Enlarged parietal foramina

What it is, symptoms and effects

From: MedlinePlus Genetics, National Library of Medicine

Enlarged parietal foramina is an inherited condition of impaired skull development. It is characterized by enlarged openings (foramina) in the parietal bones, which are the two bones that form the top and sides of the skull. This condition is due to incomplete bone formation (ossification) within the parietal bones. The openings are symmetrical and circular in shape, ranging in size from a few millimeters to several centimeters wide. Parietal foramina are a normal feature of fetal development, but typically they close before the baby is born, usually by the fifth month of pregnancy. However, in people with this condition, the parietal foramina remain open throughout life.

The enlarged parietal foramina are soft to the touch due to the lack of bone at those areas of the skull. People with enlarged parietal foramina usually do not have any related health problems; however, scalp defects, seizures, and structural brain abnormalities have been noted in a small percentage of affected people. Pressure applied to the openings can lead to severe headaches, and individuals with this condition have an increased risk of brain damage or skull fractures if any trauma is experienced in the area of the openings.

There are two forms of enlarged parietal foramina, called type 1 and type 2, which differ in their genetic cause.

Causes and biological mechanisms

From: MedlinePlus Genetics, National Library of Medicine

Mutations in the ALX4 gene account for 60 percent of cases of enlarged parietal foramina and mutations in the MSX2 gene account for 40 percent of cases. These genes provide instructions for producing proteins called transcription factors, which are required for proper development throughout the body. Transcription factors attach (bind) to specific regions of DNA and help control the activity of particular genes. The ALX4 and MSX2 transcription factor proteins are involved in regulating genes that are needed in various cell processes in early development.

Mutations in either the ALX4 or MSX2 gene likely impair the ability of their respective transcription factors to bind to DNA. As a result, the regulation of multiple genes is altered, which disrupts a number of necessary cell functions. The processes that guide skull development seem to be particularly sensitive to changes in the activity of these transcription factors.

If the condition is caused by a mutation in the MSX2 gene, it is called enlarged parietal foramina type 1. Mutations in the ALX4 gene cause enlarged parietal foramina type 2. There appears to be no difference in the size of the openings between enlarged parietal foramina types 1 and 2.

Inheritance and family implications

From: MedlinePlus Genetics, National Library of Medicine

This condition is inherited in an autosomal dominant pattern, which means one copy of the altered gene in each cell is sufficient to cause the disorder. In most cases, an affected person has one parent with the condition.

However, in rare cases, people who inherit an altered gene do not have enlarged parietal foramina. (This situation is known as reduced penetrance.)

How common is it?

From: MedlinePlus Genetics, National Library of Medicine

The prevalence of enlarged parietal foramina is estimated to be 1 in 15,000 to 50,000 individuals.

Reported clinical features and what the terms mean

The following findings are associated with this condition in Orphanet. They are not a checklist for diagnosing yourself, and they do not all occur in every affected person. Some are examination, imaging or laboratory findings that cannot be recognised at home.

The frequency labels describe how often a finding was reported among people with the condition in the source. They do not give the chance that a person with that symptom has the condition. Definitions below reproduce HPO terminology; they explain the term, not the likely severity in an individual.

Parietal foramina · Very frequent (99-80%)

The presence of symmetrical and circular openings (foramina) in the parietal bone ranging in size from a few millimeters to several centimeters wide.

Abnormality of the posterior cranial fossa · Occasional (29-5%)

An abnormality of the fossa cranii posterior (the posterior fossa), which is made up primarily of the occipital bone and which surrounds to the foramen magnum.

Headache · Occasional (29-5%)

Cephalgia, or pain sensed in various parts of the head, not confined to the area of distribution of any nerve.

Scalp tenderness · Occasional (29-5%)

Pain or discomfort of the scalp elicited by palpation.

Venous malformation · Occasional (29-5%)

A vascular malformation resulting from a developmental error of venous tissue composed of dysmorphic channels lined by flattened endothelium and exhibiting slow turnover. A venous malformation may present as a blue patch on the skin ranging to a soft blue mass. Venous malformations are easily compressible and usually swell in thewhen venous pressure increases (e.g., when held in a dependent position or when a child cries). They may be relatively localized or quite extensive within an anatomic region.

Vomiting · Occasional (29-5%)

Forceful ejection of the contents of the stomach through the mouth by means of a series of involuntary spasmic contractions.

Abnormality of cerebral veins · Very rare (<4-1%)

An anomaly of cerebral veins.

Aplasia cutis congenita of scalp · Very rare (<4-1%)

A developmental defect resulting in the congenital absence of skin on the scalp.

Other findings in the same source

From: Orphanet

Additional reported features include Broad thumb (Very rare (<4-1%)); Cleft lip (Very rare (<4-1%)); Cleft palate (Very rare (<4-1%)); Craniosynostosis (Very rare (<4-1%)); Encephalomalacia (Very rare (<4-1%)); Intellectual disability (Very rare (<4-1%)); Multiple exostoses (Very rare (<4-1%)); Myelomeningocele (Very rare (<4-1%)); Occipital encephalocele (Very rare (<4-1%)); Seizure (Very rare (<4-1%)). This is a selected summary, not a complete description of the condition.

Which doctor should you see?

The suggested department for discussing Enlarged parietal foramina is Orthopaedics, with a orthopaedic specialist as the relevant type of clinician. General physician / Family Medicine; paediatrician for children. Referral depends on symptoms.

Additional services that may be relevant, depending on the findings, include: Clinical Genetics.

This is an editorial referral starting point. The appropriate clinic depends on the person’s age, symptoms, previous diagnosis and local services. The first clinician can decide whether another specialty or a team is needed; a department label does not confirm the diagnosis.

How to prepare for an assessment

Bring a short timeline of the main symptoms: when they first appeared, whether they are constant or episodic, what seems to change them, and how they affect daily activities. Include previous reports, discharge summaries, current medicines and supplements, allergies, and any relevant family history. A dated record is more useful than trying to match every feature in an online article.

Ask the clinician what is already established and what remains uncertain. If a test is suggested, ask what question it answers, what its limitations are and how the result would change the next step. The information here is not an instruction to arrange every possible test. In children, bring growth, developmental and school information if it is relevant to the concern.

• What explains the change in pain, movement or function?
• Which activities need adjustment while the diagnosis is being clarified?
• What are the roles of rehabilitation, observation and surgery in this situation?

Treatment discussions and follow-up

The material gathered for this draft does not provide a complete condition-specific treatment pathway for Enlarged parietal foramina. That gap does not mean that treatment is unavailable. A clinician needs to establish the diagnosis and review current guidance before recommending medicines, procedures, rehabilitation or other support.

Before leaving the appointment, clarify the next review date, who will communicate results, and whom to contact if the situation changes. Discuss difficulties with sleep, work, school, mobility, eating or emotional wellbeing when these are relevant. Practical support may require coordination between the treating clinician and other services.

The collected references do not establish a complete prevention or long-term outlook section for this entry. Missing information should not be interpreted as proof that prevention is impossible or that a particular outcome is inevitable. Ask what is known for the exact subtype, stage and personal circumstances, and which uncertainties remain.

When to seek emergency help

Severe breathing difficulty, collapse, new stroke-like symptoms, a seizure that is prolonged or repeated without recovery, uncontrolled major bleeding, or an immediate risk of self-harm require emergency help. In India, call 112 or reach the nearest emergency department. This is a general, non-exhaustive warning list; it is not a condition-specific triage tool.