Encephalocele: Symptoms, Types, Causes and Treatment

Encephalocele is a rare but serious condition in which brain tissue and its covering membranes protrude through a defect in the skull. This congenital anomaly can present with a variety of symptoms, locations, and associated conditions, affecting individuals differently depending on the type, size, and complexity of the defect. Understanding the symptoms, types, underlying causes, and available treatments for encephalocele is crucial for early diagnosis and optimal outcomes. This article synthesizes the latest research to provide a comprehensive, human-centered guide for patients, families, and healthcare professionals.

Symptoms of Encephalocele

Encephalocele presents with a range of symptoms depending on its size, location, and the structures involved. While some symptoms are immediately noticeable at birth, others may develop or become apparent later in life. Recognizing these symptoms is essential for prompt diagnosis and timely intervention.

Symptom	Description	Frequency/Significance	Sources
Visible Swelling	Protrusion or sac on the head/face	Most common in occipital and anterior types	4 5 6 7 9
Neurological Deficits	Developmental delay, seizures, weakness	Varies with brain tissue involvement	3 5 6 12 14
Hearing Loss	Diminished hearing, fullness in ear	Especially temporal encephaloceles	1 11 12
Nasal Obstruction	Difficulty breathing through nose	Basal/ethmoidal/nasal encephaloceles	2 4 13
CSF Leak/Otorrhea	Fluid discharge from nose/ear	Risk of meningitis, recurrent infections	1 2 11 13
Hydrocephalus	Accumulation of fluid in brain	Common with occipital encephaloceles	5 9 14

Table 1: Key Symptoms of Encephalocele

Understanding the Symptom Spectrum

Symptoms of encephalocele can be highly variable. The most obvious sign is a swelling or sac on the head, often visible at birth. This protrusion may enlarge during crying or with increased intracranial pressure and can be located anywhere from the occipital region (back of the head) to the nasal or frontal areas 4 5 6 9.

Neurological and Functional Impacts

• Neurological deficits often correlate with the amount of brain tissue herniated into the sac. Children may experience developmental delays, motor weakness, seizures, or intellectual disabilities 3 5 6 12.
• Hydrocephalus (excess fluid in the brain) is commonly associated, especially with larger or occipital encephaloceles 5 9 14.
• Seizures may occur, particularly when the temporal lobe is involved, sometimes even in adulthood 12.

Sensory and Other Symptoms

• Hearing loss and aural fullness are prominent in temporal encephaloceles, which can be mistaken for chronic ear disease 1 11.
• Nasal obstruction is typical for basal or frontoethmoidal encephaloceles, and may present as difficulty breathing through the nose or persistent nasal congestion, especially in infants 2 4 13.
• Cerebrospinal fluid (CSF) leaks may manifest as a clear fluid draining from the nose or ear, which increases the risk of serious infections like meningitis 1 2 11 13.

Less Common Manifestations

• Some cases present with recurrent unexplained infections, facial deformities, or may be discovered incidentally on imaging for unrelated issues 13.
• Not all encephaloceles cause immediate symptoms; smaller or "occult" lesions can go unnoticed until complications arise 4.

Types of Encephalocele

Encephaloceles are classified based on their anatomical location and the contents of the herniated sac. Different types have distinct clinical features, implications, and management strategies.

Type/Location	Key Features	Frequency/Notes	Sources
Occipital	Back of skull; midline swelling	Most common globally	3 5 6 7 9 14
Frontoethmoidal/Sincipital	Forehead, nasal bridge, orbits	Visible at birth, affects face	4 6 7
Basal/Nasal	Skull base, nasopharynx	Often hidden, nasal obstruction	2 4 13
Parietal	Top/side of skull	Less common	5 6 14
Temporal	Side of skull, temporal bone	Hearing loss, CSF leak, epilepsy	1 11 12
Content: Meningocele	Only meninges and CSF in sac	Better outcome	3 5 7
Content: Encephalocele	Includes brain tissue in sac	Higher risk of deficits	3 5 7 14

Table 2: Types and Classifications of Encephalocele

Anatomical Location-Based Types

• Occipital Encephalocele: The most prevalent form, accounting for up to 75-80% of cases in some regions. Presents as a swelling at the back of the skull, often involving the midline. Frequently associated with hydrocephalus and neurological deficits, especially if significant brain tissue is involved 3 5 6 7 9 14.
• Frontoethmoidal (Sincipital) Encephalocele: Located at the forehead, nasal bridge, or orbits. Highly visible at birth and may cause facial deformities if left untreated. These types can distort facial growth, but surgery often leads to realignment 4 6 7.
• Basal/Nasal Encephalocele: Occur at the skull base, herniating into the nasal cavity or nasopharynx. These are often hidden and may present with nasal obstruction or recurrent meningitis 2 4 13.
• Parietal Encephalocele: Less common, occurring on the top or sides of the skull. Clinical significance depends on the amount of brain tissue involved 5 6 14.
• Temporal Encephalocele: Involve the temporal bone; adults may present with hearing loss, recurrent ear infections, CSF leaks, or even epilepsy 1 11 12.

Content-Based Types

• Meningocele: The sac contains only the meninges and cerebrospinal fluid—generally associated with a better prognosis 3 5 7.
• Encephalocele (Meningoencephalocele): The sac contains both brain tissue and meninges, increasing the risk of neurological deficits and developmental problems 3 5 7 14.

Syndromic and Associated Forms

• Encephaloceles may occur as part of genetic syndromes or with other congenital anomalies (e.g., Meckel syndrome, Dandy-Walker malformation). Associated abnormalities can involve the face, brain, or other organs 8.

Causes of Encephalocele

The development of encephalocele is complex and multifactorial, involving both genetic and environmental influences. Recent research also highlights differences in the mechanisms behind various neural tube defects.

Cause/Factor	Description	Evidence/Significance	Sources
Genetic Mutations	Inherited or spontaneous gene defects	Familial cases, animal models	5 8 10
Environmental Factors	Maternal nutrition, exposures, infections	Folate deficiency, teratogens	4 5 10
Neural Tube Defect	Failure of skull bone formation	Distinct from open NTDs	3 4 10
Syndromic Associations	Part of genetic syndromes	Meckel, Chemke, etc.	8
Unknown	Many cases have no clear cause	Multifactorial, idiopathic	4 7 10

Table 3: Causes and Risk Factors for Encephalocele

Genetic and Familial Influences

• Genetic mutations play a key role in some cases. Studies and animal models show that mutations affecting skull and brain development can lead to encephalocele. Familial clustering and parental consanguinity increase risk 5 8 10.
• Syndromic associations: Encephaloceles may be part of broader genetic syndromes, such as Meckel syndrome, Chemke syndrome, or frontonasal dysplasia, which involve multiple anomalies and can help guide diagnosis 8.

Environmental and Maternal Factors

• Environmental exposures during pregnancy, such as poor maternal nutrition (especially folate deficiency), certain infections, or exposure to teratogenic substances, can increase the risk 4 5 10.
• Geographical variation in incidence suggests that both genetic and environmental factors are at play, with some forms (e.g., frontoethmoidal) more common in certain regions 4 5 7.

Mechanism of Defect

• Although classically grouped with neural tube defects (NTDs), encephalocele results from a failure in skull bone formation, not necessarily from faulty neural tube closure itself. Recent animal studies reveal that some encephaloceles arise after the neural tube has closed, due to a disruption in the surface ectoderm and underlying bone, allowing brain tissue to herniate out 10.
• This is different from open neural tube defects like anencephaly or spina bifida, although there can be shared genetic causes 10.

Idiopathic and Unknown Cases

• In many instances, no specific cause can be identified. These cases are considered idiopathic, likely resulting from a combination of minor genetic and environmental factors 4 7 10.

Treatment of Encephalocele

Treatment of encephalocele is tailored to the location, size, and contents of the sac, as well as associated conditions. Surgery remains the mainstay of therapy, but multidisciplinary care is often required for optimal outcomes.

Treatment Option	Approach/Goal	Outcome/Considerations	Sources
Surgical Repair	Remove/reduce sac, close skull defect	Mainstay, best outcomes	5 6 7 9 13 14
Hydrocephalus Shunt	Divert excess CSF fluid	Often needed with occipital	5 14
Multidisciplinary Care	Neurosurgery, craniofacial, ENT teams	Especially for anterior types	7 13 14
Early Intervention	Surgery in infancy or as early as possible	Improves prognosis	7 14
Postoperative Care	Rehabilitation, infection prevention	Reduces morbidity/mortality	9 14

Table 4: Treatment Approaches for Encephalocele

Surgical Management

• Surgical repair is the treatment of choice for most encephaloceles. The procedure involves removing non-functional or dysplastic brain tissue (if present), reducing the herniation, and reconstructing the skull defect 5 6 7 9 13 14.
• Timing: Early surgery, ideally in infancy, prevents further neurological damage and, in anterior types, avoids distortion of facial structures 7 14.
• Techniques: Approaches vary by location:
  • Occipital and parietal: Usually approached via craniotomy.
  • Frontoethmoidal/sincipital: May require combined neurosurgical and craniofacial procedures.
  • Basal/nasal: Endoscopic or transpalatal approaches can be effective, especially in children 13.
  • Temporal: May use transmastoid or middle cranial fossa approaches; repair can resolve CSF leaks and reduce risk of infection 11 12.
• Sac contents: Non-functional or gliotic brain tissue can often be safely excised without significant loss of function 5 6 14.

Management of Associated Conditions

• Hydrocephalus is common with larger or occipital encephaloceles. Placement of a ventriculoperitoneal shunt to divert excess CSF may be necessary before or after encephalocele repair 5 14.
• Epilepsy resulting from temporal encephaloceles may require surgical resection of the herniated brain tissue or surrounding epileptogenic cortex, with good seizure outcomes 12.
• Rehabilitation: Postoperative care can include physical, occupational, and speech therapy to support neurodevelopmental recovery 9.

Outcomes and Prognosis

• Survival and function: Prognosis depends on the size and content of the encephalocele, associated anomalies, and the presence of hydrocephalus. Many children, especially those without significant brain tissue herniation, can achieve good functional outcomes 5 6 7 9 14.
• Complications: Risks include infection (e.g., meningitis), neurological deficits, or recurrence if the repair is incomplete 1 2 11 13.
• Multidisciplinary approach: Collaborative care from neurosurgeons, craniofacial surgeons, ENT specialists, and rehabilitation therapists is vital for complex cases, particularly anterior and basal encephaloceles 7 13 14.

Conclusion

Encephalocele is a diverse and challenging condition, but advances in imaging, surgical techniques, and multidisciplinary care have greatly improved outcomes for affected individuals. Early recognition of symptoms, accurate classification, and prompt, coordinated intervention are key to optimizing prognosis.

Main points covered in this article:

• Symptoms vary widely, from visible swellings and neurological deficits to hearing loss, nasal obstruction, and CSF leaks.
• Types are classified by location (occipital, frontoethmoidal, basal, parietal, temporal) and by the contents of the herniated sac.
• Causes include genetic mutations, environmental factors, syndromic associations, and unknown/idiopathic origins, with pathogenesis distinct from classic neural tube defects.
• Treatment is primarily surgical, customized to the lesion's characteristics, and often involves multidisciplinary teams; management of hydrocephalus and rehabilitation are important adjuncts.
• Prognosis has improved with modern care, especially for patients with early intervention and without major brain tissue involvement.

Understanding encephalocele empowers families and clinicians to seek timely care and make informed decisions, offering hope for improved quality of life for those affected.