Acrania is a rare congenital abnormality characterized by complete or partial absence of flat bones of cranial vault (skull bones) in the human fetus. However brain tissue of fetus develops completely but abnormally. The cranial vault, or calvarium, surrounds and encloses the brain, and is formed from several plates of bone like parietal, squamosal, occipital, temporal, and frontal bones above the supraciliary ridge. In the embryo, the vault bones develop through ossification of the ectomeninx, the outer membranous layer surrounding the brain. The normal migration of mesenchymal tissue under the calvarial ectoderm should occur by the 4th week of gestation. However the closing of anterior neuropore and lack of mesenchymal migration (responsible for cranium formation) in the fourth week of embryological age results in Acrania.
With the absence of the skull, brain floats in the amniotic fluid over the base of skull. Increased amount of amniotic fluid is usually observed. Without the bony structure, the overlying ectoderm, as a thin amnion-like membrane covers the brain tissue.The fetus will generally have normal facial structures.
Acrania is always associated with severe condition called Anencephaly where most of the brain portions are absent along with skull and scalp. In most cases, Acrania progresses to Anencephaly, because, without the cranium, the cerebral tissue is exposed and thus gets degenerated resulting in eventual loss.
Diagnosis of Acrania
Acrania can be diagnosed early in pregnancy through an ultrasound. This anomaly appears during the the fourth week of the fetus's development. However The fetal cranium is not fully calcified before 10–11 weeks; therefore, diagnosis must be confirmed only after 11th week.
There is no treatment for Acrania. The condition is termed as incompatible with life. If at all the fetus survives the term, babies are either still born or die within few hours of birth. Since Acrania is a fatal pathology, medical abortion, as soon as the confirmed diagnosis, is suggested. This will help minimize medical interventions and also reduce the emotional agony to the mother and the family.
Head injuries account for approximately 70% of traumatic accident deaths. Intracranial hematoma plays an important role in the death and disability that are associated with head injury. Intracranial hematoma is a serious and possibly a life threatening condition that often requires immediate medical attention. Many patients with intracranial hematoma harbor mass lesions that require emergency decompression. Other causes include brain tumors, liver disease, autoimmune syndromes and bleeding disorders.
The human brain floats within the skull. It is surrounded by cerebrospinal fluid which cushions the brain from the bounces of everyday movements. Sometimes it becomes impossible for the fluid to absorb the force of a sudden blow or a quick stop. Under such situations, the brain may slide forcefully against the inner wall of the skull and get bruised. An intra-cranial hematoma occurs when the blood vessel ruptures between the skull and the brain. The blood leaks between the brain and the skull. This collection of blood, hematoma, which is possibly clotted, compresses the brain tissue. Some hematomas require surgery to remove the blood clot whereas some others can be treated without surgery.
Symptoms of intracranial hematoma include headache, nausea, vomiting, lethargy and slurred speech. The pupils may appear of unequal size. Memory loss is often associated with head trauma. One may even forget that they have suffered a blow. These symptoms of intracranial hematoma may occur either immediately or several weeks or months after a blow has been received in the head.
Injury in the head is the most common cause of intracranial hematoma. Among elderly persons, even a mild head trauma is more likely to cause a hematoma in the brain. Hematoma resulting from injury in the head is classified as:
Subdural hematoma: This occurs when the blood vessels, most often the veins rupture between the brain and the dura mater which is the outermost of three membrane layers that covers the brain. The blood that leaks forms a hematoma. This compresses the brain tissue. The danger here is that if the hematoma keeps growing then there is a progressive decline in consciousness and possible death. The risk of subdural hematoma is greater in people who use aspirin or other anticoagulants regularly. Alcoholics and very young and very old people also stand to be affected by subdural hematoma. All types of subdural hematomas require medical attention as soon as the symptoms become apparent. Other wise permanent brain damage may be the result.
Epidural hematoma: This type of hematoma occurs when the blood vessel, usually the artery, ruptures between the surface of the dura mater and the skull. Morbidity and mortality from epidural hematoma is substantial unless immediate medical attention is given. The cause of epidural hematoma is most of the time road automobile accidents or any other traumatic injuries.
Intraparenchymal hematoma: When blood pools in the white matter of the brain, Intraparenchymal hematoma occurs. There may be multiple severe Intraparenchymal hematomas after a head trauma. Serious brain damage can occur, as the neurons can no longer communicate.
A physician may find it difficult to diagnose intracranial hematoma, as it may not be immediately apparent. It is better to seek medical advice after any significant blow has been received to the head and if the patient has lost consciousness or experiences symptoms such as headache, lethargy, nausea and vomiting. A CT scan or MRI scan is suggested to define the position and size of a hematoma.
After a head injury, doctors use medications such as corticosteroids and diuretics to control the edema in the brain after head injury. Often surgery is required. If the blood clot is localized and there is no excessive clotting, then perforation is made through the skull and the liquid is removed by suction. Large hematomas require opening of a section of the skull to remove blood clots.
It is essential to wear appropriate safety equipment and gadgets during sports, including helmet when riding, motorcycling, horseback riding, skating or doing any other activity that may result in injury to head. Chances of motor vehicle accidents can be minimized by wearing a seat belt.
MRI technique is used to examine the brain as it helps to provide clear pictures of the parts of body that are surrounded by bone tissue. Detailed pictures of both benign and malignant abnormal growth of tumors in the brain can be obtained through brain MRI scan. The MRI scan is also indicative whether the tumor is spread to the nearly brain tissue or not. MRI scan can detect the abnormal tissues that grow during multiple sclerosis and the changes occurring during bleeding in the brain or if the brain tissue has suffered a stroke due to lack of oxygen. The functional magnetic resonance imaging is a relatively new procedure. This is used to measure the quick, tiny, metabolic changes that take place in an active part of the brain. The functional magnetic resonance imaging not only helps the radiologist to examine the anatomy of the brain but also to determine the precise part of the brain which is handling the critical aspects of speech, movement and sensation.
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Bibliography / Reference
Collection of Pages - Last revised Date: June 20, 2019