Encephalocele (Cephalocele; Encephalocystocele; Encephalomyelocele; Hydroencephalocele; Hydromeningocele, cranial; Meningocele; Meningoencephalocele)
Encephalocele; Cephalocele; Encephalocystocele; Encephalomyelocele; Hydroencephalocele; Hydromeningocele, cranial; Meningocele; Meningoencephalocele 742.0
Are You Confident of the Diagnosis?
An encephalocele is a protrusion of intracranial contents, specifically brain and meninges, through a defect in the skull.Frontoethmoid encephaloceles will often present as external masses. Encephaloceles of the cranial base often present intranasally.
What you should be alert for in the history
History reveals a midline mass noticed at birth or at an early age, possibly with fluctuation in size. A history of meningitis, CSF leak, cellulitis in the perinasal region, or midline facial osteomyelitis, or other associated midline defects is not uncommon. Estimated incidence of these lesions varies depending the population in study, but the most often quoted level is 1:30,000. Cranial-based lesions located intranasally may have history of airway obstruction. Those lesions not in the midline will be found at another suture line. Forty percent of affected patients have an additional midline abnormality.
Characteristic findings on physical examination
Physical examination shows a bluish, soft, compressible mass in the midline of the nasal root, or intranasally with possible distortion of surrounding facial features such as hypertelorism (
Preoperative view of a meningoencephalocele.
Preoperative view of meningoencephalocele, lateral view.
Encephaloceles can be classified based on location. Occipital encephaloceles present as masses overlying the occiput or posterior neck. Sincipital encephaloceles account for one-quarter of all encephaloceles and are further divided by location, specifically the suture through which their defect presents.
Nasofrontal encephaloceles present as a glabellar mass that causes telecanthus and inferior displacement of the nasal bones. Nasoethmoidal encephaloceles present as dorsal nasal masses which displace the nasal bones superiorly and the alar cartilages inferiorly. Nasoorbital encephaloceles present as orbital masses which cause proptosis and changes in vision.
Basal encephaloceles are less common and arise between the cribriform plate and superior orbital fissure or posterior clinoid fissure, presenting as an intranasal mass and possibly causing nasal obstruction and drainage.
Expected results of diagnostic studies
Preoperative imaging must be considered for all congenital midline masses to evaluate the possibility of intracranial involvement. The study of choice in the current era is a non-contrast computed tomography (CT) scan of the head, conducted under pediatric protocols to minimize radiation exposure, as magnetic resonance imaging (MRI) in this population often requires sedation. CT will also aid in narrowing the differential, showing extension of meninges (meningocele) or meninges and brain tissue (meningoencephalocele) through a defect in the skull.
Findings that can be common to all congenital midline masses with intracranial extension include widening of the nasal septum, erosion of adjacent bones with formation of a cyst-like cavity, increased interorbital distance, or defect of the cribriform plate. The limitation of the CT scan is in the ability to identify small lesions with narrow stalks.
Although imaging should be conducted preoperatively in every case, the CT scan is particularly helpful when an intracranial abnormality is identified. CT scans are better for showing the details of bony defects, whereas MRI may have an advantage for soft tissue definition. Ultrasound can be used to ascertain the contents of a midline mass, but the type of anatomic information needed for pre-operative planning requires the detail found in a CT scan or MRI (
MRI of meningoencephalocele, sagittal view.
The midline nasal mass has an extensive differential diagnosis including congenital and acquired lesions. Congenital masses include encephalocele, glioma, dermoid cyst, sinus pericranium, and simple inclusion cyst. Acquired masses include a polyp, frontal sinus mucocele, sebaceous cyst, lipoma, fibroma, neurofibroma, adenoma, chondroma, ganglioneuroma, carcinoma, and Pott’s puffy tumor (A Pott’s puffy tumor stems from acute sinusitis and is characterized by osteomyelitis of the frontal bone with breakthrough of the anterior table resulting in a swelling on the forehead, hence the name. The infection can also spread inwards, leading to an intracranial abcess).
Despite the long differential, most possibilities are eliminated on the basis of history and physical examination alone. The main entities to consider are the encephalocele, dermoid cyst, glioma, and polyp. Defining characteristics are listed in
Dermoid cysts are ectodermal in origin and may contain skin, hair follicles, sweat glands, or sebaceous glands. A dermoid may have a central punctum with hair protruding through the opening, or a history of drainage or intermittent infection. Nasal gliomas arise from the glial cells and are thought to be encephaloceles that have lost their connection with the meninges. Mucosal polyps will be seen only intranasally and are more common in adults.
Distinguishing characteristics for differential diagnosis of encephalocele
|Patient Age||Infancy||Usually childhood||Any||Primarily adulthood|
|Past history||meningitis||local infection||no||sinus disease|
|Appearance||Blue||Punctum ± hair||Red-blue||Grey|
|Location||Intranasal External||Intranasal External||Intranasal External||Intranasal|
|Furstenberg Test (jugular vein compression)||positive||negative||negative||negative|
Who is at Risk for Developing this Disease?
Congenital midline nasal masses are rare, occurring in 1:20,000 to 1:40,000 live births. Of these rare lesions, the encephalocele, glioma, and dermoid are the most common. Neural tube defects in general have been found to have slight female predominance with environmental factors such as maternal alcohol consumption and nutritional status playing a role. Approximately ten percent of all congenital hernias of the cranium are intranasal encephaloceles. Nasal encephaloceles are more common in Southwest Asia than in the United States or Western Europe.
What is the Cause of the Disease?
The key underlying event in the development of meningoceles, encephaloceles, and gliomas is faulty closure of the anterior neuropore. Normal embryology involves closure of the ectoderm and fusion of associated mesodermal bony elements. In normal sequence the ectodermal portion will form and fuse prior to the mesenchymal elements at the base of the skull, including the sphenoid, ethmoid, frontal, and nasal bones. The space between the developing frontal and nasal bones is known as the fonticulus frontalis. This area is supposed to fuse with the foramen cecum near the developing cribriform plate to separate the intracranial structures from the intracranial structures of the nose.
When fusion of the bony elements is incomplete, but the ectodermal neuropore closes normally, intracranial contents may herniate through the fonticulus frontalis resulting in intranasal or extranasal encephalocele/meningocele.
In another scenario, the bony elements fuse in an essentially normal fashion, but there is faulty closure in the ectodermal neuropore, leading to formation of extracranial rests of glial tissue known as gliomas. Gliomas may be attached to the intracranial structures by a fibrous stalk.
Incomplete closure of the cranial bones along with a defect in the dura can lead to a cerebrospinal fluid leak in any of these entities, though this is very rare in the nasal glioma
Systemic Implications and Complications
A number of specific syndromes have been associated with encephaloceles, and these lesions can also be seen with children born with a craniofacial cleft deformity. Craniofacial clefts, defects of bone and/or soft tissue of the face or cranium, occur in defined anatomic locations and are numbered 1 through 14 by a system described by Paul Tessier. Tessier’s clefts can be seen sporadically or as part of a spectrum in another syndrome.
Frontonasal dysplasia, acrofrontofacionasal dysostosis, frontofacionasal dysplasia and oculoauriculofrontonasal syndrome comprise a spectrum of syndromes known by the eponym Morning Glory Syndrome, with midline facial defects, callosal agenesis, basal encephaloceles, and eye anomalies.
The anomalies observed are related to failure of appropriate development of the frontonasal process, midface structures, eye primordia, and midline cranial structures.
Some case reports show association with genetic mutation in the TGIF gene but a majority are multifactorial in nature.
Medical Options (Topical, Systemic)
Other than careful observation, there are no medical treatments to treat encephaloceles. In the dreaded complication of meningitis, hospital admission is warranted with aggressive antibiotic therapy. Development of an abscess would require urgent neurosurgical intervention for consideration of drainage and debridement.
The treatment of choice is complete excision. Preoperative imaging should include CT or MRI of the head to delineate the anatomy of the lesion. Surgery is conducted as a combined approach of plastic surgery or ENT and neurosurgery. A bicoronal incision is made allowing access to the cranium.
In patients with distortion of facial features, the first priority is correction of the skull deformity and repair of any dural defects. Reconstruction defects in the forehead, nose, or brow often requires multiple procedures as the child ages.
Surgical resection of the extracranial portion alone is not advised. This leads to increased risk of persistent communication with the cerebrospinal fluid and resultant meningitis.
For children with additional midline defects involving vital structures, as in agenesis of the corpus callosum, holoprosencephaly or significant cardiac defects, surgery may be delayed to allow stabilzation of the patient’s overall general medical condition.
Excision of congenital midline nasal masses must be approached in a methodical manner, and referral to plastic surgery or neurosurgery is appropriate to ensure adequate preoperative assessment (Figure 4).
Optimal Therapeutic Approach for this Disease
The treatment of choice for meningocele, encephaloceles, nasal gliomas, and nasal dermoids is complete excision. Early intervention, generally when the child is at least 10 weeks of age and 10 pounds in weight, is preferable to minimize distortion of the surrounding anatomy. Normal anatomy can be distorted by growth of the lesion as well as recurrent inflammation.
Preoperative imaging should include CT or MRI of the head to delineate the anatomy of the lesion. Surgery is conducted as a combined approach of Plastic Surgery and Neurosurgery. The entire lesion must be excised including any existing fistula tract in order to prevent recurrence.
Many surgical approaches have been tried, specifically in the case of midline nasal masses. The most important factor is correct identification of intracranial extension, determining if craniotomy will become necessary in addition to extracranial resection. Preoperative imaging is helpful in this respect, but other methods have been used to confirm this information in the operating room.
One method involved injecting the fistula tract with methylene blue and following the tract to the base. If the tract disappears prior to the skull, no intracranial exploration is warranted. Other surgeons describe the use of frozen sections of the tract base. If fibrous tissue alone is identified, the resection is complete. If cyst is identified, intracranial extension is explored.
In patients with distortion of facial features, the first priority is correction of the skull deformity and repair of any dural defects. Reconstruction defects in the forehead, nose, or brow often require multiple procedures as the child ages. The ability to restore normal appearance will vary based on the degree of the defect. Nasal masses can be approached via traditional rhinoplasty incisions aiding in post-resection reconstruction, not uncommonly requiring additional use or ear or rib cartilage to restore adequate support.
Surgical resection of the extracranial portion alone is not advised. This leads to increased risk of persistent communication with the cerebrospinal fluid and resultant meningitis.
Surgical resection offers definitive treatment. Recurrence of the mass would signify incomplete excision.
Surgery requires an inpatient stay for monitoring of neurologic status. A significant amount of edema can be expected following bicoronal incision and craniotomy, occasionally requiring additional length of hospital stay to allow edema to decrease to a point where the patient can open his/her eyes.
Post-perative follow-up is required evaluate proper healing of the incision. Development of fever or other clinical deterioration postoperatively should raise high clinical suspicion for meningitis, necessitating readmission with intravenous antibiotics.
Reconstruction of facial defects must be staged. The patient and his/her family can expect a long relationship with the plastic and reconstructive surgeon in the setting of a severe facial defect.
Unusual Clinical Scenarios to Consider in Patient Management
Midline nasal masses can be problematic in that an outwardly benign appearing lesion can serve as the tip of the iceberg to the real clinical problem. The visible cyst is therefore occasionally treated as an inclusion cyst anywhere else on the body, without consideration of potential deeper, possibly intracranial extension. This can lead to complications varying from a mere nuisance of inadequate resection and subsequent recurrence, to life threatening infection in the form of meningitis or encephalitis.
Referral to a plastic surgeon is appropriate in this case to allow for proper evaluation and coordination of operative intervention with neurosurgery as well as reconstruction of associated facial defects and proper follow-up.
What is the Evidence?
Cohen, MM, Lemire, RJ. "Syndromes with cephaloceles". Tetatology. vol. 25. 1982. pp. 161-172.Describes a variety of different malformation sequences, syndromes and associations having encephaloceles as a feature.
Elluru, RG, Wootten, CT, Flint, PW, Haughey, BH, Lund, VJ, Niparko, JK, Richardson, MA, Robbins, KT, Thomas, JR. "Chapter 188-Congenital malformations of the nose". Cummings Otolaryngology: Head & Neck Surgery. Mosby-Elsevi. 2010.(Congenital malformations of the nose and paranasal sinuses are rare manifestations of disordered development located at the origin of the aerodigestive tract. Clinical presentations range from subtle cosmetic deformities to life-threatening acute upper airway obstruction and feeding difficulties in neonates. This chapter focuses on the most common congenital lesions in the nose and paranasal sinuses. These lesions are considered within the framework of possible developmental errors in specific anatomic zones: (1) errors at the anterior neuropore, (2) errors of the central midface, and (3) errors of the nasobuccal membrane. Mesodermal and germline malformations not unique to the nose and paranasal sinuses also are discussed.)
Hughes, GB, Sharpino, G, Hunt, W, Tucker, HM. "Management of the congenital midline nasal mass: a review". Head and Heck Surg. vol. 2. 1980. pp. 222-33.(The nasal encephalocele, the glioma, and the dermoid are the most common of the congenital midline nasal masses. Due to similar embryologic development, each of these lesions may be associated with bony cranial defects and intracranial abnormalities, as well as CSF leakage and the potential for fatal meningitis if not handled properly. Properative manipulation should be avoided. Radiologic studies are instructive only if they are positive. If intracranial attachments are identified radiologically or suspected clinically, neurosurgical consultation should be obtained, and intracranial exploration and resection should be carried out as the initial procedure. Extracranial resection of the remaining mass may be performed immediately after intracranial resection, may be postponed, or may become unnecessary.)
Losee, JE, Kirschner, RE, Whitaker, LA, Bartlett, SP. "Congenital nasal anomalies: a classification scheme". Plast Reconstr Surg. vol. 113. 2004. pp. 676-89.(The purpose of this work was to develop a simple yet comprehensive classification scheme dedicated to congenital nasal anomalies. To date, no such classification system has been proposed and widely used. A 22-year retrospective review was performed. Two hundred sixty-one patients with congenital nasal anomalies were identified. From this extensive database, a systematic morphogenic classification system was devised. Congenital nasal deformities were classified into four categories. Type I, hypoplasia and atrophy, represents paucity, atrophy, or underdevelopments of skin, subcutaneous tissue, muscle, cartilage, and/or bone. Type II, hyperplasia and duplications, representing anomalies of excess tissue, ranging from duplications of parts to complete multiples, are categorized here. In the type III category, clefts, the comprehensive and widely utilized Tessier classification of craniofacial clefts is applied. Type IV deformities consist of neoplasms and vascular anomalies. Both benign and malignant neoplasms are found in this category.Despite the complicated development of the nose, congenital anomalies are rare, with an incidence of one in every 20,000 to 40,000 live births. Despite the apparently similar presentations, these anomalies vary in their nature and position. Nasal anomalies are rarely seen, which may account for misdiagnosis and treatment plans that result in a less than satisfactory outcome. Several attempts at classifying craniofacial deformities have been reported. To date, no classification system committed to congenital nasal deformities has been proposed and widely used. It was the purpose of this work to develop a simple yet comprehensive classification scheme dedicated to congenital nasal anomalies, based upon the clinical experience of a large craniofacial center and an extensive review of the literature.)
Pollock, RA. "Surgical approached to the nasal dermoid". Ann Plast Surg. vol. 10. 1983. pp. 498-501..(The dermoid cyst usually presents as a mass of the nasal dorsum with or without evidence of a fistulous tract, lined by normal skin, including hair. Approximately 50% of the time the dermoid cyst is deeply located and septal distortion, bone erosion, or intracranial connection may on occasion be discovered. The variations in presentation of these cysts have provoked a variety of recommendations regarding surgical excision. Historical approaches are briefly reviewed. The author favors one of three surgical approaches utilizing incisions that offer good exposure and cosmetically favorable scars. These are outlined in detail. Careful preoperative planning is encouraged, as is the intraoperative use of a lacrimal probe, blunt dissection, and the operating microscope.)
Richieri-Costa, A, Guion-Almeida, ML. "The syndrome of frontonasal dysplasia, callosal agenesis, basal encephalocele, and eye anomalies-phenotypic and aetiological considerations". Int J Med Sci. vol. 1. 2004. pp. 34-42.(The authors reported ten sporadic cases of Brazilian patients with facial midline defects, callosal agenesis, basal encephalocele, and ocular anomalies. This very rare cluster of anomalies has been well reported before. However, only until recently it is recognized as a syndrome belonging to frontonasal dysplasia spectrum. The ten cases confirm a distinct clinical entity and help to define the phenotype more precisely than previously. Up to now etiology remains unknown, although the authors conjecture that it is due to a mutation in TGIF gene.)
Wardinsky, TD, Pagon, RA, Kropp, RJ, Hayden, PW, Clarren, SK. "Nasal dermoid sinus cysts: association with intracranial extension and multiple malformations". Cleft Palat Craniofac J. vol. 28. 1991. pp. 87-95.(The authors identified 22 patients in a retrospective review of cases diagnosed with NDSC at their institution over the past 10 years. Nine (41%) had associated anomalies and 10 (45%) had intracranial extension of the sinus. In half of the patients with intracranial extension, the sinus transversed either the cribriform plate or foramen cecum and attached to the dura; in the other half, the sinus extended to cysts within the falx or other brain structures. Of the patients with multiple anomalies, six (67%) had intracranial extension. Presurgical complications occurred in a total of eight patients (36%): two had meningitis, two had osteomyelitis, four had periorbital-nasal cellulitis, three had a nasal abscess, and four had nasal anomalies requiring rhinoplasty.)
Winterton, RI, Wilks, DJ, Chumas, PD, Russell, JL, Liddington, MI. "Surgical correction of midline nasal dermoid sinus cysts". J Craniofac Surg. vol. 21. 2010. pp. 295-300.(Nasal dermoid sinus cysts (NDSCs) are rare congenital anomalies affecting approximately 1 in 30,000 live births. Nasal dermoid sinus cysts are unsightly, prone to infection, and, importantly, may communicate with the central nervous system. Treatment is complete surgical excision. This study retrospectively evaluated management of a large single-center cohort of intracranial NDSCs. Nineteen patients with NDSC were identified from all patients presenting to the Leeds craniofacial service between June 2000 and August 2008. Patient demographics, clinical presentation, preoperative investigations, and surgical procedures undertaken were analyzed.Mean age at presentation and surgery were 6.3 and 7.6 years, respectively. Fifty-three percent were males. Computed tomography (CT) and magnetic resonance imaging (MRI) were performed in 15 and 17 patients, respectively. One patient (5.3%) required local excision only. Eighteen (96.7%) underwent a bicoronal approach, and 13 (68.4%) of these required a craniotomy. The dura was opened in 7 (36.8%) patients. Neither CT nor MRI predicted the presence or absence of intracranial extension in all patients. Positive and negative predictive values for intracranial extension were 85.7% and 50% for CT and were 100% and 50.0% for MRI. Mean follow-up of 4.1 years shows no deep recurrences and 5 (26.3%) were superficial nasal recurrences only.A multidisciplinary approach can achieve good results with infrequent intracranial recurrence. We used a bicoronal approach to facilitate craniotomy when required intraoperatively because imaging is unable to diagnose intracranial extension with sufficient accuracy.)
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