. 4 a), while on the right side only the anterior canal filled, the sinus thus appearing narrower
Downloaded from acr.sagepub.com by guest on July 24, 2015
FIBROUS SEPTA IN THE STRAIGHT DURAL SINUS
335
than at the left angiography (Fig. 4 b); at vertebral angiography the sinus appeared to be broad and single-channelled and seemed to contain more contrast medium than at the carotid angiographies (Fig. 4 c). Various factors were probably responsible for the varying appearances. It was observed at postmortem radiography that when a septum was present the straight sinus could have a two-channelled appearance. At the left carotid angiography in the patient, thestraight sinus appeared to have two channels and the presence of a septum could therefore be considered proven. The filling of the straight sinus was more complete at the vertebral angiography than at the carotid angiographies and probably obscured the septum. This indicates that the septum was thin. These findings may be compared with the autopsy case in which a thin septum, subsequently seen on dissection, could not be identified on the films because it was obscured by the contrast medium. The different appearances of the straight sinus on the left and right carotid angiograms may have been due to differing topography of the veins draining into the deep venous channels on the left and right sides; in addition, the septum may have caused a deviant flow.
SUMMARY Postmortem exploration of the straight sinus supplemented in some cases by radiography revealed the presence of single or multiple septa or synechiae in the sinus in 44 of 145 cases. A septum should not be mistaken for a thrombus. The septa are of roentgenologic significance because of their ability to alter the appearance of the sinus from one cerebral angiography to another in one and the same patient.
ZUSAMMENFASSUNG Die postmortale Exploration des Sinus rectus, in einigen Fallen durch Rontgenuntersuchungen ergranzt, zeigte das Vorkommen einzelner oder multipler Septen oder Verwachsungen in den Sinus von 44 von 145 Hillen. Ein Septum sollte nicht mit einem Thrombus verwechselt werden. Die Septen sind wegen ihrer Fahigkeit, das Bild des Sinus von einer zerebralen Angiographie zur anderen bei ein und demselben Patienten zu andern, von rontgenologischer Bedeutung.
RESUME L'examen postmortem du sinus droit, complete dans certains cas par la radiographic, a montre la presence de cloisons uniques ou multiples ou de synechies dans le sinus dans 44 cas sur 145. II ne faut pas prendre une cloison pour un thrombus; les cloisons ant un interet radiologique car elles peuvent modifier I'aspect du sinus d'une angiographie cerebrale it I'autre chez un meme malade.
REFERENCES BERGQUIST E.: Tentorial notch and adjacent major vessels in carotid angiography. Acta radiol. (1973) Suppl. No. 327.
Downloaded from acr.sagepub.com by guest on July 24, 2015
336
ERIC BERGQUIST
GRAY'S ANATOMY. Thirty-third Edition. Longrnans, Green & Co Ltd, London 1962. KRAYENBUHL H. und YA§ARGIL M. G.: Die zerebrale Angiographie. Zweite Auflage. Georg Thieme Verlag, Stuttgart 1965. O'CONNEL J. E. A.: Some observations on the cerebral veins. Brain 57 (1934), 484. PADGET D. H.: The development of the cranial venous system in man, from the viewpoint of comparative anatomy. Carnegie Inst. Washington, Pub!. 611. Contrib. to Embryo!. 36 (1957), 79. STREETER G. L.: The developmental alterations in the vascular system of the brain of the human embryo. Carnegie Inst. Washington, Publ. 271. Contrib. to Embryol. 8 (1918), 5. TONNIS W. und SCHIEFER W.: Zirkulationsstorungen des Gehirns im Serienangiogramm. Springer Verlag, Berlin-Gottingen-Heidelberg 1959.
Downloaded from acr.sagepub.com by guest on July 24, 2015
