Cyst of the transparent septum of the brain

Among the abnormal cerebral formations of a benign nature - congenital or acquired - is also a cyst of the transparent septum of the brain.

In most cases, it is asymptomatic and is detected quite by chance during imaging of brain structures. [1]

Epidemiology

There are no clinical data on the number of diagnosable septal pellucid cysts, and septum pellucidum cysts are detected in 0.04% of patients with cerebral cystic formations.

Causes of the cysts of the transparent septum of the brain

The common causes of the appearance of most cerebral cysts, including intracerebral cysts of the transparent septum, are most often congenital. That is, their formation is due to deviations in the ontogenesis of the brain - the process of its formation by nerve stem and glial cells - in the prenatal period (in the first two months of pregnancy).

See also -  Variants and anomalies of the brain

A cyst of the transparent septum of the brain in adults can be associated with neuroinfection (meningitis), traumatic brain injury, tumor encephalopathy, or surgery on the brain.

More details in the publication -  Complications and consequences after traumatic brain injury

Risk factors

Factors that increase the risk of abnormal formations in the form of brain cysts are considered to be:

• diseases of a pregnant woman (acute viral, chronic and systemic);
• teratogenic effects on the embryo and fetus of alcohol or drugs;  
• various pathologies of pregnancy, including placental insufficiency  and fetal hypoxia;
• prematurity of the child (his birth before 35-37 weeks of gestation);
• complicated childbirth, often leading to  birth trauma ;
• cerebral edema in a newborn .

Pathogenesis

The transparent septum (septum pellucidum), located below the corpus callosum, is a vertical triangular-shaped membrane that separates the anterior horns (cornu frontale) of the left and right lateral ventricles of the brain (ventriculi laterales) located in the frontal lobes of the cerebral hemispheres and forms their middle walls. This septum has two layers in the form of plates, consisting of white matter (substantia alba), nerve cells (neurons) and fibrin fibers.

Cyst (from the Greek "pouch") is a delimited closed cavity with clear contours, often with liquid contents. The pathogenesis of congenital neuroepithelial cysts is not fully understood. Although among the hypotheses of the mechanism of formation of a cyst of the transparent septum, there is a version of its connection with the functions of the ventricular (ventricular) system and the movement of the cerebrospinal fluid - the aqueduct of the brain (aqueductus cerebri).

If the cystic formation of septum pellucidum is filled with cerebrospinal fluid (liquor cerebrospinalis), which is produced by the lateral ventricles, then a cerebrospinal fluid cyst of the transparent septum is determined.

In addition, a cyst of the cavity of the transparent septum can be detected. A slit-like closed space - a cavity between the plates of the transparent septum (cavum septum pellucidum) - is formed in the third month of intrauterine development of the fetus and is considered a marker of the development of its nervous system. During the fifth month of the prenatal period, the plates begin to fuse, and closure of this cavity is completed three to six months after birth.

But in 12-15% of cases, the cavity does not close, especially in premature babies. And when found in adults, it is considered an anatomical variant of the norm

If cerebrospinal fluid remains in the closed cavum septum pellucidum, then this is a cyst of the transparent septum in a child. [2]

Symptoms of the cysts of the transparent septum of the brain

Often a cyst of this localization does not manifest itself in any way. But it can press on brain tissue and cause symptoms such as headache accompanied by dizziness, vomiting and epileptic seizures, vision and hearing problems (patients often complain of tinnitus).

The first signs of the presence of a cyst of the cavity of the transparent septum are also manifested by periodic headaches. In addition, patient complaints include dizziness, nausea and vomiting, visual disturbances. [3]

Complications and consequences

The consequences and complications associated with this cerebral cyst arise due to its significant size. It can exert pressure on the occipital and temporal horns of the lateral ventricles of the brain and part of the aqueductus cerebri - with the development of obstructive hydrocephalus. In such cases, there are morning headaches in the frontal region, difficulty concentrating and other  symptoms of increased intracranial pressure .

In addition, compression of the cyst may impair venous outflow from the brain or affect hypothalamic structures and midbrain areas, causing autonomic or sensorimotor symptoms.

Also, a rupture of a cystic formation is not excluded, which is fraught with quite serious problems of the central nervous system.

Diagnostics of the cysts of the transparent septum of the brain

Symptoms and patient history are not sufficient for diagnosis. Required instrumental diagnostics:

• echoencephaloscopy  or neurosonography;
• color duplex ultrasound of brain structures;
• CT -  computed tomography of the brain ;
• magnetic resonance imaging (MRI) of the brain .

Differential diagnosis

Differential diagnosis is carried out with an arachnoid cyst of the interhemispheric fissure, a cyst of the pineal gland of the brain, an arteriovenous malformation (aneurysm) of the vein of Galen.

Treatment of the cysts of the transparent septum of the brain

Only when a septal pellucid cyst causes symptoms should it be treated.

Although there is no cure for this cystic formation, 

Drugs are empirically prescribed to improve metabolic processes in brain tissues -  nootropics  ( Piracetam, Pyriditol,  Cerebrolysin ).

So, Piracetam (Nootropil), used for memory impairment, cognitive decline and myoclonus, is taken at 1.24-4.8 mg per day (the dosage is determined by the doctor). In this case, the side effects of this drug are manifested by nausea and vomiting, weight gain, nervousness and depression, increased excitability and hyperkinesis, insomnia or drowsiness.

Diuretic drugs - osmotic diuretics Diacarb (Acetazolamide), Mannitol - are prescribed for increased intracranial pressure. Diakarb tablets are taken at 0.125–0.25 g twice a day, but it is contraindicated in liver and kidney failure, angle-closure glaucoma, and children under 12 years of age. Side effects are possible in the form of electrolyte imbalance in the body, thrombocytopenia, suicidal thoughts, growth retardation in children.

Mannitol is administered intravenously (with the calculation of the dose by body weight); its side effects are headache, nausea and vomiting, poor blood circulation, dehydration and electrolyte imbalance.

In the event of an enlarged cyst, surgical treatment may be required, which includes shunting of the cyst cavity or its endoscopic fenestration. [4]

Prevention

The ability to prevent the formation of a congenital cyst of the transparent septum of the brain is limited by the fact that not all risk factors for the development of anomalies in the prenatal period can be avoided. Therefore, prevention, in fact, concerns only the complete rejection of alcohol before and during pregnancy, as well as extreme caution in the use of drugs.

Forecast

In the treatment of a symptomatic cyst of the transparent septum of the brain and the absence of neurological complications, the prognosis is considered favorable.