Cephalocele (Cephalocele)
This is a hernial protrusion located along the midline of the skull and emerging through a bone defect. The pathology is rare, occurring in approximately 1 out of every 4,000–5,000 newborns.
The hernial ring is a rounded opening with smooth edges in the bones of the cranial vault. Through this opening, the meninges herniate into the subcutaneous tissue, forming a hernial sac. Its contents may include cerebrospinal fluid, brain tissue, or a combination of both.
Clinical presentation and diagnostics:
- The size of the mass varies from a few centimeters to the volume of the child's head. Its consistency is elastic.
- The reduction sign is characteristic: upon pressure, the volume decreases due to the displacement of cerebrospinal fluid back into the cranial cavity.
- Radiography is used to determine the exact size and localization of the bone defect.
- The pathology is often accompanied by other anomalies: cleft lip, cleft hard and soft palate, as well as hydrocephalus.
The prognosis for this malformation is unfavorable. Early infant mortality is high, and surviving patients exhibit marked intellectual disability.
Treatment: exclusively surgical. The hernial sac along with its contents is excised (the brain tissue inside is degenerated, so its removal does not impair CNS function). The bone defect is closed surgically using a periosteal-aponeurotic flap or bone grafts (for large openings).
Hydrocephalus (Hydrocephalia)
Hydrocephalus (water on the brain) occurs due to the excessive production and accumulation of cerebrospinal fluid inside the skull.
Depending on the localization of the fluid, two forms are distinguished:
- External form: cerebrospinal fluid accumulates between the meninges, compressing the brain from the outside.
- Internal form: fluid overfills the brain ventricles, causing compression of the brain tissue from within.
Constant compression inevitably leads to brain atrophy. Clinically, this manifests as a sharp increase in head size. The cranial vault significantly predominates over the facial skeleton, and the forehead overhangs the orbits. Affected children exhibit poor overall development and severe developmental delay.
Treatment:
- As an emergency measure, ventricular puncture is used to evacuate the fluid.
- The primary method is surgical shunting. Pathways are created for cerebrospinal fluid outflow from the ventricles into the jugular veins or the abdominal cavity (e.g., ventriculoperitoneal shunt).
Craniostenosis (Craniostenosis)
This is an anomaly caused by the premature fusion of sutures and fontanelles. Foci of calcification form in the cranial growth zones, causing the skull to stop growing in volume.
The pathogenesis of the disease is related to the growing brain becoming trapped within a narrow, non-expandable space. This leads to stunted growth, compression, and subsequent atrophy.
Unlike hydrocephalus, in craniostenosis the size of the cranial vault is reduced, and the facial skeleton predominates over the cranium. Patients suffer from both physical and intellectual developmental delays.
Treatment: early decompressive surgery is indicated. Surgeons perform craniotomy, resection, or fragmentation of the cranial vault bones to give the brain room for normal growth.
Briefly: answers to topical questions
What clinical and anatomical forms of cerebral hernias are distinguished based on their contents?
Depending on the contents of the hernial sac, three main clinical and anatomical forms of cerebral hernias are distinguished.
- Meningocele (meningocele) — contains only the pia and arachnoid maters, as well as cerebrospinal fluid.
- Encephalocele (encephalocele) — contains nervous tissue, which is usually abnormal, non-functional, and has areas of necrosis, calcification, and malformation.
- Encephalocystocele (encephalocystocele) — a part of the cerebral ventricle is involved in the hernial protrusion.
What types of shunting procedures are used for cerebrospinal fluid drainage in hydrocephalus?
Various types of shunting procedures are used for cerebrospinal fluid drainage in hydrocephalus, creating bypass routes to divert cerebrospinal fluid.
- Ventriculoperitoneal shunting — creation of a shunt between the ventricular system of the brain and the abdominal cavity.
- Lumboperitoneal shunting — formation of a shunt between the subarachnoid space of the spinal canal and the abdominal cavity.
- Ventriculoatrial shunting — diversion of cerebrospinal fluid from the ventricles into the jugular veins.
- Endoscopic third ventriculostomy — creation of an opening in the floor of the third ventricle for cerebrospinal fluid outflow into the suprasellar cistern.
Which specific cranial sutures undergo premature fusion in various forms of craniostenosis?
Craniosynostosis involves the premature closure of one or more sutures of the cranial vault or skull base. In simple non-syndromic forms, a single suture is typically involved; the most frequent type of primary craniosynostosis is isolated premature closure of the sagittal suture. Complex syndromic forms involve multiple sutures.
To remember head proportions: in hydrocephalus, the head resembles a "balloon" (the cranial vault is much larger than the facial skeleton, distended by fluid), whereas in craniostenosis, it is like being in a "vise" (the cranial vault is smaller than the facial skeleton, as the bones fused prematurely).
Class and exam questions
Why is it acceptable to excise part of the brain tissue during the removal of an encephalocele?
Brain tissue herniated into the hernial sac has already undergone profound degeneration. Its resection does not affect central nervous system functions.
What is the danger of the reduction sign in cerebral hernias?
When pressure is applied to the elastic hernial sac, fluid rushes rapidly into the cranial cavity. A spike in intracranial pressure can trigger seizures and loss of consciousness.
What is the main visual difference in the skull between hydrocephalus and craniostenosis?
In hydrocephalus, the cranial vault is gigantic and significantly predominates over the facial skeleton. In craniostenosis, conversely, the cranial vault is reduced, and the facial skeleton appears more massive by comparison.
What else to study on this topic
- Techniques for plastic closure of cranial bone defects
- Types of shunting systems in the treatment of hydrocephalus (ventriculoperitoneal shunting, etc.)
- Methods of decompressive surgery in craniostenosis (craniotomy, vault fragmentation)
- Associated maxillofacial anomalies (cleft lip and palate)
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