Neurenteric cysts are congenital malformations that occur during the embryonic phase and are therefore not true neoplasms. There are many different synonyms (enterogenous-, teratomatous-, archenteric-cyst, intestinom). The endothelium of the cyst wall resembles that of the gastrointestinal tract or, less commonly, the respiratory tract. This pathology is most commonly found in the area of the thoracic spine, and less frequently intracranially. The cysts arise in the third week of pregnancy during embryogenesis due to a local breakthrough at the base of the notochord canal.

Epidemiology

Neurenteric cysts are extremely rare, accounting for only about 0.01% of all brain and 0.3–1.3% of all spinal tumors. The most common intracranial locations are: cerebellopontine angle, anterior to the brainstem, and cisterna magna. Patients most frequently become clinically symptomatic in the first decade of life (newborns, children). However, these cysts can also manifest clinically in young adulthood.

Clinical presentation

Localized pain in the area of the spine or myelopathic dysfunction due to spinal cord compression are the most common symptoms in older children and adults. Newborns may develop recurrent meningitis if fistulas are present.

Radiological findings

On MRI, neurenteric cysts show no contrast enhancement. They are iso- to hyperintense compared to cerebrospinal fluid. In the spine (with 40% thoracic localization), the cysts are usually intradural extramedullary (80–90%) and ventral to the spinal cord. The size of the cysts is highly variable (<1 cm to several cm).

Differential diagnoses

• Cerebral or spinal metastasis
• Epidermoid and Dermoid
• Rathke’s cyst
• Colloid cyst
• Craniopharyngioma

Special consideration

When located in the spine, additional associated developmental anomalies may be present, such as fistulous or connective tissue connections to the gastrointestinal tract. Vertebral anomalies such as Klippel-Feil syndrome, hemivertebrae, or spina bifida have been described in connection with neurenteric cysts.

Indication for surgery

For symptomatic patients, the indication is for “in toto” resection. The cyst wall should also be removed due to the increased risk of recurrence if parts are left in situ. Marsupialization techniques have been described for adherent cyst wall portions in the area of the brainstem. For intracranially located neurenteric cysts and subsequent resection, postoperative VP shunt dependency may occur.

Outcome

With complete resection of the cyst including the cyst wall, recurrences are rare. There is a higher risk of recurrence with incomplete resection, although the data is limited due to the rarity of the pathology. Follow-up monitoring is recommended in cases of incomplete resection.

References

• Goel A. Comment on Lin J, et al.: Ventral brainstem enterogenous cyst: an unusual location. Acta Neurochir (Wien). 2004; 146