Lateral meningocele syndrome

What it is, symptoms and effects

From: MedlinePlus Genetics, National Library of Medicine

Lateral meningocele syndrome is a disorder that affects the nervous system, the bones and muscles, and other body systems. The condition is characterized by abnormalities known as lateral meningoceles. Lateral meningoceles are protrusions of the membranes surrounding the spinal cord (known as the meninges) through gaps in the bones of the spine (vertebrae). The protrusions are most common and typically larger in the lower spine.

The meningoceles associated with this disorder may damage the nerves that spread from the spine to the rest of the body. Damage to the nerves that control bladder function, a condition called neurogenic bladder, causes affected individuals to have progressive difficulty controlling the flow of urine. Prickling or tingling sensations (paresthesias), progressive stiffness and weakness in the legs (paraparesis), and back pain can also occur. Delayed development of motor skills in infancy, such as sitting and crawling, often occurs in this disorder; intelligence is usually unaffected.

Other features of lateral meningocele syndrome can include low muscle tone (hypotonia) during infancy, decreased muscle bulk, loose (hyperextensible) joints that can lead to dislocations, and protrusion of organs through gaps in muscles (hernias). Spinal abnormalities are also common, including side-to-side curvature of the spine (scoliosis), abnormal joining (fusion) of two or more vertebrae, and vertebrae that are unusually shaped (scalloped).

People with lateral meningocele syndrome typically have a particular pattern of facial features that may include high arched eyebrows, widely spaced eyes (hypertelorism), outside corners of the eyes that point downward (downslanting palpebral fissures), and droopy eyelids (ptosis). Affected individuals may have a flat appearance of the middle of the face and cheekbones (midface and malar hypoplasia); low-set ears; a long area between the nose and mouth (long philtrum); a thin upper lip; a high, narrow roof of the mouth, occasionally with an abnormal opening (a cleft palate); a small jaw (micrognathia); coarse hair; and a low hairline at the back of the neck.

Other signs and symptoms that can occur in lateral meningocele syndrome include a high and nasal voice, hearing loss, abnormalities of the heart or the genitourinary system, poor feeding, difficulty swallowing (dysphagia), and backflow of stomach acids into the esophagus (called gastroesophageal reflux or GERD).

Causes and biological mechanisms

From: MedlinePlus Genetics, National Library of Medicine

Lateral meningocele syndrome is caused by mutations in the NOTCH3 gene. This gene provides instructions for making a protein with one end (the intracellular end) that remains inside the cell, a middle (transmembrane) section that spans the cell membrane, and another end (the extracellular end) that projects from the outer surface of the cell. The NOTCH3 protein is called a receptor protein because certain other proteins, called ligands, attach (bind) to the extracellular end of NOTCH3, fitting like a key into a lock. This binding causes detachment of the intracellular end of the NOTCH3 protein, called the NOTCH3 intracellular domain, or NICD. The NICD enters the cell nucleus and helps control the activity (transcription) of other genes.

The NOTCH3 gene mutations that cause lateral meningocele syndrome occur at the end of the gene in a region known as exon 33. These gene mutations result in a NOTCH3 protein with an abnormally short (truncated) NICD. The shortened protein is missing the portion that normally causes the breakdown of the NICD after it has performed its function in the cell nucleus and is no longer needed. As a result, the presence of the NICD in the cell is prolonged, and the protein continues to affect the activity of other genes. However, the result of this prolonged NICD activity and its connection to the specific features of lateral meningocele syndrome are not well understood.

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. Most cases result from new mutations in the gene and occur in people with no history of the disorder in their family. Occasionally, an affected person inherits the mutation from one affected parent.

How common is it?

From: MedlinePlus Genetics, National Library of Medicine

Lateral meningocele syndrome is a very rare disorder. Only a small number of cases have been described in the medical literature.

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.

Atresia of the external auditory canal · Very frequent (99-80%)

Absence or failure to form of the external auditory canal.

Conductive hearing impairment · Very frequent (99-80%)

An abnormality of vibrational conductance of sound to the inner ear leading to impairment of sensory perception of sound.

Dolichocephaly · Very frequent (99-80%)

An abnormality of skull shape characterized by a increased anterior-posterior diameter, i.e., an increased antero-posterior dimension of the skull. Cephalic index less than 76%. Alternatively, an apparently increased antero-posterior length of the head compared to width. Often due to premature closure of the sagittal suture.

Downslanted palpebral fissures · Very frequent (99-80%)

The palpebral fissure inclination is more than two standard deviations below the mean.

Dural ectasia · Very frequent (99-80%)

A widening or ballooning of the dural sac surrounding the spinal cord usually at the lumbosacral level.

High, narrow palate · Very frequent (99-80%)

The presence of a high and narrow palate.

Low-set ears · Very frequent (99-80%)

Upper insertion of the ear to the scalp below an imaginary horizontal line drawn between the inner canthi of the eye and extending posteriorly to the ear.

Malar flattening · Very frequent (99-80%)

Underdevelopment of the malar prominence of the jugal bone (zygomatic bone in mammals), appreciated in profile, frontal view, and/or by palpation.

Other findings in the same source

From: Orphanet

Additional reported features include Meningocele (Very frequent (99-80%)); Micrognathia (Very frequent (99-80%)); Narrow face (Very frequent (99-80%)); Posteriorly rotated ears (Very frequent (99-80%)); Ptosis (Very frequent (99-80%)); Wormian bones (Very frequent (99-80%)); Abnormal form of the vertebral bodies (Frequent (79-30%)); Abnormality of the middle ear ossicles (Frequent (79-30%)); Craniofacial hyperostosis (Frequent (79-30%)); Dental crowding (Frequent (79-30%)). This is a selected summary, not a complete description of the condition.

Which doctor should you see?

The suggested department for discussing Lateral meningocele syndrome 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 Lateral meningocele syndrome. 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.