craniostenosis

Generality

Craniostenoses are a group of cranial malformations, characterized by the premature fusion of one or more cranial sutures.

A craniostenosis can be an isolated phenomenon, with no apparent cause, or the consequence of some particular genetic diseases such as, for example, Crouzon syndrome or Apert syndrome.

Child with premature closure (craniostenosis) of the lambdoid suture. Note the swelling on the right side of the head. Image taken from wikipedia.org

The presence of craniostenosis deprives the encephalic structures of the space that serves the latter, to grow properly. This can have serious consequences, including cognitive deficits, permanent eye changes and low IQ.

With rare exceptions, episodes of craniostenosis require surgical therapy, which involves remodeling the bones forming the cranial vault.

Recalls of anatomy of the human skull

Including bones and cartilages, the skull is the skeletal structure of the head, which constitutes the face and protects the brain, the cerebellum, the brainstem and most of the sensory organs.

The skull is structurally quite complex; at its constitution, in fact, between 22 and 28 bones participate, some peers and other unequal ones, which have an irregular shape and are of a flat type.

To simplify the study and understanding of the skull, the anatomists have thought of dividing it into two compartments, identified with the terms neurocranium and splancnocranium .

neurocranium

The neurocranium is the upper region of the skull, in which the brain and the eyes reside.

Its most important bones are the frontal, temporal, parietal and occipital bones; taken together, these bony elements form the so-called cranial vault .

Figure: human skull. The main bones of the cranial vault and the anatomical subdivision of the neurocranium / splancnocranium are reported (NB: the red line ideally separates the neurocranium from the splancnocranium).

splanchnocranium

Also known as facial massif, the splanchocranium is the antero-inferior region of the skull.

Represents the skeletal structure of the face, therefore it contains bony elements such as the mandible, upper jaw, cheekbones, nasal bone etc.

What is craniostenosis?

Craniostenosis is the medical term that indicates a series of morphological abnormalities of the skull, due to the premature fusion of one or more cranial sutures .

The cranial sutures are the fibrous joints, which join together the bones of the cranial vault (ie the frontal, temporal, parietal and occipital bones).

"Stenosis" is the word that, in medical jargon, indicates the abnormal narrowing of a hollow organ, a hollow bone structure, a blood vessel and all those tubular anatomical structures (eg, urethra).

When should the cranial sutures be closed? Because it is important?

In normal conditions, the fusion of the cranial sutures occurs in the post-natal period and ends, for some bones of the skull, at the threshold of 20 years. This long process of fusion allows the brain to grow and develop properly.

What are the consequences of early fusion of cranial sutures?

If, as in the case of craniostenosis, the fusion of the cranial sutures occurs during prenatal, perinatal (*) or early childhood, encephalic organs such as the brain, cerebellum and brainstem, and sense organs such as the eyes, undergo alterations either in growth and in form.

* NB: the term "perinatal" refers to the period of life of a human being that goes from the 27th week of gestation to the first 28 days after the birth.

Synonyms of craniostenosis

In medicine, the word craniosynostosis is synonymous with craniostenosis.

Causes

The premature fusion of the cranial sutures can be an isolated phenomenon - that is not dependent on any morbid condition - or a consequence of particular genetic mold syndromes .

According to the most popular classification, craniostenoses responding to the first circumstance are examples of non-syndromic craniostenosis, while craniostenoses responding to the second circumstance are examples of syndromic craniostenosis .

Non-syndromic craniostenosis and syndromic craniostenosis are the names chosen by doctors to distinguish the possible craniostenoses that can affect human beings in two broad categories.

This is a distinction based on the triggering factors.

Non syndromic craniostenosis

Currently, the precise causes of the phenomenon of non-syndromic craniostenosis are unknown.

On the subject, several doctors and researchers have proposed, in the past, different theories, which however have not been confirmed by the experimental results.

The aforementioned theories took into consideration the possible influence of environmental factors or hormonal problems.

Syndromic craniostenosis

According to the latest medical studies, the genetic syndromes related to the phenomenon of syndromic craniostenosis would be more than 150 .

Of all these syndromes, they stand out for their importance and notoriety:

Crouzon's syndrome . It affects one newborn every 60, 000;
Apert's syndrome . It affects one newborn every 100, 000;
Pfeiffer's syndrome . It affects a new born every 100, 000 or so;
Saethre-Chotzen's syndrome . It is found in one newborn every 50, 000.

Epidemiology

Craniostenoses are rare malformations; according to the statistics, in fact, there would be a new born every 1, 800-3, 000.

For reasons that are still unknown, craniostenoses prefer male sex (3 patients out of 4 are males).

Of the two types of recognized craniostenosis (non-syndromic and syndromic), non-syndromic craniostenosis is definitely the most common, with a frequency percentage ranging between 80 and 90% (ie, out of 100 newborns with craniostenosis, in 80-90 the premature fusion of the cranial sutures does not depend on any particular disease).

Risk factors

The risk factors of craniostenosis include:

Low birth weight;
Premature birth;
The advanced age of the father;
Maternal smoking during pregnancy.

Symptoms and complications

The characteristic symptoms of craniostenosis depend on an increase in pressure inside the skull ; in medicine, this increase is called intracranial hypertension or intracranial hypertension .

What causes intracranial hypertension?

In the presence of craniostenosis, intracranial hypertension is the result of the abnormal pressure that the growing encephalus exerts, from the inside, on the cranial vault sutured prematurely, narrower than normal and no longer mouldable.

To understand, think of inflating a gym ball inside a small rigid box: when the ball reaches certain dimensions it pushes on the walls of the box, exerting a certain pressure (which, in the case of craniostenosis, is intracranial hypertension ).

It is important to point out that the number of cranial sutures subject to premature fusion has a decisive effect on the presence of intracranial hypertension; the doctors, in fact, observed that the involvement of a single cranial suture is responsible for intracranial hypertension in 15% of the patients, while the involvement of at least two cranial sutures determines the increase of the internal pressure to the skull in at least 60% of patients.

Under normal conditions, the cranial sutures not yet fused together make the skull mouldable according to the growth of the brain. It is for this reason that, in such circumstances, the pressure inside the skull remains normal.

Symptoms of intracranial hypertension

Having explained the mechanism of intracranial hypertension, it is now necessary to report the typical symptoms; these are:

Persistent headache, with more intense moments in the morning and evening;
Vision problems (double vision, blurred vision, blurred vision, etc.);
He retched;
Irritability;
Puffy eyes;
Difficulty in following the movement of objects;
Hearing problems;
Respiratory problems;
Changes in mental status;
papilledema;
Epileptic attacks.

Curiosity

In the presence of a non-severe craniostenosis, intracranial hypertension begins to be symptomatic only around 4-8 years of life.

Craniostenosis signs

Craniostenoses are also responsible for characteristic signs, such as:

Presence of rigid ridges along the cranial sutures;
Abnormalities of cranial fontanelles;
Head with dimensions not proportionate to the rest of the body;
Abnormally shaped head.

Morphological types of craniostenosis

The shape of the head of patients with craniostenosis depends on which cranial sutures have been subjected to premature fusion.

Based on the shape of the head - therefore based on the cranial sutures subject to premature fusion - the doctors distinguish the craniostenosis in at least 4 different morphological types, which they call:

Dolicocefalia (or sagittal craniostenosis ). It is the craniostenosis due to the premature fusion of the sagittal cranial sutures, ie the cranial sutures located in the anterior part of the skull, between the parietal bones.
In about half of clinical cases, it is the most common morphological type of craniostenosis.
Brachycephaly (or coronal craniostenosis ). Its presence involves the premature fusion of the coronal sutures, which run between the frontal bone and the parietal bones.
It can be found in approximately one clinical case every 4, representing the second most common morphological type of craniostenosis.
Trigonocephaly (or metopic craniostenosis ). It is the result of the anti-time fusion of the metopic (or frontal) suture, which runs from the nose to the upper part of the head, separating the frontal bone in two.
Trigonocephaly is a very rare craniostenosis; in fact, it only characterizes 4-10% of clinical cases.
Plagiocephaly (or lambdoid craniostenosis ). It is the craniostenosis due to the premature fusion of the lambdoid suture, which resides between the parietal bones and the occipital bone, in the back of the head.
Only in 2-4% of clinical cases, plagiocephaly is the rarest morphological type of craniostenosis.

From the site: //www.wkomsi.com/

Complications

Several complications may depend on severe or inadequately treated craniostenosis, including:

Reduced development of cognitive faculties and low IQ;
The syndrome of obstructive sleep apnea;
Permanent facial alterations, especially in the eyes and ears;
Permanent deformities at the base of the skull (eg: malformation or Arnold-Chiari syndrome);
Hydrocephalus.

Diagnosis

In general, the diagnosis of a craniostenosis is based on an accurate physical examination, a scrupulous medical history and radiological images obtainable from instrumental tests such as X-rays or CT scans on the head .

In the event that the patient under examination has further malformations, typical of syndromic craniostenosis, the diagnostic doctor prescribes, in addition to the aforementioned investigations, a blood test and a genetic test, in order to discover the precise syndrome responsible for the whole symptom picture.

Radiological examinations

X-rays and CT at the head serve to confirm the information collected during the physical examination and clinical history and to clarify, definitively, which cranial sutures have undergone the premature fusion process.

Precise knowledge of fused cranial sutures prematurely is essential for therapy planning.

Therapy

Except in rare circumstances and only when the cranial malformations are mild, the craniostenoses always impose recourse to a surgical operation to separate the cranial sutures that have undergone an early fusion.

The final therapeutic objective of the aforementioned surgical intervention is to provide the necessary space for their growth and correct development to the encephalic structures and the sense organs, such as the eyes, for example.

What is non-surgical therapy?

The non-surgical therapy of mild craniostenoses involves the use of a special helmet which, made to measure for the patient, allows the modeling of the latter's skull and eliminating deformities.

The use of non-surgical treatment is reserved for a few clinical cases and only when the craniostenosis is mild; moreover, it must occur during the first years of life, when the pliability of the cranial bones is greater.

What is the best time to have surgery?

The best time to perform craniostenosis surgery has always been the subject of debates and discussions.

According to some experts, the ideal period for the operation would be late childhood (6-12 months life), due to a lower risk of surgical complications; according to other experts, however, the most suitable period for surgery would be early childhood (4-6 months of life), for reasons related to greater plasticity of the bones of the skull.

In any case, the entire medical community agrees not to postpone surgical treatment after the year of life, as from this moment on the risk of failure of the intervention is increasing.

Possible surgical approaches

There are two different surgical approaches: traditional surgery, also called "open", and endoscopic surgery.

The "open-air" approach is an invasive but very effective practice; the endoscopic surgical approach, on the other hand, is a minimally invasive treatment, but a real risk of failure

The "open" approach is suitable for children over 6 months of age, while the endoscopic surgical approach is only possible for children under the age of 6 months.

Post-hospitalization

Regardless of the surgical approach used, the operation for the elimination of a craniostenosis always foresees, at its conclusion, a hospitalization lasting 4-5 days . During this time, the medical staff periodically monitors the patient's vital signs and ensures, with various tests, that the intervention has had the desired results.

What happens after the resignation?

After discharge, a patient undergoing craniostenosis correction surgery must undergo a series of periodic checks of his condition, at the cranial level.

Initially, the checks are six-monthly; after that, they become annual.

Prognosis

The prognosis in case of craniostenosis depends on various factors, including:

The cause of craniostenosis. Some genetic diseases that cause craniostenosis are very serious, sometimes incompatible with life.
The position of the cranial sutures fused prematurely. If the cranial sutures subjected to premature fusion occupy a position difficult to reach by the surgeon, the surgical operation is complex and may not provide the desired results.