Many symptoms and diseases have historically been attributed to cysts of the CSP - mental disturbances, ataxia, disordered speech, epilepsy, and bilateral pyramidal signs. But these are now being questioned because of a lack of proper evidence. 

CSP cysts may also cause acute or chronic headaches, papilledema, emesis, syncope, cognitive impairment, emotional and behavioral disturbances, and visual and sensorimotor findings.

Proper evaluation of cavum septum pellucidum requires magnetic resonance imaging of the brain.

In fetal life, visualization of the CSP between 18 and 20 weeks’ gestation implies normal development of the brain.[8] Its assessment is a mandatory part of second-trimester ultrasound. The absence of CSP is a marker of associated fetal anomalies (listed under complications).

Treatment indications for cavum septum pellucidum are the following conditions:

1. Association of a CSP cyst on imaging studies and clinical signs and symptoms because of the obstruction of the cerebrospinal fluid flow in the foramen of Monro
2. Direct compression of surrounding tissues by the cyst
3. Mental status changes or focal neurological deficits attributable to the CSP cyst

The primary goal of treatment is to relieve the mass effect caused by the cyst, and it is only surgical. 

The classic treatment in these cases is surgical approaches, including open surgical procedures, conventional shunting, and stereotactic fenestration.

Dandy published the first treated CSP cyst in 1931; he treated a 4.5-year-old boy by a transcallosal fenestration.[9]

Since 1995 when Jacowski et al. described the first endoscopic approach,[10] neuroendoscopic fenestration has become a well-established therapeutic option and currently the treatment of choice for symptomatic CSP cysts.

Three endoscopic approaches are described:[11]

1. A frontal approach on the coronal suture 3 cm from the midline targeting the frontal horn of the lateral ventricle (used by the majority of authors)
2. The same cortical frontal approach but directly targeting the cyst that is punctured and then a fenestration of the two walls is performed
3. An occipital burr hole to optimize the trajectory into the atrium of the lateral ventricle, which would allow an approach both leaflets of the cyst perpendicularly.

The endoscopic fenestration offers a less invasive approach, direct visualization, and effectiveness. Direct visualization of neural and vascular structures prevents inadvertent injury. It is also important to inspect the foramina of Monro to search potential adhesions, which may play a role in the hydrocephalus to persist after apparently successful drainage of the cyst. Additionally, this technique avoids the need to place a shunt and allows a biopsy of the cyst walls.

The presence of CSP and cavum vergae may affect the choice of route for intracranial endoscopic surgery, with the transcavum interforniceal path preferred over the transforaminal approach into the third ventricle.[6]

• The cavum vergae extends from the cavum septum pellucidum posterior to the anterior columns of the fornix, lying anterior to the splenium of the corpus callosum
• The cavum veli interpositi extends from below the splenium of the corpus callosum and the column of the fornix and above the internal cerebral veins. Its shape is triangular, with the apex pointing anteriorly reaching as far forward as the foramen of Munro
• Vein of Galen aneurysm - Diagnosed by color Doppler technology
• Arachnoid cyst
• Dilated third ventricle (distinguished by its location between the thalami)

Cavum septum pellucidum is usually an incidental diagnosis and typically asymptomatic.

Enlarged cavum septum pellucidum is seen in the following conditions[12][13][6][14]:

1. Schizophrenia patients (First reported by De Greef)
2. Aggressive, individuals with an alcohol use disorder
3. People with neurological development disorders
4. Boxers due to repeated head trauma
5. Post-traumatic stress disorder patients
6. Military population currently participating in war conflicts or veterans of wars
7. Obsessive-compulsive disorders

The absence of the cavum septum pellucidum in fetal life correlates with the following conditions:

1. Holoprosencephaly
2. Septo-optic dysplasia
3. Agenesis of the corpus callosum
4. Alexander disease
5. Tuberous sclerosis
6. Phacomatosis
7. Pinealoma
8. Trisomy 21
9. Schizencephaly
10. Lissencephaly
11. Chiari malformation

Patients need reassurance that cavum septum pellucidum is a normal anatomical variation and requires no surgical intervention and is unlikely to progress.

Only if the size is >1 cm or if symptomatic, enlarged CSP requires further evaluation and management.

Symptomatic enlargement of the cavum septum pellucidum is rare and most commonly causes intermittent obstructive hydrocephalus with headache and loss of consciousness. It is amenable to surgical treatment such as cyst puncture or shunting, ventriculoperitoneal shunting, or radical excision.

CSP is an important marker for the evaluation of normal development of the fetal neural axis. 

A rigorous evaluation, neurological and radiological examinations are necessary before treatment. Hence discussions with the radiologist, neurologist, neuropsychiatrist are needed before proceeding with surgery for CSP cysts even though they appear to be symptomatic.