|Year : 2015 | Volume
| Issue : 1 | Page : 66-69
Large midline persistent parietal foramina with occipital encephalocele and abnormal venous drainage
Parag Agarwal, Mithelesh Pandey, Sunil Baranwal, Kaushik Roy
Department of Neurosurgery, Nilratan Sircar Medical College and Hospital, Kolkata, West Bengal, India
|Date of Web Publication||4-Feb-2015|
Dr. Parag Agarwal
Department of Neurosurgery, 6th Floor, U.N.B. Building, Nilratan Sircar Medical College and Hospital, 138, A J C Bose Road, Sealdah, Kolkata - 700 014, West Bengal
Source of Support: None, Conflict of Interest: None
Enlarged persistent parietal foramen is rare congenital skull defect and associated anomalies like underlying encephalomalacia, and venous malformations are known. We here report a very rare association with persistent occipital foramina and occipital encephalocele. This patient presented later in life with complaints of headache and seizure. Basic clinical examination like palpation of scalp was helpful in diagnosing this rare condition. Radiological investigations later revealed an array of associated congenital abnormalities like hypoplastic inferior sagittal sinus, which is even rare finding in a single case.
Keywords: Encephalocele, encephalomalacia, hypoplastic inferior sagittal sinus, persistent parietal foramina, persistent occipital foramina
|How to cite this article:|
Agarwal P, Pandey M, Baranwal S, Roy K. Large midline persistent parietal foramina with occipital encephalocele and abnormal venous drainage. J Cleft Lip Palate Craniofac Anomal 2015;2:66-9
|How to cite this URL:|
Agarwal P, Pandey M, Baranwal S, Roy K. Large midline persistent parietal foramina with occipital encephalocele and abnormal venous drainage. J Cleft Lip Palate Craniofac Anomal [serial online] 2015 [cited 2020 Dec 3];2:66-9. Available from: https://www.jclpca.org/text.asp?2015/2/1/66/150757
| Introduction|| |
Enlarged parietal foramina, otherwise known as foramina parietalia permagna, giant parietal foramina, fenestrae parietals symmetricae or Catlin marks, are a rare congenital skull defects detected on clinical examination and confirmed by radiological investigation. These are round or oval defects located on each parietal eminence for the passage of emissary veins.
These are usually asymptomatic. Some patients may present with complaints of headaches, vomiting, or intense local pain, especially on the application of mild pressure to the unprotected cerebral cortex. Some cases may predispose to epilepsy. These are occasionally associated with various cerebral and vascular malformations, which should be looked for.
| Case Report|| |
A 19-year-old girl was referred to our neurosurgery out-patient department with complaints of intermittent headache and an episode of complex partial seizure, followed by postictal weakness. Since her birth, a palpable skull defects in the middle of the high parietal area and a soft tissue swelling over the occiput of her head was noticed, which was painful to touch and caused severe occipital headaches when local pressure was applied.
Physical examination results were normal except for a slight elevated, hairless and mild tender, nonpulsatile, soft swelling located in the occipital region of the scalp [Figure 1]. No change in shape or size of mass was noted when she coughed. There was an 8 cm × 6 cm mid parietal bony gap palpable with smooth margins and without any bony ridge. On neurological examination, she showed no abnormal response.
|Figure 1: Slight elevated, hairless swelling located in the occipital region of scalp|
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Laboratory examination showed normal blood ranges.
Plain radiography of the skull revealed a large circular, well-defined bony defect at the posterior inter-parietal region [Figure 2].
|Figure 2: Plain radiography skull showing a large circular posterior parietal bony defect|
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Computed tomography (CT) scan with three-dimensional (3D) reconstruction reported a single ossification defect involving both parietal bones, but without herniation of membranes or brain beyond the confines of the skull. Gliosis of both underlying parietal lobes with dilation of the posterior horn of both lateral ventricles was visualized. A small midline occipital defect with encephalocele was detected [Figure 3].
|Figure 3: Computed tomography scan with three-dimensional reconstruction showing single parietal bone defect with small midline occipital defect|
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Magnetic resonance imaging (MRI) revealed bilateral symmetric encephalomalacic changes in bilateral occipito-parietal lobes with exvacuuo-dilation of posterior lateral ventricles. In the parietal foramina region, there was no mass, and the overlying scalp was normal. Occipital encephalocele with midline skull defects and abnormality of the overlying scalp was seen [Figure 4].
|Figure 4: Magnetic resonance imaging showing encephalomalacic changes in occipito-parietal lobes with occipital encephalocele|
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Three-dimensional MR venography clearly demonstrated hypoplastic inferior sagittal sinus, left transverse sinus and adjacent jugular vein with intact superior sagittal sinus and straight sinus [[Figure 5]a] and [[Figure 5]b].
|Figure 5: Three-dimensional magnetic resonance venography showing (a) hypoplastic inferior sagittal sinus, (b) left transverse sinus and adjacent jugular vein|
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Surgery was done under general anesthesia with the patient in the prone position and neck flexed. "T" shaped incision was made, and flaps were raised exposing both occipital and parietal defects [Figure 6]. Excision and closure of the occipital encephalocele sac, followed by titanium mesh cranioplasty of parietal and occipital defects were under taken [Figure 7]. Postoperative period was uneventful.
|Figure 6: Peroperative picture showing parietal bone defect with occipital encephalocele|
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| Discussion|| |
During development, a single defect initially involves the bones on either side of the midline and is subsequently divided into two foramina by parasagittal islands of ossification. This defect persists as small round or oval parietal foramina, situated on either side of the midline typically contain emissary or santorini's veins.  These veins connect occipital veins with the superior sagittal sinuses as well as an anastomosis between the middle meningeal and occipital arteries. No satisfactory explanation for their functional significance has been given.  Thus at birth, either a large midline or bilateral skull defects are present. The underlying brain is covered with a membrane of dura and pericranium. There is no mass and the overlying scalp is intact. The defects tend to close during mid-childhood, or often leaving small symmetrical foramina. 
Small parietal foramina (1-2 mm), are common finding in up to 60-70% of normal skulls.  Persistent parietal foramina that are over 5 mm in their greatest diameter are considered to be enlarged and are a rare occurrence, with a prevalence of 1:15,000 to 1:25,000. , Very few cases of large parietal foramina have been reported. 
Our patient had large 80 mm × 60 mm round, persistent midline parietal skull defect even at adolescence, without any bony parasagittal ridge.
Familial incidences with autosomal dominant inheritance are recognized, but without complete penetrance. More recently specific gene mutations have been identified known to cause isolated (nonsyndromic) enlarged parietal foramina.
Mutations in two genes are:
- Gross structural changes involving MSX2 on chromosome 5q35.2 
- Large deletions involving ALX4 on chromosome 11p11.2 
The girl had no medical syndrome, and none of the parents had a similar defect. The association of genetic abnormalities could not be evaluated due to financial constraints.
Enlarged parietal foramina are usually a benign clinical condition, but may present with headache, seizure, associated parietal meningo-myelocele, encephalocele, cortical or venous malformations, persistent falcine sinus, atretic straight sinus, occipital polymicrogyria, mental retardation, encephalomalacia, Duane's syndrome, and/or an enlarged posterior fossa. ,,
In young children, the disorder may be first noticed as a persistently enlarged posterior fontanelle caused by a single large central parietal bone defect (cranium bifidum). 3D CT scanning clearly reveals the bony defect. MRI is useful in detecting associated intracranial anatomic changes and screening for any other associated developmental brain anomalies. 
Our patient presented late in adolescence with complains of headache and seizure. Large parietal foramina with underlying encephalomalacia and venous malformations have been reported by many, but the simultaneous presence of persistent occipital foramen with occipital encephalocele is a rarity.
Conservative management of enlarged parietal foramina is favored by many as the skull defects has benign natural history, their tendency to reduce in size with age and uncertainty as to whether symptoms such as headaches are improved. Though the risk of penetrating injury to the brain is small, it may lead to anxiety. Reassurance and education of parents and the affected child to avoid risky actions that could result in injury may suffice in most circumstances.
Although surgical closure of parietal bone defects has been advocated, its role is controversial. However, large defects may warrant operative closure with autologous calvarial bone grafts, mesh plating system, and hydroxyapatite. 
We employed titanium mesh plating system for closure of both parietal and occipital defects, after excision and closure of occipital encephalocele.
| Conclusion|| |
Basic clinical examinations like palpation of the skull can diagnose rare conditions. This is a very rare case of central enlarged persistent parietal foramina with underlying encephalomalacia, simultaneous presence of persistent occipital foramina, occipital encephalocele along with hypoplastic inferior sagittal and left transverse sinuses presenting later in life as headache and seizure. Awareness of the venous anomaly is imperative before surgical management. Imaging in childhood to screen for any other associated developmental brain anomaly, may be warranted.
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[Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5], [Figure 6], [Figure 7]