Falcine Sinus: Incidence and Imaging Characteristics of Three-Dimensional Contrast-Enhanced Thin-Section Magnetic Resonance Imaging

OBJECTIVE: To evaluate the incidence, characteristics, and variations of the falcine sinus with contrast-enhanced three-dimentional (3D) thin-section magnetic resonance (MR) images. MATERIALS AND METHODS: retrospective review identified 1531 patients (745 males and 786 females, 2 months to 85 years) who underwent cranial MR imaging including T1-weighted imaging, T2-weighted imaging, T2-weighted fluid-attenuated inversion recovery, contrast-enhanced 3D thin-section sagittal scans, and MR venography, from June 2014 to January 2016. The incidence, characteristics of the falcine sinus, and coexisted intracranial lesions were confirmed by two neuroradiologists. RESULTS: Falcine sinuses were identified in 81 (38 males and 43 females) cases (5.3%, 81/1531, 5 months to 76 years of age) with calibers ranging from 2.3 mm to 17.0 mm. Three major forms of falcine sinuses were defined: arch-like (n = 47), stick-like (n = 22), and bifurcated (n = 12). Persistent falcine sinuses were found in 57 cases, among which 3 cases showed complicated cerebral anomalies, and 2 cases showed smaller straight sinuses. Recanalization of falcine sinuses were found in 24 cases, including 17 cases with tumor compression, 6 cases with cerebral venous sinus thrombosis, and one case with hypertrophic meningitis. CONCLUSION: Falcine sinus is not as rare as has been reported previously. Most falcine sinuses are not associated with congenital cerebral abnormalities. Diseases that cause increased pressure in the venous sinus may lead to recanalization of falcine sinus. Illustrating the characteristics of falcine sinus may prompt a more comprehensive understanding and diagnosis of associated diseases, and avoid potential surgical damage in the future.

Enlarged parietal foramina presenting as scalp swelling in an infant

“Enlarged parietal foramina” is a congenital malformation with autosomal dominant inheritance. The condition is usually self-limiting and doesn’t require any treatment. However, it may also be associated with encephalocele, vascular anomalies or may be a part of syndrome. We present a case of enlarged parietal foramina in a child and discuss its imaging findings and the associated intracranial vascular malformations.

Two Cases with Persistent Falcine Sinus as Congenital Variation

The falcine sinus is an abnormal anatomic structure located in the falx cerebri that is closed after birth and is rarely observed. We describe two cases of persistent falcine sinus. A 60-year-old woman presented with headache. An 11-year-old girl presented with intermittent headache and a palpable scalp mass in the middle of the high parietal area. The straight sinuses were absent in both patients. In both patients, drainage of the galenic system took place through a sinus within the falx, also known as a falcine sinus. Suspicious dysplastic tentorium cerebelli was observed in one patient. It can be concluded that a mesenchymal disorder can be the primary cause for a persistent falcine sinus.

MR Images of Spontaneously Involuted Atretic Cephalocele Concomitant with Persistent Falcine Sinus in an Adult

Atretic cephalocelces are defined as skin-covered midline subscalp lesions that contain meninges and rest of glial and/or central nervous system tissue. When the straight sinus is absent or rudimentary, the falcine sinus can be recanalized to enable venous drainage. Although the atretic cephalocele or persistent falcine sinus has largely been described in the pediatric population, it is a rarely observed in the adult population. We report a unique case of spontaneously involuted atretic cephalocele coexistent with persistent falcine sinus in an adult. MR images and MR venography were useful for diagnosis and accurate anatomical depiction.