Introduction

Sinus pericranii (SP) is a rare vascular malformation characterized by an abnormal communication between the extracranial and intracranial venous systems, usually involving the superior sagittal sinus (SSS) and occasionally the transverse sinus.2)4) SP is usually found in the pediatric age group in which it presents as a small circumscribed swelling of the scalp. SP is generally considered a congenital abnormality, although trauma is believed to be a possible causative factor in acquired SP.8)9)10)12)13)

The natural history of SP involves increase in swelling and development of potential life-threatening complications, including thrombosis, hemorrhage, or air embolism. Thus, surgical or endovascular management is necessary for treatment.

Case Report

A 28-year-old man presented with a round, fluctuant, nonpulsatile scalp mass in the frontal area near the midline. The patient sustained a closed head injury while serving in the army and he stated that since that time he had noticed some degree of intermittent swelling over that area. An expansile cough impulse could be elicited and further provocative tests such as the Valsalva maneuver and bending his head down significantly increased the swelling with visible pulsations on its surface (Fig. 1). A three-dimensional computed tomography (CT) scan revealed a soft tissue mass overlying the frontal bone just above the SSS with a focal bony defect and a mild depression of the frontal bone beneath the mass (Fig. 2). Contrast-enhanced magnetic resonance (MR) images showed a paramedian scalp varix extending through a bony defect in the vertex of the skull to the adjacent SSS (Fig. 3).

Operation

The mass was located beneath the periosteum of the cranial vault, beside the sagittal suture. It was reddish and connected to multiple veins of the scalp. The area between the soft tissues and veins were dissected while hemostasis was performed using bipolar coagulation; thereafter, the mass was elevated from the skull. After confirming the penetration of the extracranial veins through the bone defect area, the proximal part of the extracranial veins were ligated by tying. The distal part of the tied area was then dissected and bleeding was controlled using a bipolar coagulator. Thereafter, the emissary communication vein was coagulated using a bipolar coagulator and the bone defect area was reconstructed using a mesh plate.

Discussion

SP was first described by Hecker in 1845 and its name was coined by Stromeyer in 1850.2)17) SP is a rather rare vascular malformation of the cranial vault characterized by abnormal communication between an extracranial vein and an intracranial venous sinus, which usually involves the SSS and occasionally the transverse sinus, communicating through diploic veins.2) SP presents as a round, soft, tumor-like lesion that is fluctuant, nonpulsatile, easily compressible and collapsible and is located in the midline along the SSS, mainly in the frontal region.16) The soft, fluctuant mass disappears if the patient sits up. Compressing the jugular veins bilaterally and/or performing the Valsalva maneuver cause the lesion to reappear. The lesion is readily apparent when the patient is lying down.

SP typically appears in childhood, grows larger over time and may be congenital or acquired. Congenital lesions may be caused by incomplete sutural fusion or in-utero dural sinus thrombosis. Acquired lesions are either spontaneous or traumatic.7)18) Spontaneous lesions may be caused by subclinical dural thrombosis. Some lesions have been attributed to trauma, an unusual stress or strain that involves tearing of the emissary veins.8) The main difference between spontaneous and traumatic lesions is the presence of endothelial lining.3) The presence of connective tissue suggests a traumatic origin, whereas the presence of vascular endothelium indicates a congenital or spontaneous origin.

In this report, although traumatic SP was first suspected based on the patient’s clinical history, pathological examinations revealed the presence of vascular endothelium. Thus, the patient was diagnosed with spontaneous SP (Fig. 4).

A diagnosis of SP can be suggested from the clinical appearance of a soft, fluctuant mass that can vary in size, located near the intracranial sinus. Investigations that are useful in diagnosing SP include plain X rays, CT, MR imaging or digital subtraction angiography (DSA).1)2)15)16) Plain skull radiography shows bony defects, cortical thinning, or focal bony erosions. CT scans may reveal a dense soft tissue mass overlying the bony defect. An MRI scan shows the signal characteristics of the sinus content and the relationship of the lesion to the subjacent sinus. DSA after direct injection of contrast medium through the wall of the mass shows a quick passage of contrast medium into the sinus.

The differential diagnosis is broad and includes skin lesions and other vascular anomalies, such as hemangiomas, arteriovenous malformations, dermoid cysts and epidermoid cysts.11)18)

SP is usually asymptomatic. However, it may cause fatal complications such as thrombosis, traumatic air embolism, or massive hemorrhage.1)2)12)16) Rare symptomatic cases with increased intracranial pressure have been previously reported. Thus, prompt treatment after diagnosis is required for prophylactic purposes to prevent such complications, as well as for aesthetic purposes.

Endovascular therapy may be suitable for smaller SP. This technique has been performed using the transvenous approach combined with direct puncture6) and the recently introduced endovascular embolization with Onyx.14) Percutaneous injection into draining scalp veins has also been described.5) Several investigators have performed a craniectomy to correct this malformation.1)12)16) Bone wax or gelfoam has also been used to obliterate the communication.1)8)

In surgical treatment, the key point is to resect the extracranial venous package and ligate the emissary communicating vein. In the case presented in this report, craniectomy was not performed. The soft tissue and vein were properly dissected, the extracranial venous package was ligated by tying, and the emissary communicating vein was coagulated using a bipolar coagulator.

Conclusion

SP is a rare vascular malformation. Although it is rare, diagnosis is possible based on its unique clinical features. Moreover, because SP may cause life-threatening complications and cosmetic problems, early surgical or endovascular management is required. Here, we report a case of successful surgical treatment of a patient with spontaneous SP.

REFERENCES

1)Alexander EJ, Ball MR. Sinus pericranii. In: Wilkins RH, Rengachary SS, eds. Neurosurgery Update II; Vascular, Spinal, Pediatric, and Functional Neurosurgery. New York: McGraw-Hill, 1991, pp 70-2.

2)Bollar A, Allut AG, Prieto A, Gelabert M, Becerra E. Sinus pericranii: radiological and etiolopathological considerations. J Neurosurg 77:469-72, 1992.

3)Cohn I. Sinus pericranii (Stromeyer). Report of a case; review of the literature. Surg Gynecol Obstet 42:614-24, 1926.

4)Desai K, Bhayani R, Goel A, Muzumdar D. Sinus pericranii in the frontal region: a case report. Neurol India 49:305-7, 2001.

5)Higuchi M, Fujimoto Y, Ikeda H, Kato A. Sinus pericranii: neuroradiologic findings and clinical management. Pediatr Neurosurg 27:325-8, 1997.

6)Kessler IM, Esmanhoto B, Riva R, Mounayer C. Endovascular transvenous embolization combined with direct punction of the sinus pericranii. A case report. Interv Neuroradiol 15:429-34, 2009.

7)Lo PA, Besser M, Lam AH. Sinus pericranii: a clinical and radiological review of an unusual condition. J Clin Neurosci 4:247-52, 1997.

8)Mori K, Yoneda S, Handa H. Post-traumatic subepicranial varix. Surg Neurol 5:337-9, 1976.

9)Nakasu Y, Nakasu S, Minouchi K, Handa J. Multiple sinus pericranii with systemic angiomas: case report. Surg Neurol 39:41-5, 1993.

10)Nakayama T, Matsukado Y. Sinus pericranii with aneurysmal malformation of the internal cerebral vein. Surg Neurol 3:133-7, 1975.

11)Nomura S, Kato S, Ishi hari H, Yoneda H, Ideguchi M, Suzuki M. Association of intra and extradural developmental anomalies, so-called venous angioma and sinus pericranii. Childs Nerv Syst 22:428-31, 2006.

12)Ota T, Waga S, Handa H, Nishimura S, Mitani T. Sinus pericranii. J Neurosurg 42:704-12, 1975.

13)Poppel MH, Roach JF, Hamlin H. Cavernous hemangioma of the frontal bone with report of a case of sinus. Am J Roentgenol Radium Ther 59:505-10, 1948.

14)Rangel-Castilla L, Krishna C, Klucznik R, Diaz O. Endovascular embolization with Onyx in the management of sinus pericranii: a case report. Neurosurg Focus 27:E13, 2009.

15)Sadler LR, Tarr RW, Jungreis CA, Sekhar L. Sinus pericranii: CT and MR findings. J Comput Assist Tomogr 14:124-7, 1990.

16)Spektor S, Weinberger G, Constantini S, Gomori JM, Beni–Adani L. Giant lateral sinus pericranii. Case report. J Neurosurg 88:145-7, 1998.

17)Stromeyer L. About sinus pericranii (translation of original 1850 text). Surg Neurol 40:3-4, 1993.

18)Vinas FC, Valenzuela S, Zuleta A. Literature review: sinus pericranii. Neurol Res 16:471-4, 1994.